Bremsstrahlung-induced fission and spallation of the pre-actinide nucleusTa181

Abstract

A study of photofission on $^{181}\mathrm{Ta}$ induced by bremsstrahlung with endpoint energies of 50 and 3500 MeV has been performed. The fission yields have been measured by using the induced-activity method in an off-line analysis. The total photofission yields for the tantalum target at 50 and 3500 MeV are found to be $5.4\ifmmode\pm\else\textpm\fi{}1.1 \ensuremath{\mu}\mathrm{b}$/ equivalent quanta per second (eq.q) and $0.77\ifmmode\pm\else\textpm\fi{}0.11$ mb/eq.q, respectively, and the corresponding deduced fissilities are $(0.23\ifmmode\pm\else\textpm\fi{}0.05)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ and $(2.9\ifmmode\pm\else\textpm\fi{}0.5)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$. Mass- and charge-yield distributions were derived from the data. The results were compared with the simulated results from the crisp code for multimodal fission by the assuming symmetrical fission mode.