News from ANTARES and KM3NeT
Despite COVID difficulties, the ARCA junction box and five Detection units (DUs) are ready to be deployed. The deployment vessel will set sail from Malta on April 8 for a week-long sea operation.
… and the Junction box, waiting in Catania:
News from Baikal-GVD
Big shots at Lake Baikal: On March 13, Russia’s Minister of Education and Science, Valery Falkov, visited the ice camp of GVD Baikal. He was accompanied by the director of JINR Dubna, Grigori Trubnikov, the director of INR Moscow, Maxim Libanov, and the governor of the Irkutsk region, Igor Kobzev. Needless to say that they were surrounded by a crowd of secretaries and journalists. At this occasion, Trubnikov and Falkov signed a Memorandum of Understanding between JINR and the Ministry of Science and Education on the further development of the Baikal neutrino telescope.
Sunset at Lake Baikal is always an impressive spectacle. Bair Shaibonov from JINR Dubna made all the photos which you see here. The following photos show the sunset behind two winches to deploy a string and Bair himself holding the sinking Sun in his hand.
Right now, the Baikal winter expedition is coming closer to its end. One new cluster (number eight) has been almost fully deployed. In addition, a "test cluster" consisting of a single string equipped with vertical optical fibres instead of copper cables is going to be completed in the next few days.
On the occasion of the minister’s visit, a beautiful 26-minute film “The cosmos in the cube” has been produced by ROSSIA 24 TV and is available at Космос в кубе. Специальный репортаж – Россия 24 - YouTube.
News from IceCube
If it comes to beautiful sunsets, the South Pole of course is also in the competition, see the following telephoto shot.
From March 17 to March 26, the IceCube collaboration had its spring collaboration meeting. Needless to mention that it was an online meeting.
Many analyses have been presented which are in their final stages. This promises another year rich in publications. Many of these results will also be presented at ICRC. The collaboration has submitted the record number of 90 abstracts to ICRC.
Preparation of the IceCube Upgrade (7 densely instrumented strings in the center of DeepCore) is
well underway. Hundred of the 300 planned D-Egg optical modules have been produced. These modules host two 8 -inch PMTs, one looking up and the other down. In parallel, 400 mDOMs are going to be produced (each housing 24 3-inch PMTs). On February 15, 2020, the first full verification mDOM has been assembled.
Due to the COVID-related cancellation of the 2020/21 field season, there is a one-year of the Upgrade project, i.e. the deployment is now foreseen for the season 2023/2024.
Not a part of IceCube, but closely related to a possible radio extension of IceCube-Gen2, is RNO-G, the Radio Neutrino Observatory in Greenland (see J.A. Aguilar et al., 2021 JINST 16 P03025 and arXiv:2010.12279). RNO-G will be the first “production-scale” radio detector for in-ice neutrino signals and seeks to measure neutrinos above 10 PeV. The figure shows a top view of RNO-G.
RNO-G is planned to be deployed over three seasons. The deployment foreseen for this season is still on "GO" (starting May 2021). Hardware for 10 stations has been shipped.
New IceCube Spokesperson
In January 2021, the IceCube Collaboration has elected Ignacio Taboada (Georgia Institute of Technology) as new Spokesperson. He is now in the process of taking over from Darren Grant who has served at this position for two election periods (four years). Thanks to Darren for doing an excellent job and good luck for Ignacio!
The ANTARES collaboration has posted a paper“A search for neutrinos from the Tidal Disruption Event AT2019dsg with the ANTARES Telescope” (arxiv.org).
This search was motivated by the muon track neutrino IC191001A which IceCube had recorded on October 1, 2019, with a high probability of being of astrophysical origin. Soon after, the tidal disruption event (TDE) AT2019dsg, observed by the Zwicky Transient Facility, was indicated as the most likely counterpart of the IceCube track (see also GNN Monthly from last month). Using the data collected since the discovery of the TDE (April 2019), ANTARES has investigated the location of AT2019dsg (Right Ascension =314.26°, Declination = 14.20°) to search for spatial clustering of events above the known background expectation following an unbinned maximum likelihood ratio approach.
As shown in the figure, only one ANTARES event has been detected within 5° from the TDE. The result is consistent with background, yielding an upper limit on the one-flavour neutrino flux normalization for a E-2ν neutrino spectrum of 1.0 x 10-7 GeV-1 cm-2 s-1.
The KM3NeT Collaboration has submitted a paper Determining the Neutrino Mass Ordering and Oscillation Parameters with KM3NeT/ORCA to EPJ C (posted at 2103.09885.pdf (arxiv.org).
The paper presents the KM3NeT/ORCA sensitivity to atmospheric neutrino oscillation. It describes event reconstruction, selection and classification. The sensitivity to determine the neutrino mass ordering after three years of data taking was evaluated and found to be 4.4σ if the true ordering is normal and 2.3σ if inverted. The precision to measure ∆m232 and θ23 were also estimated and found to be 85 · 10−6 eV2 and (+1.9/−3.1)° for normal neutrino mass ordering and 75 · 10−6 eV2 and (+2.0/−7.0 )° for inverted ordering (see the figure below). Finally, the unitary 3 × 3 neutrino mixing paradigm can be assessed by confronting the (anti-) ν τ event rate to the expectation in this model. Three years of data taking were found to be sufficient to exclude (anti-) ντ event rate variations larger than 20% at 3σ level.
The IceCube Collaboration has published a paper Detection of a particle shower at the Glashow resonance with IceCube in Nature (Vol 591, 220) on 11 March 2021 (an arXiv-version is in preparation). The Glashow resonance describes the resonant formation of a W− boson during the interaction of a high-energy electron antineutrino with an electron, peaking at an antineutrino energy of 6.3 PeV in the rest frame of the electron, see the next figure.
Whereas this energy scale is out of reach for currently operating and future planned particle accelerators, natural astrophysical phenomena are expected to produce antineutrinos with energies beyond the PeV scale. The paper reports the detection of a high-energy cascade consistent with being created at the Glashow resonance (see the next figure).
The shower energy was measured as 6.05 ± 0.72 PeV as shown in the following figure:
Features consistent with the production of secondary muons in the particle shower indicate the hadronic decay of a resonant W− boson, confirm that the source is astrophysical and provide improved directional localization. The evidence of the Glashow resonance suggests the presence of electron antineutrinos in the astrophysical flux, while also providing further validation of the standard model of particle physics. Its unique signature indicates a method of distinguishing neutrinos from antineutrinos, thus providing a way to identify astronomical accelerators that produce neutrinos via hadronuclear or photohadronic interactions, with or without strong magnetic fields. As such, knowledge of both the favour (that is, electron, muon or tau neutrinos) and charge (neutrino or antineutrino) will facilitate the advancement of neutrino astronomy.
Symposium Very Large Volume Neutrino Telescopes (VLVNT)
Marcel Grossmann Meeting
The 16th Marcel Grossmann Meeting on Recent Developments in Theoretical and Experimental General Relativity, Astrophysics and Relativistic Field Theories (MG16) will be held, as virtual meeting, during the period July 5-9, 2021. More information at http://www.icra.it/mg/mg16/ . The registration is open, the abstract submission will be opened on April 15th. The list of plenary speakers includes Francis Halzen with a talk ”IceCube: Cosmic Neutrinos and Multimessenger Astronomy”. Parallel session H2 (High Energy Astrophysical Neutrino Detection) is convened by Tonino Capone who invites our community to submit contributions.
International Cosmic Ray Conference (ICRC)
About 1400 abstracts have been submitted for ICRC, 1500-2000 participants are expected. Therefore, the participation fees could be substantially lowered.
Registration is still open, undergrad participation is free.
Further nominations for the Yodh Prize can be made, as the deadline has been extended to 30 April.