Bremsstrahlung Beams from High-Power Electron Accelerators for Use in Radiation Processing

Abstract

In this paper, the authors present the results of calculations of bremsstrahlung produced by a high power electron beam that is incident on a water cooled target. The calculation yields the efficiency of conversion of electron beam power to bremsstrahlung, the energy and angular distributions of the photons and the dose distribution of the resultant photon spectrum in a water phantom. The result is used to estimate radiation processing rates with bremsstrahlung photons and comparison is made with Co-60 radioisotope sources. In their analysis, 4 and 5 MeV electron beam sources are considered, since these machines are now available commercially at power levels up to 200 kW. Furthermore, while higher energy would provide higher conversion efficiency, 5 MeV is chosen as the maximum electron beam energy because it is likely that the U.S. Food and Drug Administration will place an upper limit of 5 MeV on bremsstrahlung sources for food irradiation. The bremsstrahlung converter is assumed to consist of a high-Z slab followed by a water filled copper channel, which provides the required cooling and reduces the transmission of electrons through the converter.