New solar axion search using the CERN Axion Solar Telescope with He-4 filling
MetadataShow full item record
CitationArık, M., Aune, S., Barth, K., Belov, A., Borghi, S., Brauninger, H., ... CAST Collaboration. (2015). New solar axion search using the CERN Axion Solar Telescope with He-4 filling. Physical Review D, 92(2), 1-6. https://dx.doi.org/10.1103/PhysRevD.92.021101
The CERN Axion Solar Telescope (CAST) searches for a -> gamma conversion in the 9 T magnetic field of a refurbished LHC test magnet that can be directed toward the Sun. Two parallel magnet bores can be filled with helium of adjustable pressure to match the x-ray refractive mass m(gamma) to the axion search mass m(a). After the vacuum phase (2003-2004), which is optimal for m(a) less than or similar to 0.02 eV, we used He-4 in 2005-2007 to cover the mass range of 0.02-0.39 eV and He-3 in 2009-2011 to scan from 0.39 to 1.17 eV. After improving the detectors and shielding, we returned to He-4 in 2012 to investigate a narrow m(a) range around 0.2 eV ("candidate setting" of our earlier search) and 0.39-0.42 eV, the upper axion mass range reachable with He-4, to "cross the axion line" for the KSVZ model. We have improved the limit on the axion-photon coupling to g(a gamma) < 1.47 x 10(-10) GeV-1 (95% C.L.), depending on the pressure settings. Since 2013, we have returned to the vacuum and aim for a significant increase in sensitivity.