27 September 2011 Long-term room temperature stability of TlBr gamma detectors
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TlBr is a material of interest for use in room temperature gamma ray detector applications due to is wide bandgap 2.7 eV and high average atomic number (Tl 81, Br 35). Researchers have achieved energy resolutions of 1.3 % at 662 keV, demonstrating the potential of this material system. However, these detectors are known to polarize using conventional configurations, limiting their use. Continued improvement of room temperature, high-resolution gamma ray detectors based on TlBr requires further understanding of the degradation mechanisms. While high quality material is a critical starting point for excellent detector performance, we show that the room temperature stability of planar TlBr gamma spectrometers can be significantly enhanced by treatment with both hydrofluoric and hydrochloric acid. By incorporating F or Cl into the surface of TlBr, current instabilities are eliminated and the longer term current of the detectors remains unchanged. 241Am spectra are also shown to be more stable for extended periods; detectors have been held at 2000 V/cm for 52 days with less than 10% degradation in peak centroid position. In addition, evidence for the long term degradation mechanism being related to the contact metal is presented.
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A. M. Conway, L. F. Voss, A. J. Nelson, P. R. Beck, R. T. Graff, R. J. Nikolic, S. A. Payne, H. Kim, L. J. Cirignano, K. Shah, "Long-term room temperature stability of TlBr gamma detectors", Proc. SPIE 8142, Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XIII, 81420J (27 September 2011); doi: 10.1117/12.896713; https://doi.org/10.1117/12.896713

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