A new approach to determine muon multiplicity at the GRAPES-3 experiment

Abstract

The muon content in extensive air showers (EAS) is a sensitive observable for measuring the primary cosmic ray composition. An accurate determination of the muon multiplicity in an EAS is thus imperative for composition studies. The GRAPES-3 experiment, located in Ooty, India, contains a dense scintillator array to measure the electromagnetic components and a large area muon telescope to measure the muonic component in the EAS by counting the reconstructed muon tracks based on the proportional counter hit information. However, due to the large dimension of the proportional counters (6m × 0.1m × 0.1m), saturation of tracks in a given module (35 m2 area) occurs below about 20 muons. Here, we present a new method to calculate the number of muons in an EAS based on the pulse height information recorded in the proportional counters in addition to the hit information. The pulse height is proportional to the energy deposited by the muons. The preliminary results of the analysis show that the dynamic range of detecting muons has increased by more than a factor of two. This is an important development for reliable measurement of PCRs’ composition beyond the Knee region (∼ 3 PeV) of the cosmic ray spectrum when the the density of muons is higher than the saturation limit with the current method. © Copyright owned by the author(s) under the terms of the Creative Commons.