Fission fragment angular momentum: Ratios of independent yields of isomers ofNb95andI132in thermal-neutron-induced fission ofU233

Abstract

Independent isomeric yield ratios of the fission products $^{95}\mathrm{Nb}$ and $^{132}\mathrm{I}$ in thermal-neutron-induced fission of $^{233}\mathrm{U}$ have been determined radiochemically. The determined ratios are 0.248 \ifmmode\pm\else\textpm\fi{} 0.029 and 0.268 \ifmmode\pm\else\textpm\fi{} 0.084 for the isomers of $^{95}\mathrm{Nb}$ and of $^{132}\mathrm{I}$, respectively. On the basis of these yield ratios the average angular momenta of the primary fragments, respective of the fission products $^{95}\mathrm{Nb}$ and $^{132}\mathrm{I}$, have been estimated using the statistical model formalism. The estimated values are ${6.35}_{\ensuremath{-}0.95}^{+1.25}\ensuremath{\hbar}$ and $5.7\ifmmode\pm\else\textpm\fi{}1.2 \ensuremath{\hbar}$ for $^{95}\mathrm{Nb}$ and $^{132}\mathrm{I}$, respectively. These data along with other literature data show that fragment angular momenta decrease as proton number deviates from spherical magic shell 50 for given neutron number. Besides, fragment angular momenta do not correlate with prompt neutron number.