SCINT 2017 - 14th Int. Conference on Scintillating Materials and their Applications

Growth and characterization of eutectic scintillator taking the advantage of composite material

19 Sept 2017, 09:00

15m

Congress Centre "Le Majestic"

Oral presentation S05_Crystal Growth (Orals) Crystal growth

Speaker

Prof. Akira Yoshikawa (IMR&NICHe, Tohoku University, C&A Corp.)

Description

As eutectic crystals consist of at least two different crystals, it can have two or more properties in the one body. The directionally solidified eutectic (DSE) systems have been discovered in various materials for many applications [1,2]. We have proposed mainly two approaches to develop the scintillators using the DSE system. One is the neutron scintillator using a eutectic body composed of lithium containing crystal and scintillation crystal [3,4]. Lithium containing crystal plays a role to react with neutron and generates alpha particle. The alpha particle reacts with the scintillation crystal and will give scintillation light.　Another attempt is the submicron-diameter phase separated scintillator fibers (PSSFs). They possessed both the properties of an optical fiber and a radiation-to-light conversion. The PSSFs were fabricated using a DSE system. In PSSFs, the light emitted from the scintillator fibers is confined and transported along the fiber direction by a total reflection mode, so that high-resolution radiation imaging can be achieved. CsI/NaCl [5] and GAP/alpha-Al2O3[6] have been reported as PSSFs. The aim of this presentation is to review the growth and characterization of DSE system for scintillator application.
DSE systems were grown by the micro-pulling-down (u-PD) method with an RF heating system [1] at the eutectic composition. The eutectic phase structure was investigated by back scattered electron image (BEI). Radio-luminescence spectrum at room temperature was measured with the above spectrometer (EI FLS920) excited by 5.5MeV alpha rays from an 241Am source. To determine the light yield, we obtained the pulse height spectra of these crystals irradiated with gamma rays from a 137Cs (662 keV) source. Scintillation photons were detected with a photomultiplier tube (PMT, Hamamatsu, R7600U-200). The signals were amplified with a preamplifier (ORTEC, 113), shaped with a shaping time of 2 micro-sec (ORTEC, 572A) and read out with a multi-channel analyser (MCA, Amptek 8000A).

1. A. Yoshikawa , et. al., J. Cryst. Growth 218(2000)67
2. J. Llorca, et. al., Prog. Mater Sci. 51, (2006) 711.
3. N. Kawaguchi, A. Yoshikawa, et.al., Nucl. Instr. Meth. A 652 (2011) 209-211
4. K. Hishinuma, A. Yoshikawa, et.al., Jpn. J. Appl. Phys. 54, 04DH04 (2015)
5. N. Yasui, et. al. Adv. Mater. 24, 5464 (2012).
6. Y. Ohashi, A. Yoshikawa, et. al., App. Phy. Lett. 102, (2013) 051907.