Repurposing a low-cost commercial Si photodiode as a detector for X-ray and γ-ray spectroscopy at temperatures up to 80 °C

A commercial-off-the-shelf (COTS) Si p+-i-n+ photodiode (Hamamatsu S5973), designed for visible and infrared detection, was repurposed for use as a low-cost and readily available detector for photon counting X-ray and γ-ray spectroscopy. The detector was investigated for its spectroscopic performance, while being coupled to a custom-made charge sensitive preamplifier, under the illumination of photons with energies up to 59.54 keV. The detector-preamplifier system was subjected to temperatures from 80 °C to 20 °C. Energy resolutions (Full Width at Half Maximum, FWHM) of 0.66 keV ± 0.05 keV at 5.9 keV, 0.70 keV ± 0.04 keV at 22.16 keV, and 0.74 keV ± 0.06 keV at 59.54 keV, were achieved at 20 °C. The energy resolution deteriorated at 80 °C, reaching a value of 1.8 keV ± 0.1 keV FWHM at 59.54 keV. The results suggested that the performance, in terms of energy resolution, of the currently reported COTS Si detector was better than that achieved with certain purpose-grown wide bandgap detectors at 20 °C and 40 °C and better than that achieved with other repurposed Si detectors at 20 °C, opening new possibilities for applications for the Hamamatsu S5973 detectors and increasing the availability of low cost X-ray and γ-ray spectroscopy instrumentation.