Measurement of Linac Thick-Target Bremsstrahlung Spectra Using a Large NaI Scintillation Spectrometer

Thick-target bremsstrahlung spectra produced by electron bombardment of a 0.2 radiation-length gold-tungsten target were measured for electron energies in the range of 5.3 to 20.9 MeV. A large NaI spectrometer coupled to a pulse pile-up rejection system measured pulse-height distributions for bremsstrahlung emitted in the forward direction, and a response matrix developed for the spectrometer was used to convert the pulse-height distributions into photon energy spectra. The shapes of the measured spectra show good agreement with those obtained by others for the same target configuration. Apparatus and experimental methods are described and thick-target bremsstrahlung spectra are presented for electron energies of 5.3, 10.0, 14.8, 16.4, 18.22, and 20.9 MeV.