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

Abstract

The $\frac{1}{v}$ thermal line for iodine is $\sigma =\left[\right(3.8\mathrm{}\pm 0.2)+(1.12\pm 0.05\left)E^{-\frac{1}{2}}\right]$. Crystal interference effects are apparent at low energies. There is a resonance at (20.6±0.4) ev with ${\sigma }_0{\Gamma }^2\sim 4$. A flat-bottomed dip at 37 ev suggests two levels at (32±2) ev and (42±2) ev with approximately equal values of ${\sigma }_0{\Gamma }^2\sim 135$. The $\frac{1}{v}$ thermal line for osmium is $\sigma =\left[\right(15\mathrm{}\pm 0.4)+(2.7\pm 0.1\left)E^{-\frac{1}{2}}\right]$ with crystal interference effects at low energies. There are levels at (6.5±0.3) ev with ${\sigma }_0{\Gamma }^2\sim 10$, at (8.8±0.3) ev with ${\sigma }_0{\Gamma }^2\sim 35$, at (20±1) ev with ${\sigma }_0{\Gamma }^2\sim 25$, probable levels at (28±1.5) ev with ${\sigma }_0{\Gamma }^2\sim 8$, at (42±2) ev with ${\sigma }_0{\Gamma }^2\sim 10$, at 84 ev and several unresolved levels above 84 ev. The $\frac{1}{v}$ thermal line for cobalt is $\sigma =\left[\right(6.7\mathrm{}\pm 0.3)+(6.4\pm 0.15\left)E^{-\frac{1}{2}}\right]$. There is an unusually strong dip at (115±5) ev with ${\sigma }_0{\Gamma }^2\sim 200,000$ (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 [$\sigma =(9.7\mathrm{}\pm 0.2)+(0.6\pm 0.2)E^{-\frac{1}{2}}$]. 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 $\sigma =\left[\right(6.4\mathrm{}\pm 0.2)+(0.10\pm 0.04\left)E^{-\frac{1}{2}}\right]$ 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 ${\sigma }_0{\Gamma }^2\sim 800$.