Author/Authors :
Chang، نويسنده , , Y.-Y. and Chen، نويسنده , , C.R. and Chen، نويسنده , , P. and Huang، نويسنده , , J.-J. and Huang، نويسنده , , Yuan-liang Ma
Wei Liu، نويسنده , , T.-C. and Nam، نويسنده , , J.W. and Wang، نويسنده , , M.-Z. and Bogomolov، نويسنده , , V. and Brandt، نويسنده , , S. and Budtz-J?rgensen، نويسنده , , C. and Castro-Tirado، نويسنده , , A.J. and Choi، نويسنده , , H.S. and Connell، نويسنده , , P.H. and Eyles، نويسنده , , C. and Jeong، نويسنده , , S. and Kim، نويسنده , , J.E. and Kim، نويسنده , , M.B. and Kim، نويسنده , , S.-W. and Lee، نويسنده , , J. and Lim، نويسنده , , H. and Min، نويسنده , , K.W. and Panasyuk، نويسنده , , M.I. and Park، نويسنده , , I.H. and Petrov، نويسنده , , V. and Reglero، نويسنده , , V. and ??pa، نويسنده , , J. and Rodrigo، نويسنده , , J.M. and Svertilov، نويسنده , , S. and Yashin، نويسنده , , I.، نويسنده ,
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.
