A STUDY OF THE MAIN GLOW PEAK FOR CAF2-MN

The overlapped glow peaks of CaF2:Mn (with the composition of the main glow peak around 260 degrees C) become distinguishable through a seri es of high-level irradiations. Our investigation revealed the fact tha t the main glow peak consists of three closely approximate peaks, deno ted as P-2, P-3 and P-4. These three peaks together with P-1, which ap pears only under high exposures, constitute the main TL spectrum from room temperature to 350 degrees C. The P-2 is believed to be related t o the electron trap defect, F-A center, and contributes to approx. 90% of the cooled optically stimulated luminescence (COSL) response. The other peaks are made by hole trap defects; modified V-K centers and/or the oxidation of Mn2+ to Mn3+. The temperature shift between the TL s ignal and its corresponding PTTL signal is a consequence of the absenc e of P-2 after u.v. irradiation. The absence of P-2 is a result of the further phototransfer from P-2, to the lower temperature peak, which is unstable above room temperature rather than insensitive to u.v. irr adiation. A plausible COSL mechanism is also presented in this investi gation.