Neutron Resonance Spectroscopy. VI. Mo, Sb, Te, and Pr

The total neutron cross sections of natural Mo, Te, Sb, and Pr have been measured from about 6 eV to a maximum energy of 250 keV for Mo and Pr and to about 5 keV for Sb and Te, using the Nevis synchrocyclotron and a 200-m flight path. The maximum time resolution is 0.5 nsec/m. The resonance energies and the neutron reduced widths of about 1000 levels have been obtained, using area analysis. Values of Γ_γ~100 meV were obtained for the capture widths of 15 levels in natural Sb. Values of the spin J of the compound nucleus were obtained for a number of levels of Pr. Our values for the s-wave strength function for Mo, Sb, Te, and Pr are ${S}₀=(0.35±{}0.06), (0.34±{}0.05), (0.15±{}0.03), and (1.72±{}0.25)×{}{10}^{{-}4}$, respectively. An average level spacing $〈D〉=75.2$ eV was obtained for Pr. The presence of many $p$-wave levels led to a strong energy dependence of the observed $〈D〉$ for Mo, Sb, and Te. The observed statistical distributions of the neutron reduced widths and nearest-neighbor level spacings for Pr and natural Sb are compared with the Porter-Thomas and Wigner distributions, respectively.