Cosmic Ray Susceptibility of the Terahertz Intensity Mapper Detector Arrays

Lun Jun Liu, Reinier M.J. Janssen, Bruce Bumble, Elijah Kane, Logan M. Foote, Charles M. Bradford, Steven Hailey Dunsheath, Shubh Agrawal, James E. Aguirre, Hrushi Athreya, Justin S. Bracks, Brockton S. Brendal, Anthony J. Corso, Jeffrey P. Filippini, Jianyang Fu, Christopher E. Groppi, Dylan Joralmon, Ryan P. Keenan, Mikolaj Kowalik, Ian N. LoweAlex Manduca, Daniel P. Marrone, Philip D. Mauskopf, Evan C. Mayer, Rong Nie, Vesal Razavimaleki, Talia Saeid, Isaac Trumper, Joaquin D. Vieira

Research output: Contribution to journalArticlepeer-review


We report on the effects of cosmic ray interactions with the kinetic inductance detector (KID)-based focal plane array for the terahertz intensity mapper (TIM). TIM is a NASA-funded balloon-borne experiment designed to probe the peak of the star formation in the Universe. It employs two spectroscopic bands, each equipped with a focal plane of four ∼900-pixel, KID-based array chips. Measurements of an 864-pixel TIM array show 791 resonators in a 0.5 GHz bandwidth. We discuss challenges with resonator calibration caused by this high multiplexing density. We robustly identify the physical positions of 788 (99.6 %) detectors using a custom LED-based identification scheme. Using this information, we show that cosmic ray events occur at a rate of 2.1events/min/cm2 in our array. 66 % of the events affect a single pixel, and other 33 % affect <5 KIDs per event spread over a 0.66cm2 region (2 pixel pitches in radius). We observe a total cosmic ray dead fraction of 0.0011 % and predict that the maximum possible in-flight dead fraction is ∼0.124 %, which demonstrates our design will be robust against these high-energy events.

Original languageEnglish (US)
JournalJournal of Low Temperature Physics
StateAccepted/In press - 2024


  • Aluminum
  • Astrophysics
  • Balloon
  • Kinetic inductance detectors
  • Spectroscopy
  • Terahertz

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • General Materials Science
  • Condensed Matter Physics


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