We present a measurement of the energy spectrum of ultra-high-energy cosmic rays performed by the Telescope Array experiment using monocular observations from its two new FADC-based fluorescence detectors. After a short description of the experiment, we describe the data analysis and event reconstruction procedures. Since the aperture of the experiment must be calculated by Monte Carlo simulation, we describe this calculation and the comparisons of simulated and real data used to verify the validity of the aperture calculation. Finally, we present the energy spectrum calculated from the merged monocular data sets of the two FADC-based detectors, and also the combination of this merged spectrum with an independent, previously published monocular spectrum measurement performed by Telescope Array's third fluorescence detector [T. Abu-Zayyad et al., The energy spectrum of Telescope Array's middle drum detector and the direct comparison to the high resolution fly's eye experiment, Astroparticle Physics 39 (2012) 109-119, http://dx.doi.org/10.1016/j.astropartphys.2012.05. 012, Available from: <arXiv:1202.5141>]. This combined spectrum corroborates the recently published Telescope Array surface detector spectrum [T. Abu-Zayyad, et al., The cosmic-ray energy spectrum observed with the surface detector of the Telescope Array experiment, ApJ 768 (2013) L1, http://dx.doi.org/10.1088/2041-8205/768/1/L1, Available from: <arXiv:1205.5067>] with independent systematic uncertainties.
|Number of pages||9|
|Publication status||Published - 2013|
Bibliographical noteFunding Information:
The Telescope Array experiment is supported by the Japan Society for the Promotion of Science through Grants-in-Aid for Scientific Research on Specially Promoted Research ( 21000002 ) “Extreme Phenomena in the Universe Explored by Highest Energy Cosmic Rays,” and the Inter-University Research Program of the Institute for Cosmic Ray Research; by the US National Science Foundation awards PHY-0307098 , PHY-0601915 , PHY-0703893 , PHY-0758342 , PHY-0848320 , PHY-1069280 , and PHY-1069286 (Utah) and PHY-0649681 (Rutgers) , and through TeraGrid resources provided by Purdue University and Indiana University  ; by the National Research Foundation of Korea ( 2006-0050031 , 2007-0056005 , 2007-0093860 , 2010-0011378 , 2010-0028071 , R32-10130 ); by the Russian Academy of Sciences, RFBR Grants 10-02-01406a and 11-02-01528a (INR) , IISN project No. 4.4509.10 , and Belgian Science Policy under IUAP VI/11 (ULB). The foundations of Dr. Ezekiel R. and Edna Wattis Dumke, Willard L. Eccles, and George S. and Dolores Doré Eccles all helped with generous donations. The State of Utah supported the project through its Economic Development Board, and the University of Utah through the Office of the Vice President for Research. The experimental site became available through the cooperation of the Utah School and Institutional Trust Lands Administration (SITLA), the US Bureau of Land Management, and the US Air Force. We also wish to thank the people and the officials of Millard County, Utah, for their steadfast and warm support. We gratefully acknowledge the contributions from the technical staffs of our home institutions as well as the University of Utah Center for High Performance Computing (CHPC).
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics