Dark Matter is one of the main puzzles in fundamental physics and Weakly Interacting Massive Particles (WIMP) are among the best-motivated dark matter particle candidates. As of today, the most sensitive experimental technique to discover the WIMPs in the mass range from 2 GeV to 10 TeV is the dual phase Time Projection Chamber (TPC) filled with noble liquids. DarkSide-20k is the next generation of Liquid Argon (LAr) TPC, which will be running at LNGS (Italy) from 2026 with 50-ton active mass. At that date, DarkSide-20k will be the most massive noble liquid experiment for dark matter search, with the highest discovery potential. Beyond the search for dark matter, DarkSide-20k also has strong potential in neutrino physics, particularly for neutrinos from the Sun and Supernovae. All of this will be possible thanks to the unique scintillation pulse shape discrimination (PSD) technique, able to separate a WIMP candidate event from >10^9 electron-like events, a power recently demonstrated by the DarkSide- 50 and DEAP-3600 collaborations. The PSD, in addition to the neutron veto detector surrounding the TPC, and to the high-granularity of the detector able to reconstruct the event topology with ~1cm resolution, will allow for a dark matter search in an instrumental “background-free” regime, corresponding to <0.1 events across the foreseen 5-year exposure.

Within the DarkSide program, APC is leading data reconstruction, simulation, and sensitivity studies. Particle interactions are detected by looking at light signals from scintillation in liquid (S1) and electroluminescence in gas (S2), the latter induced by ionization electrons, delayed by drift time. The APC team has identified a strategy for single photoelectron detection, and for the evaluation of instrumental noise based on a highly optimized python-based data reconstruction framework, which uses, among the different algorithms, the matched filter for fast processing signals. The candidate will validate and test the performance of such an approach in order to identify photoelectron pulses and classify them as scintillation or ionization ones. 

During the stage, the candidate will acquire competences in nuclear, particle and astroparticle physics, and skills in Monte Carlo simulations and data reconstruction and analysis.