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Varsi F, Ahmad S, Chakraborty M, Chandra A, Dugad SR, Goswami UD, Gupta SK, Hariharan B, Hayashi Y, Jagadeesan P, Jain A, Jain P, Kawakami S, Kojima H, Lipari P, Mahapatra S, Mohanty PK, Moharana R, Muraki Y, Nayak PK, Nonaka T, Oshima A, Pant BP, Pattanaik D, Paul S, Pradhan GS, Rameez M, Ramesh K, Reddy LV, Saha S, Sahoo R, Scaria R, Shibata S, Zuberi M. Evidence of a Hardening in the Cosmic Ray Proton Spectrum at around 166 TeV Observed by the GRAPES-3 Experiment. Phys Rev Lett 2024; 132:051002. [PMID: 38364164 DOI: 10.1103/physrevlett.132.051002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 10/16/2023] [Accepted: 01/04/2024] [Indexed: 02/18/2024]
Abstract
We present the measurement of the cosmic ray proton spectrum from 50 TeV to 1.3 PeV using 7.81×10^{6} extensive air shower events recorded by the ground-based GRAPES-3 experiment between 1 January 2014 and 26 October 2015 with a live time of 460 day. Our measurements provide an overlap with direct observations by satellite and balloon-based experiments. The electromagnetic and muon components in the shower were measured by a dense array of plastic scintillator detectors and a tracking muon telescope, respectively. The relative composition of the proton primary from the air shower data containing all primary particles was extracted using the multiplicity distribution of muons which is a sensitive observable for mass composition. The observed proton spectrum suggests a spectral hardening at ∼166 TeV and disfavors a single power law description of the spectrum up to the Knee energy (∼3 PeV).
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Affiliation(s)
- F Varsi
- Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - S Ahmad
- Aligarh Muslim University, Aligarh 202002, India
| | - M Chakraborty
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - A Chandra
- Aligarh Muslim University, Aligarh 202002, India
| | - S R Dugad
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - U D Goswami
- Dibrugarh University, Dibrugarh 786004, India
| | - S K Gupta
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - B Hariharan
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - Y Hayashi
- Graduate School of Science, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan
| | - P Jagadeesan
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - A Jain
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - P Jain
- Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - S Kawakami
- Graduate School of Science, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan
| | - H Kojima
- College of Engineering, Chubu University, Kasugai, Aichi 487-8501, Japan
| | - P Lipari
- INFN, Sezione Roma "Sapienza", Piazzale Aldo Moro 2, 00185 Roma, Italy
| | | | - P K Mohanty
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - R Moharana
- Indian Institute of Technology Jodhpur, Jodhpur 342037, India
| | - Y Muraki
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya 464-8601, Japan
| | - P K Nayak
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - T Nonaka
- Institute for Cosmic Ray Research, Tokyo University, Kashiwa, Chiba 277-8582, Japan
| | - A Oshima
- College of Engineering, Chubu University, Kasugai, Aichi 487-8501, Japan
| | - B P Pant
- Indian Institute of Technology Jodhpur, Jodhpur 342037, India
| | - D Pattanaik
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
- Utkal University, Bhubaneswar 751004, India
| | - S Paul
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - G S Pradhan
- Indian Institute of Technology Indore, Indore 453552, India
| | - M Rameez
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - K Ramesh
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - L V Reddy
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - S Saha
- Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - R Sahoo
- Indian Institute of Technology Indore, Indore 453552, India
| | - R Scaria
- Indian Institute of Technology Indore, Indore 453552, India
| | - S Shibata
- College of Engineering, Chubu University, Kasugai, Aichi 487-8501, Japan
| | - M Zuberi
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
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