Statistical Model Analysis of Neutron Multiplicities from Fission of Compound Nuclei in ~ 200 and 250 Mass Region

Statistical model analysis has been performed with and without the inclusion of shell correction in level density and the collective enhancement of level density (CELD) effect for two different mass regions of compound nuclei, i.e., ~ 200 and 250 for the currently available data of neutron multiplicity (M_pre) in the literature in both mass regions. The chosen reactions have comparable excitation energy range. The measured neutron multiplicities are found to be increasing with the excitation energy of the compound nuclei for all the studied reactions except for ¹⁹F + ¹⁸4W. The calculated values of pre-scission neutron multiplicities are found to be significantly underestimated when compared to the experimental values for overlapping excitation energy range for both mass regions and found to be further underestimated in the heavier mass region (A_CN ~ 250) as compared to the relatively lighter mass region (A_CN ~ 200). The dissipation strength required to reproduce experimental values is found to increase with an increase in excitation energy of the compound nucleus in both the mass regions. Dissipation strength was found to be higher when the effects of shell correction in level density and CELD were included as compared to the dissipation obtained without incorporating these effects.