A 7-9 MEV ISOTOPIC GAMMA-RAY SOURCE FOR DETECTOR TESTING

An isotopic source of high-energy gamma rays has been constructed and tested. The source uses either a long-lived americium-beryllium neutro n source or Cf-252 to produce fast neutrons, which are moderated in pa raffin and then absorbed in metallic nickel. The radiative capture of thermal neutrons in natural metallic Ni produced five prominent gamma- ray energies in the range 7.5-9 MeV, of which the 8.997 MeV line is th e strongest by more than a factor of two. The source was optimized for counting rate by measuring gamma-ray energy spectra with a 76 mm diam . NaI detector, then used to test an imaging BGO detector with gamma r ays in the energy range 7.5-9 MeV. (C) 1998 Elsevier Science B.V. All rights reserved.