PoS - Proceedings of Science
Volume 395 - 37th International Cosmic Ray Conference (ICRC2021) - CRI - Cosmic Ray Indirect
Cosmic ray energy spectrum and composition measurements from the GRAPES-3 experiment: Latest results
F. Varsi*, S. Ahmad, M. Chakraborty, A. Chandra, S.R. Dugad, U.D. Goswami, S.K. Gupta, B. Hariharan, Y. Hayashi, P. Jagadeesan, A. Jain, P. Jain, S. Kawakami, H. Kojima, S. Mahapatra, P.K. Mohanty, R. Moharana, Y. Muraki, P.K. Nayak, T. Nonaka, A. Oshima, B.P. Pant, D. Pattanaik, G.S. Pradhan, P.S. Rakshe, M. Rameez, K. Ramesh, L.V. Reddy, R. Sahoo, R. Scaria, S. Shibata, J. Soni, K. Tanaka and M. Zuberiet al. (click to show)
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Pre-published on: July 14, 2021
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Abstract
The Gamma Ray Astronomy at PeV EnergieS phase-3 (GRAPES-3) experiment is located at Ooty in India (11.4$^{\circ}$ N, 76.7$^{\circ}$ E and 2200 m above m.s.l.). It consists of a densely packed array of 400 plastic scintillator detectors and a large area muon telescope (560 m$^{2}$). It measures cosmic rays from several TeV to over 10 PeV energies providing a substantial overlap with direct experiments, while covering the knee region. Shower parameters are reconstructed by fitting the observed particle densities with the NKG lateral distribution function (LDF). Relations between shower size and energy of primary cosmic rays are derived using air shower simulation with SIBYLL-2.3c and QGSJET-II-04 hadronic interaction models. These relations are used for obtaining the reconstructed energy spectrum and the Bayesian method is used for unfolding. In addition, precise measurements of the average nuclear composition are obtained by fitting muon multiplicity distributions (MMDs) for proton, helium, nitrogen, aluminium, and iron primaries with the MMDs measured by the muon telescope. Details of the analysis and preliminary results for the extracted energy spectrum and composition from a few tens of TeV to 10 PeV will be presented.
DOI: https://doi.org/10.22323/1.395.0388
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