Pure 90Sr External Bremsstrahlung Spectra
Bremsstrahlung
Spectra
Beta particles emitted from a 90Sr/90Y source have two different end point energies; 546 keV for 90Sr and 2274 keV for 90Y. The external bremsstrahlung (EB) photons produced by the complete absorption of 90Sr/90Y betas stopped in thick targets will therefore be convoluted with both 90Sr and 90Y sources at the energy range less than 546 keV. In this investigation spectral distribution of pure 90Sr EB was deduced for the first time from the matching between the measured spectrum of EB by 90Sr/90Y and the Spectral distribution of 90Y of the exact numerical screened calculations of Pratt et al.
for energy range above 550 keV. The fraction of EB production probability in 90Sr in that of 90Sr/90Y was determined as a function of EB photon energy. The results are quite necessary for accurate measurements of EB intensity and thereby the gamma dose produced by 90Sr EB photons in different targets.