First results from a microwave cavity axion search at 24 micro-eV
  We report on the first results from a new microwave cavity search for dark matter axions with masses above $20~\mu\text{eV}$. We exclude axion models with two-photon coupling $g_{a\gamma\gamma} \gtrsim 2\times10^{-14}~\text{GeV}^{-1}$ over the range $23.55~\mu\text{eV} < m_a < 24.0~\mu\text{eV}$. 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. 
B. M. Brubaker, L. Zhong, Y. V. Gurevich, S. B. Cahn, S. K. Lamoreaux,   M. Simanovskaia, J. R. Root, S. M. Lewis, S. Al Ken...
astro-ph.CO astro-ph.IM hep-ex