Parity deduction from cross section analysis of isotopes of some transuranium elements

Abstract

Coupled-channels optical model code OPTMAN is used as an alternative to experimental approach to evaluate the total reaction cross section for eight selected isotopes of heavy rotational nuclei of the transuranium elements over an energy range of 10 to 20 MeV. The selected isotopes are the ₉₃Np²³⁷, ₉₄Pu²³⁸, ₉₄Pu²⁴⁰, ₉₄Pu²⁴¹, ₉₄Pu²⁴², ₉₅Am²⁴³, ₉₆Cm²⁴⁴ and ₉₅Am²⁴⁵. Their choice is as a result of their importance in the modern day nuclear reactor and the energy range 10 – 20 MeV is the energy range of neutron produced in neutron generators and the maximum energy possessed by neutrons which are born in fission reaction. Results show that the percentage deviation of total cross section from ENDF values obtained for this work is less than 1% at 14 MeV and above for ₉₃Np²³⁷ and at 16 MeV and above for ₉₄Pu²³⁸, ₉₄Pu²⁴⁰, ₉₄Pu²⁴¹ and ₉₅Am²⁴³ while at 18 MeV and above for ₉₄Pu²⁴², ₉₆Cm²⁴⁴ and ₉₅Am²⁴⁵. This work observed that the nucleus of transuranium elements is symmetric and the activities of rotation and vibrations (β–quadrupole, octupole vibrations and γ-quadrupole vibrations) cannot be ignored. Deductions in terms of parity in the transuranium elements revealed that the effects of the collective characteristics are exhibited by the neutrons and countered by the protons. This work compared well with the 6 % of Basunia in 2009 and 5 % of Paradela in 2011 using indirect measurement based on the surrogate ratio method and ECIS code respectively and is found to agree with about 1.3 % increase in accuracy.