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

The use of 40Ca100MoO in experimental searches for neutrinoless double beta decay (0νDBD) 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. © 2013 IOP Publishing Ltd and Sissa Medialab srl

X-ray, optical and dielectric studies of diffused phase transitions in NaNbO3-based solid solution crystals

In flux-grown (1-x)NaNbO3 -(x)Gd1/3NbO3 solid solution crystals a diffusion of the dielectric permittivity epsilon maximum grows with x and increases dramatically when x exceeds a threshold value x 0 approximate to 0.1. Optical studies by the rotating-polarizer method show that Gd-doping results in a very small mean size of twins and the distribution of the birefringence image becomes very messy. In the x < x(0) range the changes of lattice parameters and birefringence corresponding to the epsilon(T) anomaly were revealed. The results obtained are in line with the assumption that phase transition diffusion in NaNbO3 is a result of the local strains stemmed from the impurities

Structural instability of epitaxial (001) BiFeO3 thin films under tensile strain

10.1038/srep04631Scientific Reports4