Precision measurement of the specific activity of ^{39}Ar in atmospheric argon with the DEAP-3600 detector

P Adhikari ,W Bonivento,M Cárdenas-Montes ,A B Mcdonald ,A Flower ,J Bonatt ,Isabel Rodríguez García ,J B Ruhland ,C Ouellet ,F Rad ,M Chen ,R J Ford ,S Haskins ,M Ward ,S Choudhary ,M -C Piro ,P J Harvey ,A Ilyasov ,V Pesudo ,J Soukup ,F A Duncan ,G Dolganov ,V V Golovko ,G Kaur ,N Fatemighomi ,A Leonhardt ,D J Auty ,P Nadeau ,J Mason ,J Monroe ,M Walczak ,A Erlandson ,S Pal ,P Gorel ,A Giménez-Alcázar ,R Crampton ,M Batygov ,M Hamstra ,A Joy ,J Digioseffo ,K Sobotkiewich ,E O'dwyer ,N Seeburn ,T Lindner ,F La Zia ,G Oliviéro ,S S Farahani ,R Gagnon ,T Hugues ,I Machulin ,B Broerman ,E Vázquez-Jáuregui ,R Stainforth ,C Ng ,M Kuźniak ,M G Boulay ,A Grobov ,S Daughtery ,B Cai ,L Mirasola ,E Ellingwood ,K Singhrao ,B Jigmeddorj ,D Gallacher ,V Shalamova ,A J Noble ,T Mcginn ,R Mehdiyev ,N Levashko ,A Kemp ,D Cranshaw ,L Veloce ,M Baldwin ,C E Bina ,B Smith ,K Graham ,H Benmansour ,S Seth ,S J M Peeters ,J Sosiak ,J F Bueno ,P García Abia ,D R Grant ,A Butcher ,J Lock ,S Langrock ,P Di Stefano ,S Cavuoti ,L Doria ,A L Hallin ,E Picciau ,K Dering ,R Santorelli ,S Westerdale ,M Dunford ,J Lidgard ,B Sur ,S Viel ,J Walding ,J Anstey ,F Retière ,T Mcelroy ,O Kamaev ,E T Rand ,M Lai ,J Hu ,G Fiorillo ,P Skensved ,T R Pollmann ,F G Schuckman ,C Mielnichuk ,B Beltran ,P Majewski ,B Vyas ,P Giampa ,M Perry ,C Rethmeier ,P Pasuthip ,Joe Mclaughlin ,S Garg ,D Papi ,C Hearns ,P Delgobbo ,P M Burghardt ,J M Corning ,Y Chen ,A Maru ,J Hucker ,S Florian ,L Roszkowski ,C Nantais ,Nell Smith ,J Tang ,B T Cleveland ,M Alpízar-Venegas ,J Lepage-Bourbonnais ,T Sonley ,J Willis ,C J Jillings ,D Goeldi ,C Stone ,V Strickland ,G R Araujo ,M Stringer ,R Ajaj ,P -A Amaudruz ,B Lehnert ,M Cadeddu,M Lissia,A Zuñiga-Reyes

doi:10.1140/epjc/s10052-023-11678-6

Abstract

The specific activity of the beta decay of ^{39}Ar in atmospheric argon is measured using the DEAP-3600 detector. DEAP-3600, located 2 km underground at SNOLAB, uses a total of (3269 ± 24) kg of liquid argon distilled from the atmosphere to search for dark matter. This detector is well-suited to measure the decay of ^{39}Ar owing to its very low background levels. This is achieved in two ways: it uses low background construction materials; and it uses pulse-shape discrimination to differentiate between nuclear recoils and electron recoils. With 167 live-days of data, the measured specific activity at the time of atmospheric extraction is (0.964 ± 0.001_textrm{stat} ± 0.024_textrm{sys}) Bq/kg_textrm{atmAr}, which is consistent with results from other experiments. A cross-check analysis using different event selection criteria and a different statistical method confirms the result.

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