Nuclear Resonant Scattering of Gamma Radiation of Variable Energy

Abstract

A variable-energy gamma-ray system is described. Monoenergetic gamma radiation undergoing Compton scattering produced this energy variability over a significant range. The parameters of the system are described.Gamma radiation from a ${\mathrm{Co}}^{60}$ source of strength 1200 C was Compton scattered from a copper scatterer. The energy of the scattered radiation varies continuously from 1.33 MeV in the forward direction to 0.21 MeV at a scattering angle of 180\ifmmode^\circ\else\textdegree\fi{}. The rays of mean energy 480 keV, corresponding to a mean scattering angle of 69.5\ifmmode^\circ\else\textdegree\fi{}, were resonantly scattered by lithium. From a self-absorption experiment the mean life of the first excited state of ${\mathrm{Li}}^{7}$ was found to be (1.48\ifmmode\pm\else\textpm\fi{}0.35)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}13}$ sec.