Capture-Cross-Section Studies for 30—220-keV Neutrons Using a New Technique

Abstract

Neutron-radiative-capture cross sections have been measured at various energies from 30-220 keV using a new "total-energy-detector" technique of high sensitivity, applicable to small samples of separated stable isotopes. Samples studied are: V, Fe, Ni, ${}_{}{}^{86}{}_{}{}^{}\mathrm{Sr}$, ${}_{}{}^{87}{}_{}{}^{}\mathrm{Sr}$, Y, Nb, Rh, Ag, ${}_{}{}^{122}{}_{}{}^{}\mathrm{Te}$, ${}_{}{}^{123}{}_{}{}^{}\mathrm{Te}$, ${}_{}{}^{124}{}_{}{}^{}\mathrm{Te}$, ${}_{}{}^{125}{}_{}{}^{}\mathrm{Te}$, ${}_{}{}^{126}{}_{}{}^{}\mathrm{Te}$, ${}_{}{}^{128}{}_{}{}^{}\mathrm{Te}$, ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}$, I, Eu, ${}_{}{}^{175}{}_{}{}^{}\mathrm{Lu}$, ${}_{}{}^{176}{}_{}{}^{}\mathrm{Lu}$, W, Au, ${}_{}{}^{204}{}_{}{}^{}\mathrm{Pb}$, and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$. The odd-odd isotope ${}_{}{}^{176}{}_{}{}^{}\mathrm{Lu}$ shows a substantially higher cross section than those of neighboring odd-even and even-odd nuclei. The results for europium (2 b near 65 keV) emphasize the peak expected from previous studies of systematics. The Sr and Te isotopic results strongly confirm the predictions of $s$-process stellar nucleosynthesis.