Abstract: Initially proposed as part of the solution to the strong CP problem of the Standard Model of particle physics, axions and axion-like particles appear on several Beyond Standard Model extensions. These pseudoscalar pseudo-Nambu-Goldstone bosons could also be the answer to one of the most puzzling questions on cosmology, the Dark Matter problem.
In this PhD work we compile three different contributions to axion searches within the same framework. The first comprises the work developed in a proposal that paves the path for haloscope searches at BabyIAXO. In the second part we expose the characterization and optimization of the radioactive background of the acquisition electronics for the BabyIAXO helioscope. In the last part a general framework for treating multicavity resonators is presented as an extension of the theory developed for the first RADES prototype, based on this idea two new prototypes were designed, manufactured and characterized.

Directors: Eduardo Picatoste Olloqui and Babette Doebrich