Photostimulated luminescence and thermoluminescence of LSO scintillators

Abstract

Photostimulated luminescence (PSL) and thermoluminescence (TL) from five L~2(1-~)Ce2~(Si04)0 &SO) crystals with different light outputs is reported. Optical irradiation into the Ce3+ absorption bands causes the appearance of a broad absorption band near 280 nm which is ascribed to Ce4+. In addition, a tail is observed extending beyond 700 nm. Optical irradiation into this tail (PSL) or heating of the crystal (TL) results in Ce3+ emission. It is shown that both PSL and TL are due to the same traps. In addition, an anti-correlation is found between the light output under gamma-ray irradiation and the trap concentration in the crystal. The nature of the recombination centers responsible for the low light output in some crystals is not clear. Annealing experiments suggest that the traps and the recombination centers may be related to oxygen vacancies.

Complex oxide scintillators: Material defects and scintillation performance

“…16. Annealing experiments in reducing or oxidizing atmosphere led to the suggestion that traps could be related to oxygen vacancies [136]. Evaluation of trap depths of these peaks shows approximately the same values up to 250 °C; the values are reported in the inset of Fig.…”

Growth and luminescent properties of Lu2SiO5:Ce and (Lu1−xGdx)2SiO5:Ce single crystalline films

“…6, curve 2). Such dependence in LSO:Ce and LGSO:Ce SCF is more flat (curves 1,4), similar to that in high quality LYSO:Ce SC (curve 3) where the influence of the oxygen vacancies on scintillation processes is strongly diminished [17][18][19][20][21][22].…”

“…It is well known, that the oxygen vacancies are most easily created at non-bounded chains between Lu1 and Lu2 positions of LSO host [27,33] and they are responsible for large afterglow of LSO:Ce crystals and decrease of their scintillation LY [17,[19][20][21]. Therefore, we expect that in the case of elimination or strong decreasing the influence of Pb 2 þ flux impurity on the luminescence of Ce 3 þ ions in LSO:Ce SCF, one could possess even better scintillation properties in comparison with SC counterparts.…”

“…To improve the scintillation properties of LSO:Ce crystals, degraded by presence of the oxygen vacancies acting as electron trapping centers [17,18], the Gd-admixed (Lu 1 À x Gd x ) 2 SiO 5 :Ce (LGSO:Ce) [19,20] and Y-admixed (LuY) 2 SiO 5 :Ce SC scintillators [21,22] were also developed. The increase of the distance between Ce 3 þ ions as emission centers and oxygen vacancies as trapping center in LGSO:Ce and LYSO:Ce SCs might be one of the reasons of the observed significant decrease of the content of slow components in scintillation decay of the latter crystals with respect to LSO:Ce SC [17][18][19][20][21][22].…”

VUV spectroscopy and low temperature thermoluminescence of LSO:Ce and YSO:Ce

“…Dorenbos et al [7] analyzed glow curves recorded in the 300-650 K range, evaluated trap parameters and discussed possible nature of traps. Visser et al [8] observed an anti-correlation between TL intensities (300-730 K) and light yields of their crystals. Low temperature glow curves of two LSO:Ce samples were first published by Lempicki and Glodo [9].…”