Cosmic-ray-related signals from detectors in space: the spitzer/irac si:As ibc devices

J. Brendan Hagan, George Rieke, Ori D. Fox, Alberto Noriega-Crespo, Dean C. Hines, Misty Cracraft, Macarena García Marín

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


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 solidstate 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.

Original languageEnglish (US)
Article number114503
JournalPublications of the Astronomical Society of the Pacific
Issue number1029
StatePublished - Nov 1 2021


  • Infrared Astronomical Satellite
  • Infrared astronomy
  • Space vehicle instruments

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'Cosmic-ray-related signals from detectors in space: the spitzer/irac si:As ibc devices'. Together they form a unique fingerprint.

Cite this