Spectroscopic Performance of Thick HgI₂ Detectors

Area of Science:

• Semiconductor detector development
• Nuclear instrumentation
• Materials science

Background:

• Pixelated detectors offer improved spatial resolution for radiation detection.
• Mercuric iodide (HgI2) is a promising material for room-temperature semiconductor detectors.
• Characterizing detector performance is crucial for optimizing applications.

Purpose of the Study:

• To evaluate the spectroscopic performance of novel pixelated HgI2 detectors.
• To measure key electronic properties, including electron mobility-lifetime product and electron lifetime.
• To investigate spatial uniformity of detector response and internal electric fields.

Main Methods:

• Fabrication and characterization of two pixelated HgI2 detectors (1x1x0.814 cm3 and 1x1x1.016 cm3).
• Signal readout using discrete electronics with A-250 pre-amplifiers and digital oscilloscope.
• Application of depth sensing technique to correct for depth-dependent photopeak variations.

Main Results:

• Achieved energy resolutions between 0.85% and 1.3%.
• Measured electron mobility-lifetime product of approximately 1x10^-2 cm^2/V and electron lifetime of ~200 μs.
• Observed variations in electron drifting properties and significant non-uniformity in internal electric field strength across anode pixels.

Conclusions:

• The developed pixelated HgI2 detectors demonstrate high spectroscopic performance.
• Characterization revealed important electron transport properties and spatial non-uniformities.
• Further optimization of detector design and fabrication is needed to address field non-uniformity.