Study of the astrophysical potential of the KM3NeT Deep-Sea Neutrino Observatory at Low Energy

Ph.D. project proposed by the ANTARES/KM3NeT group at Laboratoire Astroparticules et Cosmologie (APC)

Possible co-tutorship with the Instituto de Fisica Corpucular of Valencia, Spain

Neutrino telescopes instrument large volumes of water or ice with photomultipliers (PMT) to detect the Cherenkov radiation emitted by charged leptons induced neutrino that interact with the target transparent medium, inside or near the instrumented volume. Depending on their size and of the density of the PMT configuration, such detectors can be used for different physics purposes: 

- km3-scale (or Gigaton-scale) detectors focus on the detection of high-energy (TeV--PeV) cosmic neutrinos originating from astrophysical sources. The recent observation of an excess in the diffuse high-energy flux by the IceCube experiment has opened new perspectives for neutrino astronomy, calling for an increase in the detection efforts also in the Northern Hemisphere, in particular to increase the coverage of the Galactic region;

-  megaton-scale, denser detectors can address the fundamental properties of neutrinos, and in particular their mass ordering needed to constrain the models that seek to explain the origin of mass in the leptonic sector and the differences within the mass spectrum of all elementary particles. They focus on lower energy (~GeV) neutrinos produced in the atmosphere.

            Within this double perspective, the European KM3NeT project is deploying the next-generation neutrino telescope in the Mediterranean Sea, with one site dedicated to TeV-PeV neutrino astronomy in Italy (ARCA), and one site dedicated to the measurement of the neutrino mass hierarchy in France (ORCA). KM3NeT builds on the expertise gained in the operation of the smaller detector ANTARES, deployed at a depth of ~2500m, off Toulon and currently the most sensitive detector in the Northern Hemisphere. A major technological upgrade of KM3NeT consists in the use of novel multi-PMT optical modules (OM) whose first prototypes are now successfully tested undersea. The construction of the detector on both sites has already started and is expected to extend during the period of this Ph.D.

The scope of this Ph.D subject is to study the astrophysical potential of both ORCA and ARCA at low energies taking advantage of the multi-PMT concept. This possibly includes indirect searches for neutrinos from Dark Matter annihilations in the Sun or the Galactic Center, searches for neutrinos from Colliding Wind Binaries, or other searches for transient phenomena yielding a neutrino flux in the GeV domain. Lower energy neutrinos (MeV range) cannot be reconstructed on an event-by-event basis, but a high rate of interactions resulting from cataclysmic phenomena, such as Core-Collapse Supernovae (CCSN), would infer a sizeable increase of the overall detector counting rate. In this context, the KM3NeT design offers new opportunities. In particular the possibility to ask for coincidences on the same OM to mitigate the optical background induced by 40K decays and bioluminescence bursts, may provide an efficient way to increase the detector sensitivity.

The applicant will participate to the software development and to the implementation in the KM3NeT Monte Carlo of the relevant observables related to the above-mentioned phenomena (e.g. expected neutrino flux features: modulations, flavor ratio,etc).

The applicant’s research activities will be carried out in tight link with other French and European research groups participating to the project. In particular, a co-tutorship with the Group of Valencia (Spain) is proposed, with travel funds available from a bilateral agreement (PICS).

The Ph.D. thesis may also include a more technical aspect dedicated to the development of the Calibration Units (responsibility of APC with KM3NeT. The Calibration Units are meant for the monitoring of the detector behavior in terms of collection efficiency, time and energy resolution... Specific tools will also be installed for the long-term monitoring of environmental parameters, thus offering a bridge with Earth and Sea Sciences.


Antoine Kouchner and Alexis Coleiro






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