Calibration of the liquid argon ionization response to low energy electronic and nuclear recoils with DarkSide-50

Agnes, P.; Albuquerque, I.  F.  M.; Alexander, T.; Alton, A.  K.; Ave, M.; Back, H.  O.; Batignani, G.; Biery, K.; Bocci, V.; Bonivento, W.  M.; Bottino, B.; Bussino, S.; Cadeddu, M.; Cadoni, M.; Calaprice, F.; Caminata, A.; Canci, N.; Caravati, M.; Cariello, M.; Carlini, M.; Carpinelli, M.; Catalanotti, S.; Cataudella, V.; Cavalcante, P.; Cavuoti, S.; Chepurnov, A.; Cicalò, C.; Cocco, A.  G.; Covone, G.; D’Angelo, D.; Davini, S.; De Candia, A.; De Cecco, S.; De Filippis, G.; De Rosa, G.; Derbin, A.  V.; Devoto, A.; D’Incecco, M.; Dionisi, C.; Dordei, F.; Downing, M.; D’Urso, D.; Fiorillo, G.; Franco, D.; Gabriele, F.; Galbiati, C.; Ghiano, C.; Giganti, C.; Giovanetti, G.  K.; Gorchakov, O.; Goretti, A.  M.; Grobov, A.; Gromov, M.; Guan, M.; Guardincerri, Y.; Gulino, M.; Hackett, B.  R.; Herner, K.; Hosseini, B.; Hubaut, F.; Hungerford, E.  V.; Ianni, An.; Ippolito, V.; Keeter, K.; Kendziora, C.  L.; Kochanek, I.; Korablev, D.; Korga, G.; Kubankin, A.; Kuss, M.; La Commara, M.; Lai, M.; Li, X.; Lissia, M.; Longo, G.; Machulin, I.  N.; Mapelli, L.  P.; Mari, S.  M.; Maricic, J.; Martoff, C.  J.; Messina, A.; Meyers, P.  D.; Milincic, R.; Morrocchi, M.; Mougeot, X.; Muratova, V.  N.; Musico, P.; Navrer Agasson, A.; Nozdrina, A.  O.; Oleinik, A.; Ortica, F.; Pagani, L.; Pallavicini, M.; Pandola, L.; Pantic, E.; Paoloni, E.; Pelczar, K.; Pelliccia, N.; Picciau, E.; Pocar, A.; Pordes, S.; Poudel, S.  S.; Pralavorio, P.; Ragusa, F.; Razeti, M.; Razeto, A.; Renshaw, A.  L.; Rescigno, M.; Rode, J.; Romani, A.; Sablone, D.; Samoylov, O.; Sands, W.; Sanfilippo, S.; Savarese, C.; Schlitzer, B.; Semenov, D.  A.; Shchagin, A.; Sheshukov, A.; Skorokhvatov, M.  D.; Smirnov, O.; Sotnikov, A.; Stracka, S.; Suvorov, Y.; Tartaglia, R.; Testera, G.; Tonazzo, A.; Unzhakov, E.  V.; Vishneva, A.; Vogelaar, R.  B.; Wada, M.; Wang, H.; Wang, Y.; Westerdale, S.; Wojcik, M.  M.; Xiao, X.; Yang, C.; Zuzel, G.

doi:10.1103/PhysRevD.104.082005

DarkSide-50 has demonstrated the high potential of dual-phase liquid argon time projection chambers in exploring interactions of WIMPs in the GeV=c2 mass range. The technique, based on the detection of the ionization signal amplified via electroluminescence in the gas phase, allows us to explore recoil energies down to the sub-keV range. We report here on the DarkSide-50 measurement of the ionization yield of electronic recoils down to ∼180 eVer , exploiting 37Ar and 39Ar decays, and extrapolated to a few ionization electrons with the Thomas-Imel box model. Moreover, we present a model-dependent determination of the ionization response to nuclear recoils down to ∼500 eVnr, the lowest ever achieved in liquid argon, using in situ neutron calibration sources and external datasets from neutron beam experiments.