Mechanism of luminescence from a cerium-doped gadolinium orthosilicate (Gd 2SiO 5) scintillator

Abstract

Time dependence of luminescence in a Ce-doped Gd 2SiO 5 scintillator has been measured as a function of the Ce concentration ranging from 0.1 to 0.95 mol% and of the temperature ranging from 170 to 330 K. It has been shown that the time dependence of the luminescence has a fast rise of about 3 ns which corresponds to a lifetime of excited Ce 3+ and a decay time up to 2 μs. This decay is not described by a single exponential curve and becomes faster with increasing Ce concentration and with increasing temperature. These experimental results of the decay curves are well explained by the recombination luminescence model which is associated with electron-capture Ce 3+ (i.e. Ce 2+) and self-trapped holes (i.e. V k-centers), by considering a probability of hot-electron escape from the ideal tube of coulomb attraction. Cross sections for the recombination between Ce 2+ and V k-centers are estimated to be 3.2 × 10 −16 cm 2 at 295 K and to be 1.7 × 10 −16 cm 2 at 230 K.