ИСТИНА

A prototype of gamma ray observatory TAIGA (Tunka Advanced Instrument for cosmic ray physics and Gamma Astronomy) is currently comprises 28 wide-angle stations for registration of Cherenkov light from extensive air showers (EAS). Station fill the area of an ellipse with main axes 600 and 450 m. Minimum distance between stations is 106 m. All stations are tilted from Zenith to the South to 25°. The sensitive elements of each station are 4 PMTs with hemispherical photo-cathodes with a diameter of 20 cm, equipped with a light-collecting Winston cones to increase the effective area. Full effective area of light collection is about 0.5 m^2. The signals of each PMT are digitized every 0.5 ns, resulting in trace of 512 ns. Each station uses its own local trigger and the formation of EAS event is performed off-line according to the timing of local triggers of different stations. The pulses are merged to a joint event in case of coincidence of the delays at 4 or more stations inside the time gate of 2 microseconds. The data acquisition has been carried out from October 2015 to March 2016. During 250 hours on a clear moonless night 10^7 events have been collected. The methods of the EAS main parameters reconstruction for different energy ranges are discussed. A preliminary differential energy spectrum of cosmic rays in the range of 3.10^14 – 3.10^16 eV according to the new array version is presented.