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°C) become distinguishable through a series of high-level irradiations. Our investigation revealed the fact that the main glow peak consists of three closely approximate peaks,denoted as P2, P3 and P4. These three peaks together with P1, which appears only under high exposures, constitute the main TL spectrum from room temperature to 350°C. The P2 is believed to be related to the electron trap defect, FA center, and contributes to approx. 90% of the cooled optically stimulated luminescence (COSL) response. The other peaks are made by hole trap defects, modified VK centers and/or the oxidation of Mn2+ to Mn3+. The temperature shift between the TL signal and its corresponding PTTL signal is a consequence of the absence of P2 after u.v. irradiation. The absence of P2 is a result of the further phototransfer from P2, to the lower temperature peak, which is unstable above room temperature rather than insensitive to u.v. irradiation. A plausible COSL mechanism is also presented in this investigation.