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

• Published in: The European physical journal. C, Particles and fields Particles and fields, 2023-07, Vol.83 (7), p.642
• Main Authors: Amaudruz, P.-A., Anstey, J., Araujo, G. R., Auty, D. J., Baldwin, M., Bonatt, J., Bonivento, W., Boulay, M. G., Broerman, B., Bueno, J. F., Burghardt, P. M., Cadeddu, M., Cai, B., Cárdenas-Montes, M., Chen, Y., Choudhary, S., Crampton, R., Cranshaw, D., Daugherty, S., DelGobbo, P., Dering, K., Stefano, P. Di, DiGioseffo, J., Duncan, F. A., Dunford, M., Farahani, S. S., Fatemighomi, N., Florian, S., Flower, A., Ford, R. J., Gagnon, R., Gallacher, D., Giampa, P., Golovko, V. V., Gorel, P., Graham, K., Grant, D. R., Grobov, A., Hamstra, M., Harvey, P. J., Hearns, C., Hucker, J., Hugues, T., Ilyasov, A., Jigmeddorj, B., Joy, A., Kamaev, O., Kaur, G., Kemp, A., Kuźniak, M., Zia, F. La, Langrock, S., Lehnert, B., Leonhardt, A., Levashko, N., Lidgard, J., Lindner, T., Lissia, M., McDonald, A. B., McElroy, T., McGinn, T., McLaughlin, J. B., Mehdiyev, R., Mielnichuk, C., Mirasola, L., Monroe, J., Nadeau, P., Nantais, C., Ng, C., Noble, A. J., O’Dwyer, E., Oliviéro, G., Pasuthip, P., Peeters, S. J. M., Pesudo, V., Picciau, E., Pollmann, T. R., Rand, E. T., Rodríguez García, I., Santorelli, R., Schuckman II, F. G., Seeburn, N., Seth, S., Shalamova, V., Singhrao, K., Skensved, P., Smith, B., Sobotkiewich, K., Sonley, T., Sosiak, J., Soukup, J., Sur, B., Tang, J., Veloce, L., Viel, S., Vyas, B., Walding, J., Ward, M., Westerdale, S., Zuñiga-Reyes, A.
• Format: Article
• Language: English
• Subjects: Argon; Astronomy; Astrophysics and Cosmology; Atmosphere; Collaboration; Construction materials; Dark matter; Decay; Elementary Particles; Hadrons; Heavy Ions; Laboratories; Measurement Science and Instrumentation; Nuclear Energy; Nuclear Physics; Physics; Physics and Astronomy; Pulse shape; Quantum Field Theories; Quantum Field Theory; Regular Article - Experimental Physics; Sensors; Statistical analysis; Statistical methods; String Theory
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-023-11678-6

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.