Direct and indirect signal detection of 122 keV photons with a novel detector combining a pnCCD and a CsI(T1) scintillator

Abstract

By combining a low noise fully depleted pnCCD detector with a CsI(TI) scintillator, an energy-dispersive area detector can be realized with a high quantum efficiency (QE) in the range from below 1 keV to above 100 keV. In direct detection mode the pnCCD exhibits a relative energy resolution of 1% at 122 keV and spatial resolution of less than 75 mu m, the pixel size of the pnCCD. In the indirect detection mode, i.e. conversion of the incoming X-rays in the scintillator, the measured energy resolution was about 9-13% at 122 keV, depending on the depth of interaction in the scintillator, while the position resolution, extracted with the help of simulations, was 30 mu m only. We show simulated data for incident photons of 122 keV and compare the various interaction processes and relevant physical parameters to experimental results obtained with a radioactive Co-57 source. (C) 2015 Elsevier B.V. All rights reserved.