Measurement of Underground Cosmic Muons Charge Ratio at INO-ICAL Detector

Abstract

Cosmic rays primarily composed of high energy protons and atomic nuclei which interact with the earth’s atmospheric nuclei and produce pions and kaons, these particles further decay to muons. The charge ratio of these energetic muons is an important measurable which carries information about (i) pi/k hadronic production ratio (ii) Composition of cosmic ray primaries (iii) Contribution of charmed hadrons (iv) Neutrino flux at very high energies etc. Measurement of this ratio up to tens of TeV has been made by several experiments(MINOS (Adamson et al., Phys Rev, D76:052003, (2007), [4]), OPERA (Agafonova et al., Eur Phys J, C67:25,(2010), [5]), CMS (Khachatryan et al., Phys Lett, B692:83, (2010), [6]) etc.). The proposed ICAL detector at INO (Chatterjee et al., JINST, 9(2014):PO7001, (2014), [1]) is a large underground magnetized iron detector. This detector is shielded by 1.2 Km of rock(approx). When the muons produced in the atmosphere pass through rock, low energy muons are stopped in the rock but the high energy muons will reach the detector. ICAL being a magnetized detector is capable of identifying charge of the particle, hence we can identify \(\mu \)+ and \(\mu \)- separately. In this work we have generated muon flux at the top of the hill using Corsika(Cosmic ray generator) (Agostinelli et al., Nucl Instrum Meth A 506:250, (2003), [3]) and this flux passes through the hill to the detector, detector simulation is done using the Geant4 based code developed by INO collaboration. We have also added the hill topography as shown in Fig. 180.2 to the code, rock composition considered here is same as that of the standard rock. Highly energetic muons will then enter the detector and give tracks in the detector. Muon tracks will be reconstructed via Kalman filter technique. Finally we are measuring energy and number of \(\mu \)+ and \(\mu \)- particles passing through the rock to the detector.