Post-Neutron Mass Yield Distribution in the Thermal Neutron Induced Fission of ²³³U

Abstract

In the thermal neutron–induced fission of ²³³U, the cumulative and independent yields of various fission products within the mass ranges of 77 to 109 and 123 to 155 have been measured by using an off-line gamma-ray spectrometric technique. The lower yields of ⁸⁶Br and ¹³⁶I than usual trend indicate the formation of delayed neutron emitters ⁸⁷Br and ¹³⁷I. From the cumulative yields, the post-neutron mass yield distribution was obtained after applying the charge distribution correction. The data from the present and earlier work of our laboratory in the ²³³U(n_th,f) reaction were compared with similar data of ^232,235U(n_th,f) and ²³⁸U(n,f) reactions to examine the effect of mass difference of the fissioning systems on the fine structure of the mass yield distribution. The mass yield distribution in the ²³³U(n_th,f) reaction was also compared with those of ²²⁹Th(n_th,f), ²⁴¹Pu(n_th,f), and ²⁴⁵Cm(n_th,f) reactions to examine the effect of charge and mass difference of the fissioning systems and also to examine the different behaviors of standard I and standard II asymmetric modes of fission.

Keywords:

• ²³³U(n,f) reaction
• measured fission product yields
• mass chain yield distribution
• off-line gamma-ray spectrometric technique

Acknowledgments

We are thankful to R. H. Iyer of the BARC Radiochemistry Division for his keen interest and support during this work. The authors are also thankful to members of the staff of the reactors CIRUS and APSARA at BARC for their help in providing the irradiation facility and successfully carrying out the irradiations during the experiment.

Disclosure Statement

No potential conflict of interest was reported by the author(s).