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.