Some Aspects of Solid State Radioluminescence

In this paper we review results of radioluminescence studies on two scintillator materials, LuAlO$\text{}_{3}$ and YAlO$\text{}_{3}$, activated with Ce. The experiments include measurements of ther moluminescence, isothermal phosphorescence decays, scintillation light yield as function of temperature, and scintillation time profiles under gamma excitation. Experimental results are interpreted in the frame of a simple kinetic model that includes a number of electron traps. We have identified and characterized a number of deep and shallow traps and demonstrated that traps in LuAlO$\text{}_{3}$:Ce are deeper than corresponding traps in YAlO$\text{}_{3}$:Ce. Unlike deep traps which are responsible for some scintillation light loss but otherwise do not have any impact on generation of scintillation light, shallow traps are shown to actively interfere with the process of radiative recombination via Ce ions. We demonstrate that shallow traps are responsible for some as yet unexplained observations including a higher room temperature light yield of YAlO$\text{}_{3}$:Ce and its longer scintillation decay time, as well as a longer scintillation rise time in LuAlO$\text{}_{3}$:Ce.