Determining the angular resolution of an air shower array including five scintillation detectors using two methods: Shadow of the moon and the CORSIKA simulation

摘要

An array including five scintillation detectors at Sharif University of Technology in Tehran (35 degrees 43'N, 51 degrees 20'E, 1200m a.s.l = 897 gcm(-2)), over a year from October 2016 to October 2017, collected more than 5.6 x 10(5) extensive air shower (EAS) events in the energy range between 0.03PeV and 3PeV. Data from the array were used to examine the cosmic ray shadow of the Moon in the energy range mentioned. The observation of a deficit of cosmic rays in the direction of the moon can be an estimate of the accuracy of the measurement of the primary particles of the air showers. The deficit of cosmic rays from the direction of the moon, in fact, is due to the presence of the moon in the early direction of the cosmic rays which prevents them from reaching the earth, and is interpreted as the shadow of the moon.A preliminary analysis of the directions of cosmic rays has been done in a two-dimensional sky map (zenith and azimuth angles) to compare the deficit of cosmic rays in terms of the angular radius from the moving moon center with the centers randomly selected in the sky. In this method, a two-dimensional Gaussian distribution for shadowed events is considered, which the standard deviation of this distribution is interpreted as the angular resolution of the array. Also, using the CORSIKA simulation data, the angular resolution of this array is obtained for different energies and different zenith angles and its mean value is calculated by considering the probability of detecting different energies by the array. The angular resolutions obtained with these two methods are comparable.