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Energetic Cosmic Ray Events in SIPIN-H2RG-015 Device

Energetic Cosmic Ray Events in SIPIN-H2RG-015 Device. Lance Simms. H2RG Device Layout. 800 micron CdZnTe substrate. Supposedly not photo-sensitive. 10 micron HgCdTe bulk. Photosensitive. Electron-Hole Pairs in Substrate?.

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Energetic Cosmic Ray Events in SIPIN-H2RG-015 Device

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  1. Energetic Cosmic Ray Events in SIPIN-H2RG-015 Device Lance Simms

  2. H2RG Device Layout 800 micron CdZnTe substrate Supposedly not photo-sensitive 10 micron HgCdTe bulk Photosensitive

  3. Electron-Hole Pairs in Substrate? • Photoelectrons generated in substrate will diffuse and cause multiple events in bulk material • This might lead to “Poofy Events” in Detector, i.e. events with large spatial extent

  4. H2RG-15 Dark Current Data • Examined the following • 5 ramps, 125 reads, minimum time between reads=10.7 seconds • At temperature of 37K • 45 ramps, 250 reads, minimum time between reads=10.7 seconds • 9 sets of 5 ramps at temperatures between 26-50K • Total Exposure time ~ 127,000 seconds

  5. Analysis • Took difference between last reads of successive ramps at a given temperature -should eliminate hot pixels and bias structure • Applied 2 separate search algorithms to flag large events (large > at least 5 pixels)

  6. 1st Search for Large Events 1st Algorithm only flagged hit if each pixel in 3x3 region registered >100 counts For each region, a Gaussian Fit was applied to the encompassing 10x10 area & Returned -Sigma -coordinates -Amplitude -background *Units are in Counts

  7. 1st Search Results Total=2407 events spanning 3x3 region

  8. 1st Search Results Total=2407 events spanning 3x3 region

  9. 2nd Search Looked for symmetric patterns where pixels where greater than a certain threshold n=1 n=2 …etc. …….

  10. 2nd Search Results *n=4 to n=9 are tabulated

  11. Overall Results No events found with spatial extent > 20 pixels Largest Events found ~19 pixels wide (SNR ~ 2) Background ~ 5 counts All pixel values above 10 counts

  12. Comparison with other H2RG images Large Events like the ones in this image not seen (or at least not detected) Signal to Noise Ratio of circled events unknown Image courtesy of Roger Smith

  13. Comparison with other H2RG images No events of this type detected. Either search algorithm should have flagged such an event. Central Region: 5x noise ~2400 pixels Image Courtesy of Amy Mainzer

  14. Possibilities for lack of large hits • Particles that constitute these events might not make it into basement where IDTL is located (Steel girders)? • Search criteria need to be modified (i.e. look for large events based on comparison to local noise rather than threshold)?

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