[17p-A304-1~17] 2.1 放射線物理一般・検出器基礎

▲ [17p-A304-14] Effect of Mg²⁺ codoping on cathodoluminescence properties of Ce³⁺ activated GGAG single crystals

〇(P)Karol Bartosiewicz^1,2、Sergey Omelkov³、Alena Beitlerova¹、Pavel Bohacek¹、Martin Nikl¹、Akira Yoshikawa^2,4,5 (1.Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 1999/2, Prague 8, 18221, Czech Republic、2.Tohoku University, Institute for Material Reseach, 2-1-1 Katahira Aoba-ku, Sendai, Miyagi 980-8577, Japan、3.Institute of Physics, University of Tartu, W. Ostwaldi Str. 1, Tartu 50411, Estonia、4.Tohoku University, New Industry Creation Hatchery Center, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8579, Japan、5.C & A corporation, T-Biz, 6-6-40 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579, Japan)

キーワード：Scintillator, Single Crystal, Luminescence

High R&D activity in the field of inorganic scintillators used for ionizing radiation detection has been triggered mainly by the pressing needs of modern medical imaging, high energy physics, homeland security and environmental applications [1]. Recently, a new material concept was defined based on multicomponent (Gd, RE)₃(Ga,Al)₅O₁₂ host, RE=Y, Lu. Doped with Ce³⁺ and admixture with balanced Gd and Ga content host compositions showed amazingly high light yield up to 58 000 photons/MeV [2]. More recently, a strategy based on co-doping with alkali earth AE²⁺ into Ce³⁺ activated YAG [3], LuAG [5] or GGAG [5] single crystal garnet scintillators significantly improved some scintillation characteristics.
Therefore, in this work, the effect of Mg²⁺ codoping in Gd₃Ga_2.7Al_2.3O₁₂:Ce (GGAG:Ce) on the scintillation properties under electron beam excitation was studied. The Mg²⁺ free and Mg²⁺ codoped GGAG:Ce crystals were grown from the melt using Czochralski technique. The absorption spectra revealed the presence of both Ce⁴⁺ and Ce³⁺ ions in Mg²⁺ codoped sample. The RT cathodoluminescence spectra were recorded in the fast (0-32 ns) and slow (5 µs- 2 ms) gated detection mode. Scintillation decay kinetics were recorded with 250 ps time resolution and high dynamic range in a large time window (50 µs), within the 77-500 K temperature range. Finally, the defect states were investigated by thermally stimulated luminescence. The results showed that Mg²⁺ codoping leads to enormous improvement of several scintillation characteristics of investigated samples while keeping its stable scintillation efficiency up to high temperature.
[1] M. Nikl, A. Yoshikawa, Adv. Opt. Mater. 3 (2015) 463.
[2] K. Kamada, et al., Opt. Mater. 36 (2014) 1942.
[3] A. Nagura, et al., Jpn. J. Appl. Phys. 54 (2015) 04DH1.
[4] M. Nikl et al, Crystal Growth Design 14, (2014) 4827.
[5] M. Tyagi, et al J. Phys. D: Appl. Phys. 46 (2013) 475302.