SUPPRESSION OF THE SLOW COMPONENT OF BAF2 CRYSTAL BY INTRODUCTION OF SRF2 AND MGF2 CRYSTALS

The emission spectrum, the time dependence of the luminescence, the li ght output, the excitation and the reflectance spectra have been measu red for pure BaF2 crystal, for BaF2:Sr crystals with Sr2+ concentratio ns of 2 and 5 mol% and for BaF2:MgF2 crystal with a mole mixing ratio of 1:2. The measurements have been made by using synchrotron orbital r adiation and high-energy electrons produced by gamma-rays. It is shown that the BaF2, BaF2:Sr and BaF2:MgF2 crystals have a fast component l uminescence with decay times around 0.90 ns. The slow and fast compone nts luminescence of the BaF, crystal are suppressed by the introductio n of Sr2+ and Mg2+ ions. It is, however, clearly seen that the suppres sion of the slow component is more effective than that of the fast com ponent, especially in the BaF2:MgF2 crystal. The Sr2+ and Mg2+ ions ac t as electron trapping centers, preventing the formation of self-trapp ed excitons by electron-hole pairs, that is the slow component.