Luminescence and Decay Time Properties of Pure CsI Crystals

doi:10.15541/jim20160304

Abstract

Abstract:

Pure CsI crystal is a kind of fast scintillators which can be used to detect γ-rays, neutrons as well as other radiation. Optical transmission and luminescence properties of pure CsI crystal grown with Vertical Bridgman method were measured under the excitation of UV, continuous X-ray, pulse X-ray as well as cosmic rays at room temperature. Cut-off edge of the grown CsI crystal reaches 240 nm, which is the shortest among the literature reported previously. Excitation and emission wavelength are 241 nm and 318 nm, respectively. The decay times of the fast intrinsic luminescence can be fitted into two components, 2~3 nm and 18~25 nm under the excitation of X-ray or cosmic rays. The light outputs measured from the crystal with size of 30 mm×30 mm×200 mm are 143 p.e/MeV and 127 p.e./MeV as its seed end and tail end were coupled with PMT, respectively. Even though the non-uniformity (12.6%) exists along the growth direction of the crystal, no significant slow component longer than 100 ns are observed. All of these properties prove that the pure CsI crystal is a promising fast scintillator.

Key words: pure CsI, crystal, transmittance, luminescence, decay time, light output

CLC Number:

O734

REN Guo-Hao, SONG Zhao-Hui, ZHANG Zi-Chuan, ZHANG Kan, YANG Fan, LI Huan-Ying, CHEN Xiao-Feng. Luminescence and Decay Time Properties of Pure CsI Crystals[J]. Journal of Inorganic Materials, 2017, 32(2): 169-174.

Figures/Tables 11

Fig. 1 Photo (a) and longitudinal and transversal transmittance (b) of pure CsI crystal

Fig. 2 Photoluminescence spectra of pure CsI crystal

Fig. 3 X-ray excited luminescence (XEL) spectra of pure CsI crystals

Table 1 Response of 8# CsI crystal to the pulse X-ray

Test No.	8#CsI			Reference
Test No.	Rise time/ns	Decaytime/ns	FWHM/ns	Rise time/ns	Decaytime/ns	FWHM/ns
1	1.07	37.31	5.29	1.85	7.96	4.79
2	1.16	39.88	5.36	1.86	7.85	4.97
3	1.17	44.96	5.50	1.95	8.40	4.90
4	1.10	40.88	5.49	1.85	7.25	4.80
mean	1.13	40.76	5.41	1.88	7.87	4.87

Fig. 4 Response of pure CsI crystal to the pulse X-ray

Fig. 5 Decay curve and its fitted line of 8# CsI crystal excited by pulse X-ray

Fig. 6 Response of 8# CsI crystal to the cosmic ray

Table 2 Response of 8# pure CsI crystal to the cosmic ray

Sample	Rise time /ns	Decay time/ns	FWHM/ns
8#CsI(pure)	3.678	25.509	8.003

Fig. 7 Decay curves and their fitted lines from channel 1 and channel 2 of pure CsI crystal excited with cosmic ray

Table 3 Comparison of decay times of pure CsI reported previously and those tested in this work

	Kubota	Woody	Schotanus	Amsler	Belsky	This work
τ₁ / ns	10	7	2	6±1	5-9	2-3
τ₂/ ns	36	29	22	28±2	10-25	18-25
Reference	[6]	[13]	[9]	[12]	[16]

Fig. 8 Light outputs of CsI crystal when it is coupled by A (top) and B (bottom) ends and integrated from different time gate

References 16

[1]	RODNYI P A.Progress in fast scintillators.Radiation Measurements, 2001, 33: 605-614.
[2]	BIASINIA, CASSIDY D B, DENG S H M,et al. Suppression of the slow component of scintillation light in BaF2.Nucl. Instrum. Methods. Phys. Res. A, 2005, 553: 550-558.
[3]	GU MU, GAO PAN, LIU XIAO-LIN,et al. Crystal growth and characterization of CuI single crystals by solvent evaporation technique.Mater. Res. Bull., 2010, 45: 636-639.
[4]	KUZMIN A.Endcap calorimeter for SuperBelle based on pure CsI crystals.Nucl. Instrum. Methods. Phys. Res. A, 2010, 623: 252-254.
[5]	ATOANOV N, BARANOV V, BUDAGOV J,et al. Design and status of the Mu2e electromagnetic calorimeter.Nucl. Instrum. Methods. Phys. Res. A, 2016, 824: 695-698.
[6]	KUBOTA S, SAKURAGI S, HASHIMOTO S,et al. A new scintillation material: Pure CsI with 10 ns decay time.Nucl. Instrum. Methods. Phys. Res. A, 1988, 268: 275-277.
[7]	WEI ZONG-YING, ZHU REN-YUAN.Study on undoped CsI crystals.Nucl. Instrum. Methods. Phys. Res.A, 1993, 326: 508-512.
[8]	WU Z, YANG B, TOWNSEND P D.Radioluminescence and thermoluminescence properties of X-ray-irradiated pure CsI.J. Luminescence, 2008, 128: 1191-1196.
[9]	SCHOTANUS P, KAMERMANA R, DORENBOS P,et al. Scintillation characteristics of pure and Tl-doped CsI crystals.IEEE. Trans. Nuc.l Sci., 1990, 37(2): 177-182.
[10]	SHEN DING-ZHONG, DENG QUN, YUAN XIANG-LONG, et al. Luminescent Performance of pure CsI crystals.Journal of Inorganic Materials, 1997, 12(3): 273-278.
[11]	BABIN V, KRASNIKOV A, WIECZOREK H,et al. Luminescence of complicated thallium centers in CsI: Tl.Nucl. Instrum. Methods. Phys. Res.A, 2002, 486: 486-489.
[12]	AMSLER C, GROGLER D, JOFFRAIN W,et al. Temperature dependence of pure CsI: scintillation light yield and decay time.Nucl. Instrum. Methods. Phys. Res. A, 2002, 480: 494-500.
[13]	WOODY C L, LEVY P W, KIERSTEAD J A,et al. Readout techniques and radiation damage of undoped Cesium Iodide.IEEE. Trans. Nucl. Sci., 1990, 37(2): 492-499.
[14]	HAMADA M M, NUNOY Y, KUBOTA S,et al. Suppression of the slow emission component in pure CsI by heat treatment.Nucl. Instrum. Methods. Phys. Res.A, 1995, 365: 98-103.
[15]	BABIN V, KRASNIKOV A, NIKL M,et al. Luminescence and relaxed excited state origin in CsI: Pb crystals.J. Luminescence, 2003, 101: 219-226.
[16]	BELSKY A N, VASILEV A N, MIKHAILIN V V,et al. Time-resolved XEOL spectroscopy of new scintillators based on CsI.Rev. Sci. Instrum., 1992, 63(1): 806-809.