First Search for Axion Dark Matter with a MADMAX Prototype

This Letter presents the first search for dark matter axions with mass in the ranges 76.56 to 76.82 μeV and 79.31 to 79.53 μeV using a prototype setup for the MAgnetized Disk and Mirror Axion eXperiment (MADMAX). The experimental setup employs a dielectric haloscope consisting of three sapphire disks and a mirror to resonantly enhance the axion-induced microwave signal within the magnetic dipole field provided by the 1.6 T Morpurgo magnet at CERN. Over 14.5 days of data collection, no axion signal was detected. A 95% CL upper limit on the axion-photon coupling strength down to |gaγ|∼2×10-11 GeV-1 is set in the targeted mass ranges, surpassing previous constraints, assuming a local axion dark matter density ρa of 0.3 GeV/cm3. This study marks the first axion dark matter search using a dielectric haloscope.