The Energy Dependence of the Resonant Scattering of Slow Neutrons from Gold

Abstract

The energy dependence of slow neutrons scattered from a thick gold target has been measured using a newly developed scattering chamber in conjunction with the Columbia slow neutron velocity spectrometer. A method of analysis has been developed for determining the ratio of the scattering cross section to the total cross section, $\frac{{\ensuremath{\sigma}}_{s}}{{\ensuremath{\sigma}}_{t}}$, as a function of energy for an "unknown" sample in terms of a calibration target for which $(\frac{{\ensuremath{\sigma}}_{s}}{{\ensuremath{\sigma}}_{t}})(E)$ is known. The agreement between the experimental determination of $(\frac{{\ensuremath{\sigma}}_{s}}{{\ensuremath{\sigma}}_{t}})(E)$ for gold in the energy range 0.7 to 8 ev and the Breit-Wigner theory is excellent. All the level parameters can be evaluated by combining these scattering data with the results of transmission experiments and the cross section for self-indication. The final results for the 4.9-ev gold level are: $J=1$, $\ensuremath{\Gamma}=0.172$ ev, ${\ensuremath{\Gamma}}_{N}=0.0211$ ev, ${R}_{J=1}=1.03$ ${\mathrm{barn}}^{\mathrm{\textonehalf{}}}$, ${R}_{J=2}=0.917$ ${\mathrm{barn}}^{\mathrm{\textonehalf{}}}$.