Review of (n,3n) reaction cross-sections for fast neutrons and its dependence on the neutron excess term

The available information on the (n,3n) reaction, as well as the neutron cross-sections for the neutron energies from 23 to 29 MeV are reviewed for the interval of 27< Z < 83 .. For practical purposes, an empirical expression has been found by using the experimental (n,3n) cross-sectIOn values as a functIOn of (N-Z) and (En + Qn)1/2 where (N-Z) is the neutron excess of the target nucleus, En and. Qn are the incident neutron energy and the (n,3n) reaction energy, respectively. It is seen that the en;tpmc~1 relatIOn gives good fits with the experimental values