Improved search for solar chameleons with a GridPix detector at CAST

V. Anastassopoulos, S. Aune, K. Barth, A. Belov, H. Braueninger, G. Cantatore, J. M. Carmona, J. F. Castel, S. A. Cetin, F. Christensen, T. Dafni, M. Davenport, A. Dermenev, K. Desch, B. Doebrich, C. Eleftheriadis, G. Fanourakis, E. Ferrer-Ribas, Hanne Lis Fischer, W. FunkJ. A. Garcia, A. Gardikiotis, J. G. Garza, E. N. Gazis, T. Geralis, I Giomataris, S. Gninenko, C. J. Hailey, M. D. Hasinoff, D. H. H. Hoffmann, F. J. Iguaz, I. G. Irastorza, A. Jakobsen, J. Jacoby, K. Jakovcic, J. Kaminski, M. Karuza, S. Kostoglou, N. Kralj, M. Krcmar, C. Krieger*, B. Lakic, J. M. Laurent, A. Liolios, A. Ljubicic, G. Luzon, M. Maroudas, L. Miceli, S. Schmidt, J. K. Vogel, M. Vretenar, W. Wuensch, S. C. Yildiz, K. Zioutasa, P. Braxab

*Corresponding author for this work

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    We report on a new search for solar chameleons with the CERN Axion Solar Telescope (CAST). A GridPix detector was used to search for soft X-ray photons in the energy range from 200 eV to 10 keV from converted solar chameleons. No significant excess over the expected background has been observed in the data taken in 2014 and 2015. We set an improved limit on the chameleon photon coupling, βγ#5.7×1010 for 1<βm<106 at 95% C.L. improving our previous results by a factor two and for the first time reaching sensitivity below the solar luminosity bound for tachocline magnetic fields up to 12.5 T.
    Original languageEnglish
    Article number32
    JournalJournal of Cosmology and Astroparticle Physics
    Issue number1
    Number of pages18
    Publication statusPublished - 2019

    Bibliographical note

    © 2019 CERN. Published by IOP Publishing Ltd on behalf of Sissa Medialab. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.


    • Dark energy experiments
    • Modified gravity
    • Particle physics - cosmology connection
    • Solar physics


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