A Low Background Setup for Low Energy X-ray Detection in the Context of the BabyIAXO/IAXO Axion Searches

In the context of axion search in the BabyIAXO and IAXO helioscopes, various types of cryogenic detectors are investigated as high energy resolution, low energy threshold alternatives for the standard micromegas X-ray detectors. The setup presented in this paper comprising metallic magnetic calorimeter (MMC) X-ray detectors, a cryogenic local muon veto read out by an MMC, and internal and external lead shields, aims at establishing the background level that can be reached with MMCs in an above-ground experimental site. The low background setup is described in detail, and first observations from a low-temperature run are presented.