The dependence of fluorescent decay time of ZnO:Ga crystal on instantaneous non-equilibrium carriers induced by charged particles

We have investigated the fluorescence decay time of ZnO:Ga scintillator under the excitation of different type charged particles, namely β (0–1.173 MeV), α (5.48 MeV), H⁺ (15 MeV), Li⁺ (42 MeV) and O⁸⁺ (100 MeV) ions. A strong dependence of decay time on the rate of energy loss dE/dx can be observed. Simulation result shows that the instantaneous non-equilibrium carriers induced by charged particles significantly decrease the local refractive index of semiconductor, which consequently gives rise to a slower decay time for a larger value of dE/dx. The present result has an entire different physical mechanism from the traditional organic and inorganic scintillators such as CsI:Na. This finding could be applied in pulse shape discrimination measurement in a mixed transient radiation field.