Fission fragment angular momentum in the spontaneous fission of 244Cm

Abstract

Summary Independent isomeric yield ratios (IYR) of 128Sb, 130Sb, 132Sb, 131Te, 133Te, 132I, 134I, 135Xe and 138Cs have been determined in the spontaneous fission of 244Cm using off-line gamma ray spectrometric technique. From the IYR, fragment angular momenta (J rms) have been deduced using spin dependent statistical model analysis. It was observed that: (i) J rms of fragments having spherical 82n shell and even-Z products are lower than the fragments away from spherical neutron shell and odd-Z products which indicates the effect of nuclear structure. (ii) The yield-weighted average angular momentum shows an inverse correlation with the elemental yield which indicate coupling between collective and intrinsic degrees of freedom. (iii) Comparison of the present data in 244Cm(SF) with similar data for 245Cm(n th, f) shows comparable odd-even effect on fragment angular momentum in both fissioning systems inspite of higher odd-even effect on elemental yield in the former compared to latter. This may be due to the linear correlation of J rms with deformation parameter and thus with deformation energy unlike the exponential dependence of the proton odd-even effect on intrinsic excitation energy.