Eur. Phys. J. C (2010) 67: 25-37
https://doi.org/10.1140/epjc/s10052-010-1284-8

Regular Article - Experimental Physics

Measurement of the atmospheric muon charge ratio with the OPERA detector

¹ INR—Institute for Nuclear Research of the Russian Academy of Sciences, 117312, Moscow, Russia
² SINP MSU—Skobeltsyn Institute of Nuclear Physics of Moscow State University, 119992, Moscow, Russia
³ Kobe University, 657-8501, Kobe, Japan
⁴ Albert Einstein Center for Fundamental Physics, Laboratory for High Energy Physics (LHEP), University of Bern, 3012, Bern, Switzerland
⁵ IPNL, Université Claude Bernard Lyon 1, CNRS/IN2P3, 69622, Villeurbanne, France
⁶ ETH Zurich, Institute for Particle Physics, 8093, Zurich, Switzerland
⁷ LPI—Lebedev Physical Institute of the Russian Academy of Sciences, 117924, Moscow, Russia
⁸ INFN Sezione di Padova, 35131, Padova, Italy
⁹ LAPP, Université de Savoie, CNRS/IN2P3, 74941, Annecy-le-Vieux, France
¹⁰ Hamburg University, 22761, Hamburg, Germany
¹¹ Dipartimento di Fisica dell’Università di Salerno and INFN, 84084, Fisciano, Salerno, Italy
¹² Dipartimento di Fisica dell’Università di Padova, 35131, Padova, Italy
¹³ Dipartimento di Fisica dell’Università di Bologna, 40127, Bologna, Italy
¹⁴ INFN Sezione di Bologna, 40127, Bologna, Italy
¹⁵ INFN Sezione di Napoli, 80125, Napoli, Italy
¹⁶ INFN—Laboratori Nazionali di Frascati dell’INFN, 00044, Frascati (Roma), Italy
¹⁷ IPHC, Université de Strasbourg, CNRS/IN2P3, CNRS/IN2P3, 67037, Strasbourg, France
¹⁸ INFN—Laboratori Nazionali del Gran Sasso, 67010, Assergi (L’Aquila), Italy
¹⁹ Dipartimento di Fisica dell’Università Federico II di Napoli, 80125, Napoli, Italy
²⁰ INFN Sezione di Bari, 70126, Bari, Italy
²¹ Dipartimento di Fisica dell’Università dell’Aquila and INFN, 67100, L’Aquila, Italy
²² JINR—Joint Institute for Nuclear Research, 141980, Dubna, Russia
²³ ITEP—Institute for Theoretical and Experimental Physics, 117218, Moscow, Russia
²⁴ University of Münster, 48149, Münster, Germany
²⁵ Nagoya University, 464-8602, Nagoya, Japan
²⁶ Toho University, 274-8510, Funabashi, Japan
²⁷ Department of Physics, Technion, 32000, Haifa, Israel
²⁸ METU—Middle East Technical University, 06531, Ankara, Turkey
²⁹ Fachbereich Physik der Universität Rostock, 18051, Rostock, Germany
³⁰ IRB—Rudjer Boskovic Institute, 10002, Zagreb, Croatia
³¹ Gyeongsang National University, 900 Gazwa-dong, Jinju, 660-701, South Korea
³² Aichi University of Education, 448-8542, Kariya (Aichi-Ken), Japan
³³ Dipartimento di Fisica dell’Università di Bari, 70126, Bari, Italy
³⁴ Dipartimento di Fisica dell’Università di Roma “La Sapienza” and INFN, 00185, Roma, Italy
³⁵ Utsunomiya University, 321-8505, Tochigi-Ken, Utsunomiya, Japan
³⁶ IIHE, Université Libre de Bruxelles, 1050, Brussels, Belgium

^* e-mail: sioli@bo.infn.it

Received: 14 December 2009
Revised: 17 February 2010
Published online: 23 March 2010

Abstract

The OPERA detector at the Gran Sasso underground laboratory (LNGS) was used to measure the atmospheric muon charge ratio in the TeV energy region. We analyzed 403069 atmospheric muons corresponding to 113.4 days of livetime during the 2008 CNGS run. We computed separately the muon charge ratio for single and for multiple muon events in order to select different energy regions of the primary cosmic ray spectrum and to test the R _μ dependence on the primary composition. The measured R _μ values were corrected taking into account the charge-misidentification errors. Data have also been grouped in five bins of the “vertical surface energy” ℰ _μ cos θ. A fit to a simplified model of muon production in the atmosphere allowed the determination of the pion and kaon charge ratios weighted by the cosmic ray energy spectrum.