Sang Jun Kang

The Growth and Scintillation Characteristics of CsI:CO

We present the luminescent and scintillation characteristics of CsI:CO3 single crystals. The CsI:CO3 single crystals were grown by using Czochralski method for different concentrations of CO3 from 0.007 to 0.1 mole%. The crystals were cut into a size of 10 mm times 10 mm times 5 mm. The luminescent characteristics were measured with X-rays to study the emission spectra of the CsI:CO3 crystals. The scintillation properties of the CsI:CO3 crystals such as fluorescence decay time, energy resolution, pulse height spectra, proportionality, and relative light output were studied by using various gamma-ray sources with a photomultiplier tube (PMT) at room temperature. The absolute light outputs of the crystals were also measured with an avalanche photo-diode (APD).

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In the present work, we reported on the scintillation characterizations of our newly developed cerium doped Rb2LiGdCl6 (RLGC) single crystal. RLGC belongs to elpasolite family and is grown by vertical Bridgman technique with 0% and 1% Ce3+ contents (mole %). Under X-ray excitation, two overlapped emission peaks are obtained between 350 to 450 nm wavelengths for 1% Ce sample. Such emission is attributed to cerium ion present in the crystal matrix. At 662 keV γ-rays RLGC: 1% Ce3+ crystal showed energy resolution and light yield of 8.1% (FWHM) and ~13,000 ph/MeV, respectively at room temperature. Under γ-ray excitation, RLGC: 1% Ce3+ crystal showed three exponential decay time components. Further improvement in the scintillation properties is expected with higher values of Ce- concentrations. A major drawback of this material is the presence of 87Rb radioisotope and its highly hygroscopic nature. However, the presence of Li and Gd ions in the matrix make this material suitable candidate for the use of thermal neutron detection.