Increasing the sensitivity of the Baikal-GVD neutrino telescope by using external strings of optical modules

TL;DR

This paper explores enhancing the Baikal-GVD neutrino telescope's sensitivity by installing external optical module strings, presenting initial test results and technical implementation details.

Contribution

It introduces a novel configuration with external strings to improve detector efficiency, based on recent operational experience and in-situ testing.

Findings

External strings potentially increase detection efficiency.

Successful deployment and initial testing of external strings.

Technical feasibility demonstrated through in-situ tests.

Abstract

The deployment of the Baikal-GVD deep underwater neutrino telescope is continuing in Lake Baikal. By April 2022, ten clusters of the telescope were put into operation, with 2880 optical modules in total. One of the relevant tasks in this context is to study the possibilities of increasing the efficiency of the detector based on the experience of its operation and the results obtained at other neutrino telescopes in recent years. In this paper, a variant of optimizing the configuration of the telescope is considered, based on the installation of additional strings of optical modules between the clusters (external strings). An experimental version of the external string was installed in Lake Baikal in April 2022. This paper presents a first estimate of the impact of adding external strings on the neutrino detection efficiency, as well as the technical implementation of the detection and data acquisition systems of the external string and first results of its in-situ tests.