Today the BASE collaboration reports in Physical Review Letters on a new method to constrain the conversion of axion-like particles into photons, measured using the superconducting resonant single particle detection circuit of one of our cryogenic Penning traps at BASE-CERN, see the publication here. By searching the noise spectrum of our fixed frequency resonant circuit for peaks caused by axion-to-photon conversion in the strong magnetic field of the Penning trap magnet, we are able to constrain the coupling of ALPs with masses around 2.7906-2.7914 neV to be gag<1*10-11 / GeV. This is more than one order of magnitude lower than the best laboratory haloscope and approximately five times lower than the CAST helioscope, setting limits in a mass and coupling range, which is not constrained by astrophysical observations. This approach can be extended to many other Penning trap experiments, and has the potential to provide stringent high-resolution limits in the low ma range. Using the existing technologies available in BASE and developing a purpose-built experiment, the detection bandwidth could be increased by a factor of >1000 at about 200-fold improved detection sensitivity.
Text & image credits: Jack Devlin (CERN/RIKEN), Stefan Ulmer (RIKEN)