Neutron Resonance Spectroscopy. XIV. Potassium

Abstract

Results are presented of high-resolution transmission measurements using pure natural K metal samples. The measured total $\sigma$ vs $E$ to 400 keV is given, and resonance parameter evaluations are given for 65 resonances below 200 keV. The isosopte assignments, $A=39\mathrm{} or 41$, are mainly based on recent unpublished measurements of Good and Harvey at the Oak Ridge electron linear accelerator using separated K isotope samples. Values of level strengths, $\mathrm{ag}{\Gamma }_n$, are mainly based on transmission dip area analysis, which with evidence from the resonance shape and peak cross sections permits assignment of $l$ and $J$ for most resonances, and $A$ for many of the resonances not identified in the separated isotope measurements. We obtain for the $s$ and $p$ strength functions: $10{}_{}{}^4{}_{}{}^{}S_0^{}{}_{}{}^{}=\left({0.66}_{-0.30\mathrm{}}^{+0.63\mathrm{}}\right),\left({0.78}_{-0.41\mathrm{}}^{+1.08\mathrm{}}\right)$, and $10{}_{}{}^4{}_{}{}^{}S_1^{}{}_{}{}^{}=\left({1.8}_{-0.5\mathrm{}}^{+0.7\mathrm{}}\right) \mathrm{and} \left({2.4}_{-0.8\mathrm{}}^{+1.3\mathrm{}}\right)$ for ${}_{}{}^{39}{}_{}{}^{}\mathrm{K}$ and ${}_{}{}^{41}{}_{}{}^{}\mathrm{K}$, respectively.