The Tunka-133 EAS Cherenkov light array: status of 2011

TL;DR

The paper reports on the status and initial results of the Tunka-133 Cherenkov light array, a large-scale detector for studying cosmic rays in the 10^16 to 10^18 eV energy range, including its construction, calibration, and preliminary findings.

Contribution

It presents the design, calibration, and initial data analysis of the Tunka-133 array, including methods for energy and composition measurement and plans for future upgrades.

Findings

Energy spectrum consistent with previous measurements

Estimated depth of EAS maximum X_max vs. energy

Preliminary radio detection results

Abstract

A new EAS Cherenkov light array, Tunka-133, with ~1 km^2 geometrical area has been installed at the Tunka Valley (50 km from Lake Baikal) in 2009. The array permits a detailed study of cosmic ray energy spectrum and mass composition in the energy range 10^16 - 10^18 eV with a uniform method. We describe the array construction, DAQ and methods of the array calibration.The method of energy reconstruction and absolute calibration of measurements are discussed. The analysis of spatial and time structure of EAS Cherenkov light allows to estimate the depth of the EAS maximum X_max. The results on the all particles energy spectrum and the mean depth of the EAS maximum X_max vs. primary energy derived from the data of two winter seasons (2009 -- 2011), are presented. Preliminary results of joint operation of the Cherenkov array with antennas for detection of EAS radio signals are shown. Plans for future upgrades -- deployment of remote clusters, radioantennas and a scintillator detector network and a prototype of the HiSCORE gamma-telescope -- are discussed.