We report on the first results from a new microwave cavity search for dark matter axions with masses above 20 μ eV . We exclude axion models with two-photon coupling ga γ γ≳2 ×10-14 GeV-1 over the range 23.55 <ma<24.0 μ eV . These results represent two important achievements. First, we have reached cosmologically relevant sensitivity an order of magnitude higher in mass than any existing limits. Second, by incorporating a dilution refrigerator and Josephson parametric amplifier, we have demonstrated total noise approaching the standard quantum limit for the first time in an axion search.
Physical Review Letters
- Pub Date:
- February 2017
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- Astrophysics - Instrumentation and Methods for Astrophysics;
- High Energy Physics - Experiment
- 5 pages, 3 figures, accepted for publication in PRL. v2: added changes made during the review process