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## Search for Dark Matter with the DarkSide Liquid Argon detector at LNGS

Equipe thématique “Matière Noire et Energie Noire”; expérience: DarkSide

Directeur de thèse: Claudio Giganti

tél : 01 44 27 39 05

Title : Search for Dark Matter with the DarkSide Liquid Argon detector at LNGS

The 20% of the Universe is composed by yet undiscovered matter, the so-called “Dark Matter”. Its existence is inferred by cosmological data but no direct evidences for it exist yet. Among the possible Dark Matter candidates, one of the most appealing and actively searched nowadays are the WIMP (Weakly Interacting Massive Particles).

One of the most promising experiments searching for WIMPs is the DarkSide experiment, a double phase Liquid Argon Time Projection Chamber (LArTPC) installed at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy.
Liquid Argon is an excellent candidate for WIMPs searches because of its capability of distinguishing electron-recoils (ER) produced by β or γ from nuclear recoils (NR) produced by WIMPs (or by neutrons). This is possible in LAr thanks to the different shape of the scintillation signals produced by ER and NR.

Currently DarkSide-50 (DS-50), a 50 kg LArTPC is taking data at LNGS using depleted Liquid Argon as a target and it will continue the data taking for the next 3 years. Depleted Argon is extracted from underground sources and is naturally depleted in 39Ar, a β emitter that contribute to the largest electron-recoils backgrounds in detectors based on atmospheric LAr that are searching for WIMPs.

In its first two physics runs DS-50 has demonstrated a discrimination power between ER and NR larger than 1.5x107 and has measured a 39Ar depletion factor of 1400.

Thanks to the excellent performances already demonstrated, the collaboration is working towards the conception and the construction of the next generation experiment, a 20-ton LArTPC (DS-20K).
DS-20K is expected to be background free for an exposure that would allow to put the world best limits in the search of high masses WIMPs.

The LPNHE DarkSide group is deeply involved in both, the analyses of DS-50 and the conceptual design of DS-20K and has a leading role in the simulation of the experiments.
French groups participating in DarkSide are also proposing to build and operate a small TPC prototype to be exposed at the IPNO Licorne neutron beam to study the liquid argon scintillation and ionization response, investigating the possibility of reconstructing the direction of the incoming particle from the amount of observed ionization and scintillation.

The PhD will work on the following areas:

• Operations of DS-50 detector, analysis of the data and the development of the Monte Carlo simulation of the experiment;
• Optimization of the design of the TPC prototype to be exposed at the IPNO neutron beam and analysis of the data;
• Simulations, R&D and construction of DS-20K;

Lieu de travail : LPNHE - Paris

Déplacements éventuels: déplacements réguliers au Laboratoire du Gran Sasso, Italie pour prise de données, réunions de groupe d’analyse, opérations du détécteur, réunions de collaboration, shifts de prise de données et travail de recherche et développement pour les projets futurs.

Documentation:

Contact:

Ecole doctorale de rattachement :
Ecole doctorale Sciences de la Terre et de l’Environnement et Physique
de l’Univers

Lien sur les offres de thèse et candidature:
http://ed109.ipgp.fr/index.php/Offres_de_th%C3%A8se