Optimization of light collection from crystal scintillators for cryogenic experiments

Abstract

High light collection efficiency is an important requirement in any application of scintillation detectors. The purpose of this study is to investigate the possibility for improving this parameter in cryogenic scintillation bolometers, which can be considered as a promising detectors in experiments investigating neutrinoless double beta decay and dark matter. Energy resolutions and relative pulse amplitudes of scintillation detectors using ZnWO 4 scintillation crystals of different shapes (cylinder  20  20 mm and hexagonal prism with diagonal 20 mm and height 20 mm), reflector materials and shapes, optical contact and surface properties (polished and diffused) were measured at room temperature. Propagation of optical photons in these experimental conditions was simulated using Geant4 and ZEMAX codes. The results of the simulations are found to be in good agreement with each other and with direct measurements of the crystals. This could be applied to optimize the geometry of scintillation detectors used in the cryogenic experiments.

Neganov-Luke amplified cryogenic light detectors for the background discrimination in neutrinoless double beta decay search with TeO2bolometers

“…A 20 × 20 × 10 mm 3 TeO 2 crystal with a mass of ∼ 23 g is mounted inside the housing using Teflon (PTFE) clamps. All sides of the crystal are roughened to reduce the amount of light trapped inside the crystal [17]. Since all sides are roughened, the IrAu transition edge sensor (TES) [18] is deposited onto a silicon carrier substrate (5 × 3 × 0.5 mm 3 ) and then glued to the crystal.…”

Low background techniques in bolometers for double-beta decay search

“…63,87,[186][187][188][189] Consequently, the light collection efficiency is crucial for detectors with low light yield, thus the study of light production and transport, as e.g., 190 are rather important for the detector optimization. In particular, the light collection can be enhanced by improving the material quality (transmittance to the emitted light), by choosing a proper crystal shape and surface treatment, 102,191,192 by reducing the light reflection in the photodetector, [193][194][195] by adding an efficient reflector, 41,63 as well as by using an optical bolometer with an area comparable to a crystal-side surface. 41, 63…”

Optical, luminescence and thermal properties of radiopure ZnMoO4 crystals used in scintillating bolometers for double beta decay search

“…We assume 30 cm of attenuation length in ZnMoO 4 crystals. The technique of the Monte Carlo simulation was tested with two ZnWO 4 crystal scintillators (of cylindrical and hexagonal shape) measured in different conditions of optical contact, reflector material, configuration and surface treatment [57]. As one can see from Table 6, crystal scintillators of hexagonal shape with diffused surface provide the best light collection.…”