Calibration of the liquid argon ionization response to low energy electronic and nuclear recoils with DarkSide-50
P. Agnes, I. F. M. Albuquerque, T. Alexander, A. K. Alton, M. Ave, H. O. Back, G. Batignani, K. Biery, V. Bocci, W. M. Bonivento, B. Bottino, S. Bussino, M. Cadeddu, M. Cadoni, F. Calaprice, A. Caminata, N. Canci, M. Caravati, M. Cariello, M. Carlini, M. Carpinelli, S. Catalanotti, V. Cataudella, P. Cavalcante, S. Cavuoti, A. Chepurnov, C. Cicalò, A. G. Cocco, G. Covone, D. D’Angelo, S. Davini, A. De Candia, S. De Cecco, G. De Filippis, G. De Rosa, A. V. Derbin, A. Devoto, M. D’Incecco, C. Dionisi, F. Dordei, M. Downing, D. D’Urso, G. Fiorillo, D. Franco, F. Gabriele, C. Galbiati, C. Ghiano, C. Giganti, G. K. Giovanetti, O. Gorchakov, A. M. Goretti, A. Grobov, M. Gromov, M. Guan, Y. Guardincerri, M. Gulino, B. R. Hackett, K. Herner, B. Hosseini, F. Hubaut, E. V. Hungerford, An. Ianni, V. Ippolito, K. Keeter, C. L. Kendziora, I. Kochanek, D. Korablev, G. Korga, A. Kubankin, M. Kuss, M. La Commara, M. Lai, X. Li, M. Lissia, G. Longo, I. N. Machulin, L. P. Mapelli, S. M. Mari, J. Maricic, C. J. Martoff, A. Messina, P. D. Meyers, R. Milincic, M. Morrocchi, X. Mougeot, V. N. Muratova, P. Musico, A. Navrer Agasson, A. O. Nozdrina, A. Oleinik, F. Ortica, L. Pagani, M. Pallavicini, L. Pandola, E. Pantic, E. Paoloni, K. Pelczar, N. Pelliccia, E. Picciau, A. Pocar
Abstract
DarkSide-50 has demonstrated the high potential of dual-phase liquid argon time projection chambers in exploring interactions of WIMPs in the $\mathrm{GeV}/{\mathrm{c}}^{2}$ 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 $\ensuremath{\sim}180\text{ }\text{ }{\mathrm{eV}}_{\mathrm{er}}$, exploiting $^{37}\mathrm{Ar}$ and $^{39}\mathrm{Ar}$ 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 $\ensuremath{\sim}500\text{ }\text{ }{\mathrm{eV}}_{\mathrm{nr}}$, the lowest ever achieved in liquid argon, using in situ neutron calibration sources and external datasets from neutron beam experiments.