Inverted-conical light guide for crosstalk reduction in tightly-packed scintillator matrix and MAPMT assembly

Y. Y. Chang, C. R. Chen, P. Chen, J. J. Huang, M. A. Huang, T. C. Liu, J. W. Nam, M. Z. Wang, V. Bogomolov, S. Brandt, C. Budtz-Jørgensen, A. J. Castro-Tirado, H. S. Choi, P. H. Connell, C. Eyles, S. Jeong, J. E. Kim, M. B. Kim, S. W. Kim, J. LeeH. Lim, K. W. Min, M. I. Panasyuk, I. H. Park, V. Petrov, V. Reglero, J. Řípa, J. M. Rodrigo, S. Svertilov, I. Yashin

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Abstract

In this paper we present the Inverted-Conical light guide designed for optical crosstalk reduction in the scintillator-MAPMT assemblies. The research was motivated by the 30% crosstalk observed in UFFO X-ray telescope, UBAT, during the preliminary calibration with MAPMTs of 64 2.88 × 2.88 mm2 pixels and identically gridded YSO crystal matrices. We began the study with the energy and crosstalk calibrations of the detector, then we constructed a GEANT4 simulation with the customized metallic film model as the MAPMT photocathode. The simulation reproduced more than 70% of the crosstalk and explained it as a consequence of the total reflection produced by the photocathode. The result indicated that the crosstalk mechanism could be a common case in most of the contact-assembled scintillation detectors. The concept of the Inverted-Conical light guide was to suppress the total reflection by contracting the incident angle of the scintillation. We optimized the design in the simulation and fabricated a test sample. The test sample reduced 52% crosstalk with a loss of 6% signal yield. The idea of the Inverted-Conical light guide can be adapted by scintillation detectors multi-pixel, imaging-purpose scintillation detectors such as the ultra-fast GRB observatory UFFO-UBAT, whose performances are sensitive to responding time, image resolution, and geometrical modifications.

Original languageEnglish
Pages (from-to)55-65
Number of pages11
JournalNuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Volume771
DOIs
Publication statusPublished - 2015 Jan 21

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Instrumentation

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    Chang, Y. Y., Chen, C. R., Chen, P., Huang, J. J., Huang, M. A., Liu, T. C., Nam, J. W., Wang, M. Z., Bogomolov, V., Brandt, S., Budtz-Jørgensen, C., Castro-Tirado, A. J., Choi, H. S., Connell, P. H., Eyles, C., Jeong, S., Kim, J. E., Kim, M. B., Kim, S. W., ... Yashin, I. (2015). Inverted-conical light guide for crosstalk reduction in tightly-packed scintillator matrix and MAPMT assembly. Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 771, 55-65. https://doi.org/10.1016/j.nima.2014.10.037