Status of the first phase of the Alborz Observatory Array: Alborz-I

Abstract

Alborz-I as the first phase of the Alborz Observatory Array supposed to study the cosmic ray spectrum around the knee at Sharif University of Technology campus, Tehran (1200 m a.s.l). In this paper theoretical results obtained from study of the design features, performance, array response and angular resolution of the Alborz-I consists of 20 plastic scintillation detectors each one with surface area of 0.25 m 2 spread over an area of 40⇥40 m 2 are described. Using Monte Carlo simulation of showers, the rate of detected events per day and the trigger probability function, i.e., the probability for an extensive air shower to trigger a ground based array as a function of the shower core distance to the center of array are presented for energies around the knee and zenith angles up to 60. Moreover, the angular resolution of the array is estimated in the energies of ⇠3⇥10 14 eV, which contains the most rate of detected events by the array.

Simulation and experimental results of daily Cosmic Ray detection rate by an array including 5 detectors

“…The result was inconsitent with simulation published in [2]. Major part of inconsistency is ascribed to detectors efficiency.…”

“…Daily rate of CR detection, for configuration of Alborz-1, is estimated by simulation in [2] and for trigger condition of "5 out of 5" in the central cluster corresponding result is 5645 (+948 -891). In order to be able to compare the value of simulation by experiment, we have to adjust zenith angle interval for both results.…”

“…It should be noted that, a major part of observed discrepancy can be referred to detectors efficiency. In the simulation [2], detectors efficiency was not taken into account. While, it is shown in [3] that efficiency of Alborz-1 detectors is something less than 66%.…”

“…Central cluster of Alborz-1 has been operating separately since October 2016 in order to perform several primary tests. Details of Albroz-1 configuration can be found on [1,2]. Data collected during the first 10 weeks of operation is used to measure daily rate of CR detection.…”