Study of Long-Term CdZnTe Stability Using the Polaris System

The first Polaris system was built in September 2010 and has gone through significant testing at multiple DOD and DOE facilities as well as at the University of Michigan. It has been biased almost continuously for the 18 months of its current lifespan without any replacement of its detectors. The second Polaris system was built in June 2011 and has also been almost continuously biased during its lifespan. The continuous operation of both devices has provided the best opportunity to study the long-term stability of pixelated CdZnTe detectors. Spectroscopic performance has been monitored throughout each system´s lifespan to study their performance over time and the impact on long term operation of these devices. It is shown that the charge transport properties and spectroscopic performance of these CdZnTe detectors are stable over time and devoid of fabrication or assembly issues. It is expected that future detectors will exhibit excellent stability.