Description du sujet de thèse

Dark matter is one of the major challenges in fundamental physics. Among the most studied theoretical candidates are Weakly Interacting Massive Particles (WIMPs). Dual-phase Time Projection Chambers (TPCs) filled with noble liquids currently represent the most sensitive technology for detecting WIMPs across a wide mass range.

The DarkSide-20k detector, based on 50 tons of liquid argon, is currently under construction at the Laboratori Nazionali del Gran Sasso (Italy), with data taking expected to start in 2027. It combines ionization and scintillation signals to enable precise event reconstruction and effective discrimination between electronic and nuclear recoils. The APC team is heavily involved in developing simulation, reconstruction, and data analysis tools.

To extend the scientific reach of DarkSide-20k to lower energies (light WIMPs, solar and supernova neutrinos), it is essential to refine the liquid argon response model to nuclear recoils. For this purpose, APC collaborates with the University of São Paulo (USP, Brazil) within the ReD experiment, a TPC exposed to neutron sources, designed to study argon's response in the keV energy range.

The main objectives of this PhD project are:
to participate in upcoming ReD measurement campaigns and analyze neutron source data;
to contribute to Monte Carlo simulations and interpretation of results;
to evaluate the impact of this improved modeling on the sensitivity of DarkSide-20k to light WIMPs and neutrinos;
to participate in the development of DarkSide-20k reconstruction algorithms, with a focus on ionization signals.

The PhD candidate will also contribute to the first DarkSide-20k data analyses and related collaboration activities. This work is part of a joint doctoral program co-supervised by APC and USP.

The candidate should hold a Master's degree (or equivalent) in physics. Skills in programming (C++, Python) and data analysis are desirable.

Contexte de travail

The host laboratory is the Astroparticle and Cosmology Laboratory (APC – UMR 7164, https://apc.u-paris.fr), a joint research unit of CNRS, Université Paris Cité, CEA, and the Observatoire de Paris. Located on the Paris Rive Gauche campus, APC brings together about 200 researchers, faculty, engineers, postdoctoral fellows, and doctoral students, working on projects in astroparticle physics, cosmology, and high-energy astrophysics.

The PhD candidate will join the Particles team, which is deeply involved in direct dark matter and neutrino detection experiments, as well as in the development of cryogenic liquid argon detectors.

Contraintes et risques

Travel outside the region and abroad is expected during the PhD, notably for measurement campaigns at INFN-LNS (Catania, Italy), collaboration meetings of DarkSide-20k at the Laboratori Nazionali del Gran Sasso (LNGS, Italy), as well as scientific stays at the University of São Paulo (Brazil), within the framework of the international collaboration between APC and USP that led to the funding of this thesis. The PhD candidate will also be encouraged to participate in international conferences.