Slow Neutron Velocity Spectrometer Studies. III. I, Os, Co, Tl, Cb, Ge

Abstract

The $\frac{1}{v}$ thermal line for iodine is $\ensuremath{\sigma}=[(3.8\ifmmode\pm\else\textpm\fi{}0.2)+(1.12\ifmmode\pm\else\textpm\fi{}0.05){E}^{\ensuremath{-}\frac{1}{2}}]$. Crystal interference effects are apparent at low energies. There is a resonance at (20.6\ifmmode\pm\else\textpm\fi{}0.4) ev with ${\ensuremath{\sigma}}_{0}{\ensuremath{\Gamma}}^{2}\ensuremath{\sim}4$. A flat-bottomed dip at 37 ev suggests two levels at (32\ifmmode\pm\else\textpm\fi{}2) ev and (42\ifmmode\pm\else\textpm\fi{}2) ev with approximately equal values of ${\ensuremath{\sigma}}_{0}{\ensuremath{\Gamma}}^{2}\ensuremath{\sim}135$. The $\frac{1}{v}$ thermal line for osmium is $\ensuremath{\sigma}=[(15\ifmmode\pm\else\textpm\fi{}0.4)+(2.7\ifmmode\pm\else\textpm\fi{}0.1){E}^{\ensuremath{-}\frac{1}{2}}]$ with crystal interference effects at low energies. There are levels at (6.5\ifmmode\pm\else\textpm\fi{}0.3) ev with ${\ensuremath{\sigma}}_{0}{\ensuremath{\Gamma}}^{2}\ensuremath{\sim}10$, at (8.8\ifmmode\pm\else\textpm\fi{}0.3) ev with ${\ensuremath{\sigma}}_{0}{\ensuremath{\Gamma}}^{2}\ensuremath{\sim}35$, at (20\ifmmode\pm\else\textpm\fi{}1) ev with ${\ensuremath{\sigma}}_{0}{\ensuremath{\Gamma}}^{2}\ensuremath{\sim}25$, probable levels at (28\ifmmode\pm\else\textpm\fi{}1.5) ev with ${\ensuremath{\sigma}}_{0}{\ensuremath{\Gamma}}^{2}\ensuremath{\sim}8$, at (42\ifmmode\pm\else\textpm\fi{}2) ev with ${\ensuremath{\sigma}}_{0}{\ensuremath{\Gamma}}^{2}\ensuremath{\sim}10$, at 84 ev and several unresolved levels above 84 ev. The $\frac{1}{v}$ thermal line for cobalt is $\ensuremath{\sigma}=[(6.7\ifmmode\pm\else\textpm\fi{}0.3)+(6.4\ifmmode\pm\else\textpm\fi{}0.15){E}^{\ensuremath{-}\frac{1}{2}}]$. There is an unusually strong dip at (115\ifmmode\pm\else\textpm\fi{}5) ev with ${\ensuremath{\sigma}}_{0}{\ensuremath{\Gamma}}^{2}\ensuremath{\sim}200,000$ (if single) and indications of other strong unresolved levels in the region of 1000 to 10,000 ev. The $\frac{1}{v}$ thermal line for thallium is probably [$\ensuremath{\sigma}=(9.7\ifmmode\pm\else\textpm\fi{}0.2)+(0.6\ifmmode\pm\else\textpm\fi{}0.2){E}^{\ensuremath{-}\frac{1}{2}}$]. There are strong crystal interference effects at low energies. There is a strong dip in the transmission curve at 270 ev and another broad dip near 1100 ev. Columbium shows only a slight $\frac{1}{v}$ effect $\ensuremath{\sigma}=[(6.4\ifmmode\pm\else\textpm\fi{}0.2)+(0.10\ifmmode\pm\else\textpm\fi{}0.04){E}^{\ensuremath{-}\frac{1}{2}}]$ with strong crystal interference effects at lower energies. Only a slight dip at 4.1 ev attributed to a slight Ta impurity was found in the higher energy region. Germanium shows no $\frac{1}{v}$ thermal slope because of the strong crystal interference effects. There is a (perhaps multiple) level at 95 ev with ${\ensuremath{\sigma}}_{0}{\ensuremath{\Gamma}}^{2}\ensuremath{\sim}800$.