-ray yield and spectra produced by irradiating backing materials with protons

Abstract

Thick targets of copper, silver, gold, tungsten, molybdenum, titanium, tantalum and tin were irradiated by protons in the energy range 0.6 to 2.8 MeV and the total γ-ray yield measured as a function of proton energy. The γ-ray spectra were also measured for a fixed proton energy of 2.2 MeV. The total γ-ray yields of the materials were found to decrease in the order given above, indicating that tungsten backings produce less total γ-ray background than any other. If high energy γ-rays are being investigated it may be advisable to use tin or gold backings since the γ-ray spectrum from these is concentrated towards the lower energies and can consequently be biased out in the counting equipment, but both materials are rather fragile under heavy proton irradiation.