Studies of PTTL and OSL in TLD-400

We present data on the mechanisms of phototransferred thermoluminescence (PTTL) and optically stimulated luminescence (OSL) in single crystal CaF2:Mn (3%) and in TLD-400 chips. The TL peak under study is the main dosimetry peak near 275 oC. From measurements of the excitation spectra for PTTL it is found that the maximum transfer rate occurs when the wavelength of the illuminating light is 280 nm. This corresponds to the wavelength of an absorption peak which remains in the sample following initial irradiation and heating to 400 oC. This wavelength also corresponds to a complex peak which is seen in the OSL excitation spectra of irradiated samples. Possible models based on optical stimulation of electrons and diffusion of excited F centres are discussed.