Mass composition anisotropy with the Telescope Array Surface Detector data

The Telescope Array Collaboration

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Mass composition anisotropy is predicted by a number of theories describing sources of ultrahigh-energy cosmic rays. Event-by-event determination of a type of a primary cosmic-ray particle is impossible due to large shower-to-shower fluctuations, and the mass composition usually is obtained by averaging over some composition-sensitive observable determined independently for each extensive air shower (EAS) over a large number of events. In the present study we propose to employ the observable ξ used in the TA mass composition analysis for the mass composition anisotropy analysis. The ξ variable is determined with the use of Boosted Decision Trees (BDT) technique trained with the Monte-Carlo sets, and the ξ value is assigned for each event, where ξ = 1 corresponds to an event initiated by the primary iron nuclei and ξ = −1 corresponds to a proton event. Use of ξ distributions obtained for the Monte-Carlo sets allows us to separate proton and iron candidate events from a data set with some given accuracy and study its distributions over the observed part of the sky. Results for the TA SD 11-year data set mass composition anisotropy will be presented.

Original languageEnglish
Article number299
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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