Search for Solar Axions with the CCD Detector and X-ray Telescope at CAST Experiment

The CERN Axion Solar Telescope (CAST) is an experiment that uses the world’s highest sensitivity Helioscope to date for solar Axions searches. Axions are weakly interacting pseudoscalar particles proposed to solve the so-called Strong Charge-Parity Problem of the Standard Model. The principle of detection is the inverse Primakoff Effect, which is a mechanism for converting the Axions into easily detectable X-ray photons in a strong transverse magnetic field. The solar Axions are produced due to the Primakoff effect in the hot and dense core of from the coupling of a real and a virtual photon. The solar models predict a peak Axion luminosity at an energy of 3 keV originating mostly from the inner 20% of the solar radius. Thus an intensity peak at an energy of 3 keV is also expected in the case of the X-ray radiation resulting from Axion conversion. CAST uses a high precision movement system for tracking the Sun twice a day with a LHC dipole twin aperture prototype magnet, 9.26 meters long and with a field of 9 Tesla. On the four apertures of the magnet, X-ray detectors look for photons resulted from Axion conversion. For investigating different Axion masses, 3He and 4He buffer gas was injected in the magnetic region, restoring the coherence for Axion-to-photon conversion into mass regions so far unexplored, favoured by QCD Axion models. Using this scanning strategy, Axion masses were investigated in the range 0.02 eV to 1.17 eV between 2003 and 2013. One of CAST Detectors is a pn-CCD chip placed in the focal plane of an X-ray Telescope. In this thesis an overview of 2009, 2010 and 2011 data taken with this detector is presented. Signal and background levels were extracted, indicating that no conversion signature was detected. The analysed data is being used within the collaboration for improving the combined upper limits on the Axion-to- photon coupling constant parameter space (g!! ≲ 3.3×10!!" 𝐺𝑒𝑉!! 𝑎𝑡 95% 𝐶. 𝐿.), for the mass range 0.65 eV to 1.17 eV, by merging it with the results from the other detectors. Besides this, X-ray Telescope mirror module reflectivity checks and alignment were performed, together with long-term detector system monitoring, stability studies and calibrations, spanning the interval 2009-2014. In order to ensure the highest discovery potential and the best sensitivity of the setup, the mirror module was tested at the Panter X-ray test facility in Munich, and the performance was found to be within the expected margins after 11 years operation of.