PhD ceremony Mr. Q. Dorosti Hasankiadeh: Reconstruction of neutrino-induced showers with ANTARES

PhD ceremony: Mr. Q. Dorosti Hasankiadeh, 11.00 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Reconstruction of neutrino-induced showers with ANTARES

Promotor(s): prof. H. Löhner

Faculty: Mathematics and Natural Sciences

Extremely energetic particles (cosmic rays) have been measured on Earth but we do not know there galactic or extragalactic sources. If violent processes cause such particles, we should observe neutrinos as well. Among all particles, neutrinos have the advantage that they can reach us undisturbed due to their very weak interaction. However, neutrino detection requires high sensitivity in a large detector volume. In the ANTARES neutrino telescope we exploit the clear water in the Mediterranean Sea as detector medium and measure the faint flashes of light produced by high-energy neutrinos. Looking for particles having passed through the Earth, we purely identify neutrinos. Until now ANTARES aimed for tracks of secondary particles produced by only one sort (flavour) of neutrinos. Here we investigated the sensitivity to local showers of light which can be produced by all three neutrino flavours. A major challenge is the clean selection of showers from an overwhelming background of neutrinos produced in the atmosphere of the Earth. We have developed a novel strategy to select neutrino-induced showers by characterizing their directions and topologies. We have applied this strategy to ANTARES experimental data to determine the (limits on the) flux of neutrinos originating from unresolved astrophysical sources. Such measurements can exclude theories on various production mechanisms. The success achieved with ANTARES allows us to ultimately exploit the studied strategy on the future, about 50 times larger, KM3NeT telescope comprising several cubic-kilometres of water. The boosted sensitivity will reveal novel insight into the origin of extremely energetic cosmic particles.