Application of the Monte-Carlo refractive index matching (MCRIM) technique to the determination of the absolute light yield of a calcium molybdate scintillator

TL;DR

This study applies the Monte-Carlo refractive index matching (MCRIM) technique combining experiments and simulations to accurately determine the absolute light yield of calcium molybdate scintillators, crucial for neutrinoless double beta decay research.

Contribution

The paper introduces and validates the MCRIM technique for precise measurement of scintillator light yield, accounting for optical effects through combined experimental and simulation methods.

Findings

Absolute light yield of 7.5±1.2 ph/keV for CaMoO4 at room temperature

MCRIM technique effectively models light collection efficiency considering refraction, scattering, and absorption

Good agreement with reference measurements using CaWO4 scintillator

Abstract

The use of 40Ca100MoO in experimental searches for neutrinoless double beta decay (0{\nu}DBD) relies on knowledge of fundamental scintillation properties of the material. In this work we determine the absolute light yield of calcium molybdate using Monte-Carlo refractive index matching technique (MCRIM). The MCRIM technique is a combination of experiment and simulations that allows the absolute light yield of scintillators to be determined by taking into account effects of refraction, scattering and absorption in the material. The light collection efficiency of the scintillator-detector assembly was simulated using the ZEMAX ray-tracing software. By tuning the optical parameters of the scintillation crystal, a model was derived that gives good agreement with the experimental results. It is shown that the light collection efficiency of scintillators increases with transmittance and scattering due to an enhanced probability for photons to escape the crystal volume. Using MCRIM, the absolute light yield for the 40Ca100MoO4 scintillator was found to be 7.5+-1.2 ph/keV at room temperature. Comparative measurements using a CaWO4 scintillator as a reference show good agreement with this result. In that way, the study demonstrated the potential of the MCRIM technique as a tool for quantitative characterization of scintillation materials.