# Difference between revisions of "Nucleus Recoil-Energy in Neutron Capture Reactions"

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The conservation of momentum demands that<br> | The conservation of momentum demands that<br> | ||

− | <math>\overrightarrow{P}_n + \overrightarrow{P}_T = \overrightarrow{P}_{T+n} = \overrightarrow{P}_R</math> | + | <math>\overrightarrow{P}_n + \overrightarrow{P}_T = \overrightarrow{P}_{T+n} = \overrightarrow{P}_R</math> |

− | where P denotes the momentum, index n denots the neutron, index T the target nucleus, and index R the recoil. | + | where P denotes the momentum, index ''n'' denots the neutron, index ''T'' the target nucleus, and index ''R'' the recoil. |

− | The kinetic energy, E<sub>K</sub>, is given by: | + | The general relationship between kinetic energy, ''E<sub>K</sub>'', and momentum ''p'' is given by: |

− | <math>E_K = \frac{\ | + | <math>E_K = \frac{\overrightarrow{p}^2}{2m}</math> |

+ | |||

+ | 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 | ||

+ | |||

+ | | ||

==== Recoil energy from γ emission<br> ==== | ==== Recoil energy from γ emission<br> ==== | ||

d | d |

## Revision as of 14:16, 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, *E _{K}*, 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

#### Recoil energy from γ emission

d