Difference between revisions of "Nucleus Recoil-Energy in Neutron Capture Reactions"
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Jonpo@uio.no (talk | contribs) |
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(remember that the momemtun of the target nucleus initially is 0.) | (remember that the momemtun of the target nucleus initially is 0.) | ||
− | ==== Recoil energy from γ emission<br> ==== | + | ==== Recoil energy from γ emission<br> ==== |
− | + | For emission of the mass-less quantas we have the following relationship: | |
+ | |||
+ | <math>\overrightarrow{P}_R = \overrightarrow{P}_\gamma</math> | ||
+ | |||
+ | and | ||
+ | |||
+ | <math>P_\gamma = \frac{E_\gamma}{c}</math> |
Revision as of 13:27, 14 November 2012
A nucleus which captures a thermal neutron must, since the momentum is conserved, receive a recoil energy. Immediately after capturing a neutron, the nucleus will emit γ quantas to get rid of the excess energy liberated when the neutron is bound to the nucleus. This also result in a certain amount of recoil energy on the nucleus.
Recoil energy from n-capture
The conservation of momentum demands that
where P denotes the momentum, index n denots the neutron, index T the target nucleus, and index R the recoil.
The general relationship between kinetic energy, EK, and momentum p is given by:
The mass of the neutron is 1 (atomic mass unit). the mass of the target nucleus is A. The new nucleus will therefore have mass A+1. Then
(remember that the momemtun of the target nucleus initially is 0.)
Recoil energy from γ emission
For emission of the mass-less quantas we have the following relationship:
and