Limits on thermally-distributed halo dark-matter axions from ADMX

The Axion Dark Matter eXperiment (ADMX) at LLNL searches for dark-matter axions through their Primakoff conversion to microwave photons, resonantly enhanced in a high-Q cavity permeated by a strong magnetic field. The most general assumption is that halo axions are thermalized with the local virial velocity of the Milky Way, about 270 km/sec, which implies a spectral line-broadening of one part in a million. ADMX has set limits on halo axions for realistic models over an octave of mass range in the few microelectronvolt range. The experiment is the most sensitive spectral receiver in the world, able to detect signals in the GHz range well below a yoctowatt. This talk will outline the experimental technique, data analysis and results for the medium-resolution search.