Background Determination for the LUX-ZEPLIN (LZ) Dark Matter Experiment

• Published in: arXiv.org 2023-07
• Main Authors: Aalbers, J, Akerib, D S, Al Musalhi, A K, Alsum, S K, Ames, A, Angelides, N, Armstrong, J E, Bang, J, Brew, C A J, Brás, P, Burdin, S, Cabrita, R, Chan, C, Chawla, A, Chen, H, Chiang, A P S, Chott, N I, Dahl, C E, Dey, S, de Viveiros, L, Ding, C, Dobson, J E Y, Druszkiewicz, E, Fiorucci, S, Fraser, E D, Gaitskell, R J, Genovesi, J, Ghag, C, Gilchriese, M G D, M G D van der Grinten, Gwilliam, C B, Hall, C R, Han, S, Hartigan-O'Connor, E, Heuermann, G, Jacobsen, R G, Jahangir, O, James, R S, Johnson, J, Khurana, I, Kodroff, D, Korolkova, E V, Leonard, D S, Lesko, K T, Lin, J, E Lopez Asamar, B López Paredes, Lorenzon, W, C Lu, Majewski, P A, Mannino, R L, Marangou, N, McCarthy, M E, McKinsey, D N, McLaughlin, J, Morales Mendoza, J D, Mount, B J, Murdy, M, Murphy, A St J, Naim, D, Nedlik, C, Nguyen, A, Orpwood, J, Palladino, K J, Parveen, N, Patton, S J, Penning, B, Perry, E, Piepke, A, Poudel, S, Reichenbacher, J, Riffard, Q, Riyat, H S, Rosero, R, Rossiter, P, Santone, D, A B M R Sazzad, Shutt, T, Silk, J J, Silva, C, Sinev, G, Solmaz, M, Stancu, I, Stevens, A, Suerfu, B, Taylor, R, Taylor, W C, Terman, P A, Tong, Z, Tovey, D R, Utku, U, Wang, J J, Wang, Y, Watson, J R, Webb, R C, Wolfs, F L H, Woodford, S, Xia, Q, Xiang, X, Yeh, M
• Format: Article
• Language: English
• Subjects: Beta decay; Confidence intervals; Dark matter; Field theory; Weakly interacting massive particles
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2211.17120

The LUX-ZEPLIN experiment recently reported limits on WIMP-nucleus interactions from its initial science run, down to \(9.2\times10^{-48}\) cm\(^2\) for the spin-independent interaction of a 36 GeV/c\(^2\) WIMP at 90% confidence level. In this paper, we present a comprehensive analysis of the backgrounds important for this result and for other upcoming physics analyses, including neutrinoless double-beta decay searches and effective field theory interpretations of LUX-ZEPLIN data. We confirm that the in-situ determinations of bulk and fixed radioactive backgrounds are consistent with expectations from the ex-situ assays. The observed background rate after WIMP search criteria were applied was \((6.3\pm0.5)\times10^{-5}\) events/keV\(_{ee}\)/kg/day in the low-energy region, approximately 60 times lower than the equivalent rate reported by the LUX experiment.