4th.nuclear.assi

Page 1

Q.1

Therefore

so

is given

M = 30

so we have :

we can actually workout the energy level :

Looking at the NNDC : we can tell that the three low-energy groups crosspond to the first three 2+ excited states.


........... ....... ...... .....


Q.2


Q.3 a) The absorption coefficient:

given that

b) The effective cross-section inbarns, assuming that the absorption is totally due to hydrogen (which is true because the absorption cross-section of oxygen is very small compared to hydrogen.

finding the R for Hyderogen effective cross-section = C) The thickness of water needed to reduce the flux to one-tenth and to one hundredth.:


d. The mean free path for thermal neutrons in water


Explain briefly and clearly whether it is ever possible to use neutrons from 14C(p,n)14N to produce the inverse reaction 14N(n,p)14C in another target. these are two reaction that we are looking at :

and

are spinless and the condition for inverse reaction for these two reactions is if the cross-section which is just the reverse reaction

from the equation :

Therefore we can not use neutrons from 14C(p,n)14N to produce the inverse reaction 14N(n,p)14C in another target.


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