The effects of cosmic rays and solar flares on the IRAC detectors: the first two years of in-flight operation

Hora, J. L.; Patten, B. M.; Fazio, G. G.; Glaccum, W.

doi:10.1117/12.672017

Cited by 7 publications

(2 citation statements)

References 14 publications

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“…The number of cosmic rays affecting an IRAC image is determined from the calibration skydark measurements of 100s frametimes taken once a week, using the same techniques as were preformed in the cryogenic mission. 11 The dark frames consist of 27 individual images taken in a 3x3 mapping pattern in the "Best NEP dark" region chosen at the beginning of the mission. This is within the continuous viewing zone and contained no bright sources that would saturate in 100s images.…”

Section: Date Of Observationmentioning

confidence: 99%

Calibration trending in the Spitzer beyond era

Lowrance

Krick

Ingalls

et al. 2018

Observatory Operations: Strategies, Processes, and Systems VII

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The Spitzer Space Telescope currently operates in the "Beyond Era", over nine years past an original cryogenic mission. As the astronomy community continues to advance scientific boundaries and push beyond original specifications, the stability of the Infrared Array Camera (IRAC) instrument is paramount. The Instrument Team (IST) monitors the pointing accuracy, temperature, and calibration and provides the information in a timely manner to observers. The IRAC IST created a calibration trending web page, available to the general astronomy community, where the team posts updates of three most pertinent scientific stability measures of the IRAC data: calibration, bias, and bad pixels. In addition, photometry and telescope properties from all the staring observations (>1500 as of April 2018) are trended to examine correlations with changes in the age or thermal properties of the telescope. A long, well-sampled baseline established by consistent monitoring outside anomalies and space weather events allows even the smallest changes to be detected.

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Section: Date Of Observationmentioning

confidence: 99%

Calibration trending in the Spitzer beyond era

Lowrance

Krick

Ingalls

et al. 2018

Observatory Operations: Strategies, Processes, and Systems VII

Self Cite

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“…The IRAC InSb and Si:As detector arrays on the Spitzer Space Telescope, with similar aluminum shielding, experienced transient rates of pixels hit ranging from 3 to 10 s −1 over the course of the cryogenic mission, except during solar flares, which led to much higher rates. 22 …”

Section: Proton Stopping Powermentioning

confidence: 99%

Proton irradiation results for long-wave HgCdTe infrared detector arrays for Near-Earth Object Camera

Dorn

Pipher

McMurtry

et al. 2016

J. Astron. Telesc. Instrum. Syst

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Abstract. HgCdTe detector arrays with a cutoff wavelength of ∼10 μm intended for the Near-Earth Object Camera (NEOCam) space mission were subjected to proton-beam irradiation at the University of California Davis Crocker Nuclear Laboratory. Three arrays were tested-one with 800-μm substrate intact, one with 30-μm substrate, and one completely substrate-removed. The CdZnTe substrate, on which the HgCdTe detector is grown, has been shown to produce luminescence in shorter wave HgCdTe arrays that causes an elevated signal in nonhit pixels when subjected to proton irradiation. This testing was conducted to ascertain whether or not full substrate removal is necessary. At the dark level of the dewar, we detect no luminescence in nonhit pixels during proton testing for both the substrate-removed detector array and the array with 30-μm substrate. The detector array with full 800-μm substrate exhibited substantial photocurrent for a flux of 103 protons∕cm 2 s at a beam energy of 18.1 MeV (∼750 e − ∕s) and 34.4 MeV (∼65 e − ∕s). For the integrated space-like ambient proton flux level measured by the Spitzer Space Telescope, the luminescence would be well below the NEOCam dark current requirement of <200 e − ∕s, but the pattern of luminescence could be problematic, possibly complicating calibration. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Cosmic-ray-related Signals from Detectors in Space: The Spitzer/IRAC Si:As IBC Devices

Hagan

Rieke

Fox

et al. 2021

PASP

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We evaluate the hit rate of cosmic rays and their daughter particles on the Si:As IBC detectors in the IRAC instrument on the Spitzer Space Telescope. The hit rate follows the ambient proton flux closely, but the hits occur at more than twice the rate expected just from this flux. Toward large amplitudes, the size distribution of hits by single-charge particles (muons) follows the Landau Distribution. The amplitudes of the hits are distributed to well below the energy loss of a traditional “average minimum-ionizing proton” as a result of statistical fluctuations in the ionization loss within the detectors. Nonetheless, hits with amplitudes less than a few hundred electrons are rare; this places nearly all hits in an amplitude range that is readily identified given the read noises of modern solid-state detectors. The spread of individual hits over multiple pixels is dominated by geometric effects, i.e., the range of incident angles, but shows a modest excess probably due to: (1) showering and scattering of particles; (2) the energy imparted on the ionization products by the energetic protons; and (3) interpixel capacitance. Although this study is focused on a specific detector type, it should have general application to operation of modern solid-state detectors in space.

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The effects of cosmic rays and solar flares on the IRAC detectors: the first two years of in-flight operation

Cited by 7 publications

References 14 publications

Calibration trending in the Spitzer beyond era

Calibration trending in the Spitzer beyond era

Proton irradiation results for long-wave HgCdTe infrared detector arrays for Near-Earth Object Camera

Cosmic-ray-related Signals from Detectors in Space: The Spitzer/IRAC Si:As IBC Devices

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