Long-term stability of 1-cm thick pixelated HgI2 gamma-ray spectrometers operating at room temperature

Thick mercuric iodide (HgI₂) detectors are being investigated as potential room temperature gamma-ray spectrometers. This paper presents an investigation of the polarization effects and long-term spectral stability of pixelated HgI₂. Pixelated HgI₂ detectors have shown good stability over several months of measurements. After the first four days, the photopeak position and resolution have remained relatively constant. Current pixelated HgI₂ detectors may not suffer from polarization effects that once severely limited past planar HgI₂ devices, and can have good energy resolution (approximately 2% for a Cs-137 source) while using a modest electric field (∼2500 V/cm) and a relatively short shaping time (8 μs).