Probing reaction dynamics with the 196Pt(n,xnγ) reactions for x~15

Abstract

Discrete \ensuremath{\gamma}-ray spectra have been measured as a function of incident neutron energy for nuclei produced in the ${}^{196}\mathrm{Pt}(n,xn\ensuremath{\gamma})$ reactions. Spectroscopy was done using the large-scale Compton suppressed Ge \ensuremath{\gamma}-ray spectrometer GEANIE. The ``white'' source neutron beam was produced at the Los Alamos Neutron Science WNR facility. Reaction neutron energy was determined using the time-of-flight technique. Reaction-channel yields were inferred from the measured intensity sum of the ${2}_{1}^{+}\ensuremath{\rightarrow}{0}_{1}^{+}$ and the ${2}_{2}^{+}\ensuremath{\rightarrow}{0}_{1}^{+}$ transitions for the ${}^{196}\mathrm{Pt}(n,xn)$ reactions for $x<~15.$ Weisskopf-Ewing calculations (including precompound) done with the HMS-ALICE code correctly predict the bulk of the $(n,xn)$ reaction products for low multiplicity. However, they do not accurately predict yield ratios of the different $(n,xn)$ reactions for $x>~9.$ In addition, there is no consistent experimental indication of charged-particle reaction channels $(n,pxn)$ for incident neutron energies above 60 MeV where they are predicted to account for approximately $1/3$ of the total reaction cross section. Several possible causes are discussed for these discrepancies. Finally, the region of $E\ensuremath{-}J$ phase space populated in this reaction is probed for several of the strongest reaction channels through the observation of relative yields for different yrast and off-yrast states.