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Accueil > Thèses, Stages, Formation et Enseignement > Propositions de thèses 2022 > Search for Coherent Elastic Scattering of Supernova Neutrinos with the XENONnT Experiment

## Search for Coherent Elastic Scattering of Supernova Neutrinos with the XENONnT Experiment

by - 21 April 2022

Title : Search for Coherent Elastic Scattering of Supernova Neutrinos with the
XENONnT Experiment

Supervisor : Luca Scotto Lavina

Team : RCMN (rayons cosmiques et matière noire), XENON group

Description :

The XENONnT experiment, based on a TPC (Time Projection Chamber) having liquid xenon as active target, is one of the most sensitive dark matter detectors in the world. The first scientific run is ongoing and the experiment will collect data for 4-5 years.

Neutrinos from the Sun, atmospheric cosmic-ray showers, and certain kinds of supernovae can produce observable nuclear recoils via coherent elastic scattering off nuclei in liquid xenon detectors searching for dark matter. The coherent elastic neutrino-nucleus scattering (CEνNS) process produces the same signature as the one expected from DM-nucleus interactions. Thus, the only way to distinguish the two processes is by studying the energy recoil spectra. In a TPC based on liquid xenon, neutrinos coming from a core-collapse supernova located anywhere in the Milky Way are expected to be detected with a good significance.

In the absence of a nearby supernova, the XENON1T experiment (the previous phase of XENONnT with an active volume three times smaller) hasn’t observed an excess of neutrinos. XENONnT aims to acquire a 20 tonne*year exposure, i.e. about 30 times larger than XENON1T. Together with an improvement of the xenon purification techniques and data analysis, XENONnT will have a strong potential to discover CEνNS from supernovae neutrinos.

The work of this thesis first consists in reviewing the production mechanisms of neutrinos in core-collapse supernovae, then their travel to the Earth, with the goal of having the most precise estimation of the neutrino flux expected to reach the XENONnT detector, as well as the detector of the future DARWIN Project (200 tonne*year after 4 years). Then, the work consists in joining the multimessenger astronomy effort of the XENON Collaboration, through the analysis of XENONnT data to search for a possible CEνNS signal and/or dark matter, and the link of the experiment to alert networks connecting different observatories throughout the world. A challenge consists in developing new analysis techniques to reduce some expected background sources, like accidental coincidences that mimic real signals, by profiting from the novel triggerless data acquisition mode developed for XENONnT, meant to understand this background better than what we were capable to do with XENON1T. The goal of the analysis will be to search for a CEνNS signal and at the same time to better constrain the search for dark matter. Finally, the thesis could lead to a study on the potentiality of DARWIN to improve the analysis on the same subject, thanks to Monte Carlo simulations.

It will be asked to the student to be familiar with the python language and with low-background experiments analysis techniques. An interest on the activities on data processing and management of the experiment would be welcome.

http://xenonnt.org/

Workplace :

LPNHE, Paris

Possible travels :

Regular travels at the Gran Sasso underground laboratory (LNGS) , Italy, for participating to the data taking, joining XENON and DARWIN Collaboration Meetings. Presentation at one international conference and at one summer school.

Contact :

Luca SCOTTO LAVINA, +33 (0)1 44 27 41 79