Monte Carlo Calculations of Irradiation Test Photon Spectra

Calculations of scattered photon spectra in concrete rooms are made, by means of the Monte Carlo method, for Co-60 sources of the type used in irradiation testing of electronic devices. It is found that the scattered photon spectrum shape is heavily dependent on the location of source and target, and that in devices where dose enhancement can occur, there can be substantial variation in the absorbed dose due to this strong dependence on location. Scattered photon spectra are also obtained for two types of irradiation test cells. Additionally, dose enhancement ratios obtained with a coupled photon-electron Monte Carlo calculation are given for a gold-metallized silicon device.