Acquisition and Evaluation of Gamma-ray Energy Spectrum with CsPbBr3
Lei R. Cao a, Lei Pan a, Yuanxiang Feng b, Praneeth Kandlakunta a, Jinsong Huang b
a 1. Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio, 43210, USA
b Department of Applied Physical Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27514, USA
nanoGe Fall Meeting
Proceedings of nanoGe Fall Meeting19 (NGFM19)
#RadDet19. Radiation Detection Semiconductors Materials, Physics and Devices
Berlin, Germany, 2019 November 3rd - 8th
Organizers: Mahshid Ahmadi and Germà Garcia-Belmonte
Invited Speaker, Lei R. Cao, presentation 310
Publication date: 16th July 2019

The all-inorganic CsPbBr3 perovskite has advantages over the organic-inorganic perovskites for X- and gamma-rays detection due to the structural stability. It also has a series of desirable properties for ionizing radiation detection such as high attenuation coefficient, a wide band gap energy, and a large mobility-lifetime (mt) product. We have grown and fabricated CsPbBr3 single crystals into gamma detector and was able to acquire gamma energy spectrum from Cs-137 and Co-57 sources. The surface condition and metal contacts are proved to be critical factors in improving the performance of the detector for gamma ray detection. The energy resolution, in full-width-at-half-maximum, of the gamma spectra is 5.5% at 662 keV and 13.1% at 122 keV, respectively. The 59.5 keV gamma-rays from Np-237 nuclear decay in a Am-241 source is also clearly distinguishable with resolution of 28.3% when the detector is exposed to an Am-241 source. Electron-hole averaged mobility-lifetime mt product is evaluated to be 7.91´10-4 cm2 V-1 by Hecht equation fitting. It has found that the hole mobility is higher than electron mobility, which subsequently affects the resolution of the full energy peak. We demonstrated the effects of a better hole transport properties compared to that of electron at spectroscopy level by acquiring gamma-rays’ spectra, in other words, the overserved lower energy tailing of a full energy peak is attributed to low electron mobility. The small pixel and digital pulse processing (DPP) are suggested as possible solutions to improve the energy resolution of gamma spectrum acquired by CsPbBr3. A DPP algorithm is also developed to process the preamplifier signal with potentially long rise time (in the order of tens of micro seconds) in perovskite detectors, which ensures the elimination of ballistic deficit in the charge collection as well as in pulse shaping for distortion-free energy histogram reconstruction.



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