Abstract
The only cosmic rayRoy, S. extended air shower (EAS) arrayChakraborty, S. in the eastern partChatterjee, S. of India, consisting of 7 activeBiswas, S. plastic scintillatorDas, S. detectors, has been commissionedGhosh, S. K. at an altitude of aboutMaulik, A. 2200 m above sea level in theRaha, S. Eastern Himalayas (Darjeeling) at the end of January 2018. Six detectors are kept at the vertices of a hexagon and one at the center of it. The distance between two consecutive detectors is 8 m. Each detector element is made up of four plastic scintillators of dimension 50 cm ×\documentclass[12pt]{minimal}
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\begin{document}$$\times $$\end{document} 50 cm ×\documentclass[12pt]{minimal}
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\begin{document}$$\times $$\end{document} 1 cm thereby forming a total active area of 1 m ×\documentclass[12pt]{minimal}
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\begin{document}$$\times $$\end{document} 1 m. These scintillators are fabricated indigenously in the Cosmic Ray Laboratory (CRL), TIFR, Ooty, India. All four scintillators of a detector are coupled with a single Photo Multiplier Tube (PMT) using wavelength shifting (WLS) fibers. A custom-built module with seven inputs is used to generate a multifold trigger. Measurement of the number of cosmic ray air showers is going on since the end of January 2018. The secondary cosmic ray flux and its variation over time are also recorded at the laboratory in Darjeeling using a threefold coincidence technique with plastic scintillators. All the details of the experimental setup and techniques of measurement are reported earlier. The updates in the results are presented in this article.