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Accueil > Thèses, Stages, Formation et Enseignement > Propositions de thèses 2022 > Search for Coherent Elastic Scattering of Solar Neutrinos in the XENONnT Dark Matter Experiment

Search for Coherent Elastic Scattering of Solar Neutrinos in the XENONnT Dark Matter Experiment

Title : Search for Coherent Elastic Scattering of Solar Neutrinos in the XENONnT Dark Matter Experiment

Supervisor : Luca Scotto Lavina

Team : Rayonnement Cosmique et Matière Noire ; expériences XENON et DARWIN

Description :

The XENONnT experiment, based on a TPC (Time Projection Chamber) having liquid xenon as active target, is one of the most sentitive 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 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, Solar Boron-8 neutrinos are expected to contribute the greatest number of CEνNS events.

The XENON1T experiment (the previous phase of XENONnT with an active volume three times smaller) collected an exposure of 0.6 tonne*year and, as expected, hasn’t observed any significant excess of neutrinos.
However, XENON1T used the non-detection of neutrinos to better constrain the dark matter search in a mass range between 3 and 11 GeV, allowing us to improve its sensitivity by an order of magnitude.

XENONnT aims to acquire a 20 tonne*year exposure, i.e. about 30 times larger than XENON1T. Together with an improvement of the purification techniques and data analysis, XENONnT will have a strong potential to discover CEνNS from the Sun.

The work of this thesis consists first in reviewing the production mechanism of neutrinos in the Sun, 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 analysing XENONnT data to search for a possible CEνNS signal and/or dark matter. Next, the 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.

Work Location : LPNHE, Paris

Possible trips : 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

Documentation :http://xenonnt.org/