Charge distribution in low energy fission of actinides

Abstract

Charge distribution studies were carried out for heavy mass fission products in the thermal neutron induced fission of 232U and 238Pu as well as in the spontaneous fission of 244Cm using off-line gamma ray spectrometry. The width parameter (σZ/σA), the most probable charge/mass (Zp/Ap) and the charge polarization (ΔZ) as a function of fragment mass were deduced. The slope of charge polarization with mass asymmetry (δ(ΔZ)/δA′), average charge dispersion parameter (⟨σZ⟩) and proton odd–even effect (δp) were also obtained for these fissioning systems. The δ(ΔZ)/δA′ and ⟨σZ⟩ for the above three fissioning systems are determined for the first time. The δp value in 244Cm(SF) is also determined for the first time. These data along with the literature data for other even-Z fissioning systems such as 230Th*, 232Th*, 233Th*, 234U*, 236U*, 238U*, 239U*, 240Pu*, 241Pu*, 242Pu*, 245Cm*, 246Cm*, 250Cf* and 252Cf(SF) are discussed in terms of nuclear structure effect and dynamics of descent from saddle to the scission point. The role of excitation energy in low energy fission is also discussed by comparing the data of spontaneous, thermal and fast neutron induced fission of actinides.