Growth of LiF/LiBaF3 eutectic scintillator crystals and their optical properties
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Li-containing materials can be applied as neutron scintillators, and LiBaF3 can discriminate neutron and gamma rays. Moreover, LIF/LiBaF3 can have higher cross section of thermal-neutron capture compared with LiBaF3. In this study, LiF (82.5 mol%) and (Ba1−x RE x )F2 (17.5 mol%, RE = Ce and Eu, x = 0.002) eutectic crystals, LiF/RE:LiBaF3, were grown by the micropulling down method with different pulling rates (growth rate) in order to observe the eutectic structure. Lamellar microstructure was formed for each pulling rate. LiF/Ce:LiBaF3 excited by 5.5-MeV alpha rays had a broad peak at ~350 nm corresponding to 5d–4f transition of Ce3+. On the other hand, LiF/Eu:LiBaF3 had two scintillation processes; a sharp emission was originated from 6P7/2 → 8S7/2 transitions in the 4f electronic configuration of Eu2+ at 360 nm, and a broad one was attributed to Eu2+ trapped exciton recombination at 400–450 nm. Since scintillation light was observed for these materials, these scintillators are sensitive to neutrons.
KeywordsThermal Neutron BaF2 Lamellar Microstructure Scintillation Light Sharp Emission
This work was partially supported by (1) Japan Society for the Promotion of Science (JSPS), KAKENHI Grant Number 14462961, 15597934, 15619740 (Grant-in-Aid for Young Scientists (B), S. Kurosawa), (2) Bilateral AS CR-JSPS Joint Research Project, (3) Japan Science and Technology Agency (JST), Development of Systems and Technology for Advanced Measurement and Analysis (SENTAN), (4) JST, Adaptable & Seamless Technology Transfer Program through Target-driven R&D, (5) the Association for the Progress of New Chemical Technology, (6) the Murata Science Foundation, (7) Nippon Sheet Glass Foundation for Materials Science and Engineering, (8) Tonen General Sekiyu Foundation, (9) Yazaki Memorial Foundation for Science and Technology, (10) Tokin Science and Technology Promotion Foundation, (11) Intelligent Cosmos Research Institute, (12) Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, and (13) International Collaboration Center Institute for Materials Research (ICC-IMR), Tohoku University. In addition, we would like to thank following persons for their support: Mr. Yoshihiro Nakamura of Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, and Mr. Hiroshi Uemura, Ms. Keiko Toguchi, Ms. Megumi Sasaki, Ms. Yuka Takeda and Ms. Kuniko Kawaguchi of IMR, Tohoku University.
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