Angular and Spectral Distributions of Backscatter Radiation from Slabs of Water, Brass, and Lead Irradiated by Photons between 50 and 250 keV

The energy distribution of radiation backscattered in different directions was measured in absolute units with a NaI-scintillation spectrometer. The recorded spectra were integrated over space to give the backscatter number flux. Build-up and albedo were calculated. Good agreement with backscatter factors was obtained. Once-scattered radiation and characteristic fluorescent radiation were theoretically calculated. The backscatter from brass and lead consisted mainly of once-scattered radiation and characteristic Kradiation, respectively. (auth)