The deployment of the Baikal-GVD deep underwater neutrino telescope is in
progress now. About 3500 deep underwater photodetectors (optical modules)
arranged into 12 clusters are operating in Lake ...Baikal. For increasing the
efficiency of cascade-like neutrino event detection, the telescope deployment
scheme was slightly changed. Namely, the inter-cluster distance was reduced for
the newly deployed clusters and additional string of optical modules are added
between the clusters. The first inter-cluster string was installed in 2022 and
two such strings were installed in 2023. This paper presents a Monte Carlo
estimate of the impact of these configuration changes on the cascade detection
efficiency as well as technical implementation and results of in-situ tests of
the inter-cluster strings.
Baikal Gigaton Volume Detector is a cubic kilometer scale neutrino telescope
under construction in Lake Baikal. As of July 2023, Baikal-GVD consists of 96
fully deployed strings resulting in 3456 ...optical modules installed. The
observation of neutrinos is based on detection of Cherenkov radiation emitted
by the products of neutrino interactions. In this contribution, description of
the double cascade reconstruction technique as well as evaluation of precision
of this algorithm is given.
Baikal-GVD (Gigaton Volume Detector) is a neutrino telescope installed at a
depth of 1366 m in Lake Baikal. The expedition of 2023 brought the number of
optical modules in the array up to 3492 ...(including experimental strings). These
optical modules detect the Cherenkov radiation from secondary charged particles
coming from the neutrino interactions. Neutrinos produce different kinds of
topologically distinct light signatures. Charged current muon neutrino
interactions create an elongated track in the water. Charged and neutral
current interactions of other neutrino flavors yield hadronic and
electromagnetic cascades. The background in the neutrino cascade channel arises
mainly due to discrete stochastic energy losses produced along atmospheric muon
tracks. In this paper, a developed algorithm for the cascade event selection is
presented.
PoS(ICRC2023)1458 The Baikal-GVD alert system was launched at the beginning of 2021. There are
alerts for muon neutrinos (long upward-going track-like events) and all-flavour
neutrinos (high-energy ...cascades). The system is able to get a preliminary
response to external alerts with a temporal delay of about 3-10 minutes. The
Baikal-GVD data processing and the results of the follow-up procedure are
described. We report on the analysis of the coincidence in time and direction
between the Baikal-GVD cascade GVD20211208CA with an estimated energy of 43 TeV
and the announced alert IceCube211208A possibly associated with a flaring state
of the blazar PKS 0735+178.
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.
We report on the first observation of the diffuse cosmic neutrino flux with the Baikal-GVD neutrino telescope. Using cascade-like events collected by Baikal-GVD in 2018--2021, a significant excess of ...events over the expected atmospheric background is observed. This excess is consistent with the high-energy diffuse cosmic neutrino flux observed by IceCube. The null cosmic flux assumption is rejected with a significance of 3.05\(\sigma\). Assuming a single power law model of the astrophysical neutrino flux with identical contribution from each neutrino flavor, the following best-fit parameter values are found: the spectral index \(\gamma_{astro}\) = \(2.58^{+0.27}_{-0.33}\) and the flux normalization \(\phi_{astro}\) = 3.04\(^{+1.52}_{-1.21}\) per one flavor at 100 TeV.
The large-scale deep underwater Cherenkov neutrino telescopes like Baikal-GVD, ANTARES or KM3NeT, require calibration and testing methods of their optical modules. These methods usually include ...laser-based systems which allow to check the telescope responses to the light and for real-time monitoring of the optical parameters of water such as absorption and scattering lengths, which show seasonal changes in natural reservoirs of water. We will present a testing method of a laser calibration system and a set of dedicated tools developed for Baikal- GVD, which includes a specially designed and built, compact, portable, and reconfigurable scanning station. This station is adapted to perform fast quality tests of the underwater laser sets just before their deployment in the telescope structure, even on ice, without darkroom. The testing procedure includes the energy stability test of the laser device, 3D scan of the light emission from the diffuser and attenuation test of the optical elements of the laser calibration system. The test bench consists primarily of an automatic mechanical scanner with a movable Si detector, beam splitter with a reference Si detector and, optionally, Q-switched diode-pumped solid-state laser used for laboratory scans of the diffusers. The presented test bench enables a three-dimensional scan of the light emission from diffusers, which are designed to obtain the isotropic distribution of photons around the point of emission. The results of the measurement can be easily shown on a 3D plot immediately after the test and may be also implemented to a dedicated program simulating photons propagation in water, which allows to check the quality of the diffuser in the scale of the Baikal-GVD telescope geometry.
The Baikal Gigaton Volume Detector (Baikal-GVD) is a km\(^3\)-scale neutrino detector currently under construction in Lake Baikal, Russia. The detector consists of several thousand optical sensors ...arranged on vertical strings, with 36 sensors per string. The strings are grouped into clusters of 8 strings each. Each cluster can operate as a stand-alone neutrino detector. The detector layout is optimized for the measurement of astrophysical neutrinos with energies of \(\sim\) 100 TeV and above. Events resulting from charged current interactions of muon (anti-)neutrinos will have a track-like topology in Baikal-GVD. A fast \(\chi^2\)-based reconstruction algorithm has been developed to reconstruct such track-like events. The algorithm has been applied to data collected in 2019 from the first five operational clusters of Baikal-GVD, resulting in observations of both downgoing atmospheric muons and upgoing atmospheric neutrinos. This serves as an important milestone towards experimental validation of the Baikal-GVD design. The analysis is limited to single-cluster data, favoring nearly-vertical tracks.
The high-energy muon neutrino events of the IceCube telescope, that are triggered as neutrino alerts in one of two probability ranks of astrophysical origin, "gold" and "bronze", have been followed ...up by the Baikal-GVD in a fast quasi-online mode since September 2020. Search for correlations between alerts and GVD events reconstructed in two modes, muon-track and cascades (electromagnetic or hadronic showers), for the time windows \( \pm \) 1 h and \( \pm \) 12 h does not indicate statistically significant excess of the measured events over the expected number of background events. Upper limits on the neutrino fluence will be presented for each alert.
Baikal-GVD is a neutrino telescope currently under construction in Lake Baikal. GVD is formed by multi-meganton subarrays (clusters). The design of Baikal-GVD allows one to search for astrophysical ...neutrinos already at early phases of the array construction. We present here preliminary results of a search for high-energy neutrinos with GVD in 2019-2020.
