Speaker
Description
Scintillators are widely used to detect high-energy photons and particles and applied in the medical imaging and other applications. Among the many kinds of scintillator materials, oxide scintillation materials based on garnet structure like Ce-doped Lu3Al5O12 (Ce:LuAG) are promising candidates for scintillator applications because of well mastered technology developed for laser hosts, and easy doping by rare-earth elements [1]. LuAG admixed with balanced Gd and Ga ratio was proved to be an excellent scintillator where the effect of shallow traps was suppressed; the spectrally corrected light yield value exceeded 50,000 photons/MeV [2]. Recently, cations (B, Ca, Ba) co-doping effects on scintillation mechanism and annealing effects on defect structures for Ce: Gd3Ga3Al2O12 (GGAG) has been reported [3], where further improvement of scintillation properties were also reported.
In this report, effects of annealing atmosphere and Mg co-doping on scintillation properties of Ce:GGAG were investigated. Mg 200ppm co-doped and non co-doped Ce:GGAG single crystals grown by micro pulling down method (m-PD) were prepared under N2 atmosphere. Temperature dependence of the light output and decay time were evaluated in the Mg/non co-doped samples before and after annealing under oxidizing (air) and reducing (Ar+2%H2) atmosphere. Temperature dependence of the light output was no change in the Mg co-doped sample. Temperature quenching of light output started at lower temperature in the case of non co-doped sample after annealing under reducing atmosphere. The 1st decay component of Mg/non co-doped samples changed to 50.0ns and 183ns after annealing under reducing atmosphere ( Mg co-doped:54.1ns and non co-doped:61ns before annealing), respectively. Thease results indicates suppression of O2- defect by Mg co-doping. In our presentation, details of crystal growth and crystal structure as well as optical and scintillation properties will be reported.
References
[1] M. Nikl, A. Yoshikawa et al, Cryst. Growth Des. 14 (2014) 4827–4833
[2] K. Kamada, A. Yoshikawa et al, Cryst. Growth Des. 11 (2011) 4484–4490.
[3] M. Tyagi et al, J. Phys. D; Appl. Phys. 46 (2013) 475302
