Temperature dependence of CsI(Tl) gamma-ray scintillation decay time constants and emission spectrum

John Valentine; William W. Moses; Stephen E. Derenzo; David K. Wehe; Glenn F. Knoll

doi:10.1117/12.138604

22 December 1992 Temperature dependence of CsI(Tl) gamma-ray scintillation decay time constants and emission spectrum

John Valentine, William W. Moses, Stephen E. Derenzo, David K. Wehe, Glenn F. Knoll

Proceedings Volume 1734, Gamma-Ray Detectors; (1992) https://doi.org/10.1117/12.138604
Event: San Diego '92, 1992, San Diego, CA, United States

Abstract

The gamma-ray excited, temperature dependent scintillation characteristics of CsI(Tl) are reported over the temperature range of -100 to +50 degree(s)C. The modified Bollinger-Thomas and shaped square wave methods were used to measure the rise and decay times. The emission spectra were measured using a monochromator and corrected for monochromator and photocathode spectral efficiency. The shaped square wave method was also used to determine the scintillation yield as was a current mode method. The thermoluminescence emissions of CsI(Tl) were measured using the same current mode method. At room temperature, CsI(Tl) was found to have two primary decay components with decay time constants of (tau) ₁ equals 679 +/- 10 ns (63.7%) and (tau) ₂ equals 3.34 +/- 0.14 microsecond(s) (36.1%) and to have emission bands at about 400 and 560 nm. The (tau) ₁ luminescent state was observed to be populated by an exponential process with a resulting rise time constant of 19.6 +/- 1.9 ns at room temperature. An ultra-fast decay component with a < 0.5 ns decay time was found to emit about 0.2% (about 100 photons/MeV) of the total scintillation light. At -100 degree(s)C (tau) ₂ was too long to be resolved and (tau) ₁ was determined to be 3.52 +/- 0.39 microsecond(s) , while the 400 nm emission band was not observed. At +50 degree(s)C the decay constants were found to be 628 ns (70%) and 2.63 microsecond(s) (30%) and both emission bands are present. Four different commercially available CsI(Tl) crystals were used. Minimal variations in the measured scintillation characteristics were observed among these four crystals. Thermoluminescence emissions were observed to have peak yields at -90, -65, -40, +20, and possibly -55 degree(s)C. The relative magnitudes and number of thermoluminescence peaks were found to vary from crystal to crystal.

Citation Download Citation

John Valentine, William W. Moses, Stephen E. Derenzo, David K. Wehe, and Glenn F. Knoll "Temperature dependence of CsI(Tl) gamma-ray scintillation decay time constants and emission spectrum", Proc. SPIE 1734, Gamma-Ray Detectors, (22 December 1992); https://doi.org/10.1117/12.138604

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