New solar axion search using the CERN Axion Solar Telescope with 4He filling
Abstract
The CERN Axion Solar Telescope (CAST) searches for a →γ 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 mγ to the axion search mass ma. After the vacuum phase (2003-2004), which is optimal for ma≲0.02 eV , we used 4He in 2005-2007 to cover the mass range of 0.02-0.39 eV and 3He in 2009-2011 to scan from 0.39 to 1.17 eV. After improving the detectors and shielding, we returned to 4He in 2012 to investigate a narrow ma range around 0.2 eV ("candidate setting" of our earlier search) and 0.39-0.42 eV, the upper axion mass range reachable with 4He, to "cross the axion line" for the KSVZ model. We have improved the limit on the axion-photon coupling to ga γ<1.47 ×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.
- Publication:
-
Physical Review D
- Pub Date:
- July 2015
- DOI:
- 10.1103/PhysRevD.92.021101
- arXiv:
- arXiv:1503.00610
- Bibcode:
- 2015PhRvD..92b1101A
- Keywords:
-
- 95.35.+d;
- 07.85.Nc;
- 14.80.Va;
- 84.71.Ba;
- Dark matter;
- X-ray and gamma-ray spectrometers;
- Superconducting magnets;
- magnetic levitation devices;
- High Energy Physics - Experiment;
- Physics - Instrumentation and Detectors
- E-Print:
- CAST Collaboration 6 pages 3 figures