New Upper Limit on the Axion-Photon Coupling with an Extended CAST Run with a Xe-Based Micromegas Detector

• Published in: Physical review letters 2024-11, Vol.133 (22), p.221005
• Main Authors: Altenmüller, K, Anastassopoulos, V, Arguedas-Cuendis, S, Aune, S, Baier, J, Barth, K, Bräuninger, H, Cantatore, G, Caspers, F, Castel, J F, Çetin, S A, Christensen, F, Cogollos, C, Dafni, T, Davenport, M, Decker, T A, Desch, K, Díez-Ibáñez, D, Döbrich, B, Ferrer-Ribas, E, Fischer, H, Funk, W, Galán, J, García, J A, Gardikiotis, A, Giomataris, I, Golm, J, Hailey, C H, Hasinoff, M D, Hoffmann, D H H, Irastorza, I G, Jacoby, J, Jakobsen, A C, Jakovčić, K, Kaminski, J, Karuza, M, Kostoglou, S, Krieger, C, Lakić, B, Laurent, J M, Luzón, G, Malbrunot, C, Margalejo, C, Maroudas, M, Miceli, L, Mirallas, H, Navarro, P, Obis, L, Özbey, A, Özbozduman, K, Papaevangelou, T, Pérez, O, Pivovaroff, M J, Rosu, M, Ruiz-Chóliz, E, Ruz, J, Schmidt, S, Schumann, M, Semertzidis, Y K, Solanki, S K, Stewart, L, Vafeiadis, T, Vogel, J K, Zioutas, K
• Format: Article
• Language: English
• ISSN: 1079-7114; 1079-7114
• DOI: 10.1103/PhysRevLett.133.221005

Hypothetical axions provide a compelling explanation for dark matter and could be emitted from the hot solar interior. The CERN Axion Solar Telescope has been searching for solar axions via their back conversion to x-ray photons in a 9-T 10-m long magnet directed toward the Sun. We report on an extended run with the International Axion Observatory pathfinder detector, doubling the previous exposure time. The detector was operated with a xenon-based gas mixture for part of the new run, providing technical insights for future configurations. No counts were detected in the 95% signal-encircling region during the new run, while 0.75 were expected. The new data improve the axion-photon coupling limit to 5.8×10^{-11}  GeV^{-1} at 95% CL (for m_{a}≲0.02  eV), the most restrictive experimental limit to date.