Pure 90Sr External Bremsstrahlung Spectra

Abstract

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.