Telescope Array 10-Year Monocular Spectrum Measurement

Telescope Array Collaboration

Research output: Contribution to journalConference articlepeer-review


Telescope Array (TA) is the largest cosmic ray detector in the northern hemisphere. We present a measurement of the cosmic ray energy spectrum for energies above 1017.5 eV using fluorescence telescopes in monocular mode. A novel weather classification scheme using machine learning was used to select data parts with good weather to ensure the quality of the fluorescence data. The data from the Black Rock Mesa (BR) and Long Ridge (LR) fluorescence telescope stations were analysed separately in monocular mode, with the calculated fluxes combined into a single spectrum. The 10-year monocular combined cosmic ray energy spectrum is in excellent agreement with previous measurements from the northern hemisphere. We present fits of the combined spectrum to a series of broken power law models. A thrice-broken power law is observed to be the best fit considering the Poisson deviance per degrees of freedom. The three breaks suggest an additional feature of the spectrum between the previously observed Ankle at 1018.7 eV and the GZK suppression at 1019.8 eV.

Original languageEnglish
Article number339
JournalProceedings of Science
Publication statusPublished - 2022 Mar 18
Event37th International Cosmic Ray Conference, ICRC 2021 - Virtual, Berlin, Germany
Duration: 2021 Jul 122021 Jul 23

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All Science Journal Classification (ASJC) codes

  • General


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