NEUTRON AND γ-EMISSION FROM FISSION FRAGMENTS

Authors & Affiliations

Grudzevich O.T.
Institute of Nuclear Power Engineering, Obninsk, Russia

Abstract

The statistical model of nuclear reactions is applied to describe the fission fragment neutron and gamma emission characteristics for spontaneous fission of 252Cf and fission of 233U by thermal neutrons. Averaged excitation energies of fission fragments were obtained from experimental neutron multiplicities. The observable characteristics of an emission are reproduced in a wide range of complementary fragments’ total kinetic energies and fragment masses. Observed averaged spins are also reproduced. The fractional independent isomeric yield calculation method, based on the gamma-cascade model, is used to describe experimental data for the 235U(nth,f) and 238U (α,f) reactions. The influence on the calculated isomeric yields of two opposing assumptions regarding the nuclear population spin distributions - one based on the rotational degrees of freedom and one on the internal degrees of freedom of completely accelerated fragments - is investigated.

Keywords
spontaneous fission of 252Cf, thermal neutrons, excitation energies of fission fragments, gamma-cascade model, spin distributions

Article Text (in English, PDF, Translated by IAEA)

References

UDC 539.173.8

Problems of Atomic Science and Technology. Series: Nuclear Constants, issue 1, 2000