Search for solar axions produced through the axion-electron coupling gae using a new GridPix detector at CAST

(CAST collaboration) Altenmüller, K; Anastassopoulos, V; Arguedas-Cuendis, S; Aune, S; Baier, J; Barth, K; Bräuninger, H; Cantatore, G; Caspers, F; Castel, JF; Çetin, SA; Christensen, F; Cogollos, C; Dafni, T; Davenport, M; Decker, TA; Desch, K; Díez-Ibáñez, D; Döbrich, B; Ferrer-Ribas, E; Fischer, H; Funk, W; Galán, J; García, JA; Gardikiotis, A; Giomataris, I; Golm, J; Hailey, CH; Hasinoff, MD; Hoffmann, DHH; Irastorza, IG; Jacoby, J; Jakobsen, AC; Jakovcic, K; Kaminski, J; Karuza, M; Kostoglou, S; Krieger, C; Lakic, B; Laurent, JM; Luzon, G; Malbrunot, C; Margalejo, C; Maroudas, M; Miceli, L; Mirallas, H; Navarro, P; Obis, L; Özbey, A; Özbozduman, K; Papaevangelou, T; Pérez, O; Pivovaroff, MJ; Rosu, M; Ruiz-Choliz, E; Ruz, J; Schiffer, T; Schmidt, S; Schumann, M; Semertzidis, YK; Solanki, SK; Stewart, L; Vafeiadis, T; Vogel, JK; Zioutas, K (2025) Search for solar axions produced through the axion-electron coupling gae using a new GridPix detector at CAST. Journal of High Energy Physics, 2025 (12). ISSN 1029-8479

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Abstract

We present a search for solar axions produced through the axion-electron coupling (gae) using data from a novel 7-GridPix detector installed at the CERN Axion Solar Telescope (CAST). The detector, featuring ultra-thin silicon nitride windows and multiple veto systems, collected approximately 160 hours of solar tracking data between 2017–2018. Using machine learning techniques and the veto systems, we achieved a background rate of 1.06 × 10−5 keV−1 cm−2 s−1 at a signal efficiency of about 80% in the 0.2 to 8 keV range. Analysis of the data yielded no significant excess above background, allowing us to set a new upper limit on the product of the axion-electron and axion-photon couplings of gae · gaγ < 7.35 × 10−23 GeV−1 at 95% confidence level for axion masses below 10 meV. This result improves upon the previous best helioscope limit and demonstrates the potential of GridPix technology for rare event searches. Additionally, we derived a limit on the axion-photon coupling of gaγ < 9.0 × 10−11 GeV−1 at 95% CL, which, while not surpassing CAST’s best limit, provides complementary constraints on axion models.

Item Type:	Article
Additional Information:	Preprint version retrieved from arXiv: https://doi.org/10.48550/arXiv.2505.05909
Uncontrolled Keywords:	Beyond Standard Model; CP Violation; Dark Matter; Dark Matter and Double Beta Decay (experiments)
Subjects:	NATURAL SCIENCES > Physics
Divisions:	Division of Experimental Physics
Depositing User:	Ana Zečević
Date Deposited:	20 May 2026 06:44
URI:	https://fulir.irb.hr:/id/eprint/11971
DOI:	10.1007/JHEP12(2025)009

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