posted on 2024-01-16, 10:05authored byP Adhikari, R Ajaj, M Alpízar-Venegas, PA Amaudruz, J Anstey, GR Araujo, DJ Auty, M Baldwin, M Batygov, B Beltran, H Benmansour, CE Bina, Simon PeetersSimon Peeters, et al.
The specific activity of the β 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 stat ± 0.024 sys) Bq/kg 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.
Funding
2012 Consolidated Grant for Sussex Experimental Particle Physics (EPP) : Science and Technology Facilities Council | ST/K001329/1