Time calibration of the neutrino telescope Baikal-GVD

Abstract

Baikal-GVD is a cubic-kilometer scale neutrino telescope, which is currently under construction in Lake Baikal. Baikal-GVD is an array of optical modules arranged in clusters. The first cluster of the array has been deployed and commissioned in April 2015. To date, Baikal-GVD consists of 3 clusters with 864 optical modules. One of the vital conditions for optimal energy, position and direction reconstruction of the detected particles is the time calibration of the detector. In this article, we describe calibration equipment and methods used in Baikal-GVD and demonstrate the accuracy of the calibration procedures.

Neutrino Telescope in Lake Baikal: Present and Nearest Future

“…The String Module acts as a hub for power distribution and communication with the Section Modules. The string also holds hydrophones for acoustic monitoring of the PMT positions [6] and LED beacons for detector calibration [7,8].…”

“…Additional technical strings equipped with high-power pulsed lasers are installed in-between the GVD clusters. These are used for detector calibration [8] and light propagation studies [10]. The lake is covered with thick ice (up to ~ 1m) from February to mid-April, providing a convenient solid platform for detector deployment and maintenance operations.…”

“…Baikal-GVD time calibration [7,8] consists in measuring the relative time delays of signals on the channels using calibration light sources. Light sources developed on the basis of Kingbright L7113 LEDs with a wavelength of 470 nm at the maximum radiation and a pulse duration of ~5 ns are used For time calibration.…”

Observations of track-like neutrino events with Baikal-GVD

“…After applying the necessary calibrations [11,12], the experimental dataset is passed to a χ 2 -based track reconstruction algorithm, which includes a hit selection procedure, a vector-sum…”

Neutrino telescope in Lake Baikal: Present and Future

“…Each matrix comprises 12 synchronized LEDs flashers, pulses from which can be detected by several sections. The accuracy of the time calibration is about 2 ns [5]. Laser sources are used for inter-cluster calibration.…”