Seminars and Journal Clubs
Probing eV-scale axions with the CAST experiment at CERN
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Europe/Brussels
E/3rd floor-E.349 - Seminar room (E.349) (Marc de Hemptinne (chemin du Cyclotron, 2, Louvain-la-Neuve))
E/3rd floor-E.349 - Seminar room (E.349)
Marc de Hemptinne (chemin du Cyclotron, 2, Louvain-la-Neuve)
30
Description
The CERN Axion Solar Telescope (CAST) is searching for solar axions, which could be produced in the core of the Sun via the so-called Primakoff effect. Not only would these hypothetical particles solve the strong CP problem, but they are also one of the favored candidates for dark matter. In order to look for axions originating from the Sun, CAST uses a decommissioned LHC prototype magnet. In its 10 m long magnetic field region of 9 Tesla, axions could be reconverted into X-ray photons. Therefore different X-ray detectors are installed on both ends of the magnet, which is mounted on a structure built to follow the Sun during sunrise and sunset for a total of about 3 hours per day.
The analysis of the data acquired during the first phase of the experiment with vacuum in the magnetic field region yielded the most restrictive experimental upper limit on the axion-to-photon coupling constant for axion masses up to about 0.02 eV. In order to extend the sensitivity of the experiment to a wider mass range, the CAST experiment continued its search for axions with helium in the magnet bores. In this way it is possible to restore coherence of conversion for larger masses. Changing the pressure of the helium gas enables the experiment to scan different axion masses in the range of up to about 1.2 eV.
In the first part of this second phase of CAST, helium-4 was used and the axion mass region was extended up to 0.4 eV. Therefore the experiment entered the regions favored by axion models. In CAST’s ongoing helium-3 phase the studied mass range is now being further extended.
In this talk the final results of CAST’s helium-4 phase will be presented and an outlook on the current status of the helium-3 run will be given along with future prospects of the experiment.