Description du sujet de thèse

Title : Showers reconstruction in final state of neutrino Interactions and energy reconstruction in the DUNE experiment and liquid argon TPC detectors.

This project focuses on the reconstruction of electromagnetic showers from final state particles in neutrino interactions in Liquid Argon Time Projection Chambers (LAr TPC), as the far detectors or the DUNE experiment. The project aims at improving the current reconstruction algorithms in order to achieve the ultimate calorimetric performance provided by the LAr TPC detector design and physics. This aspect is fundamental in the DUNE experiment for the neutrino energy resolution in the interactions of electron neutrinos and anti-neutrinos. These events are exploited for the CP violation search, relying on the energy spectrum of the numu-nue oscillation pattern in the region including the first and the second oscillation maxima. The CP asymmetry is stronger at the second oscillation maximum, located at lower energy, where most of neutrino interactions are quasi-elastic, in which the neutrino energy is practically converted in the energy of the final state electron, then producing an electromagnetic shower in the LAr TPC. A good reconstruction of electromagnetic showers and energy resolution are fundamental in order to enhance the sensitivity to the neutrino oscillation pattern. The DUNE experiment is currently relying on algorithms originally developed for fine grained calorimeters associated to a central tracker in detectors designed for the future International Linear Collider, then ported to DUNE for the reconstruction of neutrino interactions in LAr TPC. First studies have shown limitations of the algorithms in achieving a complete reconstruction and association of all hits of electromagnetic showers in LAr, resulting in fluctuations of the reconstructed energy and degradation of the resolution. These limitations can be resolved by retuning algorithms, taking into account the physics of electromagnetic showers in LAr, where showers cover larger distances, and the finer readout granularity of LAr TPC with respect to the detectors for which the algorithms were developed. It is also desirable to exploit the ionization profile and the topology of the electron track before showering in order to suppress the background from showers initiated by photons and, more generally, to improve the photons shower reconstruction, the hadronic showers resolution and the definition of the tracks-showers tree in neutrino interaction final states.

Contexte de travail

The selected PhD candidate will join the IP2I DUNE group, contributing since the birth to the DUNE experiment and to the development of its far detector design. He will join the efforts on the software and analysis developments on showers reconstruction in preparation to the exploitation of the first DUNE Far Detector module since 2029, and have also the opportunity of exploiting the data-sets taken with the CERN large scale DUNE prototypes. This work will be carried on in collaboration with the IRL PPC laboratory located at the University of Chicago, profiting also of the collaboration with US senior researchers historically involved in the developments on electromagnetic calorimetry.

Contraintes et risques

No risks identified