Probing tau neutrino appearance with ORCA and determination of the leptonic CP-phase with Super-ORCA
Final Report Abstract
The funded project addressed some of the most important open questions in comtem- porary neutrino physics. Firstly, it aimed at testing the established model of neutrino physics with three different flavours of neutrinos for completeness by precisely inve- stigating the mixing of the different neutrino flavours as they are generated in the at- mosphere of the Earth. Secondly, it has been investigated if it is possible to detect a violation of the so-called CP-symmetry, i.e. a different oscillatory behaviour of neutrinos and antineutrinos, when using a water-Cherenkov detector in the deep sea. The project allowed for a participation in the KM3NeT experiment. The KM3NeT Collaboration constructs a Cherenkov detector, called ORCA, for the detection of neu- trinos in the abyss of the Mediterranean Sea. The detector consists of a three-dimensional grid-like setup of photosensitive sensors, that register the light induced in the water by secondary charged particles that are generated when a neutrino collides with an ato- mic nucleus. The project has made essential contributions to detector calibration and to the understanding of the growing detector in general by contributing in various ways to the data taking and to first analyses of the data. Employing deep-learning techni- ques with convolutional neural networks a complete data analysis pipeline has been worked out that allows for a classification of different neutrino interaction types and for a measurement of the kinematic properties of the incoming neutrinos. Furthermore, a software package has been worked on and improved that, based on detailed Monte Carlo simulations of the detector, allows for an evaluation of its sensitivity to various physics scenarios for different stages of the construction. Among the relevant achieve- ments of this part of the project is the first detection and measurement of atmospheric neutrinos with ORCA, and the evaluation and optimization of its sensitivity to a tau neutrino flux from the atmosphere. In the second part of the project a feasibility and sensitvity study was done for a detector similar to ORCA, but with a denser layout of photosensors that enables the detection and measurement of neutrinos with energies below 2 GeV. The study sho- wed that a ten times denser setup than ORCA can principally reach this goal. However, it became also clear that such a setup would not have a competitive sensitivity to de- tect a possible violation of CP-symmetry, if only the atmospheric neutrino flux could be exploited for the measurement. Consequently, the study was extended to cover a sce- nario, in which a realistic neutrino beam from a particle accelerator would be targeted at the deep-sea detector. The promising results showed that this constellation would allow for a highly sensitive and competitive measurement of a possible CP-symmetry violation in the neutrino sector of particle physics.
Publications
- Measuring the neutrino mass hierarchy with KM3NeT/ORCA. J.Phys.Conf.Ser. 1342 (2020) 1, 012028, XV Int. Conf. on Topics in Astroparticle and Underground Physics 2017 (Sudbury, Kanada)
J. Hofestädt
(See online at https://doi.org/10.1088/1742-6596/1342/1/012028) - Tau neutrino appearance with KM3NeT/ORCA. PoS(ICRC2017) 1025, 35. Int. Cosmic Ray Conf. 2017 (Busan, Südkorea)
T. Eberl, S. Hallmann, J. Hofestädt
(See online at https://doi.org/10.22323/1.301.1025) - KM3NeT/Super- ORCA: Measuring the leptonic CP-phase with atmospheric neutrinos - a feasibility study. XXVIII International Conference on Neutrino Physics and Astrophysics 2018 (Heidelberg)
J. Hofestädt, T. Eberl, M. Bruchner
(See online at https://doi.org/10.22323/1.358.0911) - Tau neutrino appearance with KM3NeT/ORCA. XXVIII International Conference on Neutrino Physics and Astrophysics 2018 (Heidelberg)
T. Eberl, S. Hallmann, J. Hofestädt, M. Moser
(See online at https://doi.org/10.22323/1.301.1025) - Atmospheric Neutrinos Detected with the First KM3NeT Detection Units of ARCA and ORCA. PoS(ICRC2019) 910, 36. Int. Cosmic Ray Conf. 2019 (Madison, WI, U.S.A.)
J. Hofestädt et al.
(See online at https://doi.org/10.22323/1.358.0910) - Letter of Interest for a Neutrino Beam from Protvino to KM3NeT/ORCA. Eur. Phys. J. C79, 758 (2019)
A. V. Akindinov et al.
(See online at https://doi.org/10.1140/epjc/s10052-019-7259-5) - Machine Learning for KM3NeT/ORCA. PoS(ICRC2019) 904, 36. Int. Cosmic Ray Conf. 2019 (Madison, WI, U.S.A.)
S. Hallmann, M. Moser, S. Reck, T. Eberl
(See online at https://doi.org/10.22323/1.358.0904) - Neutrino oscillation research with KM3NeT/ORCA. PoS(ICRC2019) 1019, 36. Int. Cosmic Ray Conf. 2019 (Madison, WI, U.S.A.)
S. Hallmann et al.
(See online at https://doi.org/10.22323/1.358.1019) - Super-ORCA: Measuring the leptonic CP- phase with Atmospheric Neutrinos and Beam Neutrinos. PoS(ICRC2019) 911, 36. Int. Cosmic Ray Conf. 2019 (Madison, WI, U.S.A.)
J. Hofestädt, M. Bruchner, T. Eberl
(See online at https://doi.org/10.22323/1.358.0911) - Dependence of atmospheric muon flux on seawater depth measured with the first KM3NeT detection units. Eur. Phys. J. C80, 99 (2020)
M. Ageron et al.
(See online at https://doi.org/10.1140/epjc/s10052-020-7629-z) - Event reconstruction for KM3NeT/ORCA using convolutional neural networks. Journal of Instrumentation
S. Aiello et al.
(See online at https://doi.org/10.1088/1748-0221/15/10/P10005)
