Abstract :
Weakly interacting sub-eV particles (WISP) with masses in the 100-neV – 10 meV range are gaining prominent attention as likely candidates for explaining the dark matter. In this mass range (corresponding to frequencies of 24 MHz to 2.4 THz or wavelengths of 12 m to 0.12 mm) direct dark matter searches can be carried with radiometric measurements employing heterodyne detectors, similar to the ones developed for radio astronomical research. Over the past decade, a whole range of such experiments has been proposed and developed within a collaboration between Max Planck Institute for Radioastronomy, University of Hamburg, and DESY. This includes the broadband radiometric setup BRASS aiming at the 10 -1000 GHz frequency range, the tuned cavity setup WISPDMX using resonant modes in the 200 – 500 MHz range and extending down to 10 kHz off resonance, the WISPLC experiment employing an LC circuit design to target frequencies below 5 MHz, and the semi-resonant experiment MADMAX which will be operating in the 10 – 80 GHz regime. This presentation will review results obtained so far and future prospects which these developments present for searches for dark matter composed of axions, axion-like particles (ALP) and dark photons.
