235mU and 235U neutron-induced fissionV.M. Maslov
Joint Institute for Nuclear and Energy Research, 220109 Minsk-Sosny, Belarus
Published online: 21 May 2008
Neutron cross sections of 235U and 235mU are obtained via Hauser-Feshbach model calculations. The cross section differences are attributed to the spectroscopic properties of the transition states at saddle deformations of 236U and the coupling strengths of the deformed optical potential for the target spin values 7/2- and 1/2+. The 235mU(n,f) cross section at En ≲ 0.1 MeV depends on the position of octupole states at outer saddle, being ~2 times lower than that of 235U(n,f) at En ~ 1 keV. The capture-to-fission ratio of 235U and 235mU is affected at En ≲ 0.1 MeV, being ~2 times higher for the latter at En ~ 1 keV. 235U(n,xn) reaction cross sections and prompt fission neutron spectra (PFNS) are dependent on the emissive fission chances contributions to the observed σ(n,F) of 235U, which are much different from the latest evaluations of ENDF/B and JEFF. The role of exclusive pre-fission (n,xnf) neutron spectra for the 235U(n,F) PFNS description and prediction of PFNS for 239Pu(n,F) is exemplified.
© CEA 2008