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Explore the intricate relationship between photons, charge accumulation, and trap dynamics in semiconductor detectors. Discover how biases and cosmic rays affect depletion regions, leading to negative persistence and varying flat field responses. This comprehensive model sheds light on complex phenomena in device operation.
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Flux Dependent Non-Linearity:The Evil Twin of Persistence Mike Regan, Kevin Lindsay, Eddie Bergeron, Rachel Anderson
Photons captured in the depletion region yield an electron/hole pair.
As charge accumulates, the depletion region gets smaller exposing empty traps to free charge.
After a reset trapped electrons and holes are left in the depletion region.
During the next exposure the electrons/holes decay from the traps and are seen as an increase in the voltage.
During an exposure traps capture charge decreasing the observed voltage.
This model makes several predictions. • Flat field response will be lower at low fluxes in high trap regions. • Detector bias changes that decrease the size of the depletion region will induce “negative persistence”. • Slopes after cosmic rays will be lower.
The Ratio of high and low flux flat fields shows a difference in the high trap region. Flux ratio was a factor of 60.
The measured slopes on the device are negative after we change the bias.
The negative observed rates decay away just like persistence.
The slope after a cosmic ray is lower and is proportional to the magnitude of the CR
Conclusions • The model matches all the observations. • The observed QE is a function of the flux -> Flux dependent QE • Determining slopes when there is a cosmic ray is not simple (as I thought before).