Energy dependence of nuclear charge distribution in neutron induced fission of Z-even nuclei

V. A. Roshchenko, V. M. Piksaikin, S. G. Isaev, and A. A. Goverdovski
Phys. Rev. C 74, 014607 – Published 21 July 2006

Abstract

For the first time the distribution of nuclear charge of fission products with mass numbers 87, 88, 89, 91, 93, 94, 95, 137, 138, 139, and 140 and their complementary products have been studied for neutron induced fission of U235 and Pu239 in the energy range from thermal up to 1.2 MeV. The energy dependences of the cumulative yields of Br87, Br88, Br89, Br91, Kr93, Rb94, Rb95, I137, I138, I139, and I140 have been obtained by delayed neutron measurements. The most probable charge ZP(A)in the appropriate isobaric β-decay chains was estimated. The results were analyzed in terms of the deviation ΔZP(A') of the most probable charge of isobaric β-decay chains from the unchanged charge distribution before prompt neutron emission (nuclear charge polarization) and they are compared with experimental data of other authors and with predictions from Nethaway's ZP-formula and Wahl's ZP-model. We show that the nuclear charge polarization of primary fission fragments ΔZP(A') before prompt neutron evaporation decreases as the excitation energy of the compound nucleus increases. This decrease is more pronounced for fission of U235. The energy dependencies of ΔZP(A') and ΔZP(ZP) obtained in the present work show an attenuation of the odd-even effects in the charge distribution as the excitation energy of the compound nucleus increases.

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  • Received 7 February 2005

DOI:https://doi.org/10.1103/PhysRevC.74.014607

©2006 American Physical Society

Authors & Affiliations

V. A. Roshchenko, V. M. Piksaikin, S. G. Isaev, and A. A. Goverdovski

  • Institute of Physics and Power Engineering, RU-249033, Obninsk, Russia

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Issue

Vol. 74, Iss. 1 — July 2006

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