Mass resolved angular distribution inB10,C

Abstract

The recoil catcher technique and gamma spectrometric assay of fission products were used to measure angular distribution of 17 fission products in B, C, and 0 induced fission of Th at near barrier energies. The observed mass dependence of anisotropies of fission products in these systems is very different from that of p and n induced fission of Th at similar excitation energies. It has been suggested that the difference in the rotational energy for the symmetric and asymmetric modes for large compound nucleus spins could be responsible for the observed variation. No systematic change in the mass dependence of anisotropies across the Bussinaro-Gallone point was observed. For 0 induced fission of Th, sharp variation in anisotropies has been observed in the mass region 120 -135. This has been attributed to transfer induced fission.PACS number(s): 25.85.Ge

Statistical and dynamical aspects in fission process: The rotational degrees of freedom

“…A comprehensive analysis of the experimental data using theoretically generated correlations has not been done yet. For instance, for the 10 B+ 232 Th and 16 O+ 232 Th reactions studied in [26], the compound nuclear parameters are such that the standard saddle-point TSM predicts the same value of angular anisotropy for all masses (horizontal line in figure 3). However, the experimental data show significant deviations from this value with a certain clear pattern (symbols in figure 3), with differing magnitudes for the two reactions.…”

“…Experimental data on angular anisotropy vs. fission product mass measured using recoil catcher technique in the two reactions explained in §3.2. Experimental data are from [26]. The horizontal line is the value of anisotropy calculated using the saddle-point TSM which is very nearly the same for the two reactions [26].…”

“…Experimental data are from [26]. The horizontal line is the value of anisotropy calculated using the saddle-point TSM which is very nearly the same for the two reactions [26].…”

“…However, the experimental data show significant deviations from this value with a certain clear pattern (symbols in figure 3), with differing magnitudes for the two reactions. Pre-saddle neutron emission or influences of transfer-induced fission or pre-equilibrium fission cannot explain this observation adequately [26].…”

“…For fission induced by light particles like n, p, and α, the total angular momenta J are generally low and the influence of K on this correlation has been examined [24,25]. For heavy-ion reactions, both J and K can influence this correlation [26]. A comprehensive analysis of the experimental data using theoretically generated correlations has not been done yet.…”