The Super Kamiokande Detector
Departmental News
Top to bottom: Physics & Astronomy Thomas Kutter, Martin Tzanov, and William Metcalf
Physics &
Astronomy
LSU Physicists Highlighted in Physics World Top 10 Breakthroughs LSU Department of Physics & Astronomy Professors Thomas Kutter and Martin Tzanov and Professor Emeritus William Metcalf were recently recognized as part of the Physics World Top 10 Physics Breakthroughs of 2011 for their studies recording the first real indication of a new type of neutrino oscillation. The professors, along with graduate and undergraduate students, have been working for several years on an experiment in Japan called T2K, or Tokai to Kamioka, Long Baseline Neutrino Oscillation Experiment, which studies the most elusive of fundamental subatomic particles – the neutrino. In the spring of 2011, they announced an indication of a new type of neutrino transformation or oscillation from a muon neutrino to an electron neutrino. In the T2K experiment in Japan, a beam of muon neutrinos – one of the three types of neutrinos, which also include the electron and tau – was produced in the Japan Proton Accelerator Research Complex, or J-PARC, located in Tokai village, Ibaraki prefecture, on the east coast of Japan. The beam was aimed at the gigantic Super-Kamiokande underground detector in Kamioka, near the west coast of Japan, 295 km, or 185 miles away from Tokai. An analysis of the detected neutrino-induced events in the SuperKamiokande detector indicated that a small number of muon neutrinos traveling from Tokai to Kamioka transformed themselves into electron neutrinos. As part of the experiment, high energy protons were directed onto a carbon target, where their collisions produced charged particles called pions, which travelled through a helium-filled volume where they decayed to produce a beam of the elusive neutrinos. These neutrinos then flew about 200 meters through the earth to a sophisticated detector system capable of making detailed measurements of their energy, direction and type.
“It took the international collaboration about ten years to realize the project and bring it from first idea to first results,” said Kutter, leader of the T2K project at LSU. “The entire LSU team is honored to be part of the collaboration and proud to contribute to the experiment. We expect many more results in the near future and look forward to the new research opportunities which are likely to arise from the tantalizing indication of this new neutrino oscillation.” According to the article in Physics World, this breakthrough could allow researchers to pinpoint the final undetermined neutrino “mixing angle,” as well as provide a clue toward solving the mystery of why matter, rather than antimatter, dominates the universe. The physicists have been part of a number of measurements over the last decade, which include Super Kamiokande, SNO, and KamLAND that have shown that neutrinos possess the strange property of neutrino oscillations – one flavor of neutrino can transform into another as it travels through space. This is significant because neutrinos were first predicted theoretically in 1930, first actually detected in 1956 and for 50 years were assumed to have zero mass. But neutrino oscillations require mass. Work at T2K is ongoing, but was severely interrupted due to the 2011 earthquake in Japan that devastated the country’s infrastructure and caused significant loss of life and hardship to the nation’s population. T2K facilities were partially damaged, but a swift and dedicated recovery effort by many people led to the restart of the research facility in December 2011 and neutrino measurements resumed in January 2012. Photomultipliers from the Super Kamiokande experiment
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