1. Direct Measurement of the $^{39}$Ar Half-life from 3.4 Years of Data with the DEAP-3600 Detector
- Author
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DEAP Collaboration, Adhikari, P., Ajaj, R., Alpízar-Venegas, M., Amaudruz, P. -A., Anstey, J., Auty, D. J., Batygov, M., Beltran, B., Bina, C. E., Bonivento, W. M., Boulay, M. G., Bueno, J. F., Cadeddu, M., Cai, B., Cárdenas-Montes, M., Chen, Y., Choudhary, S., Cleveland, B. T., Crampton, R., Daugherty, S., DelGobbo, P., Di Stefano, P., Dolganov, G., Doria, L., Duncan, F. A., Dunford, M., Ellingwood, E., Erlandson, A., Farahani, S. S., Fatemighomi, N., Fiorillo, G., Ford, R. J., Gahan, D., Gallacher, D., Garai, A., Abia, P. García, Garg, S., Giampa, P., Giménez-Alcázar, A., Goeldi, D., Golovko, V. V., Gorel, P., Graham, K., Grobov, A., Hallin, A. L., Hamstra, M., Haskins, S., Hu, J., Hucker, J., Hugues, T., Ilyasov, A., Jigmeddorj, B., Jillings, C. J., Joy, A., Kaur, G., Kemp, A., Yazdi, M. Khoshraftar, Kuźniak, M., La Zia, F., Lai, M., Langrock, S., Lehnert, B., LePage-Bourbonnais, J., Levashko, N., Lissia, M., Luzzi, L., Machulin, I., Maru, A., Mason, J., McDonald, A. B., McElroy, T., McLaughlin, J. B., Mielnichuk, C., Mirasola, L., Moharana, A., Monroe, J., Murray, A., Ng, C., Oliviéro, G., Olszewski, M., Pal, S., Papi, D., Park, B., Perry, M., Pesudo, V., Pollmann, T. R., Rad, F., Rethmeier, C., Retière, F., García, I. Rodríguez, Roszkowski, L., Santorelli, R., Schuckman II, F. G., Seth, S., Shalamova, V., Skensved, P., Smirnova, T., Sobotkiewich, K., Sonley, T., Sosiak, J., Soukup, J., Stainforth, R., Stringer, M., Tang, J., Vázquez-Jáuregui, E., Viel, S., Vyas, B., Walczak, M., Walding, J., Ward, M., Westerdale, S., Wormington, R., and Zuñiga-Reyes, A.
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Nuclear Experiment ,Physics - Instrumentation and Detectors - Abstract
The half-life of $^{39}$Ar is measured using the DEAP-3600 detector located 2 km underground at SNOLAB. In 2016-2020, DEAP-3600 used a target mass of (3269 $\pm$ 24) kg of liquid argon distilled from the atmosphere in a direct-detection dark matter search. Such an argon mass also enables direct measurements of argon isotope properties. The decay of $^{39}$Ar in DEAP-3600 is the dominant source of triggers by two orders of magnitude, ensuring high statistics and making DEAP-3600 well-suited for measuring this isotope's half-life. Use of the pulse-shape discrimination technique in DEAP-3600 allows for powerful discrimination between nuclear recoils and electron recoils, resulting in the selection of a clean sample of $^{39}$Ar decays. Observing over a period of 3.4 years, the $^{39}$Ar half-life is measured to be $(302 \pm 8_{\rm stat} \pm 6_{\rm sys})$ years. This new direct measurement suggests that the half-life of $^{39}$Ar may be significantly longer than the accepted value, with potential implications for measurements using this isotope's half-life as input., Comment: 11 pages, 8 figures
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- 2025