I. Ortega

Conceptual design of the International Axion Observatory (IAXO)

The International Axion Observatory (IAXO) will be a forth generation axion helioscope. As its primary physics goal, IAXO will look for axions or axion-like particles (ALPs) originating in the Sun via the Primakoff conversion of the solar plasma photons. In terms of signal-to-noise ratio, IAXO will be about 4–5 orders of magnitude more sensitive than CAST, currently the most powerful axion helioscope, reaching sensitivity to axion-photon couplings down to a few × 10−12 GeV−1 and thus probing a large fraction of the currently unexplored axion and ALP parameter space. IAXO will also be sensitive to solar axions produced by mechanisms mediated by the axion-electron coupling gae with sensitivity — for the first time — to values of gae not previously excluded by astrophysics. With several other possible physics cases, IAXO has the potential to serve as a multi-purpose facility for generic axion and ALP research in the next decade. In this paper we present the conceptual design of IAXO, which follows the layout of an enhanced axion helioscope, based on a purpose-built 20 m-long 8-coils toroidal superconducting magnet. All the eight 60cm-diameter magnet bores are equipped with focusing x-ray optics, able to focus the signal photons into ~ 0.2 cm2 spots that are imaged by ultra-low-background Micromegas x-ray detectors. The magnet is built into a structure with elevation and azimuth drives that will allow for solar tracking for ~ 12 h each day.

New CAST limit on the axion–photon interaction

During 2003--2015, the CERN Axion Solar Telescope (CAST) has searched for

New solar axion search using the CERN Axion Solar Telescope with He 4 filling

a\to\gamma

Search for chameleons with CAST

conversion in the 9 T magnetic field of a refurbished LHC test magnet that can be directed toward the Sun. In its final phase of solar axion searches (2013--2015), CAST has returned to evacuated magnet pipes, which is optimal for small axion masses. The absence of a significant signal above background provides a world leading limit of

The IAXO Helioscope

g_{a\gamma} < 0.66 \times 10^{-10} {\rm GeV}^{-1}

Low-background X-ray detection with Micromegas for axion research

(95% C.L.) on the axion-photon coupling strength for

IAXO - The International Axion Observatory

m_a \lesssim 0.02

The International Axion Observatory IAXO. Letter of Intent to the CERN SPS committee

eV. Compared with the first vacuum phase (2003--2004), the sensitivity was vastly increased with low-background x-ray detectors and a new x-ray telescope. These innovations also serve as pathfinders for a possible next-generation axion helioscope.

The Next Generation of Axion Helioscopes: The International Axion Observatory (IAXO)

M. Arik, a S. Aune, K. Barth, A. Belov, H. Bräuninger, J. Bremer, V. Burwitz, G. Cantatore, J. M. Carmona, S. A. Cetin, J. I. Collar, E. Da Riva, T. Dafni, M. Davenport, A. Dermenev, C. Eleftheriadis, N. Elias, b G. Fanourakis, E. Ferrer-Ribas, J. Galán, J. A. Garćıa, c A. Gardikiotis, J. G. Garza, E. N. Gazis, T. Geralis, E. Georgiopoulou, I. Giomataris, S. Gninenko, M. Gómez Marzoa, d M. D. Hasinoff, D. H. H. Hoffmann, F. J. Iguaz, I. G. Irastorza, J. Jacoby, K. Jakovčić, M. Karuza, 17 M. Kavuk, a M. Krčmar, M. Kuster, 14, e B. Lakić, J. M. Laurent, A. Liolios, A. Ljubičić, G. Luzón, S. Neff, T. Niinikoski, f A. Nordt, 14, b I. Ortega, 3 T. Papaevangelou, M. J. Pivovaroff, G. Raffelt, A. Rodŕıguez, M. Rosu, J. Ruz, I. Savvidis, I. Shilon, 3, g S. K. Solanki, h L. Stewart, A. Tomás, T. Vafeiadis, 9, 11 J. Villar, J. K. Vogel, S. C. Yildiz, i and K. Zioutas 11

Improved Search for Solar Chameleons with a GridPix Detector at CAST

In this work we present a search for (solar) chameleons with the CERN Axion Solar Telescope (CAST). This novel experimental technique, in the field of dark energy research, exploits both the chameleon coupling to matter ( m) and to photons ( ) via the Primako e ect. By reducing the X-ray detection energy threshold used for axions from 1 keV to 400 eV CAST became sensitive to the converted solar chameleon spectrum which peaks around 600 eV. Even though we have not observed any excess above background, we can provide a 95% C.L. limit for the coupling strength of chameleons to photons of . 10 11 for 1 < m < 10 6 .