Spectral measurement of the Bi214 𝛽 decay to the Po214 ground state with the XENONnT experiment

Aprile, E.; Aalbers, J.; Abe, K.; Adrover, M.; Ahmed Maouloud, S.; Althueser, L.; Andrieu, B.; Angelino, E.; Antón Martin, D.; Armbruster, S. R.; Arneodo, F.; Baudis, L.; Bazyk, M.; Bellagamba, L.; Biondi, R.; Bismark, A.; Boese, K.; Braun, R. M.; Brown, A.; Bruno, G.; Budnik, R.; Cai, C.; Capelli, C.; Cardoso, J. M. R.; Cimental Chávez, A. P.; Colijn, A. P.; Conrad, J.; Cuenca-García, J. J.; D’Andrea, V.; Daniel Garcia, L. C.; Decowski, M. P.; Deisting, A.; Di Donato, C.; Di Gangi, P.; Diglio, S.; Eitel, K.; El Morabit, S.; Elleboro, R.; Elykov, A.; Ferella, A. D.; Ferrari, C.; Fischer, H.; Flehmke, T.; Flierman, M.; Fuchs, D.; Fulgione, W.; Fuselli, C.; Gaior, R.; Gao, F.; Giacomobono, R.; Girard, F.; Glade-Beucke, R.; Grandi, L.; Grigat, J.; Guan, H.; Guida, M.; Gyorgy, P.; Hammann, R.; Higuera, A.; Hils, C.; Hoetzsch, L.; Hood, N. F.; Iacovacci, M.; Itow, Y.; Jakob, J.; Joerg, F.; Kaminaga, Y.; Kara, M.; Kazama, S.; Kharbanda, P.; Kobayashi, M.; Koke, D.; Kooshkjalali, K.; Kopec, A.; Landsman, H.; Lang, R. F.; Levinson, L.; Li, I.; Li, S.; Liang, S.; Liang, Z.; Lin, Y. -T.; Lindemann, S.; Lindner, M.; Liu, K.; Liu, M.; Loizeau, J.; Lombardi, F.; Lopes, J. A. M.; Lucchetti, G. M.; Luce, T.; Ma, Y.; Macolino, C.; Mahlstedt, J.; Marignetti, F.; Marrodán Undagoitia, T.; Martens, K.; Masbou, J.; Mastroianni, S.; Mazza, V.; Melchiorre, A.; Merz, J.; Messina, M.; Miuchi, K.; Molinario, A.; Moriyama, S.; Morå, K.; Murra, M.; Müller, J.; Ni, K.; Oba Ishikawa, C. T.; Oberlack, U.; Ouahada, S.; Paetsch, B.; Pan, Y.; Pellegrini, Q.; Peres, R.; Pienaar, J.; Pierre, M.; Plante, G.; Pollmann, T. R.; Prajapati, A.; Principe, L.; Qin, J.; Ramírez García, D.; Rajado, M.; Ravindran, A.; Razeto, A.; Singh, R.; Sanchez, L.; Dos Santos, J. M. F.; Sarnoff, I.; Sartorelli, G.; Schreiner, J.; Schulte, P.; Schulze Eißing, H.; Schumann, M.; Scotto Lavina, L.; Selvi, M.; Semeria, F.; Shagin, P.; Shi, S.; Simgen, H.; Stevens, A.; Szyszka, C.; Takeda, A.; Takeuchi, Y.; Tan, P. -L.; Thers, D.; Trinchero, G.; Tunnell, C. D.; Tönnies, F.; Valerius, K.; Vecchi, S.; Vetter, S.; Volta, G.; Weinheimer, C.; Weiss, M.; Wenz, D.; Wittweg, C.; V. H. S., Wu; Xing, Y.; Xu, D.; Xu, Z.; Yamashita, M.; Yang, J.; Yang, L.; Ye, J.; Yoshida, M.; Yuan, L.; Zavattini, G.; Zhao, Y.; Zhong, M.; Zhu, T.

doi:10.1103/b3r7-6ff4

We report the measurement of the 214 Bi 𝛽-decay spectrum to the ground state of 214 Po using the XENONnT detector. This decay is classified as first-forbidden nonunique, for which theoretical predictions require detailed nuclear structure modeling. A dedicated identification algorithm isolates a high-purity sample of ground-state 𝛽 decays, explicitly excluding events with associated 𝛾-ray emission. By comparing the measured spectrum, which covers energies up to 3.27 MeV, with several nuclear models, we find that the prediction based on the conserved vector current hypothesis provides the best description of the data. Using this dataset, we additionally derive charge and light yield curves for electronic recoils, extending detector response modeling up to the megaelectronvolt scale.

Spectral measurement of the Bi214 𝛽 decay to the Po214 ground state with the XENONnT experiment / Aprile, E., Aalbers, J., Abe, K., Adrover, M., Ahmed Maouloud, S., Althueser, L., Andrieu, B., Angelino, E., Antón Martin, D., Armbruster, S.R., Arneodo, F., Baudis, L., Bazyk, M., Bellagamba, L., Biondi, R., Bismark, A., Boese, K., Braun, R.M., Brown, A., Bruno, G., et al.. - In: PHYSICAL REVIEW C. - ISSN 2469-9985. - 113:4(2026), pp. 1-12. [10.1103/b3r7-6ff4]