Neutron Resonances in the kev Region: Odd-Intermediate Nuclei

Abstract

The total neutron cross sections of ${\mathrm{Sc}}^{45}$, ${\mathrm{V}}^{51}$, ${\mathrm{Mn}}^{55}$, ${\mathrm{Co}}^{59}$, ${\mathrm{Cu}}^{63}$, and ${\mathrm{Cu}}^{65}$ have been measured in the energy range of ∼1 to ∼100 kev. The resonance parameters, including tentative $J$-value assignments, have been obtained for some of the more pronounced resonances observed. In the low-energy region, where our measurements overlap with those made with time-of-flight equipment, the results for the 2.36-kev resonance in ${\mathrm{Mn}}^{56}$ and the 4.1-kev resonance in ${\mathrm{Sc}}^{46}$ are in good agreement. $\frac{{{\overline{\Gamma }}_n}^0}{\overline{D}}$ (averaged between 1 and 100 kev) was determined for Cl, K, ${\mathrm{Ni}}^{58}$, ${\mathrm{Ni}}^{60}$, ${\mathrm{As}}^{75}$, and the above six nuclei. To calculate $\frac{{{\overline{\Gamma }}_n}^0}{\overline{D}}$ the average experimental transmission data was compared to the average Breit-Wigner transmission. The variation of $\frac{{{\overline{\Gamma }}_n}^0}{\overline{D}}$ with atomic weight has been compared to the theoretical predictions of the Feshbach, Porter, and Weisskopf model of the nucleus. The results indicated that the peak is around $A=47\mathrm{}$, and the amplitude is about 5×${10}^{-4\mathrm{}}$. These values would roughly correspond to a real potential, $V_0=46.5\mathrm{}$ Mev, and $\zeta =0.05\mathrm{}$ for the complex fraction of the potential; a square potential well and a radius $R=1.45\mathrm{}{A}^{\frac{1}{3}}\times {10}^{-13\mathrm{}}$ were assumed.