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

摘要

The use of 40Ca100MoO in experimental searches for neutrinoless double betadecay (0{\nu}DBD) relies on knowledge of fundamental scintillation propertiesof the material. In this work we determine the absolute light yield of calciummolybdate using Monte-Carlo refractive index matching technique (MCRIM). TheMCRIM technique is a combination of experiment and simulations that allows theabsolute light yield of scintillators to be determined by taking into accounteffects of refraction, scattering and absorption in the material. The lightcollection efficiency of the scintillator-detector assembly was simulated usingthe ZEMAX ray-tracing software. By tuning the optical parameters of thescintillation crystal, a model was derived that gives good agreement with theexperimental results. It is shown that the light collection efficiency ofscintillators increases with transmittance and scattering due to an enhancedprobability for photons to escape the crystal volume. Using MCRIM, the absolutelight yield for the 40Ca100MoO4 scintillator was found to be 7.5+-1.2 ph/keV atroom temperature. Comparative measurements using a CaWO4 scintillator as areference show good agreement with this result. In that way, the studydemonstrated the potential of the MCRIM technique as a tool for quantitativecharacterization of scintillation materials.