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NOTIZIARIO Neutroni e Luce di Sincrotrone Vol. 13 n. 1 2008

Rivista del Consiglio Nazionale delle Ricerche

Rivista del Consiglio Nazionale delle Ricerche

NOTIZIARIO Neutroni e Luce di Sincrotrone

ISSN 1592-7822

www.cnr.it/neutronielucedisincrotrone

EDITORIAL NEWS Neutrons and muons: how to succeed in FP7? R. McGreevy

Fermi@Elettra: the new Free Electron Laser will be operating in 2009. It will allow the study of the dynamic properties of matter L.B. Palatini

SCIENTIFIC REVIEWS ARCS: a wide Angular-Range Chopper Spectrometer at the SNS D.L. Abernathy

Brillouin scattering of neutrons for the study of the microscopic dynamics of fluids U. Bafile, F. Barocchi, E. Guarini

Bose-Einstein Condensation and Supersolid Helium J. Mayers

RESEARCH INFRASTRUCTURES ISIS Second Target Station Project M. Bull

Experiments underway at UK’s new synchrotron S. Damerell, S. Fletcher

BaD ElPh: a new beamline for band dispersion and electron-phonon coupling studies at ELETTRA P. Vilmercati et al.

MUON & NEUTRON & SYNCHROTRON RADIATION NEWS News from ILL, SNS

SCHOOL AND MEETING REPORTS CALL FOR PROPOSALS CALENDAR FACILITIES

ISSN 1592-7822

Vol. 13 n. 1

January 2008 - Aut. Trib. Roma n. 124/96 del 22-03-96 - Sped. Abb. Post. 70% Filiale di Roma - C.N.R. p.le A. Moro 7, 00185 Roma


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NOTIZIARIO Neutroni e Luce di Sincrotrone

Rivista del Consiglio Nazionale delle Ricerche

SUMMARY

Cover photo: Fermi@Elettra layout.

EDITORIAL NEWS Neutrons and muons: how to succeed in FP7?

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R. McGreevy

Fermi@Elettra: the new Free Electron Laser will be operating in 2009. It will allow the study of the dynamic properties of matter ................................................ 3 L.B. Palatini

SCIENTIFIC REVIEWS NOTIZIARIO Neutroni e Luce di Sincrotrone published by CNR in collaboration with the Faculty of Sciences and the Physics Department of the University of Rome “Tor Vergata”. Vol. 13 n. 1 Gennaio 2008 Autorizzazione del Tribunale di Roma n. 124/96 del 22-03-96

ARCS: a wide Angular-Range Chopper Spectrometer at the SNS

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D.L. Abernathy

Brillouin scattering of neutrons for the study of the microscopic dynamics of fluids ........................................... 8 U. Bafile, F. Barocchi, E. Guarini

EDITOR:

C. Andreani EXECUTIVE EDITORS:

Bose-Einstein Condensation and Supersolid Helium ................................................................................. 14 J. Mayers

M. Apice EDITORIAL OFFICE:

L. Avaldi, F. Bruni, S. Imberti, L. Palumbo, G. Paolucci, R. Triolo, M. Zoppi EDITORIAL SERVICE AND ADVERTISING

RESEARCH INFRASTRUCTURES ISIS Second Target Station Project

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M. Bull

FOR EUROPE AND USA:

Experiments underway at UK’s new synchrotron

P. Casella

S. Damerell, S. Fletcher

CORRESPONDENTS AND FACILITIES:

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J. Bellingham (NMI3) M. Bertolo (I3-IA-SFS) A.E. Ekkebus (SNS)

BaD ElPh: a new beamline for band dispersion and electron-phonon coupling studies at ELETTRA ................................................................................................................. 25

ON LINE VERSION

P. Vilmercati et al.

V. Buttaro CONTRIBUTORS TO THIS ISSUE:

C. Cicognani, F. Natali, A. Orecchini, R. Wagner GRAPHIC AND PRINTING:

om grafica srl via Fabrizio Luscino 73 00174 Roma Finito di stampare nel mese di Gennaio 2008 PREVIOUS ISSUES AND EDITORIAL INFORMATION:

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MUON & NEUTRON & SYNCHROTRON NEWS News from ILL

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News from SNS

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SCHOOL AND MEETING REPORTS ................................................................................. CALL FOR PROPOSALS .............................................................................................................. CALENDAR .............................................................................................................................................. FACILITIES ...............................................................................................................................................

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EDITORIAL NEWS

Neutrons and muons: how to succeed in FP7? uropean neutron and muon facilities have been successfully involved in EU Framework Programmes since their earliest days. Construction of the ISIS muon facility started with the help of EU funding from FP1 in 1985. Kurt Clausen ran one of the very first EU Access programmes at Risø starting in FP3 in 1991. By 1993 five other neutron and muon facilities were also offering EU funded access. Mike Johnson coordinated ENNI, the first neutron related research and technical development project in FP3, then XENNI in FP4 and TECHNI in FP5; there were six other RTD projects in FP4 and five in FP5. The Neutron Round Table was one of the first to be established, coordinated by Charles de Novion in FP3 and then Kurt Clausen in FP4 and FP5. In FP6 all of the neutron and muon facility related activities were grouped into a single project - NMI3 - the Integrated Infrastructure Initiative for Neutron Scattering and Muon Spectroscopy. NMI3 is the second largest I3 project, the synchrotron project IA-SFS being the largest, and includes EU access to all European neutron/muon facilities apart from ILL, eight Joint Research Activities, and networking activities which replace the previous Round Table. Building on the very solid foundations of all the projects in previous Framework Programmes, NMI3 has established a very high profile and has been considered a model for how European research infrastructures can work effectively together. So what does the future hold? In FP7 the Research Infrastructures budget is not as large as had been hoped. With big new activities, such as Preparatory Phase projects for the 35 potential facilities on the ESFRI Road Map and 29 potential targeted I3 projects related to the FP7 Thematic Priorities, there will be significant pressure on the budgets for the “traditional” I3. This is a great pity, since these I3 are seen to be one of the more generally successful areas of EU funding

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when it comes to useful pan-European collaboration. EU funding to neutrons and muons has been of order 5M€ per year since 2000. The total funding of European neutron and muon facilities exceeds 200M€ per year, so the EU contribution is only a small percentage. Of course all additional money is useful, particularly that coming from Access since it is a direct payment for a service delivered, with no strings attached. But there are significant opportunities for savings within normal development budgets if we collaborate more, rather than compete. Despite the high level of bureaucracy, and the emphasis on project management over scientific and technical excellence, organisations actually appear to like the fact that the EU offers a defined collaboration framework, rather than having to set it up for themselves. But it is time that we overcame this reluctance – otherwise FP7 may start to see neutron and muon facilities moving apart for the first time in over 20 years.

Vol. 13 n. 1 January 2008

R. McGreevy FP6 NMI3 Coordinator

INFORMATION ON:

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EDITORIAL NEWS

Fermi@Elettra: the new Free Electron Laser will be operating in 2009. It will allow the study of the dynamic properties of matter he “seeded” free-electron laser project FERMI@Elettra when completed will be a new 4thGeneration Synchortron Light Source. It will provide time-synchronized ultrashort femtosecond pulses and so will be used to explore topics such as ultrafast spectroscopies and microscopies. As such it will be one of the first Free-Electron Laser of its kind operating in the world for a broad user community covering the wavelength range from 100 nanometers to below 10 nanometres (from Vacuum-Ultraviolet to Soft X-Rays) with high peak-brightness, ultrashort length, and transverse and longitudinally coherent light pulses. The FERMI@Elettra project is located at the Elettra Laboratory, an international “open access” Laboratory whose mission is that of hosting researchers from any Country on the basis of quality-selected proposals. The flashes produced by FERMI will cover a time-span reaching below 100 femtoseconds. This will allow researchers to expand the boundaries from static observation of materials to the dynamic analysis of their behaviour, and to follow the working mechanism of different materials (ranging from pharmaceuticals to catalysts) by observing the evolution of properties on a time scale of atomic and electronic phenomena. The very high-peak light intensity will also allow researchers to excite atoms and create and study warm dense matter, a state of matter similar to a plasma but with very high density, that is the state of matter at the core of large planets. Thanks to the synchronization capability there will also be the possibility to use “pump and probe” techniques, and follow electronic and chemical processes. The community of synchrotron light and lasers users has been continuously involved in defining the possible applications and therefore the fundamental source parameters and configuration of FERMI@Elettra. The main experimental programs have been selected to converge into the following three core areas: Low-Density Matter (dedicated to cluster electronic structure, atomic and molecular chemistry, and atomic and molecular

T

physics), Elastic and Inelastic Scattering (dedicated to analyse excitation and structure of glasses and liquids and structure of materials in extreme conditions), and Diffraction and Projection Imaging (dedicated to single-shot microscopy, single-shot diffraction and coherent imaging). Similarly the conceptual design study for FERMI@Elettra has been developed in collaboration with most other laboratories involved in similar projects in the world, and in particular with the EUROFEL network in Europe and with the Lawrence Berkeley National Laboratory, the Massachussets Institute of Technology (MIT), and the Stanford Linear Accelerator Center (SLAC) in the USA. Jointly the various European 4th generation light sources are being developed in a coordinated effort, and the various projects formed a joint Consortium (IRUVX) at the end of 2006. This consortium aims at making the best use of services by exploiting the possible complementarities of the projects and the affiliated laboratories; furthermore, this approach is strongly endorsed and supported by the European Union. The different facilities are able to cover different parameter ranges, thus helping to extend the use of FEL-generated light over a much wider range of scientific fields. The 124 million Euro project FERMI@Elettra is funded by the Italian Government, the Friuli Venezia Giulia region and the European Union, and the project-financing is completed through an Italian government guaranteed loan from the European Investment Bank. L.B. Palatini Sincrotrone Trieste

Fermi@Elettra layout.

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SCIENTIFIC REVIEWS

ARCS: a wide Angular-Range Chopper Spectrometer at the SNS D.L. Abernathy Neutron Scattering Science Division, Oak Ridge National Laboratory, USA

Abstract ARCS, a wide angular-range thermal to epithermal neutron spectrometer, is one of an extensive suite of inelastic instruments in operation or under construction at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. By providing a high flux of neutrons with moderate resolution and a large detector coverage, ARCS will enable studies of excitations from a few to several hundreds of meV in fields such as lattice dynamics and quantum magnetism. The construction phase of the ARCS project was completed in September 2007 with several demonstration measurements. Currently ARCS is being commissioned, and will enter the SNS general user program in the fall of 2008.

Introduction ARCS is one of a suite of seven inelastic instruments at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) which covers a wide range of energy transfer (Ω) and momentum transfer (Q) space. Furthermore, each spectrometer provides unique resolution conditions for both Q and Ω, and the set complements the existing triple-axis capabilities at the High Flux Isotope Reactor (HFIR) at ORNL. [1,2] The inelastic instruments at the SNS are in various stages of installation, commissioning and operations. The Backscattering Spectrometer (BASIS) is installed and is in the SNS general user program, with a demonstrated

Figure 1. Overview of ARCS with components labeled.

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energy resolution of 3 ÂľeV. The ARCS wide AngularRange Chopper Spectrometer, which initiated first operations with neutrons in September 2007, and the Cold Neutron Chopper Spectrometer (CNCS) scheduled for commissioning in 2008, provide moderate resolution and the ability to trade resolution for flux. In addition both instruments have detector coverage out to 140o to provide a large Q range. SEQUOIA, a direct-geometry instrument that has finer resolution in the thermal and epithermal energy range, will begin commissioning in 2008. Following shortly will be the Neutron Spin-Echo spectrometer (NSE), providing the finest energy resolution of the inelastic suite. The HYSPEC spectrometer, available by 2011, will have polarized capabilities and optimized flux in the thermal energy range. Finally, the VISION chemical spectrometer will use crystal analyzers to study energy transfers into the epithermal range will be available by 2012. ARCS instrument description ARCS, located at beamline 18 of the SNS, is optimized to provide a high neutron flux at the sample and a large

the instrument has come from an active Instrument Development Team (IDT). Professor Brent Fultz from the California Institute of Technology is the Principal Investigator for the United States Department of Energy (U.S. DOE) grant to build ARCS. An overview of the instrument is shown in Figure 1, with key components indicated on a cutaway view of the ARCS engineering model [3]. There are 8 meters of high index (m= 3.6) elliptically-shaped supermirror guide in the incident flight path, which boosts the performance up to an order of magnitude in the lower Ei range. A cylindrical array of 115 modules of 8 one meter long 3He linear position sensitive detectors (LPSDs) is installed within a combined sample and detector vacuum chamber. This scattering chamber provides a window-free final flight path and incorporates a large gate valve to allow rapid sample change out. Figure 2 shows the view from the low angle area within the scattering chamber toward the neutron guide, sample position and high angle detectors. ARCS has two Fermi choppers mounted on a translation stage in the incident shielding. These devices select the desired Ei, ro-

Figure 2. View from the low angles toward the sample and high angle detectors. The neutron guide enters the sample chamber at the left, transporting neutrons to the sample position. A large semi-circular gate valve (open) can be raised to isolate the sample volume for rapid changes of sample environment.

Figure 3. View from above of the neutron optics for ARCS just before the sample chamber. Neutrons come from the guide system at the top, pass through one of two Fermi choppers mounted on a translation table, a variable aperture, beam monitor, and removable and fixed neutron guides.

solid angle of detector coverage. The spectrometer is capable of selecting incident energies (Ei) over the full energy spectrum of neutrons provided by the ambient water moderator, making it useful for studies of excitations from a few to several hundred meV. Primary science areas for the instrument include the study of lattice dynamics, such as measuring the phonon density of states of diverse materials, and applications to magnetic dynamics in systems from high temperatures superconductors to low dimensional quantum magnets. Guidance for the scientific applications, development and initial use of

tating at speeds up to 600 Hz and phase locking to the source pulse to better than 1 microsecond, and may be swapped in minutes to allow the instrument resolution to be matched to the experimental requirements without the need to remove heavy shielding blocks. Figure 3 shows the two Fermi choppers mounted in the incident beamline two meters before the sample position, as well as a variable aperture, beam monitor and removable and fixed neutron guides leading into the sample chamber. ARCS has undertaken a number of technical challenges during the project. To increase safety by

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avoiding large, thin windows and to optimize space utilization, the 3He linear sensitive detectors together with their digitizing electronics operate inside the scattering chamber vacuum. Novel B4C internal shielding uses no hydrogen in the binder material to reduce instrument background and improve vacuum performance. A new T0 neutron chopper, which blocks the fast radiation from the source when the proton beam hits the target, is being developed in collaboration with the SNS instruments SEQUOIA and HYSPEC. It will not only block the prompt radiation from the source but also eliminate unwanted neutrons from the incident beam line by utilizing a vertical axis design inspired by the first choppers in the Intense Pulsed Neutron Source spectrometers. This chopper will be available by mid-2008 and tested before general user operations in the Fall 2008. In addition to the instrument hardware, the ARCS project included a significant effort for software development [4]. A collaboration between software engineers and neutron scattering scientist led by the ARCS Principal Investigator has produced robust data reduction and analysis tools gathered into a version 1.0 release of the package Data Reduction for Chopper Spectometers (DRCS, or more affectionately, “DrChops”). As of August 2008, DRCS supports reduction of data from the direct-geometry, time-of-flight chopper spectrometers LRMECS, Pharos, and simulations of ARCS data sets. Modules are available for multiphonon corrections and for direct manipulations of data objects with standard software tools. This software is installed on a powerful computer cluster installed next to the ARCS Data Acquisition System (DAS), and the procedures to provide real time as well as post-experiment analysis will be commissioned as the instrument itself is. All software developments have been carefully coordinated with SNS initiatives to provide data storage and visualization tools. ARCS initial measurements and commissioning plans ARCS took initial neutrons for first testing of the overall instrument performance in September 2007. Due to the source run schedule, only a few basic tests were performed in order to demonstrate that the neutron optics system was operating as expected, and that the overall data collection and storage performed correctly. In addition to these tests, images of the beam at the sample location and at the beam exit from the scattering chamber were taken using neutron-sensitive image plates to confirm the correct positioning and homogeneity of the beam. Figure 4 shows the counts per 10 µs time bin in the upstream ARCS beam monitor during a run of approximately 800 seconds at an SNS beam power of 125 kW

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operating at 30 Hz. The monitor was calibrated by the SNS detector group and found to have an efficiency of 1.0 ± 0.1 x 10-5 at a wavelength of 1.8 Å. The ARCS monitor does not provide reliable data at times less than approximately 1 msec after the proton pulse on target due to the high prompt radiation that is not currently blocked by a T0 chopper. The peak at moderate neutron energies is clearly seen in the data, corresponding to the thermalized beam from the 25mm depth poisoned, decoupled water moderator. The sharp spike at 33 msec is the next prompt radiation pulse due to the 30 Hz proton on target operations. Also plotted in Figure 4 are the absolute intensities expected from the calibrated beam monitor based on the performance of the facility as calculated by the SNS neutronics group [5], taking into account the beamline geometry and source power. Data

Figure 4. ARCS beam monitor data compared to calculations from the SNS neutronics group with and without the calculated ARCS guide gain.

with and without the calculated guide gain from the ARCS neutron guide system up to the monitor position are shown. The source calculation and neutron guide performance match the data collected on ARCS within reasonable accuracy, demonstrating that the instrument is performing as expected. In addition to the beam monitor data, powder diffraction data was collected in a subset of the ARCS detector array mounted in the instrument detector chamber. Eight of the detector modules were placed near 90° scattering angle and various data sets were collected. Figure 5 shows the results of the scattering from a silicon powder sample contained in an aluminum sample can. The data has been corrected for the individual pixel scattering angles and final flightpaths and binned according to the measured crystal lattice plane (d) spacing. As can be seen from the plot, the diffraction lines may be seen above a large background due to air scattering. The positions of the expected lines are shown for some of the larger d-spacings in silicon

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Figure 5. Diffraction data from a silicon powder in an aluminum can. The peaks due to the powder diffraction lines sit on top of a large background due to air scattering. Some expected peak positions are shown by the symbols.

and aluminum, and these correspond well with the acquired data using the geometry of the instrument as designed. Since these initial results, the integration of additional spectrometer components was resumed with the goal of making detailed calibration and verification measurements during the November 2007 to February 2008 SNS run cycle. The installation and operation of up to 115 LPSD modules consisting of 8 LPSDs each inside a vacuum chamber is a large challenge that is moving ahead smoothly. Additional shielding for background suppression, both inside and outside of the scattering chamber, is also being added. Once basic operation of the instrument is satisfactory, the IDT will be solicited for early experiments to test the new spectrometer ’s capabilities in a wide range of scientific applications. Conclusions ARCS is the second spectrometer at the SNS to begin operations, joining the Backscattering Spectrometer and leading a strong contingent of new additions to follow. The commissioning phase for ARCS is well underway, and initial experiments to follow will explore a variety of research opportunities in condensed matter physics. By combining the hardware developments with new software, ARCS will be well positioned to take advantage of the rapid progress in source power and reliability at the SNS.

Acknowledgments The ARCS project was only made possible by the support of numerous colleagues at the SNS, Caltech and the IDT members. In particular, expert design work was provided by K. Shaw and S. Howard, outstanding support for neutronic calculations by E. Iverson, and excellent installation and operational support by M. Loguillo. ARCS was supported by the U.S. DOE under grant DE-FG0201ER45950. ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. DOE under contract DE-AC0500OR22725. References 1. G. Granroth, D. Abernathy, G. Ehlers, M. Hagen, K. Herwig, E. Mamontov, M. Ohl, and C. Wildgruber, The Inelastic Instrument suite at the SNS, Proceedings of the International Collaboration on Advanced Neutron Sources XVIII (2007) 2. http://neutrons.ornl.gov/index.shtml 3. D.L. Abernathy and K.M. Shaw, Design Criteria Document for the wide Angular Range Chopper Spectrometer (ARCS), SNS Document ARCS1800-DC0001-R01 (2004) 4. http://arcscluster.caltech.edu:5001/. Note that the ARCS software development has transitioned smoothly to a larger development project called DANSE (Distributed Data Analysis for Neutron Scattering Experiments). See: http://wiki.cacr.caltech.edu/danse/index.php/Main_Page 5. E.B. Iverson, P.D. Ferguson, F.X. Gallmeier and I.I. Popova, Detailed SNS neutronics calculations for scattering instrument design: SCT configuration, Technical Report SNS 110040300-DA0001-R00 (2002)

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Brillouin scattering of neutrons for the study of the microscopic dynamics of fluids U. Bafile1, F. Barocchi2, E. Guarini2 Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy

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Abstract Brillouin scattering is the spectroscopic technique applied to the probing of acoustic excitations in condensed matter. Significant advances in instrumentation have led to the development of various Brillouin spectroscopies in addition to the first exploited light scattering methods, extending the study of sound propagation to a very wide range of excitation wavelengths. The role of Brillouin scattering of neutrons is discussed and a few examples are given of its potentiality for an in-depth investigation of microscopic dynamics and interactions in fluids.

number density n, is

Since the 60s of last century, the study of sound propagation in the microscopic domain, and of the damping processes that accompany it, has been a typical field of spectroscopic application of laser sources with the measurements of Brillouin light scattering spectra. This experimental method, when applied to fluids, has provided a wealth of quantitative information on the dynamics of a variety of gaseous and liquid systems at the atomic or molecular level. One main reason for such an exploitation of light Brillouin spectroscopy, besides the relatively low cost of the instrumental setups, is the availability of an accurate theoretical framework able to account in detail for the observed dynamics. Indeed, in the wavevector range typically explored in such experiments, the explicit formulation of the lineshape in terms of thermodynamic and transport properties of the fluid under study is accurate enough to carry out spectroscopic measurements of thermophysical parameters from the spectral features. It is well known that the detected Rayleigh-Brillouin (RB) light spectrum closely reflects the dynamic structure factor S(Q,ω) as obtained from linearized-hydrodynamics theory [1]. The variables Q and ω are the wavevector and frequency, to be identified, respectively, with the momentum and energy (in units of the Planck constant -h) transferred to the sample in the scattering process, and S(Q,ω) represents, at constant Q, the frequency spectrum of the autocorrelation function of density fluctuations with wave vector magnitude Q, i.e. of the intermediate scattering function F(Q,t). The hydrodynamic line shape, in the simplest case of a monatomic liquid composed of atoms of mass m at a

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Dipartimento di Fisica, Università di Firenze, and CNR-INFM CRS-Soft, via G. Sansone 1, I-50019 Sesto Fiorentino, Italy

(1)

Here, γ0 is the ratio of the constant-pressure (cp) to the constant-volume (cv) specific heat, DT = λ/ncp is the thermal diffusivity with λ the thermal conductivity, Γs = [(γ0 - 1)DT + ν]/2 is the sound damping coefficient, ηs, ηb, and ν = [(4/3)ηs + ηb]/mn are the shear, bulk, and kinematic longitudinal viscosities, respectively, bs = [3(γ0 - 1)DT + ν]Q/(2cs) , and finally cs = 1/√nmχs and χs are the adiabatic sound speed and compressibility. The static structure factor S(Q) is the frequency integral of S(Q,ω). At constant Q, equation (1) represents a frequency spectrum composed by a triplet of lines, one (Rayleigh, quasielastic) centred at ω = 0 and two (Brillouin, inelastic) symmetrically shifted at the positions ω = ± csQ determined by the acoustic excitation frequency which, then, follows a linear dispersion law. All lines are Lorentzians with half widths at half maximum increasing quadratically with Q. Actually, the Brillouin lines are modified by the presence of extra terms that introduce an asymmetric distortion, but their effects is quite small and often negligible. The Q values typically attained in Brillouin light scattering are of the order of 10-2 nm-1, where S(Q ) can be safely approximated by S(0) = nkBTχsγ0, where kB is the Boltzmann constant and T is the temperature of the fluid. With a wavelength in the range of visibile radiation, the microscopic discreteness of matter does not come into play and the fluid is probed as a continuous medium, accordingly to the hydrodynamic assumption. If  is a typical length scale related to the distance within the particles, such a condition can be expressed as Q « 1. The onset of non-hydrodynamic regime, where the fluid behaves as a discrete collection of individual particles, is ruled by the increase of Q up to values of the order of unity. With light scattering, this is possible by increasing  towards values typical of dilute gases, but non-hydrodynamic sound-like excitations

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have also been detected by neutron scattering in many dense liquids, including, for example, liquid metals, revealing the need for experimental techniques able to deal with Q ranges above the light scattering situation while keeping  within the dense-fluid interparticle distances. This goal has prompted several efforts aimed at developing instrumentation for spectroscopic studies outside the hydrodynamic regime. Standard neutron scattering, however, typically applies for Q > 2 nm-1, and needs to be extended down to at least one-order-of-magnitude lower Q values. This requirement of very low Q is to some extent in conflict with the need of an incident neutron speed larger than the sound velocity in the material, a necessary condition to probe acoustic excitations. The better compromise is obtainable the lower is the scattering angle, and, from an instrumental point of view, neutron Brillouin scattering can indeed be seen as inelastic small-angle scattering. Thus, the first successful attempt towards a specialized spectrometer was made, nearly twenty years ago, by modifying, though not permanently, an existing one (namely, the time-of-flight, cold-neutron IN5 spectrometer of ILL) with the addition of a two-dimensional small-angle detector [2]. The state of the art in this field is now represented by the fully dedicated thermal-neutron spectrometer BRISP, also at ILL, very recently become operational [3]. Although this paper is specifically concerned with neutron Brillouin scattering, it is appropriate to mention that other spectroscopic techniques have also been recently developed to address the same scientific issues. For inelastic x-ray scattering, the most stringent technical requirement is the resolution power, which must be large enough to resolve energy separations of the order of 1 meV with incident energies in the tens of keV range. Such high photon energies, on the other hand, remove the kinematical restrictions typical of neutron scattering. This technique is thus best suited to the study of highfrequency excitations. Though the concept of high-resolution inelastic x-ray spectrometry dates back to the years 80s [4], its systematic application to the study of fluids dynamics began around the mid 90s at ESRF [5] and, later, at other synchrotron sources. Even more recently, Brillouin scattering performed with synchrotron ultraviolet radiation was also demonstrated to be able to cover the Q gap between light scattering and the other methods [6]. All together, the whole set of available experimental techniques can now cover continuously a very broad Q range. This fact is especially important if one considers that, as we will show later, the theoretical developments enabling a detailed description of the detected frequency distributions are essentially the same in the whole wavevector range of interest for the study of collective acoustic excitations. As a consequence of this remarkable

progress of instrumental capabilities, a great amount of experimental work has been performed in the last about twenty years in the field of the microscopic collective dynamics of various kind of fluids. Experimental results are usually analysed by fitting to constant-Q spectral data a suitably parametrized model of the classical S(Q,ω), modified to account for detailed-balance asymmetry and instrumental resolution broadening. By performing the model fitting separately at each investigated Q value, an experimental Q-dependence is obtained for each fit parameter. Expression (1) typically describes a triplet of sharp and well-separated lines, a well-known example being the Brillouin spectrum of liquid argon in figure 3 of Ref [7]. Instead, in the Q-range of neutron scattering, the acoustic excitations usually produce a much less structured spectral shape displaying, at most, weak side shoulders. This fact makes the determination of the peak frequencies a difficult task for which different criteria have been applied. Analogously, the evaluation of the Qrange where collective excitations have a propagating nature has also been based on various, sometimes qualitative, criteria to decide whether the sound modes are to be considered as under- or overdamped. In a recent paper [8] we showed how both the above mentioned problems can be solved rigorously. Reliable tools are thus nowadays available for a full characterization of the collective excitations in a large variety of fluids. On the contrary, much less work has been devoted so far to the more fundamental issue of the connection between the emergence of such dynamical behaviours and the underlying interaction forces among particles. The way in which the details of the potential functions affect the Q dependence of the various relaxation mechanisms associated to collective motions has not been elucidated yet, not even qualitatively. The molecular-dynamics (MD) simulation technique can play here an essential role, offering the possibility to study the microscopic motions for different model interaction potentials. We will discuss later an example of the joint application of neutron Brillouin scattering and MD simulation to the study of microscopic interactions. First, a short summary of the results recently obtained for the description of collective sound modes is presented. At low enough Q, where acoustic excitations propagate in a fluid, the normalized dynamic structure factor can be written in the form

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Here the last two terms are the spectral signature of the acoustic modes (the subscript s stands for “sound”) and represent the Brillouin lines, having a Lorentzian shape centred at ω = ±ωs with half width zs, and distorted by the presence of the asymmetry parameter bs. The other terms in the sum are also Lorentzian lines, symmetric and centred at ω = 0 , with half width -zj . The meaning of the quantities zj will be explained here below. Equation (2) is derived naturally from the memory function approach customarily adopted for the theoretical description of the collective dynamics of a fluid, and treated in detail in standard textbooks on the subject [1]. The basic idea behind this formulation is that the time evolution of F(Q,t) can be described by a Langevin-like equation modified by the introduction of a memory function M(Q,t) that expresses the effect at a given time t of the past dynamics, thus allowing for non-locality in time. The actual dynamical behaviour then depends on the choice of a suitable memory function, which however cannot be determined from theoretical arguments. One appealing feature of the memory function approach is that very simple expressions of M(Q,t) produce quite realistic models for the spectral distribution. Indeed, in nearly all experimental works published on the subject, spectral data were accurately accounted for by memory function models as simple as a sum of exponential decays. It was then shown in [8] that, in all such cases, (I) one obtains equation (2) with a number of quasielastic lines equal to the number of exponential terms in M(Q,t), (II) the Laplace transform of F(Q,t) can be written as a rational function in the complex plane with a corresponding number of real, negative poles zj = zC,zD, ... plus two complex conjugate poles zA,B = -zs±iωs, and, finally, (III) the amplitudes Ij and Is of the various lines in (2) can be explicitly calculated. The apparent similarity between the general line shape (2) and the hydrodynamic Rayleigh-Brillouin spectrum (1) is by no means coincidental, but simply reflects the fact that the development of the linearized-hydrodynamics treatment is equivalent to the assumption (3)

where

is the Q→0 limit of the

second frequency moment of the normalized spectrum (4) where the last equality is a well-known exact result [1].

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If applied to the Q range of neutron or x-ray scattering, the RB triplet (1) does not correctly describe the experimental data. Such a failure is however to be expected, as soon as one remembers that (1) is derived under the hydrodynamic assumption of very-long-wavelength excitations. The commonly adopted approach is then the formulation of different models for the memory function that may be able to account for the Q evolution of the collective motions beyond hydrodynamics. As a first step, it appears quite natural to retain the same functional form for M(Q,t), but letting its parameters to vary freely with Q. This leads to the so-called “generalized RB triplet” (GRB) lineshape [8], for which (2) still has the three-line structure of (1), but the various parameters depend on Q differently from the hydrodynamic case, and have to be determined by a best-fit procedure. The general parametrization of the line shape displayed in (2), common to all the most frequently used memory function models, provides a full understanding of the dispersion curve of the sound excitations [8]. The acoustic modes follow at each Q the dynamical behaviour of a damped harmonic oscillator with characteristic frequency Ω = √z A z B and damping coefficient zs = -(zA + zB)/2. The actual oscillation frequency is then ωs = √(Ω2 - zs2) as long as the oscillator finds itself in an underdamped state, which occurs for Ω > zs. On the other hand, if at some Q the condition is reversed (Ω < zs ), then an overdamping situation is obtained and the sound propagation is arrested. Such a condition is reflected by the loss of oscillatory behaviour in the time dependence of F(Q,t), and by a modification of the spectral shape, where zA and zB become real and negative and the Brillouin lines are transformed into Lorentzians of half widths -zA and -zB centred at zero frequency and superimposed onto the quasielastic lines. As examples of the application of the concepts just outlined, we now briefly recall a few typical results for the collective acoustic dynamics in very simple fluids. Argon is the prototype of a monatomic, classical, insulating fluid, and it is an exceptionally convenient sample for neutron studies due to the very large, totally coherent, scattering cross-section of the 36Ar isotope. A full quantitative analysis of acoustic excitations in the liquid phase, carried out through fitting the GRB model for 4 < Q / nm-1 < 38, was reported in the work of reference [9]. The resulting dispersion curve shows the so-called “propagation gap” of sound modes, that is the transition from the under- to overdamping condition of the equivalent harmonic oscillator, shortly afterwards followed by a reverse transition restoring the propagating regime. Such a phenomenon may occur around Qp, i.e. the Q value where the static structure factor displays a sharp peak, since S(Q) appears at the denominator in the expression of Ω [8].

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This was the first observation of a propagation gap in a real fluid. Acoustic modes were also studied with neutron Brillouin scattering in gaseous argon [10] at room temperature and a pressure of 200 bar where, being the density much lower, and therefore  much higher, than in the liquid phase, low values of Q (in the range 0.1 ≤ Q ≤ 1) required the use of cold neutrons. At the lowest Q values, the spectra agree with the RB line shape (1), but they begin to deviate from it with increasing Q, revealing the onset of non-hydrodynamic behaviour. In figure 1, the parameters Ω, zs and ωs of a GRB fit are plotted, both from the experiment and, for the sake of completeness, from simulation results [11]. With respect to the predictions of RB theory, one can notice a slightly stronger upward curvature of Ω(Q) and a slightly smaller damping zs.

Figure 1. GRB analysis of neutron (red, [10]) and MD (blue, [11]) data on gaseous 36Ar at 200 bar. Black lines are the corresponding calculations with RB theory. Upper frame: Ω (dots) and zs (squares). Lower frame: ωs (dots). In both frames, the straight green line csQ is also shown.

Then ωs = √(Ω2 - zs2) stays above the hydrodynamic dispersion curve, whose downward bending is effectively compensated, and a linear Q-dependence of the sound frequency is found to persist beyond the strictly hydrodynamic regime. Neutron Brillouin scattering has been mostly applied to the study of monatomic systems such as rare-gas fluids or liquid metals. Nonetheless, this technique can provide deep insight into the microscopic dynamics of molecular fluids too. Here we briefly recall some recent results obtained in the case of liquid methane, in its deuterated form for neutron experimental convenience. In the range 2 < Q/nm-1 < 15, spectral data [12] were analysed by making use of the free-rotor approximation [13], so that it was possible to extract the centre-of-mass dynamic structure factor. The parameters of the Brillouin lines were determined through the fitting of the GRB

model and successfully compared to those obtained from a parallel analysis of MD simulations. However, the experimental data also served as a validation of the potential function employed in the simulations, enabling a thorough study of the collective dynamics in a much wider Q range, extending up to nearly four times the position Qp of the main peak of the static structure factor. This analysis of the carbon-carbon partial correlation spectra revealed new interesting features. Besides the GRB one, the so-called viscoelastic model line shape was also employed for spectral fitting. This is defined by a memory function differing from the GRB one for the presence of another exponential term replacing the δ-function, and leading to a line shape (2) with two terms in the summation. This model, which therefore provides a spectrum with a central peak made of two Lorentzian lines, was shown to produce better fits for Q > 5 nm-1, revealing a transition from hydrodynamiclike to viscoelastic behaviour [8]. Moreover, it was found [14] that acoustic excitations persist up to high Q, though their contribution to the total spectral intensity is substantially reduced. Finally, the occurrence of a propagation gap in a narrow Q interval around Qp was again detected, for the first time in a molecular liquid, and a dispersion curve closely resembling that of liquid argon was found. It can thus be concluded that, notwithstanding the obvious differences between monatomic and molecular systems, methane behaves very similarly to the rare gases if the centre-of-mass dynamics is considered. The CD4 experimental data provide, however, another kind of example of the application of neutron Brillouin spectroscopy to the investigation of fundamental properties of condensed matter. In fact, without resorting to the free-rotor approximation for the separation of the centre-of-mass motions, a deep insight on the intermolecular forces was obtained [15] through the comparison of data and MD simulations at the level of the total dynamic structure factor as probed by neutron scattering. This is related to the measured intensity via the doubledifferential cross-section (5) where the subscripts refer to which neutron scattering lengths appear in each term. For the CD4 molecule, the incoherent contribution is (6) where Sα,self (Q,ω) is the self dynamic structure factor for atoms of species α = C or D.

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The coherent term (7)

is expressed in terms of the (Ashcroft-Langreth [16]) partial dynamic structure factors, and contains contributions from correlations of two different atoms, either on the same or on different molecules. MD opens the access to the direct evaluation of all S(Q,ω)’s involved, and to the study of their dependence on the used potential model. Four different potential models denoted by the acronyms TUT, SA, RP, and RMK [15], all defined as sums of site-site interactions and therefore allowing, in

figure 3, one finds that the mutual orientation of the molecules where a vertex of one tetrahedron is opposed to a face of the other (“base-vertex”, bv) is such that the above similarities in spectra correspond to close agreement between energy curves in either the medium-range attractive part or the repulsive hard-core region, most likely probed at smaller and larger Q values, respectively. This suggests that, on the time scale probed by the coherent part of S˜(Q,ω), specific pair configurations can be shown to contribute with a larger weight to the observed dynamical behaviour. This kind of analysis reveals a higher sensitivity of dynamical data to the potential function than what is found from static structure measurements. Neutron Brillouin scattering can then be used to carefully exploit the direct access to microscopic interaction effects offered by

Figure 2. Coherent dynamic structure factor of liquid CD4 at selected Q values. Neutron data (black circles with error bars) are compared with the corresponding MD results for the SA (red line), RMK (green line), TUT (blue dots) and RP (pink line) potentials. In the right frame, the SA and RMK central peaks coincide.

different ways, for a overall anisotropic intermolecular pair-interaction energy, were used in the simulations. Since the incoherent part (6) turned out to be little sensitive to the differences among the potentials, a reliable MD estimate of S˜inc(Q,ω) was obtained and subtracted from the measured total S˜(Q,ω) to give an experimental determination of the coherent part. This could be compared to the simulated ones, calculated through (7), with better sensitivity to the input potential (see figure 2). The agreement is good in the whole Q and ω range for the TUT case only, with SA and RP results looking similar to TUT ones at low and high Q only, respectively. The last model, RMK, provides poor agreement in all cases. If now the potential energy of specific configurations of the molecule pair is plotted as a function of the distance rCC between the molecular centres, as done in

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MD simulations. In conclusion, the investigation of collective dynamics in fluid systems is a very active research field, where many different kinds of liquids can now be studied with the increased accuracy made possible by technical advances in spectroscopic instrumentation and computing power. Indeed, starting from the simplest systems such as raregas fluids and liquid metals, growing attention has been shifted to molecular liquids, liquid alloys, metal vapours, molten salts and oxides, metals in solutions, and complex systems. Fundamental dynamical properties such as the propagation of sound modes, the characterization of damping processes affecting both the quasielastic and the inelastic part of the spectra, the wavevector dependence of relaxation processes of either thermal or structural origin, and the in-detail relationship of the whole dynamical behav-

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Figure 3. Three significant configurations of methane dimers (sketched in the insets) and corresponding CD4-CD4 potential energy, in units of the Boltzmann constant. Different curves refer to the RMK (green), TUT (blue), RP (pink), and SA (red) models, plotted as a function of the carbon-carbon (CC) distance. Positive energies above 100 K are plotted on a logarithmic scale.

iour to the forces acting at the atomic level, are wide open to thorough investigations by means of radiation scattering techniques, among which neutron Brillouin scattering is promising to contribute in an essential way. References 1. U. Balucani, M. Zoppi, Dynamics of the Liquid State, Clarendon, Oxford, 1994. 2. P.A. Egelstaff, G. Kearley, J.-B. Suck, J.P.A. Youden, Europhys. Lett. 10, 37 (1989); J. Youden, P.A. Egelstaff, J. Mutka, J.-B. Suck, J. Phys.: Condens. Matter 4, 8945 (1992). 3. D. Aisa et al., Nucl. Instrum. Meth. Phys. Res. A, 544, 620 (2005). 4. B. Dorner, H. Peisl, Nucl. Instrum. and Meth. 208, 587 (1983). 5. F. Sette, G. Ruocco, M. Krisch, U. Bergmann, C. Masciovecchio, V. Mazzacurati, G. Signorelli, R. Verbeni, Phys. Rev. Lett. 75, 850 (1995). 6. C. Masciovecchio, A. Gessini, S.C. Santucci, J. Non-Cryst. Solids 352, 5126 (2006). 7. P.A. Fleury, J.P. Boon, Phys. Rev. 186, 244 (1969). 8. U. Bafile, E. Guarini, F. Barocchi, Phys. Rev. E 73, 061203 (2006). 9. I.M. de Schepper, P. Verkerk, A.A. van Well, L.A. de Graaf, Phys. Rev. Lett. 50, 974 (1983).

10. U. Bafile, P. Verkerk, F. Barocchi, L.A. de Graaf, J.-B. Suck, H. Mutka, Phys. Rev. Lett. 65, 2394 (1990). 11. U. Bafile, F. Barocchi, M. Neumann, P. Verkerk, J. Phys.: Condens. Matter 6, A107 (1994). 12. E. Guarini, U. Bafile, F. Barocchi, F. Demmel, F. Formisano, M. Sampoli, G. Venturi, Europhys. Lett. 72, 969 (2005). 13. E. Guarini, J. Phys.: Condens. Matter 15, R775 (2003). 14. M. Sampoli, U. Bafile, F. Barocchi, E. Guarini, G. Venturi, J. Phys.: Condens. Matter, 2008, in press. 15. E. Guarini, M. Sampoli, G. Venturi, U. Bafile, F. Barocchi, Phys. Rev. Lett. 99, 167801 (2007). 16. N.W. Ashcroft, D.C. Langreth, Phys. Rev. 156, 685 (1967).

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Bose-Einstein Condensation and Supersolid Helium J. Mayers Rutherford Appleton Laboratory, Chilton, OX11 0QX, UK

Abstract The experimental evidence for the presence of non-viscous flow in solid helium is described and compared with experiments on liquid helium. The physical origin of superfluid and possible supersolid flow is described. We outline the results of a recent neutron scattering experiment, searching for evidence of BoseEinstein condensation in solid helium. No such evidence was found and it is inferred that supersolidity is not due to BoseEinstein condensation in crystalline helium.

fraction rotates as the disks rotate. The effective mass of the pendulum and the oscillation frequency therefore varies with T. By measuring the oscillation frequency Adronikashvilli was able to determine ρS as a function of temperature (fig. 1b). Below about 1K the liquid is almost entirely superfluid. None of the fluid rotates with the disks and the period is the same as it would be in vacuum! In (2004) Kim and Chan [2,3,4] published the remarkable result

Figure 1. (a) A column of closely spaced discs is suspended in a bath of liquid helium from a torsional fibre. (b) From a measurement of the frequency of oscillation it is inferred that a fraction ρS of helium has no viscous interaction with the discs.

Figure 2. Experiment of Kim and Chan. (a) The resonant frequency of a cell containing an annulus of solid helium is measured. (b) From the variation of this frequency with temperature it is inferred that a fraction of the mass of the frozen helium does not rotate with the container.

Experimental and theoretical work on liquid helium has been responsible for the award of nearly 20 Nobel prizes. The fundamental interest in this system is due to its manifestation of quantum mechanical effects over macroscopic length scales. One remarkable property of superfluid helium is that it has no viscous interaction with macroscopic bodies, provided these are moved only slowly in the fluid. In a classic experiment Adronikashvilli [1] suspended a column of closely spaced disks from a fibre in a bath of liquid helium (fig 1a) and measured the period of torsional oscillation as a function of temperature T. He found that the period varied and inferred that below the superfluid transition a fraction of the atomic mass (the superfluid fraction ρS ) does not have any viscous interaction with the fluid. In a fluid with normal viscosity all the liquid between the disks is trapped and the mass of the torsional pendulum is the mass of disk+fluid between disks. In the superfluid only a fraction 1 - ρS(T) of the fluid is trapped – hence only this

that if essentially the same experiment is performed on solid helium, then a fraction of the helium mass similarly behaves as a non-viscous fluid. In their measurement solid helium was frozen into an annular ring attached to a Be-Cu torsion rod (fig. 2a) and the resonant frequency of oscillation was measured as a function of temperature. As in Adronikashvilli’s experiment, this frequency changed with T. This was interpreted as being due to a supersolid fraction of helium (also known as the “nonclassical rotational inertia” fraction) which does not rotate when the container is rotated. At the lowest temperatures and smallest velocities of oscillation (fig. 2b), this fraction is ~2%. These observations have been confirmed by a number of independent groups [5,6] although their theoretical explanation is still uncertain. The possibility of flow without viscosity in solid helium was theoretically predicted more than 30 years ago [7,8,9]. The latter predictions rely upon the occurrence of Bose Einstein condensation (BEC) in the so-

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lid and the aim of the neutron experiment described here was to investigate whether BEC is also the cause of supersolidity. When BEC occurs the momentum distribution of the atoms develops a peak, centred at zero mo- /L, where L is the linear mentum and with width ∆p~h dimension of the whole system (fig. 3). In liquid helium, neutron experiments show that the weight of this peak is ƒ = 0.07 ± 0.01 as T→0 [10,11]. Due to the macroscopic size of typical samples (L~1cm), the condensate peak in liquid helium is essentially a δ function in momentum space. However its width is measurable in Bose condensed trapped atomic clouds, for which L is typically a few microns [12]. The microscopic consequences of a momentum distribution of the form shown in figure 3 can be understood by

Figure 3. Bose-Einstein condensation. A fraction f of the atoms occupy a central peak in the momentum distribution, with a width ~h/L , where L is the linear dimension of the entire system.

particle quantum mechanics – the localisation in p space implies a delocalisation in r space. It is also well known in neutron scattering. The diffraction pattern is the square of the modulus of the Fourier transform of the scattering amplitude and the width of peaks in small-angle scattering or of Bragg peaks, is inversely related to the sizes of crystallites in powders or domain sizes in magnetic materials. The physical nature of the delocalisation of the wave function in a Bose condensed system can be illustrated using a simple model for the ground state wave function of liquid 4He, introduced by Feynman [14] and used by Penrose and Onsager [15] for the first realistic calculation of the Bose condensate fraction in liquid helium.Liquid helium consists of impenetrable hard sphere atoms of diameter a = 2.56 Å with weak interactions between atoms.

Figure 4. Illustrating the delocalisation of the wave function in Bose condensed liquid helium. Any two phase coherent points 1 and 2 must be connected by a path over which is non-zero (red line). This also implies the presence of connected macroscopic loops in a Bose condensed system, as illustrated on the right

consideration of the fundamental quantum-mechanical expression [13] for the momentum distribution of N identical particles. This is (1) where Ψ(r,s) is N particle wave function, r is the coordinate of one of the particles and s denotes the other N-1 coordinates. Note that in a single particle system this expression reduces to the well known expression for the momentum distribution in terms of the single particle wave function. It is a consequence of Fourier transform - /L, then theory that if n(p) contains a peak of width ∆p~h Ψ(r,s) must be a “delocalised” function of r – that is nonzero over length scales ~L. This result is used in elementary derivations of the uncertainty principle in single

Feynman modelled this behaviour by assuming that the wave function is zero if any two atoms have coordinates rn - rm < a, but has the same value for all other configurations of atoms. The implied r dependence of Ψ(r,s) for a given s is illustrated in fig. 4. Ψ(r,s) is zero if r lies within a distance a of any of the other atoms (shown as black circles) and has the same value for all other values of r. It can be seen that Ψ(r,s) is indeed nonzero over length scales ~L, occupying the spaces between atoms in the liquid structure. The Feynman model predicts that ƒ is equal to the fraction of the total volume within which Ψ is non-zero. More generally it can be shown that Ψ is non-zero within at least a fraction ƒ of the total volume [16,17]. A second fundamental property of the ground state is that the phase of Ψ(r,s) is the same for all r. This is a fun-

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damental result of quantum mechanics [18] – the phase of the ground state wave function of any Bose system has no nodes and hence has a phase independent of both r and s. In general phase coherence in the wave function implies connectivity. For example the phase of the wave function at point 1 in fig. 4a precisely determines the phase of the wave function at point 2. This implies that it must be possible to trace a “connected” path through the fluid between these points- that is one over which Ψ(r,s) is always non-zero. This also implies that macroscopic connected loops are possible as illustrated in fig. 4b. The delocalisation of the wave function has profound consequences for the macroscopic behaviour of Bose condensed systems. Consider what happens if a fluid described by such a wave function is stirred by a macroscopic object such as the column of disks used by Adronikashvilli. In a normal viscous fluid this stirring will create a macroscopic velocity field v(r). We consider a particular arrangement s of particles and denote Ψ(r,s) as ψ(r) = ψ(r) exp[iφ(r)]. It follows from a Galilean transformation that the creation of a macroscopic velocity field v(r) will cause a phase change

croscopic flow in a Bose condensed system–the fluid does not move when the disks rotate and at T=0 there is no viscous interaction between the disks and the fluid. Hence the presence of BEC explains rather simply the results of the Adronikashvilli experiment at low temperatures. In solid helium the situation can in principle be quite similar. Figure 5 shows schematically a crystal containing many vacancies. Provided that there are sufficient vacancies, connected paths within the crystal can still be present and the wave function can delocalise within the vacancies, allowing the presence of BEC. It is very counterintuitive for significant mass flow to occur at all in a solid. To explain how this can occur within a Bose condensed solid we consider a simplified version of an argument given by Leggett [9]. We consider solid helium in its ground state contained in a thin ring of ra-

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φ(r) → φ0(r) + mv(r).r/h

(2)

The ground state phase φ0 is independent of and hence must satisfy (3) If the wave function is to remain remains single valued when the liquid is stirred – that is if BEC is maintained, its new phase must satisfy the equation (4) It follows from equations (2) to (4) that must satisfy (5) Since Ψ(r) is non-zero over macroscopic distances in the presence of BEC, equation (5) must be satisfied over macroscopic loops. Macroscopic velocity fields set up by normal viscous flow do not satisfy equation (5) – hence normal viscous processes are not possible in the presence of BEC. The only possibility for macroscopic flow is the creation of quantised vortices. It follows from the classic argument of Landau [13] that there is a critical velocity vc = ε/p required for the creation of any flow, where ε is the energy and p the momentum of the fluid flow. This critical velocity is zero for normal viscous processes, but for the creation of quantised vortices is typically a few cm/sec. Hence provided the disks rotate slowly they cannot excite any ma-

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Figure 5. Schematic illustration of a crystal of helium, containing many vacancies. Macroscopic loops over regions where Ψ(r,s) is non-zero are possible.

dius R. Assuming that the solid is connected in the sense just discussed, the phase of the wave function can be integrated around the entire ring. Since the phase of the ground state is constant, equation (3) is satisfied when the ring is stationary. It is assumed that at sufficiently low velocities of rotation, this condition is maintained. It follows from mathematical transformation of the Schrödinger equation that in a frame of reference rotating with the ring (the “ring frame”) equation (3) is equivalent to

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where φ Ω is the phase in the ring frame and - )(2πR)2Ω. ∆φR = (m/h For a very thin ring equation (6) reduces to the one dimensional expression (7) where x is the distance around the ring. The flow in the ring frame is given by standard quantum mechanics as -_ h FR(x) = m⏐ψ(x)⏐2 dφR / dx = ⏐ψ(x)⏐2 vR(x)

(8)

where vR(x) is the velocity of flow. Hence condition (3) in the laboratory frame, which is necessary for BEC to be maintained, implies that in the ring frame

gions where ψ(x) has large amplitude. In the limit ρ2 → 0, the model gives a superfluid fraction of zero and a condensate fraction of 50%! Although this model is idealised, its main implications apply to other wave function describing a Bose condensed solid. The value of the supersolid fraction is determined by the bottlenecks to flow, where the wave function has small values. The fact that the measured supersolid fraction in solid helium is only ~2%, does not necessarily imply a small condensate fraction. The condensate fraction is always smaller than the superfluid fraction in the liquid, but in the solid, ƒ can be either smaller or greater than the supersolid fraction. In fact the necessity for the wave function to be connected suggests that there must be many vacancies – random

(9) In order to illustrate the basic principles of the argument we assume a simplified model for ψ(x) in which ψ(x) has only two values; √ρ1 over 50% of its domain and √ρ2 in the other 50%. Since the solid is rigidly attached to the walls one would expect that its structure in the frame moving with the ring is constant in time. If the structure is crystalline for example, the lattice sites will rotate with the ring. However equation (9) implies that there is also a flow of mass in the ring frame. These two conditions are compatible provided the flow in the ring frame maintains a constant distribution of mass density - that is providing

ρ1v1 = ρ2v2

(10)

Equations (8)- (10) imply that

F=

h ∆ φ ρ1ρ2 m πR ρ1 + ρ 2

Figure 6. Schematic diagram of experiment on the VESUVIO instrument at ISIS.

(11)

Consider the limiting forms of this expression: when ρ2 → 0, F → 0 , and there is no flow in the ring frame. This is “normal” behaviour - all the mass of the helium rotates with the ring. This limit also demonstrates that supersolid flow can occur only if the wave function is connected. In contrast if ρ1 = ρ2 the flow has a maximum value, corresponding to none of the mass rotating with the ring and 100% supersolidity. A very important point is that the size of the supersolid fraction is not related to the size of the condensate fraction. The supersolid fraction is determined by the minimum amplitude of ψ(x), whereas the condensate fraction is determined essentially by the volume of the re-

vacancies in a crystal structure provide a connected network only at vacancy concentration 15-20%. According to the Feynman model of the wave function this would imply a condensate fraction also 10-15%. In the liquid it has been argued [19,20] that the spaces in the liquid structure, necessary for the presence of BEC, develop when BEC occurs.The development of these spaces is responsible for unique behaviour observed in superfluid helium [21,22] – pair correlations decrease as the temperature is lowered. Just as vacancies in a crystal structure remove intensity from Bragg peaks and add diffuse intensity, spaces in a liquid structure remove intensity from the peaks in S(q) and add intensity between peaks. This reduces the contrast in S(q) oscillations and hence measured pair correlations as the temperature is lowered and spaces in the structure increase. The aim of the ISIS experiment was to try and determine whether BEC is the cause of supersolidity by sear-

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ching for these two signatures of BEC, observed in the fluid: (1) a drop of ~10% in the atomic kinetic energy; (2) an increase of ~10% in the vacancy concentration. Three different samples were prepared to test the effects of crystal quality and 3He impurity concentration, which are thought to be important for the observation of supersolidity [3, 23]. Sample A was a single crystal prepared from high purity (~0.3 ppm 3He) 4He gas. Sample B was a high purity polycrystal obtained by rapid cooling and sample C a polycrystal containing 10 ppm of 3He. The experiment [24] was performed on the VESUVIO spectrometer, illustrated schematically in Figure 6. VESUVIO is an inverse geometry spectrometer with energy analysis performed using the filter difference technique. Two measurements are performed; the first

Figure 7. Illustrates the filter difference technique employed on VESUVIO. Two measurements are taken; one with a gold filter between the sample and detectors (blue line) and one with the foil removed (red line). The difference (black line) is the “raw” time of flight data analysed in the experiment.

2M

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2M

-hq2 __ M ___ y = p.qˆ = q ω 2M





(13)

Thus by measuring ω and q, the component of the atomic momentum along the unit vector qˆ (conventionally denoted as y) can be determined for each individual scattering event. By measuring a very large number of such events, the probability distribution J(y) of values can be determined. Figure 8 shows data from all detectors in a single run after binning in the space corresponding to mass 4. After

Figure 8. (a) Shows summed time of flight data from all 92 detectors after binning according to the value of y calculated for mass 4. The solid line is the sum of all fits to individual detectors. (b) Shows the data after subtraction of the contribution from the can+cryostat. The dotted line is the instrument resolution function.

with a thin gold foil placed between the sample and the detectors and the second with the foil removed. The foil absorbs neutrons strongly within a narrow window centred at 4.9±0.1 eV. By taking the difference between the foil in and foil out measurements (Figure 7) one effectively detects only neutrons absorbed by the foil. The very large final energy allows time of flight measurements with energy transfers in the range 1-100 eV and wave vector transfers 40-150 Å-1. At such large energy and momentum transfers the impulse approximation (IA) [25, 26] can be used to interpret data. According to the IA, neutrons scatter from single nuclei with conservation of momentum and kinetic energy of the neutron+nucleus. This implies that the energy tran- ω is given by sfer h - 2 p2 -hω = (p + hq) – ___

Where q is the wave vector transfer in the measurement, p is the momentum of the struck atom before the collision and M is the atomic mass. Rearranging this equation gives

subtraction of the background signal from the sample container we obtain for the helium sample (Figure 8b). In an isotropic system the mean kinetic energy of the atoms can be calculated from

-2 3h κ = ___ 2M

y

2

J(y) dy

(14)

For a Gaussian J(y)

(15) and κ = 3/2 -h σ /M . The data was analysed by fitting equation (15) convolved with the instrument resolution function. The latter was determined by fitting to liquid data collected at a tempe-

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rature of 2.5 K for which κ = 15.8 K [11]. The peak positions are determined by the kinematics of the scattering process via equation (12). Hence the fitting parameters are a Gaussian standard deviation and amplitude for each peak. In each run the Gaussian standard deviation σ of the He peak was determined for each of the 92 detectors. Figure 9 shows a typical data set with the individual σ values shown as a function of scattering angle. A very relaxed energy resolution (see Figure 8) was employed in order to increase the statistical accuracy of the measurements. Despite the rather poor resolution, which rules out any detailed line shape analysis, kinetic energies can be obtained quite accurately by this procedure. A VESUVIO measurement on liquid helium [27] using the same technique showed a sharp change in the atomic kinetic energy of ~10% at the superfluid transition and

quite accurately reproduced calculated and previously measured values of κ. The σ values and the corresponding kinetic energies obtained in each run were obtained by performing a weighted average over the κ values obtained from individual detectors. The results with statistical errors are shown in Figure 10 and within error show no change through the temperature range where the supersolid fraction develops. The VESUVIO detectors allow the simultaneous collection of diffraction patterns from the sample. These were used to determine the lattice spacings for the three samples. The results are given in table 1. The errors on the lattice spacings were the standard deviations of the determinations from the Bragg peaks observed in different detectors. For sample A the (101) peak was observable only in 2 detectors, the (100) peak in a single detector and (002)

Figure 9. Values of obtained from individual detectors for sample A at 0.400K as a function of scattering angle.

Figure 10. Kinetic energies for different runs. The open circles are results from sample A. The cross from sample B and the solid square from sample C.

Sample

(101)

(002)

(100)

Atoms/nm3

Molar Volume (cm3)

A (0.115K)

2.759 (7)

3.1055

31.2 (3)

19.3 (2)

A (0.400K)

2.759 (7)

3.1055

31.2 (3)

19.3 (2)

A (0.150K)

2.758 (7)

3.1056

31.2 (3)

19.3 (2)

A (0.070K)

2.758 (7)

3.1055

31.2 (3)

19.3 (2)

B (0.075K)

2.758 (2)

2.934 (4)

3.131 (2)

30.6 (3)

19.7 (2)

C (0.075K)

2.757 (3)

2.940 (3)

3.128 (2)

30.6 (3)

19.7 (2)

Table 1. The three longest lattice spacings in Å observed in the different runs. Column 5 contains the calculated sample density and column 6 the corresponding molar volume.

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was not observed at all. The absolute value of the d spacing of the (100) peak in sample A is uncertain to ~1%, due to the finite width of the detectors. To within 1 part in 2000 no change in the lattice parameters was observed as the temperature was changed in sample A. The data presented here should be compared with similar data on superfluid helium. In the latter case experiment [10, 11] shows that the kinetic energy decreases by 11-12% as the temperature is lowered through the superfluid transition. This is associated with the development of a 7-8% Bose condensate fraction with zero kinetic energy. Neutron [21, 22] and X-ray [28] diffraction also show a significant change in structure as the liquid is cooled through the superfluid transition. The liquid becomes more disordered, consistent [16, 17] with the development of ~10% more spaces in the liquid structure. In contrast the measurements presented here imply that the vacancy concentration does not change to within ~0.1% as the solid is cooled through the supersolid transition region. The sample was maintained at constant density and any greater change in vacancy concentration would have given a measurable change in the lattice parameter. In conclusion the measurements show that Bose-Einstein condensation in crystalline solid helium is probably not responsible for supersolidity. This conclusion is supported by recently published neutron measurements on the MARI spectrometer at ISIS, which show that the Bose condensate fraction in solid helium is zero to within 1% [29]. The microscopic origin of supersolidity is still unclear. Recent measurements [30] have shown that the supersolid fraction is significantly reduced by annealing and it has been suggested that supersolidity could be due to the presence of a glassy phase of solid helium, obtained by rapid cooling [31]. In order to investigate this possibility we plan to perform an in-situ measurement of the supersolid fraction with an arrangement similar to that shown in Figure 2a and accurately measure the helium neutron diffraction pattern in the presence and absence of supersolidity. If successful this measurement would make a vital contribution towards the understanding of the puzzling phenomenon of supersolidity.

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â&#x20AC;˘

References 1. E.L. Andronikashvili, J. Phys. (USSR) 10, 201 (1946) 2. E. Kim and M.H.W. Chan, Nature (London) 427, 225 (2004) 3. E. Kim and M.H.W. Chan, Science 305, 1941 (2004) 4. E. Kim and H.W. Chan, Phys. Rev. Lett. 97, 115302 5. A.S. Rittner and J.D. Reppy, cond-mat/0604528 6. K. Shirahama et al., http://online.kitp.ucsb.edu/online/smatter_m06/ shirahama/

7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31.

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A.F. Andreev and I.M. Lifshitz, Sov. Phys. JETP 29, 1107 (1969) G.V. Chester, Phys. Rev. A 2, 256 (1970) A.J. Leggett, Phys. Rev. Lett. 25, 1543 (1970) T.R. Sosnick, W.M. Snow and P.E. Sokol Phys. Europhys. Lett. 9, 707 (1989) R.T. Azuah, W.G. Stirling, H.R. Glyde, M. Boninsegni, P.E. Sokol, S.M. Bennington, Phys Rev. B 56, 14620 (1997) J. Stenger et al., Phys. Rev. Lett. 82, 4569 (1999) L. Landau and E.M. Lifshitz, Statistical Physics, 3rd ed. (Pergamon, New York, 1978), pp. 192â&#x20AC;&#x201C;197 R.P. Feynman, Phys. Rev. 91, 1291 (1953) O. Penrose and L. Onsager, Phys. Rev. 104, 576 (1956) J. Mayers, Phys. Rev. Lett. 84, 314 (2000) J. Mayers, Phys. Rev. B 64, 224521 (2001) K. Huang, Statistical Mechanics, 2cnd Edition, (John Wiley and Sons, New York 1987), Appendix 1. J. Mayers, Phys. Rev. Lett. 92, 135302 (2004) J. Mayers, Phys. Rev. B 74, 014516 (2006) V.F. Sears and E.C. Svensson, Phys. Rev. Lett. 43, 2009 (1979) E.C. Svensson, V.F. Sears, A.D.B. Woods and P. Martel, Phys. Rev. B 21, 3638 (1980) S. Sasaki et al., Science 313, 1098 (1997) M.A. Adams, J. Mayers, O. Kirichek and R.B.E. Down, Phys. Rev. Lett. 98, 085301 (2007) See H.R. Glyde, Phys. Rev. B 50, 6726 (1994) for a recent review of the literature on the validity of the IA J. Mayers, Phys. Rev. B 41, 41 (1990) gives a very simple derivation of the IA J. Mayers, F. Albergamo and D. Timms, Physica B 276, 811-813 (2000) H.N. Robkoff, D.A. Ewen and R.B. Hallock, Phys. Rev. Lett. 43, 2006 (1979) S.O. Diallo, J.V. Pearce, R.T. Azuah, O. Kirichek, J.W. Taylor and H.R. Glyde A.S. Ritner and J.D. Reppy, Phys. Rev. Lett 98, 205301 (2007) A.V. Balatsky, Z. Nussinov, M. Graf and S. Trugman, Phys. Rev. B 75, 094201, (2007)


RESEARCH INFRASTRUCTURES

ISIS Second Target Station Project M. Bull ISIS Spectroscopy & Support Div., Rutherford Appleton Lab. Protons on target! The ISIS Second Target Station Project at the UK Rutherford Appleton Laboratory in Oxfordshire achieved a major milestone on Friday 14 December, at the first attempt and two days ahead of schedule. Protons were successfully extracted into the new proton transfer beamline from the existing ISIS accelerator and delivered to the new target station. During the test, bunches of protons travelling at 84% of the speed of light were transferred from the circular ISIS synchrotron accelerator into the 143m long proton beamline. They were guided by a sequence of 57 steering and focusing magnets onto a graphite test target located inside the new target station. The arrival of the protons was detected by measuring the electrical current induced in the target and the beam profiles along the length of the beam line were checked. “This is a fantastic achievement and a major milestone towards realising the successful operation of the second target station and opening up new possibilities for science research in the UK,” said ISIS Director Dr. Andrew Taylor. “Following a five year construction schedule, the project continues to be on time and on budget and we are expecting our first neutrons in June 2008.” The £140 million ISIS Second Target Station will double the capacity of the world-leading ISIS research centre and significantly increase its capability for nanoscience applications. As part of the much needed expansion of facilities at the Rutherford Appleton Laboratory to meet modern research challenges, the new target station will keep European scientists at the forefront of materials research. It will enable breakthroughs

A 6000 tonne steel and concrete structure surrounds the new neutron source. High energy protons strike a tungsten target at the centre to release neutrons for experiments.

to be made that will underpin the next generation of super-fast computers, data storage, sensors, pharmaceutical and medical applications, materials processing, catalysis, biotechnology and clean energy technology. Getting ready for neutrons The pace of progress in building the Second Target Station during 2007 has been impressive. Substantial quantities of equipment have been installed and commissioned in preparation for the ISIS target station to generate its first neutrons for initial experiments in Spring 2008. During the summer months, several major milestones were achieved by the project. The 6000 tonne steel and concrete monolith structure to house the neutron target was completed, and the proton beamline stretching from the synchrotron to the target station was installed. Cryogenic cooling systems for the neutron target assembly passed their performance tests in France and were delivered to the site. The beryllium reflector to surround the target and increase neutron yield was delivered from the United States. Instrument shielding rooms have been constructed and the large vacuum tank for the Sans2d instrument is in position. Components for the Offspec reflectometer developed in collaboration with the Technical University of Delft have been successfully tested with neutrons. In December 2007, the first lengths of supermirror neutron guide for the Wish diffractometer were installed. The experimental programme on the seven new neutron instruments will begin in Autumn 2008 and the new neutron source is expected to operate for at least 20 years.

Proton bunches travel at 84% of the speed of light along the proton beamline to the new target station.

Friday 14 December 2007 14:57: Members of the ISIS Second Target Station Project celebrate the successful delivery of protons along the new proton transfer beamline.

All Image Credits: Stephen Kill for ISIS, Science and Technology Facilities Council.

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Experiments underway at UK’s new synchrotron S. Damerell and S. Fletcher Diamond Light Source Diamond Light Source is the UK’s new 3rd Generation 3GeV synchrotron, with high brightness and low emittance (2.54 nmrad). The facility, which began operating in January 2007, is co-funded in a joint venture by the UK Government (86%) via the Science and Technology Facilities Council, and the Wellcome Trust (14%), one of the largest biomedical charities in the world. Following the first two calls for proposals from the user community, Diamond received in excess of 300 applications for beamtime, of which just over 100 have been allocated experimental time at the facility. Machine parameters The machine’s linac gives the electrons an energy of 100MeV. Diamond’s booster synchrotron is 158m in circumference and here the electrons are accelerated to 3GeV before being injected into the storage ring which is 561.6m in circumference. The main parameters of Diamond’s accelerators are shown below:

Linac Energy

100 MeV

Repetition rate

5 Hz

Booster Circumference

158.4 m

Energy (injection, extraction)

100 MeV, 3 GeV

Emittance

141 nm rad

Repetition rate

5 Hz

Storage Ring Energy

3.0 GeV

Circumference

561.6 m

No. of cells

24

Free straight lenghts for IDs

18x5 m, 4x8 m

Electron beam current

300 mA (500 mA planned)

Minimum beam lifetime

10 hours (top-up planned)

Emittance (horizontal, vetical)

2.7 nm rad, 0.03 nm rad

Table 1. Main parameters of Diamond’s accelerators

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Figure 1. Diamond Light Source

In January 2007, the first seven Phase I beamlines became operational. These beamlines all operate with Insertion Devices as the source. These were installed before 3 GeV commissioning began in September 2006 and an eighth device (I22) was installed in the Dec./Jan. shutdown. Six of these are in-vacuum devices, one is an APPLE-II helical undulator and one is a multipole superconducting wiggler. The following table summarises the main properties of these devices. All of the insertion devices have been commissioned and are in routine use; the in-vacuum devices are currently operating down to the initial minimum gap of 7 mm. Trim coils are set automatically as a function of ID gap (and phase in the case of the HU64 device) and keep the closed orbit within 1-2 µm rms. Other effects of the devices on the beam are small, and so far do not need correction. No effects on lifetime have been observed. Phase I Beamlines Three of the first phase of beamlines are for Macromolecular Crystallography, and provide state-of-the-art facilities for X-ray data collection on biological macromolecules with emphasis on precision, accuracy, automation and high throughput. These beamlines are tunable over the wavelength range 0.5 - 2.5 Å, to enable Multiwavelength Anomalous Diffraction (MAD) experiments to be carried out. All three beamlines are optimised for performance around 0.98 Å to enable MAD experiments at the Se K-edge at 0.979 Å. Robotic systems for automated sample handling and crystal centring, and software allowing automated data collection mean these beamlines

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are highly efficient. Facilities for remote monitoring and beamline operation further enhances performance, and the implementation of biological containment at category 3 level on beamline I03 will allow category 3 pathogens to be studied. The Nanoscience beamline is a microfocus soft-X-ray beamline for X-ray photoelectron microscopy, exploiting the brightest region in Diamond’s spectrum. It combines microfocused soft X-rays with variable linear and circular polarization and X-ray photoelectron emission microscopy (PEEM) to provide spectroscopic data on nanometre length scales. The intense polarised beam can be focused to a spot several microns in diameter, allowing the PEEM to probe nanomagnetism and nanostructures. It is possible to perform photoemission and absorption measurements at nanometre spatial resolution, with an energy resolution of less than 300 meV. The Extreme Conditions beamline provides both white and monochromatic high-energy X-rays in both focused and unfocused mode into the 100 keV range for diffraction experiments. The intense very high-energy Xrays can penetrate into complex sample assemblies, and can be collimated to a few µm, permitting detailed mapping of structural order or disorder, chemical fingerprint, or single crystal structure determination. A diamond anvil cell enables precision control of pressures in-

Beamline

Source

Macromolecular Crystallography (I02)

below the uranium M-edges) to around 20 keV. Easily removable focusing optics enable the beamline to meet the disparate requirements for small focal spots and very high resolution diffraction and coherence. A set of remotely interchangeable crystals in the monochromator enable the beam parameters to be matched to the sample quality and a diamond crystal phase retarder is used to select the required polarisation state (circular, linear or elliptical). The Microfocus Spectroscopy beamline uses high-brightness sub-micron X-ray beams for the study of complex inhomogenous materials and systems under realistic conditions. The combination of the brilliance of the third generation synchrotron source, and optics able to focus the beam to a micron sized spot, allows compositional, temporal and spatial information to be gathered at high resolution. It provides a total energy range of 2-20 keV with a core energy range of 5 - 13 keV, and allows scanning EXAFS to k > 12 A. It has a spatial resolution of 1 µm2 with a spectral resolution of 10-4. Phase II Beamlines In addition to the Phase I beamlines, Diamond has funding in place to construct fifteen Phase II beamlines, the first of which, the Non-crystalline Diffraction beamline,

Period [mm]

No. of Periods

Field gap= gap= 5mm 7mm

In vacuum 2m U23 undulator

23

85

0.92

0.70

Macromolecular Crystallography (I03)

In vacuum 2m U21 undulator

23

94

0.86

0.64

Macromolecular Crystallography (I04)

In vacuum 2m U23 undulator

23

85

0.92

0.70

Nanoscience

2 x APPLE-II HU64 helical undulators

64

2 x 33

0.94T (15 mm)

Extreme conditions

3.5T superconducting multipole wiggler

60

24

3.5T

Materials & Magnetism

In vacuum 2m U27 undulator

27

73

1.0

0.8

Microfocus Spectroscopy

In vacuum 2m U27 undulator

27

73

1.0

0.8

Non-crystalline Diffraction

In vacuum 2m U25 undulator

25

79

0.97

0.75

Table 2. Details of Diamond’s first beamlines and insertion devices

to the 100 GPa regime. Similarly cryogenic cooling, resistive heating and heating with IR lasers allow controlled temperature environments from a few Kelvin to up to 5000 K. The Materials and Magnetism beamline is a uniquely versatile X-ray diffraction and scattering facility. The intense, low-divergence undulator beam is focused to a spot less than 100 x 400 µm, with an energy range that is continuously tuneable from 3.4 keV (just

has been built and welcomed its first users in August 2007. The remaining fourteen will go into operation at the rate of around four each year. The Phase II investment will also exploit the high brilliance of the source for imaging and determining the structures of larger biological structures, such as viruses, and will include the first UK beamlines exploiting coherence of the X-ray source. It will also establish support

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labs, adjacent to the beamlines â&#x20AC;&#x201C; bringing a holistic view to an overall scientific facility. Phase II also provides for a detector development programme to ensure that the brilliance of Diamond is fully exploited. This detector programme will also have a significant benefit for the operation of some of the Phase I beamlines by extending their capability and deliver a greater return on the initial investment. The Phase II beamlines will use a mixture of Insertion Devices and Bending Magnets as their source. To keep up to date with developments at the Diamond Light Source, please visit: www.diamond.ac.uk A research expertise booklet has just been published to enable outside researchers to identify science expertise at Diamond, download at: www.diamond.ac.uk/Publications/SciencePubs

Figure 2. Storage Ring

Figure 1. In addition to the Phase I beamlines, Diamond has funding in place to construct fifteen Phase II beamlines, the first of which, the Non-crystalline Diffraction beamline, has been built and welcomed its first users in August 2007. The remaining fourteen will go into operation at the rate of around four each year.

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â&#x20AC;˘

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BaD ElPh: a new beamline for band dispersion and electron-phonon coupling studies at ELETTRA P. Vilmercati, M. Barnaba, L. Petaccia, A. Bianco, D. Cocco, C. Masciovecchio, A. Goldoni

ELETTRA Synchrotron Light Laboratory, Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5, 34012 Trieste, Italy

Abstract The BaD ElPh (Band Dispersion and Electron-Phonon coupling) beamline has been commissioned at the ELETTRA synchrotron radiation laboratory. It is the branch-line of the IUVS beamline and exploits the same Figure-8 undulator. The beamline is based on a normal incidence monochromator and covers the photon energy range 4.7-40 eV with three gratings. The beamline is combined with an end-station for high-resolution angle-resolved photoemission spectroscopy. The system is in particular well suited for measurements of the electronic band structure, electron-phonon interaction, and thermally (or doping) driven phase transitions in low dimensional systems characterized by large (≥ 7 Å) unit cell parameters.

with very large Brillouin zone are welcome. Moreover, the inelastic electron mean free path is expected to increase drastically in the kinetic energy range < 10 eV allowing “bulk” sensitive measurements. The radiation source of the BaD ElPh beamline is a Figure-8 undulator [4,5] shared with the IUVS beamline. This undulator is made of six periodic magnetic arrays: the central rows generate a vertical field with spatial period λ, while the side blocks create a horizontal field with twice that periodicity (2λ). The resultant electron trajectory follows a figure-of-eight pattern when projected on the transverse plane. Due to the opposite helicity in any two consecutive periods, the net polarization of the emitted

Figure 1. Layout of the BaD ElPh beamline. See text for details.

From the late 1980s, Angular Resolved Photoemission Spectroscopy (ARPES) has been intensively applied to probe the quasiparticle and the electronic structure below the Fermi level in solid materials. Thanks to the improvement in the energy and angular resolution of the electron spectrometers in the last decade, ARPES has been proved to be a powerful technique to reveal more subtle details in the spectral function of complex solids, like for instance superconductors, colossal magnetoresistive oxides, non-linear optical crystals, charge density wave compounds, metal-insulator transition systems, etc. [1-3]. In this paper we present a new undulator-based synchrotron radiation beamline at the ELETTRA storage ring now available to the users community. The BaD ElPh beamline is dedicated to high-resolution photoemission experiment in the low photon energy regime (4.7-40 eV). In such condition the best sensitivity to k-vector of photoemitted electrons and high energy resolution is available. Samples

photons is linear at any observation angle. However, the radiation spectrum is composed of two sets of harmonics, conventionally defined by integer (i=1,2,3,…) and half-integer (i=1/2,3/2,5/2,…) indices and having alternatively horizontal (i=1,2,3,...) and vertical polarization direction. This undulator has 32 periods of NdFeB magnets with a 140 mm period length and it provides the maximum photon flux in the range 5 to 10 eV (about 1015 photon/s) [6]. A schematic layout of the beamline is shown in Figure 1. The beamline is based on a 4-m-long Normal Incidence Monochromator (NIM) with a constant included angle of 5°. NIMs offer the highest resolving power [7] but the photon energy range is restricted to a maximum of about 40 eV. The beamline consists of a silicon switching mirror to transfer the photon beam in the BaD ElPh or IUVS beamline, a spherical pre-focusing mirror which focuses the beam into an entrance slit, a NIM, a moveable exit slit, and a gold coated toroidal mirror which re-focuses

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the beam onto the sample. The monochromator has two interchangeable spherical gratings with laminar profile to cover energy ranges of 4.7-11 eV (1500 l/mm, AlMgF2 coated) and 10-22 eV (3000 l/mm, SiC) at 2.0 GeV of electron ring energy. A third spherical grating to provide

Figure 2. Calculated (a) absolute efficiency and (b) total resolving power of the BaD ElPh normal incidence spherical grating monochromator. The total resolving power was calculated for three different slit apertures.

photons in the energy range 20-40 eV (3000 l/mm, blazed profile, Pt coated) has been ordered and will be installed in the first semester of 2008. When ELETTRA operates at 2.4 GeV the lowest photon energy available is 6.7 eV. The pre-focusing mirror has two different coatings: Si for the 4.7-11 eV energy range and Pt for higher photon energies. The entrance slit to grating distance is 3820 mm while the lowest exit slit to grating distance is 4070 mm. The exit slit can be moved by 120 mm in order to keep the slit in focus over the energy ranges of the three gratings. The aperture of both slits can be set in the 10-500 µm range. The groove profile of the gratings were designed to opti-

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mize the first order diffraction efficiency and optimum second order suppression. The calculated absolute efficiency and total resolving power (E/∆E) of the BaD ElPh normal incidence spherical grating monochromator are shown in Figure 2. The flux through the beamline was estimated using an AXUV-100 photodiode, which can be inserted into the beam after the toroidal re-focusing mirror. The calculated typical quantum efficiency of the photodiode has been taken into account. With a pinhole angular acceptance of 0.6×0.6 mrad2, an entrance slit aperture of 300 µm, and with 200 mA accumulated in the storage ring (see Fig. 3a) the maximum photon flux, reached between 7.5 and 9.5 eV in first harmonic, is about 3×1012 photons/s on the sample with the exit slit open at 150 µm, while at 5 and 10.5 eV it decreases at about 2×1012 photons/s. For the medium-energy grating the maximum flux is reached at 19 eV: the photon flux is 7×1011 photon/s with the exit slit open at 300 µm. In the above conditions the calculated total resolving power of the beamline is about 3000 at 8 eV and 2000 at 19 eV of photon energy. Photoemission measurements suggest that the second order flux from the medium-energy grating is relative high in the 12-15 eV range. Indeed, a later atomic force microscopy (AFM) characterization has shown that this grating has not the optimum profile. We are now considering to replace this grating with a new one from a different company, Carl Zeiss GmbH. The experimental end station consists of two independent ultra-high vacuum (UHV) chambers and a simple load-lock chamber. The preparation chamber is equipped with an ion sputter gun and with several free flanges to mount the needed tools for UHV in-situ growth of thin films. In this chamber a XPS apparatus (x-ray source and 100 mm hemispherical electron energy analyzer) is present too, in order to perform chemical analysis of the sample. The main experimental chamber is made in mu-metal for magnetic shielding and houses the electron energy analyzer, a low-energy electron diffraction optics (Omicron, SpectaLEED), a high intensity vacuum ultraviolet source (Omicron, HIS 13), and a residual gas analyzer (Stanford Research Systems, RGA 200). The manipulator has 4 degree of freedom (three translations and the polar angle). The sample holder can be transferred and is mounted on a cryostat (Advanced Research Systems, Helitran LT-3M) that reaches with liquid helium a temperature lower than 10 K. The sample temperature can be measured by a K-type thermocouple or by a chromel-AuFe thermocouple connected to a Lake Shore 311S-T2 temperature controller. To improve the reliability of the readings at low temperatures we have used a silicon diode to calibrate both the thermocouples. To perform ARPES experiments, the actual electron energy analyzer in the main experimental chamber is a Scienta SES 50 (courtesy of R.

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Claessen, University of Wuerzburg, Germany) mounted on a two axis goniometer in the vacuum chamber itself. Using a small analyzer necessarily means making sacrifices in terms of overall flux. However, with this kind of set-up, the k||-vector of the outgoing electrons can be se-

temperatures, are shown in Figure 3b. The best energy resolution reached is 5.9 meV with the pass-energy (PE) of the analyzer sets to 1 eV. The maximum angular acceptance of this analyzer is about ±3° and the angular resolution is ≈0.1°. As all the Scienta analyzers, the SES 50 is forced to work at PE  KE, where KE is the kinetic energy of the photoelectrons, in order to avoid distortion of the angular and energy dispersions on the two-dimensional (2D) detector. However, to satisfy this condition, the spectrum acquisition time can become very long especially working with low energy photons at low KE of the photoelectrons. In order to improve the data acquisition, now limited by the low transmission of the SES 50, and to extend the maximum angular acceptance of the analyzer we have decided to employ an alternative and most common set-up for ARPES: a large hemispherical electron energy analyzer mounted in a fixed geometry on the experimental chamber. The large dimension of the analyzer enables the achievement of high transmission and resolution simultaneously. In the beginning of 2008 a new electron energy spectrometer, a SPECS Phoibos 150 with a 2D CCD detector system, is scheduled to be installed on a new main experimental chamber of the BaD ElPh end-station to provide better performances and a lower data acquisition time. For this new analyzer a “wide angle mode” lens operation has been specifically designed for ARPES measurements reaching an angular acceptance within ±13°. This mode guarantees a simultaneous and parallel acquisition over a wide angular range with a given angular resolution. With a 2D detection, an angular resolution better than 0.1° can be achieved in the non energydispersive direction of the analyzer without restricting the acceptance angle. The reported ultimate energy resolution is 3 meV. For the “wide angle mode” and also the

Figure 3. (a) The photon flux through the beamline to end station measured with a photodiode using a pinhole of 6¥6 mm2 at 10 m from the radiation source, an entrance slit aperture of 300 µm, the indicated exit slit, and with 200 mA of electron current accumulated in the storage ring. (b) Fermi edge spectra (dots) of a molybdenum polycrystal at different temperatures. Their best fit (lines) give the total experimental energy resolutions including both the beamline and the SES 50 electron energy analyzer contributions. Inset: Total experimental energy resolutions measured at different pass energies of the SES 50 and with the sample at 30 K.

lected by moving the analyzer or the sample angles and it is possible to determine the polarization dependence of certain photoemission features by changing both the sample and the spectrometer angles such that the angle between the incoming light and outgoing electrons is changed, keeping constant the emission angle of the electrons with respect to the sample normal. The total experimental energy resolutions, obtained by measuring the Fermi edge of a molybdenum polycrystal at various

Figure 4. Image plot of the photoemission spectra of the Au(111) surface state dispersion. The white is the highest intensity.

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“low angular dispersion” mode, the Phoibos 150 analyzer can work at PE > KE. This means that, for instance, in the “low angular dispersion” mode at KE = 2 eV it is possible to work up to PE = 40 eV, while with the SES 50 we must work up to PE = 2 eV. With the new electron analyzer, therefore, we can expect an increase in the photoemission signal by a factor of about 20 and considering that the angular acceptance is 3–5 times bigger, the acquisition time of a normal band dispersion experiment may be reduced by a factor 60–100. The Phoibos 150 analyzer can also work in “transmission” mode, collecting one spectrum integrated over the angular acceptance. To conclude this presentation, some experimental results obtained with the SES 50 analyzer are briefly reported. Figure 4 shows the dispersion of the Au(111) surface state measured at room temperature (RT), with a photon energy of 16 eV, and with an analyzer pass energy of 5 eV. We can clearly resolve the spin-orbit split states [8]. In Figure 5 we show the Mg(0001) surface state dispersion along the ΓK direction of the surface Brillouin zone measured at RT, with a photon energy of 9 eV, and with an analyzer pass energy of 2 eV. At this photon energy, apart the surface state dispersion (the most intense band), it is also evident the bulk band dispersion at lower kinetic energy [9,10]. This is due to the enhanced “bulk” sensitivity of photoemission at low photon energy, as it is also confirmed by the photoemission line shape near the Fermi level at about 5 eV of kinetic energy (see Fig. 5c) [11]. The authors wish to thank the ELETTRA staff for their technical assistance, R. Claessen (University of Wuerzburg, Germany) for providing us the SES 50 spectrometer, S. Gardonio and C. Carbone (ISM-CNR, Italy) for the Au(111) experiment. This project is supported by the Italian Ministry of Education, University and Research (MIUR), under Contract FIRB No. RBAU01B5RS. References 1. S. Hufner, Photoelectron Spectroscopy, Springer-Verlag, Berlin, (1995). 2. F. Reinert, S. Hufner, New. J. Phys. 7 97 (2005). 3. A. Damascelli, Phys. Scr. T109 61 (2004). 4. T. Tanaka, H. Kitamura, Nucl. Instr. and Meth. in Phys. Res. A 364 368 (1995). 5. B. Dviacco, Proc. Particle Accelerator Conference (2001). 6. T. Tanaka, H. Kitamura, J. Synchrotron Rad. 3 47 (1996). 7. L. Nahon et al., Rev. Sci. Instrum. 72 1320 (2001). 8. G. Nicolay et al., Phys. Rev. B 65 033407 (2001). Figure 5. (a) Photoemission spectra and (b) image plot of the Mg(0001) band dispersion along the ΓK direction. (c) Photoemission spectrum at Γ point. The photon energy is 9 eV, the sample temperature is RT.

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9. U. O. Karlsson et al., Phys. Rev. B 26 1852 (1982). 10. H. J. Gotsis et al., Phys. Rev. B 65 134101 (2002). 11. E. D. Hansen et al., Phys. Rev. B 55 1871 (1997).

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MUON & NEUTRON & SYNCHROTRON RADIATION NEWS

News from ILL The Refit Programme is completed! Following the regular 10-yearly safety review of the its High Flux Reactor, - the so called Groupe Permanent – which took place in May 2002, the ILL started a wide-ranging set of reinforcement and renewal of its nuclear installations - the Refit Programme - one of whose aims being compliance with recent changes in seismic regulations. During the period 2002-2007 a huge amount of work has been done, particularly to withstand an earthquake: • Reinforcement of the building housing the reactor • Establishment of operational and

• •

• •

command-control systems to shutdown the reactor in case of earthquake New water circuit to feed the reactor tank and the canal which are tight in case of earthquake Removal of 1500 tons of building on the upper slab of the reactor. Cutting the front part of the guides halls and reinforcement of the office building New racks for spent fuel Non destructive examination on heavy water pipes welds. It showed no detected defect and no ageing.

The REFIT is now practically completed and the final review meeting took place at the ILL on 11 October this year. The REFIT involved about 10 people from ILL and 10 people from external companies and costed approximately 30M€ including staff. Bravo to all those people who participated very actively and efficiently to the ILL Refit Programme which will enable the ILL to operate safely until 2030. G. Cicognani Communication and Scientific Support Institut Laue-Langevin

ILL 20/20 The Upgrade Programme of the Institut Laue-Langevin Founded in 1967, the Institut LaueLangevin (ILL) is an international research centre at the leading edge of neutron science and technology. It is directed by its Associates, the founder countries, Germany, France and the United Kingdom, in association with its European Scientific Member countries. As a central facility, the ILL provides access to instruments that use lowenergy neutrons of unequalled quality and breadth to a community of many thousands of researchers throughout Europe and beyond. The ILL has occupied this leading position for 35 years. In order to keep the ILL at the forefront of neutron science and to provide the best possible experimental facilities and support to its European

users over the next two decades, the Institute needs to modernise its infrastructure and instrument suite. This is the scope of the proposed ILL20/20 upgrade programme, which can be summarised as follows: 1. improving neutron moderators and delivery systems; 2. planning and prototyping new instruments and neutron technologies; 3. strengthening the links with the European Synchrotron Radiation Facility (ESRF), creating partnerships for science and joint scientific facilities accessible to ILL and ESRF users; 4. developing the site shared by the ILL, the European Molecular Biology Laboratory (EMBL) and the ESRF to improve the visibility

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and research capability of this common site. The ESFRI Project aims at optimising the preparatory phase of this ambitious programme. The preparation of the upgrade will involve: 1. feasibility studies on challenging technical projects to renew the ILL’s neutron moderators and delivery systems, and on novel neutron scattering technologies and techniques; 2. preparing the framework for a Partnership for Soft Condensed Matter; 3. planning the development of the ILL/EMBL/ESRF site, including the resolution of the administrative issues. R. Wagner Director of the Institut Laue-Langevin

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MUON & NEUTRON & SYNCHROTRON RADIATION NEWS

Next ILL proposal round: call for proposals

The deadline for proposal submission is

Tuesday, 4 March 2008, midnight (European time) Proposal submission is only possible electronically. Electronic Proposal Submission (EPS) is possible via our Visitors Club (http://club.ill.eu/cv/), once you have logged in with your personal username and password. The detailed guide-lines for the submission of a proposal at the ILL can be found on the ILL web site: http://www.ill.eu/users/proposal-submission/. The web system will be operational from 15 January 2008, and will be closed on 4 March

at midnight (European time). Please allow sufficient time for any unforeseen computing hitches. You will receive full support from the Visitors Club team. If you have any difficulties at all, please contact our web-support (club@ill.fr). For any further queries, please contact the Scientific Co-ordination Office: ILL-SCO 6 rue Jules Horowitz BP 156, F-38042 Grenoble Cedex 9 phone: +33 4 76 20 70 82, fax: +33 4 76 48 39 06 email: sco@ill.eu, http://www.ill.eu

Instruments available The following instruments will be available for the forthcoming round: ■

powder diffractometers: D1A, D1B*, D2B, D20, SALSA

diffuse-scattering spectrometer: D7

liquids diffractometer: D4

polarised neutron diffractometers: D3, D23*

three-axis spectrometers: IN1, IN8, IN12*, IN14, IN20, IN22*

single-crystal diffractometers: D9, D10, D15*,VIVALDI

time-of-flight spectrometers: IN4, IN5, IN6, BRISP*

large scale structure diffractometers: D19, DB21, LADI

small-angle scattering: D11, D22

backscattering and spin-echo spectrometers: IN10, IN11, IN13*, IN15, IN16

reflectometers: ADAM*, D17, FIGARO

nuclear-physics instruments: PN1, PN3

small momentum-transfer diffractometer: D16

fundamental-physics instruments: PF1B, PF2

* Instruments marked with an asterisk are CRG instruments, where a smaller amount of beam time is available than on ILL-funded instruments, but we encourage applications for these. You will find details of the instruments on the web http://www.ill.fr/instruments-support/instruments-groups/

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MUON & NEUTRON & SYNCHROTRON RADIATION NEWS

Scheduling period Those proposals accepted at the next round will be scheduled during the second two cycles in 2008.

Reactor Cycles for 2008 Cycle n° 150 (081)

from 31/03/2008

to 20/05/2008

Cycle n° 151 (082)

from 03/06/2008

to 23/07/2008

Cycle n° 152 (083)

from 27/08/2008

to 16/10/2008

Cycle n° 153 (084)

from 30/10/2008

to 19/12/2008

Start-ups and shut downs are planned at 8:30 am.

College Secretaries College College College College College College College College College College

1 – Applied physics, instrumentation & techniques: Emanuel Farhi 2 – Theory: Maxime Clusel 3 – Nuclear and Fundamental Physics: Ulli Koester 4 – Structural and Magnetic Excitations: Pascale Deen 5A – Crystallography: Marie Helène Lemée-Cailleau 5B – Magnetism: Anne Stunault 6 – Structure and Dynamics of Liquids and Glasses: Monica Jimenez 7 – Spectroscopy in solid state physics and chemistry: Stéphane Rols 8 – Biology: Susana Teixeira 9 – Structure and Dynamics of Soft-condensed Matter: Peter Falus

Mandatory information for user’s reimbursement Following the implementation of new software for the reimbursement of travel and hotel expenses of ILL users and staff, we now need you to provide us with the following additional information: ■

Employer (Name, Address,Town, Country)

Type of contract you have with your employer (Permanent,Temporary, Student, PostDoc, Internship,Temporary Employment Agency)

When receiving an invitation to an experiment at the ILL, you will be asked to provide – by logging into the Visitors Club and entering them in your profile - the necessary information if they are missing from your records. Please note that this information is essential to be allowed to enter the site. It will be kept confidential and not used for any other purposes.

Vol. 13 n. 1 January 2008

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MUON & NEUTRON & SYNCHROTRON RADIATION NEWS

Kick-off of the Second phase of the ILL Millennium Programme At the meeting held in June, the ILL Steering Committee fully approved and endorsed the priorities set out by the ILL management for the instrument and infrastructure projects of the second phase (M-1 phase) of the Millennium Programme. The Chairman of the Steering Committee, Prof. Michel Spiro, asked that it should be widely communicated, especially to the neutron community, that from a technical viewpoint, the ILL reactor can be operated safely beyond 2030.

This very important statement was then followed by the kick-off meeting of M-1 phase, which took place on 10 July. With an investment budget of about 52 M€ for the 2007-2013 period we are planning to: • build five new instruments: ThALES, IN16B, D33, WASP and SuperADAM (the latter as a Swedish-German CRG instrument) • upgrade four other instruments: IN1 Lagrange, IN4, D11, D17

• and phase out eight instruments: D1A, DB21, IN10, IN3, IN14, IN16, IN11 and ADAM These plans also require the timely re-siting of three instruments: D16, Cryo-EDM, LADI. G. Cicognani Communication and Scientific Support Institut Laue-Langevin

International Symposium on Pulsed Neutron and Muon Sciences (IPS 08) March 5-7, 2008 – Ibarakiken Shichouson Kaikan, Mito, Japan

The 1st J-PARC International Symposium

Second Announcement Organized by J-PARC Center Co-organized by Institute of Materials Structure Science, High Energy Accelerator Research Organization Quantum Beam Science Directorate, Japan Atomic Energy Agency Symposium Chairs Yujiro Ikeda, JAEA Susumu Ikeda, KEK

The J-PARC International Symposium on Pulsed Neutron and Muon Sciences (IPS 08), will focus on the high intensity pulsed spallation neutron and muon sources at MLF, in which the first user program will begin in J-PARC. IPS08 will provide an opportunity to introduce the performance of J-PARC and other facilities in the world, and discuss prospective sciences and technologies performed in those facilities. In order to fully respect the symposium scope, papers should concentrate on prospective aspects in sciences and technologies.

Contact Address: Hiroshi Takada, Kenji Nakajima - Materials and Life Science Division - J-PARC Center – Japan Atomic Energy Agency Tokai-mura, Naka-gun, Ibaraki-ken, 319-1195, Japan - Tel: +81 29 282 6936; Fax: +81 29 284 3889 - e-mail: IPS08@ml.j-parc.jp http://www.ips08.com

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MUON & NEUTRON & SYNCHROTRON RADIATION NEWS

News from SNS ORNL neutron facilities deliver neutrons The High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) resumed full power operations on May 16, 2007. There were three experiment cycles of 23 to 25 days in FY2007 and another six are proposed for FY2008 beginning in November 2007. During FY 2007, the High Flux Isotope Reactor delivered 1178 operating hours to users. Commissioning of two SANS instruments is under way and these instruments will join the user program in 2008. The Neutron Scattering Science Advisory Committee endorsed language encouraging development of the science case for two instruments proposed for HFIR. Information about IMAGINE, a quasi-Laue single crystal diffractometer, may be obtained from Flora Meilleur, flora_meiller@ncsu.edu. Information about the high resolution cold neutron inelastic spectrometer may be obtained from Young Lee, younglee@mit.edu. Neutron production at the SNS began on June 21, 2007, and ended September 8, 2007. SNS resumed neutron production November 8, 2007. The planned ramp-up to higher power and increased reliability is well ahead of schedule. On August 11, 2007, the SNS operated at 183 kilowatts of routine beam power over 24 hours setting a power record for a pulsed spallation neutron source. SNS cycle 2008-1 began on November 5, 2007, and ends on February 3, 2008. Neutron production is expected to be 941 hours with an expected 80% beam delivery efficiency. Initially, the run power is 120 kW with a planned ramp up to 340 kW during the period. SNS delivered 540 operating hours to users in FY2007.

The Wide Angular-Range Chopper Spectrometer (ARCS) team opened the SNS beamline 18 shutter, sending the first neutrons to the instrument September 7, 2007. Commissioning of the instrument will continue into 2008. This is the fourth SNS instrument to receive neutrons. Seven additional instruments will begin commissioning in 2008, with the Spallation Neutrons and Pressure (SNAP) diffractometer, the Cold Neutron Chopper Spectrometer (CNCS), the Extended Q-Range SANS (EQ-SANS), and the powder diffractometer (POWGEN3) leading the others. A call for experimental proposals for nine instruments at the High Flux Isotope Reactor and Spallation Neutron Source was issued June 1, 2007, and closed on July 16, 2007, with over 200 proposals submitted. A second proposal call period is scheduled for December 10, 2007 – January 18, 2008. Significant leadership changes have occurred at ORNL during the last year. Dr. Thom Mason was named the director of Oak Ridge National Laboratory effective July 1, 2007. Dr. Ian Anderson succeeds Thom as Associate Laboratory Director for Neutron Sciences and Executive Director of the Spallation Neutron Source. One of the six R&D 100 Awards received by Oak Ridge National Laboratory in 2007 was for the Pharos Neutron Detector System. These top awards are given annually by R&D Magazine to the year’s most technologically significant new products. Pharos is a small low-power neutron detection system that can be used to identify nuclear materials at airports and harbors and was developed by Richard Riedel of ORNL’s Neutron Scattering Science Division, Ronald Cooper of the Neutron Facilities De-

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velopment Division, and Lloyd Clonts of the Engineering Science and Technology Division. Neutron Scattering Science Division Senior Corporate Fellow Herb Mook was among those to be recently elected a fellow of the American Association for the Advancement of Science. He is cited for his “pioneering experiments using neutron scattering in materials that test theories leading to understanding of novel physics and new directions of research”. ORNL Users Week (October 8-11, 2007) focused on the scientific resources of four ORNL user facilities funded by the DOE Office of Basic Energy Sciences: the Spallation Neutron Source, the High Flux Isotope Reactor, the Center for Nanophase Materials Sciences, and the Shared Research Equipment Program. Of the 78 institutions represented among the 367 registrants, 55 were colleges and universities. Talks and photos are located at http://neutrons.ornl.gov/ workshops/users2007/index.shtml. A.E. Ekkebus Neutron Scattering Science Division Oak Ridge National Laboratory

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MUON & NEUTRON & SYNCHROTRON RADIATION NEWS SCIENTIFIC REVIEWS

European Conference on X-ray Spectrometry June 16-20, 2008 – Cavtat, Dubrovnik, Croatia Organized by Rud-er Bosˇkovic´ Institute in co-operation with EXSA and IAEA

Second Announcement and Call for Papers The thirteenth European Conference on Xray Spectrometry will be held in June 2008. Adriatic coast, picturesque Cavtat, magnificent and unique Dubrovnik will host scientists of different backgrounds from Europe and worldwide in attempt to recognize emerging and inventive xray spectrometry techniques as well as the important and successful applications. From experienced experts in the field, to young scientists searching for novelties and finally industrial exhibitors with state of the art instruments, all participants will have a chance to enjoy in rich scientific and social program of the forthcoming meeting, which comes after successful previous meetings in Alghero and Paris.

Important dates March 1st, 2008 Submission of abstract

April 1st, 2008 Notification of acceptance

May 1st, 2008 Early Registration

May 15th, 2008 Final announcements

Main conference topics

• Interaction of X-rays with matter • X-ray sources, optics and detectors • Quantification methodology • WDXRS • TXRF and related techniques

• Synchrotron XRF • PIXE and electron induced XRS • Microbeam techniques • X-ray absorption (EXAFS, XANES) • X-ray imaging and tomography

Contact Address EXRS-2008 Secretariat, Rud-er Bosˇkovic´ Institute, P.O. Box 180 10002 Zagreb (Croatia) E-mail: exrs2008@irb.hr Website: http://exrs2008.irb.hr

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Vol. 13 n. 1 January 2008

• Applications: Materials and nanoscience, Life sciences, Cultural heritage, Earth and Environment sciences, Industrial applications


SCHOOL AND MEETING REPORTS

4th Italian Neutron School of the Italian Society of Neutron Spectroscopy The Italian Neutron School, organised by the Italian Society of Neutron Spectroscopy (SISN) addresses to students, PhDs and young researchers aiming to approach the neutron spectroscopy by learning its performance and power in research application. The 4th edition of the School – which took place this year – was focused on the Inelastic Neutron Scattering in Liquids and Disordered Systems. The school was composed of two parts: a theoretical session was organized in Sestri Levante (Genova, Italy) from 10 to 12 September, followed by an experimental session hosted by the ILL from 14 to 20 September. During the theoretical session, together with an overview of

the principles of neutron spectroscopy, a first approach to an ideal experiment and to the data reduction was provided. The practical session was organised in cooperation with the ILL, who hosted 20 Italian students providing not only logistic support but also access to instruments and computing facilities. The students were shared between three different instruments, the two Italian CRGs, IN13 and BRISP, and the test triple-axis instrument IN3. The choice of the latter was due to its high educational character. Real experiments were performed addressing subjects such as: the influence of the environment on protein dynamics (IN13); phonons in lead and tantalum crystals (IN3); the study of Brillouin Scattering in com-

plex liquids (BRISP). Furthermore, a high educational experiment was performed on IN3, addressing the complex subject of the instrumental resolution of a triple axis spectrometer. On performing the experiments, the students were able to practice the beauties of neutron spectroscopy, which the theoretical session in Sestri Levante had previously encouraged. The enthusiastic young experimenters spent night and day both measuring spectra on the instruments and making data analysis. The outcome of their thoughtful work was finally presented in a conclusive seminar session. F. Natali and A. Orecchini ILL

Participants to the 4th Italian Neutron School.

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CALL FOR PROPOSALS

Call for proposals for

Call for proposals for

Neutron Sources

Synchrotron Radiation Sources

http://neutron.neutron-eu.net/n_about/n_where/europe

www.lightsources.org/cms/?pid=1000336#byfacility

BNC

ALS

Budapest Neutron Centre

Advanced Light Source

Deadlines for proposal submission: 15th May (estended 31st May) and 30th October 2008 www.bnc.hu/modules.php?name=News&file=article& sid=39

Deadlines for proposal submission: 15th January and 15th March 2008 www-als.lbl.gov/als/quickguide/independinvest.html

APS FRM-II

Advanced Photon Source

Deadlines for proposal submission: 25th January 2008 https://user.frm2.tum.de/

Deadlines for proposal submission: 7th March and 11th July 2008 www.aps.anl.gov/Users/Scientific_Access/General_User/ GUP_Calendar.htm

GeNF Geesthacht Neutron Facility

BESSY

Deadlines for proposal submission: Anytime during 2008 www.gkss.de/index_e.html

Deadlines for proposal submission: from 1st January to 15th February 2008 www.bessy.de/boat/www/

ILL

BSRF

Deadlines for proposal submission: 4th March 2008 www.ill.fr/users/user-news/

Beijing Synchrotron Radiation Facility Deadlines for proposal submission: Proposals are evaluated twice a year www.ihep.ac.cn/bsrf/english/userinfo/beamtime.htm

ISIS CFN

Deadlines for proposal submission: 16th April and16th October 2008 www.isis.rl.ac.uk/userOffice/

Center for Functional Nanomaterials Deadlines for proposal submission: 31st January, 31st May and 30th September 2008 www.bnl.gov/cfn/user/proposal.asp

LLB-ORPHEE-SACLAY Deadlines for proposal submission: 1st April and 1st October 2007 www-llb.cea.fr/index_e.html

CHESS Cornell High Energy Synchrotron Source Deadlines for proposal submission: 30th April and 31st October 2008 www.chess.cornell.edu/prposals/index.htm

SINQ Swiss Spallation Neutron Source Deadlines for proposal submission: 15th May 2008 http://sinq.web.psi.ch/sinq/sinq_call.html

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Vol. 13 n. 1 January 2008


CALL FOR PROPOSALS

CLS

SOLEIL

Canadian Light Source Deadlines for proposal submission: 31st March and 30th September 2008 www.lightsource.ca/uso/call_proposals.php

Deadlines for proposal submission: 15th February and 15th September 2008 http://www.synchrotron-soleil.fr/anglais/users/ index.html

ELETTRA

SPring-8

Deadlines for proposal submission: 29th February and from 1st July to 31st December 2008 https://vuo.elettra.trieste.it/pls/vuo/guest.startup

Deadlines for proposal submission: 22nd and 25th January, 4th and 7th February 2008 www.spring8.or.jp/en/news/proposal/res_bl41_38_07b/ announcements_view

ESRF

SRC

European Synchrotron Radiation Facility

Synchrotron Radiation Center

Deadlines for proposal submission: 15th January and 1st March 2008 www.esrf.eu/UsersAndScience/UserGuide/Applying/

Deadlines for proposal submission: 1st February and August 2008 www.src.wisc.edu/users/Forms/proposals.htm

HASYLAB

SSRL

Hamburger Synchrotronstrahlungslabor at DESY

Stanford Synchrotron Radiation Laboratory

Deadlines for proposal submission: 1st March 2008 http://hasylab.desy.de/user_info/write_a_proposal/ 2_deadlines/index_eng.html

Deadlines for proposal submission: 1st April, 1st May, 1st July, 1st November and 1st December 2008 www-ssrl.slac.stanford.edu/users/user_admin/ deadlines.html

NSLS National Synchrotron Light Source Deadlines for proposal submission: 31st January 2008 www.nsls.bnl.gov/

SLS Swiss Light Source Deadlines for proposal submission: 15th February, 15th March, 15th June, 15th September and 15th October 2008 http://sls.web.psi.ch/view.php/users/experiments/ proposals/opencalls/index.html

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CALENDAR

February 3-7, 2008

BIG SKY RESORT, USA

PXRMS 2008 The 9th International Conference on the Physics of X-Ray Multilayer Structures www.rxollc.com/pxrms/

February 13-15, 2008

nano tech 2008 International Nanotechnology Exhibition & Conference www.ics-inc.co.jp/nanotech/en/index.html

February 14-18, 2008 February 4-8, 2008

BOSTON, MA, USA

MELBOURNE, AUSTRALIA

AXAA 2008 Australian X-ray Analytical Association Inc. (AXAA) Schools, Advanced Workshops, Conference and Exhibition www.pco.com.au/axaa2008/

February 5-7, 2008

TOKYO, JAPAN

GRENOBLE, FRANCE

2008 AAAS Annual Meeting www.aaas.org/meetings/Annual_Meeting/

February 26-27, 2008

GRENOBLE, FRANCE

Powder Diffraction with 2-Dimensional Detectors PD2DD ILL http://wwwold.ill.fr/dif/PD2DD/

ESRF Users’ Meeting 2008 & Associated Workshops http://www.esrf.eu/events/announcements/ users-meeting-2008-associated-workshops March 3-7, 2008

February 10-15, 2008

SAINTE LUCE, MARTINIQUE

ICDS 2008 The Second International Conference on the Digital Society www.iaria.org/conferences2008/ICDS08.html

February 10-15, 2008

SAINTE LUCE, MARTINIQUE

ICQNM 2008 The Second International Conference on Quantum, Nano, and Micro Technologies www.iaria.org/conferences2008/ICQNM08.html

29th Berlin School on Neutron Scattering Hahn-Meitner-Institut, Berlin, Germany www.hmi.de/bensc/nschool2008/

March 5-8, 2008

GRENOBLE, FRANCE

1st ILL Annual School on Advanced Neutron Diffraction Data Treatment using the FullProf Suite ILL http://www.ill.eu/fpschool/

MITO, JAPAN

The First J-PARC International Symposium International Symposium on Pulsed Neutron and Muon Sciences (IPS 08) Ibarakiken Shichouson Kaikan, Mito, Japan www.ips08.com/

March 10-14, 2008

February 11-15, 2008

BERLIN, GERMANY

NEW ORLEANS, LA, USA

American Physical Society Meeting www.aps.org/meetings/march/index.cfm

March 24-28, 2008

SAN FRANCISCO, CA, USA

2008 MRS Spring Meeting www.mrs.org/s_mrs/sec.asp?CID=6689&DID=174642

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CALENDAR

April 3-4, 2008

TRIESTE, ITALY

Nanotechnologies applied to the aquatic environment Workshop www2.ogs.trieste.it/nanotechnologies/

April 6-10, 2008

May 26-29, 2008

5th International workshop on Sample Environment at Neutron Scattering Facilities Hôtel de Paris, 124 Place Pierre Chabert, 38250, Villard de Lans

NEW ORLEANS, LA, USA May 28 - June 1, 2008

235th American Chemical Society National Meeting & Exposition www.goingtomeet.com/conventions/details/10744

May 4-8, 2008

LAKE TAHOE, CA, USA May 29-31, 2008

GRENOBLE, FRANCE

Application of Neutron and Synchrotron Radiatation to Magnetism ILL The course is based on the 4th Hercules Short Course (HSC4) on Application of Neutron and Synchrotron Radiation to Magnetism, held between the 6th – 11th May 2007

May 11-15, 2008

SANTA FE, NM, USA

ACNS 2008 American Conference on Neutron Scattering http://lansce.lanl.gov/ACNS2008/index.html

GRENOBLE, FRANCE

International workshop on particle physics with slow neutrons ILL www.ill.eu/fileadmin/users_files/documents/ instruments_and_support/instruments_and_groups/ NPP/npp_workshop2008/start.html

June 7-14, 2008

BOMBANNES, GIRONDE, FRANCE

9th European Summer School on Scattering Methods applied to Soft Condensed Matter www.ill.eu/news-events/workshops-events/bombannes/

June 9-10, 2008

SASKATOON, CANADA

Canadian Light Source 11th Annual Users’ Meeting www.lightsource.ca/uac/meeting2008/index.php

June 9-12, 2008 May 21-23, 2008

AMSTERDAM, THE NETHERLANDS

WBC 2008 8th World Biomaterials Congress www.wbc2008.com/

BIW08 2008 Beam Instrumentation Workshop www-als.lbl.gov/biw08/

May 5-9, 2008

VILLARD DE LANS, FRANCE

CHONGQING, P.R. CHINA

GRENOBLE, FRANCE

Surfaces and Interfaces in Soft Matter and Biology the impact and future of neutron reflectivity ILL www.ill.fr/fileadmin/users_files/Other_Sites/events/ rktsymposium/index.html

2008 MRS International Materials Research Conference www.mrs.org/s_mrs/sec.asp?CID=7060&DID=178708

June 10-13, 2008

SASKATOON, CANADA

MEDSI/Pan-American SRI 2008 Meeting www.lightsource.ca/medsi-sri2008/index.php

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CALENDAR

June 15-20, 2008

AMELIOWKA, POLAND

ISSRNS 2008 9th International School and Symposium on Synchrotron Radiation in Natural Science www.synchrotron.org.pl/ISSRNS2008/

June 16-20, 2008

European Conference on X-Ray Spectrometry http://exrs2008.irb.hr/

July 21-25, 2008

XRM 2008 9th International Conference on X-Ray Microscopy http://xrm2008.web.psi.ch/

July 28 - August 1, 2008

SWEDEN AND DENMARK

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SYDNEY, AUSTRALIA

IUMRS-ICEM 2008 International Conference on Electronic Materials Symposium J: Synchrotron Radiation www.aumrs.com.au/ICEM-08/Symposia/?S=9

PCST-10 Malmรถ, Lund and Copenhagen, Sweden and Denmark www.vr.se/pcst

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ZURICH, SWITZERLAND

GENOA, ITALY

EPAC08 11th European Particle Accelerator Conference www.epac08.org/

June 25-27, 2008

CAMPINAS, BRAZIL

SRMS-6 6th International Conference on Synchrotron Radiation in Materials Science www.srms-6.com.br/

CAVTAT, DUBROVINIK, CROATIA

June 23-27, 2008

July 20-23, 2008

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FACILITIES

NEUTRON SOURCES NEUTRON SCATTERING WWW SERVERS IN THE WORLD (http://idb.neutron-eu.net/facilities.php) BNC - Budapest Research reactor Budapest Research Centre, Hungary Type: Swimming pool reactor, 10MW Email: tozser@sunserv.kfki.hu www.bnc.hu BENSC - Berlin Neutron Scattering Center Hahn-Meitner-Institut Glienicker Strasse 100 D-14109 Berlin, Germany Phone: +49/30/8062 2778 Fax: +49/30/8062 2523 E-mail: bensc@hmi.de www.hmi.de/bensc/index_en.html CNF Canadian Neutron Beam Centre National Research Council of Canada Building 459, Station 18 Chalk River Laboratories, Chalk River, Ontario Canada K0J 1J0 Phone: 1 (888) 243 2634 (toll free) / 1 (613) 584 8811 ext. 3973; Fax: 1 (613) 584 4040 http://cnf-ccn.gc.ca/home.html

FRJ-2 Forschungszentrum Jülich GmbH Type: DIDO (heavy water), 23 MW Research Centre Jülich, D-52425, Jülich, Germany E-mail: info@fz-juelich.de www.fz-juelich.de/iff/wns/ FRM, FRM-2 (D) Technische Universität München Type: Compact 20 MW reactor Flux: 8 x 1014 n/cm2/s Address for information: Prof. Winfried Petry, FRM-II Lichtenbergstrasse 1 - 85747 Garching Phone: 089 289 14701 Fax: 089 289 14666 E-mail: wpetry@frm2.tum.de www.frm2.tum.de/en/index.html HFIR ORNL, Oak Ridge, USA Phone: (865) 574 5231; Fax: (865) 576 7747 E-mail: ns_user@ornl.gov http://neutrons.ornl.gov/

FLNP - Frank Laboratory of Neutron Physics Gpulsed reactor, mean 2 MW, pulse 1500 MW Joint Institute for Nuclear Research Dubna, Russia E-mail: post@jinr.ru www.jinr.ru

HIFAR ANSTO, Australia New Illawarra Road, Lucas Heights NSW, Australia Phone: 61 2 9717 3111 E-mail: enquiries@ansto.gov.au www.ansto.gov.au/information_about/our_facilities.html

FRG-1 Geesthacht (D) Type: Swimming Pool Cold Neutron Source Flux: 8.7 x 1013 n/cm2/s Address for application forms and informations: Reinhard Kampmann, Institute for Materials Science, Div. Wfn-Neutronscattering, GKSS, Research Centre, 21502 Geesthacht, Germany Phone: +49 (0)4152 87 1316/2503; Fax: +49 (0)4152 87 1338 E-mail: reinhard.kampmann@gkss.de www.gkss.de

ILL Grenoble (F) Type: 58MW High Flux Reactor Flux: 1.5 x 1015 n/cm2/s Scientific Coordinator: Dr. G. Cicognani ILL, BP 156, 38042 Grenoble Cedex 9, France Phone: +33 4 7620 7179 Fax: +33 4 76483906 E-mail: cico@ill.fr and sco@ill.fr www.ill.fr

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FACILITIES

IPNS - Intense Pulsed Neutron at Argonne (USA) For proposal submission by e-mail send to cpeters@anl.gov or mail/fax to: IPNS Scientific Secretary, Building 360 Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439-4814, USA Phone: 630/252 7820; Fax: 630/252 7722 www.pns.anl.gov ISIS Didcot Type: Pulsed Spallation Source Flux: 2.5 x 1016n fast/s Address for application forms: ISIS Users Liaison Office, Building R3, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX Phone: +44 (0) 1235 445592 Fax: +44 (0) 1235 445103 E-mail: uls@isis.rl.ac.uk www.isis.rl.ac.uk

JEEP-II Reactor Kjeller Type: D2O moderated 3.5% enriched UO2 fuel. Flux: 2 x 1013 n/cm2/s Address for application forms: Institutt for Energiteknikk K.H. Bendiksen, Managing Director Box 40, 2007 Kjeller, Norway Phone: +47 63 806000 - 806275 Fax: +47 63 816356 E-mail: kjell.bendiksen@ife.no www.ife.no KENS Institute of Materials Structure Science High Energy Accelerator research Organisation 1-1 Oho, Tsukuba-shi, Ibaraki-ken, 305-0801, Japan E-mail: kens-pac@nml.kek.jp http://neutron-www.kek.jp/index_e.html

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LANSCE - Los Alamos Neutron Science Center TA-53, Building 1, MS H831 Los Alamos National Lab, Los Alamos, USA Phone: +1 505 665 8122 E-mail: tichavez@lanl.gov www.lansce.lanl.gov/index.html LLB Orphée Saclay (F) Type: Reactor. Flux: 3.0 x 1014 n/cm2/s Laboratoire Léon Brillouin (CEA-CNRS) E-mail: experience@llb.saclay.cea.fr www-llb.cea.fr/index_e.html

JRR-3M Tokai-mura, Naka-gun, Ibaraki-ken 319-11, Japan. Jun-ichi Suzuki, JAERI - Japan Atomic Energy Research Institute Yuji Ito (ISSP, Univ. of Tokyo) Fax: +81 292 82 59227; Telex: JAERIJ24596 E-mail: www-admin@www.jaea.go.jp http://ciscpyon.tokai-sc.jaea.go.jp/english/index.cgi

NOTIZIARIO NEUTRONI E LUCE DI SINCROTRONE

KUR - Kyoto University Research Reactor Institute Kumatori-cho Sennan-gun, Osaka 590-0494,Japan Phone:+81 72 451 2300; Fax:+81 72 451 2600 www.rri.kyoto-u.ac.jp/en/

NFL – Studsvick Neutron Research Laboratory Uppsala University Studsvik Nuclear AB, Stockholm, Sweden Type: swimming pool type reactor, 50 MW, with additional reactor 1 MW http://idb.neutron-eu.net/facilities.php NCNR - NIST Center for Neutron Research National Institute of Standards and Technology 100 Bureau Drive, MS 8560 Gaithersburg, MD 20899-8560, USA Patrick Gallagher, Director Phone: (301) 975 6210 Fax: (301) 869 4770 E-email: pgallagher@nist.gov http://rrdjazz.nist.gov NPL – NRI Type: 10 MW research reactor Address for informations: Zdenek Kriz, Scientific Secretary Nuclear Research Institute Rez plc, 250 68 Rez - Czech Republic Phone: +420 2 20941177 / 66173428 Fax: +420 2 20941155 E-mail: krz@ujv.cz and brv@nri.cz www.nri.cz

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FACILITIES

NRU Chalk River Laboratories The peak thermal flux 3x1014 cm-2 sec-1 Neutron Program for Materials Research National Research Council Canada Building 459, Station 18 Chalk River Laboratories Chalk River, Ontario - Canada K0J 1J0 Phone: 1 (888) 243 2634 (toll free) Phone: 1 (613) 584 8811 ext. 3973; Fax: 1 (613) 584 4040 http://neutron.nrc-cnrc.gc.ca/home.html

RID Reactor Institute Delft (NL) Type: 2MW light water swimming pool Flux: 1.5 x 1013 n/cm2/s Address for application forms: Dr. M. Blaauw, Head of Facilities and Services Dept. Reactor Institute Delft, Faculty of Applied Sciences Delft University of Technology, Mekelweg 15 2629 JB Delft, The Netherlands Phone: +31 15 2783528; Fax: +31 15 2788303 E-mail: m.blaauw@tudelft.nl www.rid.tudelft.nl

SINQ Villigen (CH) Type: Steady spallation source Flux: 2.0 x 1014 n/cm2/s Contact address: PSI-Paul Scherrer Institut User Office, CH-5232 Villigen PSI, Switzerland Phone: +41 56 310 4666; Fax: +41 56 310 3294 E-mail: sinq@psi.ch http://sinq.web.psi.ch SNS - Spallation Neutron Source ORNL, Oak Ridge, USA Address for information: Allen E. Ekkebus Spallation Neutron Source, Oak Ridge National Laboratory One Bethel Valley Road, Bldg 8600 P.O. Box 2008, MS 6460 Oak Ridge, TN 37831-6460 Phone: (865) 241 5644 Fax: (865) 241 5177 E-mail: ekkebusae@ornl.gov www.sns.gov

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FACILITIES

SYNCHROTRON RADIATION SOURCES SYNCHROTRON SOURCES WWW SERVERS IN THE WORLD (http://www.lightsources.org/cms/?pid=1000098)

ALBA – Synchrotron Light Facility CELLS - ALBA Edifici Ciències. C-3 central. Campus UAB Campus Universitari de Bellaterra. Universitat Autònoma de Barcelona 08193 Bellaterra, Barcelona – Spain Phone: +34 93 592 43 00 Fax: +34 93 592 43 01 www.cells.es

BSRF - Beijing Synchrotron Radiation Facility BEPC National Laboratory Institute of High Energy Physics Chinese Academy of Sciences P.O. Box 918 Beijing 100039 – P.R. China Phone: +86-10-68235125 Fax: +86-10-68222013 E-mail: houbz@mail.ihep.ac.cn www.ihep.ac.cn/bsrf/english/main/main.htm

ALS - Advanced Light Source Berkeley Lab, 1 Cyclotron Rd, MS6R2100, Berkeley, CA 94720 Phone: +1 510 486 7745 Fax: +1 510 486 4773 E-mail: alsuser@lbl.gov www-als.lbl.gov/als/

CAMD - Center Advanced Microstructures & Devices CAMD/LSU 6980 Jefferson Hwy. – Baton Rouge, L.A. 70806 USA Phone: +1 (225) 578 8887 Fax : +1 (225) 578 6954 E-mail: leeann@lsu.edu www.camd.lsu.edu

ANKA Forschungszentrum Karlsruhe Institut für Synchrotronstrahlung Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany Phone: +49 (0)7247 82 6071 Fax: +49-(0)7247 82 6172 E-mail: info@fzk.de http://ankaweb.fzk.de/

CANDLE - Center for the Advancement of Natural Discoveries using Light Emission Acharyan 31 375040, Yerevan, Armenia Phone/Fax: +374 1 629806 E-mail: baghiryan@asls.candle.am www.candle.am/index.html

APS - Advanced Photon Source Argonne Nat. Lab. 9700 S. Cass Avenue, Argonne, Il 60439, USA Phone: (630) 252 2000, Fax: +1 708 252 3222 E-mail: fenner@aps.anl.gov www.aps.anl.gov

CFN - Center for Functional Nanomaterials User Administration Office Brookhaven National Laboratory P.O. Box 5000, Bldg. 555 Upton, NY 11973-5000, USA Phone: +1 (631) 344 6266 Fax: +1 (631) 344 3093 E-mail: cfnuser@bnl.gov www.bnl.gov/cfn/

AS - Australian Synchrotron Level 17, 80 Collins St., Melbourne, VIC 3000, Australia Phone: +61 3 9655 3315 Fax: +61 3 9655 8666 E-mail: contact.us@synchrotron.vic.gov.au www.synchrotron.vic.gov.au/content.asp?Document_ID=1

CHESS - Cornell High Energy Synchrotron Source Cornell High Energy Synchrotron Source 200L Wilson Lab, Rt. 366 & Pine Tree Road Ithaca, NY 14853 – USA Phone: +1 (607) 255 7163 , +1 (607) 255 9001 www.chess.cornell.edu

BESSY - Berliner Elektronenspeicherring Gessellschaft. für Synchrotronstrahlung BESSY GmbH, Albert Einstein Str.15, 12489 Berlin, Germany Phone: +49 (0)30 6392 2999 Fax: +49 (0)30 6392 2990 E-mail: info@bessy.de www.bessy.de

CLIO - Centre Laser Infrarouge d’Orsay CLIO/LCP Bat. 201 - P2 Campus Universitaire 91405 ORSAY Cedex, France www.lcp.u-psud.fr/clio/clio_eng/clio_eng.htm

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FACILITIES

CLS - Canadian Light Source Canadian Light Source Inc. University of Saskatchewan 101 Perimeter Road Saskatoon, SK. Canada. S7N 0X4 Phone: (306) 657 3500; Fax: (306) 657 3535 E-mail: clsuo@lightsource.ca www.lightsource.ca

ELETTRA Synchrotron Light Lab. Sincrotrone Trieste S.C.p.A Strada Statale 14 - Km 163,5 in AREA Science Park, 34012 Basovizza, Trieste, Italy Phone: +39 40 37581 Fax: +39 (040) 938 0902 www.elettra.trieste.it

CNM - Center for Nanoscale Materials Argonne National Laboratory 9700 S. Cass Avenue. Bldg. 440 Argonne, IL 60439, USA Phone: (630) 252 2000 http://nano.anl.gov/facilities/index.html

ELSA - Electron Stretcher Accelerator Physikalisches Institut der Universität Bonn Beschleunigeranlage ELSA, Nußallee 12, D-53115 Bonn, Germany Phone: +49 228 735926 Fax +49 228 733620 E-mail: roy@physik.uni-bonn.de www-elsa.physik.uni-bonn.de/elsa-facility_en.html

CTST - UCSB Center for Terahertz Science and Technology University of California, Santa Barbara (UCSB), USA http://sbfel3.ucsb.edu/

ESRF - European Synchrotron Radiation Lab. ESRF, 6 Rue Jules Horowitz, BP 220, 38043 Grenoble Cedex 9 FRANCE Phone: +33 (0)4 7688 2000 Fax: +33 (0)4 7688 2020 E-mail: useroff@esrf.fr www.esrf.eu

DAFNE Light INFN – LNF Via Enrico Fermi, 40, I-00044 Frascati (Rome), Italy fax: +39 6 94032597 www.lnf.infn.it/esperimenti/sr_dafne_light/ DELSY - Dubna ELectron SYnchrotron JINR Joliot-Curie 6, 141980 Dubna, Moscow region, Russia Phone: + 7 09621 65 059 Fax: + 7 09621 65 891 E-mail: post@jinr.ru www.jinr.ru/delsy/

FELBE - Free-Electron Lasers at the ELBE radiation source at the FZR/Dresden Bautzner Landstrasse 128 – 01328 Dresden, Germany www.fzd.de/db/Cms?pNid=471 FELIX - Free Electron Laser for Infrared eXperiments FOM Institute for Plasma Physics 'Rijnhuizen' Edisonbaan, 14 3439 MN Nieuwegein, The Netherlands P.O. Box 1207, 3430 BE Nieuwegein, The Netherlands Phone: +31 30 6096999 Fax: +31 30 6031204 E-mail: B.Redlich@rijnh.nl www.rijnh.nl/felix/

DELTA - Dortmund Electron Test Accelerator FELICITA I (FEL) Institut für Beschleunigerphysik und Synchrotronstrahlung, Universität Dortmund Maria-Goeppert-Mayer-Str. 2, 44221 Dortmund, Germany Fax: +49 (0)231 755 5383 http://www.delta.uni-dortmund.de/ index.php?id=2&L=1

HASYLAB - Hamburger Synchrotronstrahlungslabor DORIS III, PETRA II / III, FLASH DESY - HASYLAB Notkestrasse 85, 22607 Hamburg, Germany Phone: +49 40/8998 2304 Fax: +49 40/8998 2020 E-mail: HASYLAB@DESY.de http://hasylab.desy.de/

DFELL - Duke Free Electron Laser Laboratory Duke Free Electron Laser Laboratory P.O. Box 90319 Duke University Durham, North Carolina 27708-0319 USA Phone: 1 (919) 660 2666; Fax: +1 (919) 660 2671 E-mail: beamtime@fel.duke.edu www.fel.duke.edu Diamond Light Source Diamond Light Source Ltd Diamond House, Chilton, Didcot OXON OX11 0DE UK Phone: +44 (0)1235 778000; Fax: +44 (0)1235 778499 E-mail: useroffice@diamond.ac.uk http://www.diamond.ac.uk/default.htm

HSRC Hiroshima Synchrotron Radiation Center - HiSOR Hiroshima University 2-313 Kagamiyama, Higashi-Hiroshima, 739-8526 Japan Phone: +81 82 424 6293 Fax: +81 82 424 6294 www.hsrc.hiroshima-u.ac.jp/index.html

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FACILITIES

iFEL Institute of Free Electron Laser, Graduate School of Engineering, Osaka University 2-9-5 Tsuda-Yamate, Hirakata, Osaka 573-0128 Japan Phone: +81 (0)72 897 6410 www.fel.eng.osaka-u.ac.jp/english/index_e.html INDUS -1 / INDUS -2 Centre for Advanced Technology Department of Atomic Energy Government of India P.O.: CAT Indore M.P. - 452 013 India Phone: +91 731 248 8003 Fax: 91 731 248 8000 E-mail: rvn@cat.ernet.in www.cat.ernet.in/technology/accel/indus/index.html www.cat.ernet.in/technology/accel/atdhome.html IR FEL Research Center – FEL-SUT IR FEL Research Center Research Institutes for Science and Technology The Tokyo University of Science, Yamazaki 2641, Noda, Chiba 278-8510, Japan Phone: +81 4 7121 4290 Fax: +81 4 7121 4298 E-mail: felsut@rs.noda.sut.ac.jp www.rs.noda.sut.ac.jp/~felsut/english/index.htm ISA - Institute for Storage Ring Facilities – ASTRID-1 ISA, University of Aarhus, Ny Munkegade, bygn. 520, DK-8000 Aarhus C, Denmark Phone: +45 8942 3778 Fax: +45 8612 0740 E-mail: fyssp@phys.au.dk www.isa.au.dk

KSR Nuclear Science Research Facility Accelerator Laboratory Gokasho,Uji, Kyoto 611 Fax: +81 774 38 3289 wwwal.kuicr.kyoto-u.ac.jp/www/index-e.htmlx KSRS - Kurchatov Synchrotron Radiation Source KSRS - Siberia-1 / Siberia-2 Kurtchatov Institute 1 Kurtchatov Sq., Moscow 123182, Russia http://www.kiae.ru/ LCLS - Linac Coherent Light Source Stanford Linear Accelerator Center (SLAC) 2575 Sand Hill Road, MS 18, Menlo Park CA 94025 USA Phone: +1 (650) 926 3191 Fax: +1 (650) 926 3600 E-mail: knotts@ssrl.slac.stanford.edu www-ssrl.slac.stanford.edu/lcls/ LNLS - Laboratorio Nacional de Luz Sincrotron Caixa Postal 6192, CEP 13084-971 Campinas, SP, Brazil Phone: +55 (0) 19 3512 1010 Fax: +55 (0)19 3512 1004 E-mail: sau@lnls.br www.lnls.br/index.asp?idioma=2&opcaoesq MAX-Lab Box 118, University of Lund, S-22100 Lund, Sweden Phone: +46 222 9872; Fax: +46 222 4710 www.maxlab.lu.se/ Medical Synchrotron Radiation Facility National Institute of Radiological Sciences (NIRS) 4-9-1, Anagawa, Inage-ku, Chiba-shi, 263-8555, Japan Phone: +81 (0)43 251 2111 http://www.nirs.go.jp/ENG/index.html

ISI-800 Institute of Metal Physics National Academy of Sciences of Ukraine Phone: +(380) 44 424 1005 Fax: +(380) 44 424 2561 E-mail: metall@imp.kiev.ua Jlab - Jefferson Lab FEL 12000 Jefferson Avenue, Newport News, Virginia 23606 USA Phone: (757) 269 7767 www.jlab.org/FEL

MLS - Metrology Light Source Physikalisch-Technische Bundesanstalt Willy-Wien-Laboratorium Magnusstraße 9, 12489 Berlin, Germany Phone: +49 30 3481 7312; Fax: +49 30 3481 7550 E-mail: Gerhard.Ulm@ptb.de www.ptb.de/mls/

Kharkov Institute of Physics and Technology Pulse Stretcher/Synchrotron Radiation National Science Center, KIPT, 1 Akademicheskaya St., Kharkov, 61108 Ukraine Phone: 38 (057) 335 35 30 Fax: 38 (057) 335 16 88 http://www.kipt.kharkov.ua/.indexe.html

NSLS - National Synchrotron Light Source NSLS User Administration Office Brookhaven National Laboratory, P.O. Box 5000, Bldg. 725B Upton, NY 11973-5000 USA Phone: +1 (631) 344 7976; Fax: +1 (631) 344 7206 E-mail: nslsuser@bnl.gov www.nsls.bnl.gov

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FACILITIES

SESAME Synchrotron-light for Experimental Science and Applications in the Middle East E-mail: hhelal@mailer.eun.eg www.sesame.org.jo/index.aspx

NSRL - National Synchrotron Radiation Lab. University od Science and Technology China (USTC) Hefei, Anhui 230029, P.R. China Phone: +86 551 5132231, 3602034 Fax: +86 551 5141078 E-mail: zdh@ustc.edu.cn www.nsrl.ustc.edu.cn/en/

SLS - Swiss Light Source Paul Scherrer Institut reception building, PSI West, CH-5232 Villigen PSI, Switzerland Phone: +41 56 310 4666; Fax: +41 56 310 3294 E-mail: slsuo@psi.ch http://sls.web.psi.ch/view.php/about/index.html

NSRRC - National Synchrotron Radiation Research Center National Synchrotron Radiation Research Center 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan, R.O.C. Phone: +886 3 578 0281 Fax: +886 3 578 9816 E-mail: user@nsrrc.org.tw www.nsrrc.org.tw NSSR - Nagoya University Small Synchrotron Radiation Facility Nagoya University 4-9-1,Anagawa, Inage-ku, Chiba-shi, 263-8555 Japan Phone: +81 (0)43 251 2111 www.nagoya-u.ac.jp/en/ PAL - Pohang Accelerator Lab. San-31 Hyoja-dong Pohang, Kyungbuk 790-784, Korea http://pal.postech.ac.kr/eng/index.html PF - Photon Factory KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan Phone: +81 (0) 29 879 6009; Fax: +81 (0) 29 864 4402 E-mail: users.office2@post.kek.jp http://pfwww.kek.jp/ PSLS - Polish Synchrotron Light Source Centrum Promieniowania Synchrotronowego Sp. z o.o.ul. Reymonta 4, PL - 30-059 Krakรณw Phone: +48 (12) 663 58 20 E-mail: mail@synchrotron.pl www.if.uj.edu.pl/Synchro/ RitS Ritsumeikan University SR Center Ritsumeikan University (RitS) SR Center Biwako-Kusatsu Campus, Noji Higashi 1-chome, 1-1 Kusatsu, 525-8577 Shiga-ken, Japan Phone: +81 (0)77 561 2806 Fax: +81 (0)77 561 2859 E-mail: d11-www-adm@se.ritsumei.ac.jp www.ritsumei.ac.jp/se/re/SLLS/newpage13.htm SAGA-LS - Saga Light Source Kyushu Synchrotron Light Research Center 8-7 Yayoigaoka, Tosu, Saga 841-0005, Japan Phone: +81 942 83 5017; Fax: +81 942 83 5196 www.saga-ls.jp/english/index.htm

SOLEIL Synchrotron SOLEIL L'Orme des Merisiers Saint-Aubin - BP 48 91192 Gif-sur-Yvette Cedex, France Phone: +33 1 6935 9652; Fax: +33 1 6935 9456 E-mail: frederique.fraissard@synchrotron-soleil.fr http://www.synchrotron-soleil.fr/ SPL - Siam Photon Laboratory The Siam Photon Laboratory of the National Synchrotron Research Center 111 University Avenue, Muang District, Nakhon Ratchasima 30000, Thailand PO. Box 93, Nakhon Ratchasima 30000, Thailand Phone: +66 44 21 7040 Fax: +66 44 21 7047, +66 44 21 7040, ext. 211 www.nsrc.or.th/eng/ SPring-8 Japan Synchrotron Radiation Research Institute (JASRI) Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan Phone: +81 (0) 791 58 0961 Fax: +81 (0) 791 58 0965 E-mail: sp8jasri@spring8.or.jp www.spring8.or.jp/en/ SRC - Synchrotron Radiation Center Synchrotron Radiation Center 3731 Schneider Dr., Stoughton, WI 53589-3097, USA Phone: +1 (608) 877 2000 Fax: +1 (608) 877 2001 www.src.wisc.edu SRS - Synchrotron Radiation Source CCLRC Daresbury Laboratory, Warrington, Cheshire, UK WA4 4AD Phone: +44 (0)1925 603223 Fax: +44 (0)1925 603174 E-mail: srs-ulo@dl.ac.uk www.srs.ac.uk/srs/

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FACILITIES

SSLS Singapore Synchrotron Light Source – Helios II National University of Singapore (NUS) Singapore Synchrotron Light Source, National University of Singapore 5 Research Link, Singapore 117603, Singapore Phone: (65) 6874 6568; Fax: (65) 6773 6734 http://ssls.nus.edu.sg/index.html SSRC Siberian Synchrotron Research Centre VEPP3/VEPP4 Lavrentyev av. 11, Budker INP, Novosibirsk 630090, Russia Phone: +7 (3832) 39 44 98; Fax: +7 (3832) 34 21 63 E-mail: G.N.Kulipanov@inp.nsk.su http://ssrc.inp.nsk.su/english/load.pl?right=general.html SSRF - Shanghai Synchrotron Radiation http://ssrf.sinap.ac.cn/english/ SSRL - Stanford Synchrotron Radiation Lab. Stanford Linear Accelerator Center, 2575 Sand Hill Road, Menlo Park, CA 94025, USA Phone: +1 650 926 4000; Fax: +1 650 926 3600 E-mail: knotts@ssrl.slac.stanford.edu www-ssrl.slac.stanford.edu/users/user_admin/ ura_staff_new.html

SURF-II / SURF-III - Synchrotron Ultraviolet Radiation Facility NIST, 100 Bureau Drive, Stop 3460, Gaithersburg, MD 20899-3460 USA Phone: +1 301 975 6478 http://physics.nist.gov/MajResFac/SURF/SURF/ index.html TNK _ F.V. Lukin Institute State Research Center of Russian Federation 103460, Moscow, Zelenograd Phone: +7(095) 531 1306 / +7(095) 531 1603 Fax: +7(095) 531 4656 E-mail: admin@niifp.ru http://www.niifp.ru/index_e.html TSRF - Tohoku Synchrotron Radiation Facility Laboratory of Nuclear Science Tohoku University Phone: +81 (022) 743 3400; Fax: +81 (022) 743 3401 E-mail: koho@LNS.tohoku.ac.jp www.lns.tohoku.ac.jp/index.php UVSOR - Ultraviolet Synchrotron Orbital Radiation Facility UVSOR Facility, Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan www.uvsor.ims.ac.jp/defaultE.html VU FEL – W. M. Keck Vanderbilt Free-electron Laser Center 410 24th Avenue Nashville, TN 37212, Box 1816, Stn B, Nashville, TN 37235 USA www.vanderbilt.edu/fel/

SRS - Synchrotron Radiation Source CCLRC Daresbury Lab. Warrington, Cheshire, WA4 4AD, U.K. Phone: +44 (0)1925 603223 Fax: +44 (0)1925 603174 E-mail: srs-ulo@dl.ac.uk www.srs.ac.uk/srs/ SuperSOR Synchrotron Radiation Facility Synchrotron Radiation Laboratory Institute for Solid State Physics, University of Tokyo 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan Phone: +81 (0471) 36 3405; Fax: +81(0471) 34 6041 E-mail: kakizaki@issp.u-tokyo.ac.jp www.issp.u-tokyo.ac.jp/labs/sor/project/MENU.html

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NOTIZIARIO Neutroni e Luce di Sincrotrone - Issue 13 n.1, 2008  

Notiziario Neutroni e Luce di Sincrotrone is published by CNR (Publishing and Promotion of Scientific Information) in collaboration with the...