title: Local coordination state of rare earth in eutectic scintillators for neutron detector applications.
abstract: Atomic distribution in phosphors for neutron detection has not been fully elucidated, although their ionization efficiency is strongly dependent on the state of the rare earth in the matrix. In this work, we examine optical properties of Eu-doped 80LiF-20CaF2 eutectics for neutron detector applications based on the Eu distribution. At low concentrations, aggregation of Eu cations is observed, whereas homogeneous atomic dispersion in the CaF2 layer, to substitute Ca(2+) ions, is observed in the eutectics at high concentrations. Eu LIII edge X-ray absorption fine structure (XAFS) analysis suggests that neutron responses do not depend on the amount of Eu(2+) ions. However, transparency, which depends on an ordered lamellar structure, is found to be important for a high light yield in neutron detection. The results confirm the effectiveness of the basic idea concerning the separation of radiation absorbers and activators in particle radiation scintillation and present potential for further improvement of novel bulk detectors.
authors: Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.
authors: Hirokazu
authors: H
authors: Masai
authors: Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu, Fukuoka, 808-0135, Japan.
authors: Takayuki
authors: T
authors: Yanagida
authors: Institute of Industrial Science, Tokyo University, 4-6-1, Komaba, Meguro, Tokyo 153-8505, Japan.
authors: Teruyasu
authors: T
authors: Mizoguchi
authors: Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), Kouto, Sayo-cho, Hyogo, 679-5198, Japan.
authors: Toshiaki
authors: T
authors: Ina
authors: Technical Division, Graduate School of Engineering, Tohoku University, 6-6-11, Aoba, Sendai 980-8579, Japan.
authors: Takamichi
authors: T
authors: Miyazaki
authors: Tokuyama Corporation, 1-1 Harumi-cho, Shunan, Yamaguchi, 745-0024, Japan.
authors: Noriaki
authors: N
authors: Kawaguti
authors: Tokuyama Corporation, 1-1 Harumi-cho, Shunan, Yamaguchi, 745-0024, Japan.
authors: Kentaro
authors: K
authors: Fukuda