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Wide-angle atmospheric Cherenkov array TAIGA-HiSCORE

Name
Aleksandr
Surname
Pakhorukov
Scientific organization
Irkutsk State University
Academic degree
PhD
Position
Junior research fellow
Scientific discipline
Physics & Astronomy
Topic
Wide-angle atmospheric Cherenkov array TAIGA-HiSCORE
Abstract
TAIGA-HISCORE, deployed in the Tunka Valley (50 km west of Lake Baikal), is one part of the planned integrated gamma observatory TAIGA intended for investigations in the field of high-energy (>30 TeV) gamma-ray astronomy and cosmic-ray physics as well as the search for dark matter. The brief array description, estimation of energy threshold, measurement of angular sensitivity and time-calibration as well as first results from operating a prototype array composed of nine stations spread over an area of ~0.1 square kilometers during the winter of 2013–2014 are presented.
Keywords
cosmic ray; gamma-ray astronomy; PeVatron; elementary particles; high-energy physics; Cherenkov light; EAS
Summary

TAIGA-HISCORE is wide-angle non-imaging atmospheric Cherenkov array. Its appellation is abbreviation, deciphered as the Tunka Advanced Instrument for Gamma-ray and cosmic ray Astrophysics - High Sensitive Cosmic ORigin Explorer.

The array consists of optical stations, located at the lattice point. The distance between the closest neighboring stations is around 106 m. There are 28 OS in area of 0,25 km2 at this stage of deployment (2016).

Each optical station consists of four optical modules – photoelectric multipliers with photocathodes 20 cm in diameter, equipped by Winston cones, which fourfold enlarge the light collecting area of each photomultiplier. The station’s solid angle of view is 0,6 sr. To lower the station’s energy threshold, the signals from the anodes of the four photomultipliers are added together, and the total signal is fed to the comparator input of the local triggering system. The signals from the photomultiplier anodes and intermediate dynodes are digitized at a sampling rate of 0.5 ns. The comparator threshold of the local triggering system is selected to lie in the region where the amplitude spectrum of the signals generated by an EAS (density spectrum) intersect with the fluctuation spectrum of the night sky background. The station’s count rate is 12–16 Hz. The modeling of the count rate of a single station showed that this count rate corresponds to a threshold Cherenkov light flux of 0.3 photons per square centimeter. With this threshold, an EAS generated by 30 TeV gamma quanta should be detected at distances of up to 120 m from the shower axis and an EAS generated by 30 TeV protons should be detected at distances of up to 50 m from the shower axis.