Ph.d. degree
Universidad de Zaragoza, Spain 2014

Javier Gracia Garza

Supervisor: Igor Garcia Irastorza

Micromegas for the search of solar axions in CAST an low-mass WIMPs in TREX-DM

 Keywords:

• Charge transport and multiplication in gas
• Dark Matter detectors (WIMPs, axions, etc.)
• X-ray detectors
• Time projection chambers

 Abstract:
In this thesis work I present the application of Time Projection Chambers equipped with Micromegas readouts, a charge-amplification strucutre, to the field of the Rare Event Searches.
In particular, I present the application to the search of solar axions in the CAST Experiment. The data analysis and results of the experiment with the Micromegas detectors for the years 2012 (He-4 as buffer gas), 2013 and 2014 with vacuum in the magnet bores are presented. We also present the background model of the detector and the prospects to further reduce it.
On the other side, we show the commissioning and first results of a Micromegas-based TPC detector for the search of low-mass WIMPs. The results of the characterization of the bulk Micromegas detectors are presented at several pressures. The background model of the detector is presented and the expected sensitivity of the search is finally derived.