EPJ Web Conf.
Volume 210, 2019Ultra High Energy Cosmic Rays 2018 (UHECR 2018)
|Number of page(s)||10|
|Section||Spectrum, Anisotropies, Mass Composition|
|Published online||17 May 2019|
Measurements of UHECR Mass Composition by Telescope Array
University of Utah Dept. of Physics and Astronomy & High Energy Astrophysics Institute, 201 James Fletcher Bldg., 115 S 1400 E, Salt Lake City, UT 84112, USA
* e-mail: firstname.lastname@example.org
Published online: 17 May 2019
Telescope Array (TA) has recently published results of nearly nine years of Xmax observations providing its highest statistics measurement of ultra high energy cosmic ray (UHECR) mass composition to date for energies exceeding 1018.2 eV. This analysis measured agreement of observed data with results expected for four different single elements. Instead of relying only on the first and second moments of Xmax distributions, we employ a morphological test of agreement between data and Monte Carlo to allow for systematic uncertainties in data and in current UHECR hadronic models. Results of this latest analysis and implications of UHECR composition observed by TA are presented. TA can utilize different analysis methods to understand composition as both a crosscheck on results and as a tool to understand systematics affecting Xmax measurements. The different analysis efforts utilizing fluorescence detector stereo, surface detector and fluorescence detector hybrid, and surface detector-only, currently underway at TA performed to understand composition are also discussed.
© The Authors, published by EDP Sciences, 2019
This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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