Total Cross Sections for 410-Mev Neutrons

Abstract

Good geometry transmission measurements were conducted in the high-energy neutron beam of the University of Chicago synchrocyclotron. Total cross sections of fourteen elements, measured at an effective neutron energy of 410 Mev, were determined as follows (units of millibarns): It was found that the following two-parameter empirical formula was consistent with the measured cross sections to within the accuracy of their determination: $\ensuremath{\sigma}=2\ensuremath{\pi}{R}^{2}[1\ensuremath{-}\mathrm{exp}(\ensuremath{-}KR)],$ where $R={r}_{0}{A}^{\frac{1}{3}}$, and the two constants were chosen as ${r}_{0}=1.20\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}$ cm, and $K=0.360\ifmmode\times\else\texttimes\fi{}{10}^{13}$ ${\mathrm{cm}}^{\ensuremath{-}1}$. The sole exception was hydrogen, for which the prediction by the formula was 5 percent below the measured value.The results are compared with neutron cross sections at lower energies, with proton cross sections at the same energy, and are discussed from the point of view of the transparent optical model.