Charge Distribution in Fission: Fractional Cumulative Fission Yields ofBa143andBa144from Thermal-Neutron-Induced Fission ofU235

Abstract

Rapid chemical separations of Cs and Ba from La and Ce have been used to measure half-lives and cumulative yields of $^{143}\mathrm{Ba}$ and $^{144}\mathrm{Ba}$ from thermal-neutron-induced fission of $^{235}\mathrm{U}$. The half-lives are 13.2\ifmmode\pm\else\textpm\fi{}0.3 sec for $^{143}\mathrm{Ba}$ and 11.9\ifmmode\pm\else\textpm\fi{}0.3 sec for $^{144}\mathrm{Ba}$. The yields, each expressed as a fraction of the total chain, are 0.88\ifmmode\pm\else\textpm\fi{}0.06 and 0.78\ifmmode\pm\else\textpm\fi{}0.06 for $^{143}\mathrm{Ba}$ and $^{144}\mathrm{Ba}$, respectively. Charge distribution for $A=144$ can be represented by a Gaussian distribution with width parameter $\ensuremath{\sigma}=0.52\ifmmode\pm\else\textpm\fi{}0.02$ and ${Z}_{p}=56.09\ifmmode\pm\else\textpm\fi{}0.05$. For $A=143$, $\ensuremath{\sigma}=0.58\ifmmode\pm\else\textpm\fi{}0.05$, and ${Z}_{p}=55.87\ifmmode\pm\else\textpm\fi{}0.05$, in agreement with previously reported values. Evidence is presented that charge distribution as determined from yields of several isotopes of the even-$Z$ elements Xe, Ba, Kr, and Sr can be satisfactorily represented by a single Gaussian distribution with $\ensuremath{\sigma}=0.56$. A possible even-odd effect in nuclear charge distribution from fission of $^{235}\mathrm{U}$ is noted.