Measurement of the $^{39}$Ar specific activity in atmospheric argon with DArT at the Canfranc Underground Laboratory
Year: 2026
Type: preprint
Abstract: We report the measurement of the $^{39}$Ar specific activity of atmospheric argon using DArT, a low-background single-phase liquid-argon detector read out by cryogenic silicon photomultipliers, at the Canfranc Underground Laboratory (LSC) in Spain. DArT was first filled with atmospheric argon and then with a sample of underground argon of known radioactivity from the DarkSide-50 experiment. The underground argon serves as a background reference in this measurement, making the result robust because we do not rely on background simulations. We measure the $^{39}$Ar specific activity with both a cut-and-count method and a binned maximum-likelihood fit, yielding consistent results. We obtain $a_{\text{AAr}}= 0.955 \pm 0.008~\text{Bq}/\text{kg}$. This result agrees with previous measurements from other experiments and provides the most precise determination of the $^{39}$Ar specific activity in atmospheric argon to date. It also validates DArT as a key component of the DArTInArDM experiment at LSC, which aims to measure the $^{39}$Ar activity of the argon extracted from deep underground wells in Colorado (USA) for the Darkside-20k and LEGEND-1000 experiments at Laboratori Nazionali del Gran Sasso in Italy.
Source: arXiv (Cornell University)
Authors: Agnes, P., Back, H. O., Bharat, S., Bonivento, W. M., Boulay, M., Caboni, M., Canci, N., Cargioli, N., Castello, P., Cebrián, S., Consiglio, L., Crampton, R., Mairena, D. Diaz, Franco, D., Fuente-Ortega, I., Gabriele, F., Gahan, D., Galbiati, C., Abia, P. Garcia, Hessel, T., Horikawa, S., Ianni, A., Korga, G., Kuźniak, M., Luzzi, L., Marasciulli, A., Martínez, M., Organtini, P., de Solórzano, A. Ortiz, Pavarani, R., Pegoraro, P., Fortes, V. Pesudo, Razeti, M., Rehman, O. U., Romero, L., Sablone, D., García, E. Sánchez, Santorelli, R., Seoane, C., Sosiak, J., Sulis, S., Tierney, C., Tullio, S., Díaz, G. Vera
Institutions: Istituto Nazionale di Fisica Nucleare, Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Gran Sasso, Gran Sasso Science Institute, Savannah River National Laboratory, Universidad de Zaragoza, Centro de Astropartículas y Física de Altas Energías, Istituto Nazionale di Fisica Nucleare, Sezione di Cagliari, Carleton University, Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, University of Cagliari, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, Centre National de la Recherche Scientifique, Université Paris Cité, Laboratoire AstroParticule et Cosmologie, Princeton University, University of Hawaiʻi at Mānoa, University of Hawaii System, University of Oxford, Nicolaus Copernicus Astronomical Center, University of California, Davis, University of Padua, Max Planck Institute for Nuclear Physics
Language: English
Topic: Neutrino Physics Research
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G1928350784, G8920660035
OpenAlex ID: W7215098828