Akademik Veri Yönetim Sistemi
RADIATION MEASUREMENTS, cilt.120, ss.241-246, 2018 (SCI-Expanded)
Durango apatite is a material that exhibits very strong athermal fading (AF) of luminescence signal. In this study, the EPR signals of natural Durango apatite in various different grain dimensions (ball milled for various duradons up to 48 h and microscale grain size) were studied. The obtained EPR signal at room temperature yielded three different components with g values 2.0534 (hole center), 2.0398 (hole center) and 1.9920 (electron center). These components were observed for the reference grain size fraction of 100-180 mu m; however, prolonged ball milling erases the two hole centers. The behaviour of all obtained components was investigated by step annealing processes (a) between room temperature and 400 degrees C in steps of 25 degrees C for 5 min and (b) between 400 degrees C and 1100 degrees C, in steps of 100 degrees C for 1 h. The EPR component with g value 1.9918 was almost totally removed until 1100 degrees C, while those with g values 2.0534, 2.0398 were erased after annealing at 500 degrees C and 400 degrees C respectively. The fading of EPR components was investigated for each ball milling (BM) and microscale grain size independently, at different storage times between 0 and 1000 min. Based on the results of fading and step annealing studies, the EPR component with g value 2.0398 could be directly correlated to the main dosimetric TL trap, while the component with g value 1.9920 appears to be responsible for TA - OSL signal for microscale grain size apatite, corresponding thus to a very deep trap. The behaviour of remnant EPR signal versus storage time could be successfully described by equations based on quantum mechanical tunnelling mechanism.