All astrophysical and cosmological data now point convincingly to a large component of Cold Dark Matter (CDM) in the Universe, but a dark matter particle has yet to be directly detected. A well-motivated possible candidate is a light axion. Should axions constitute the dark matter of our Milky Way halo, they may be detected through their conversion into a narrow microwave signal by an apparatus consisting of a microwave cavity resonator permeated by a magnetic field. Using this concept the Axion Dark Matter eXperiment (ADMX) has performed a search for such axions within the mass range of a few micro-eV. Recently a smaller microwave cavity experiment was constructed called ADMX-HF (High Frequency), specifically to explore higher ranges of axion masses. ADMX-HF also serves as a test-bed for innovations in microwave cavity and amplifier technologies that could be migrated to the larger ADMX platform. ADMX-HF and ADMX operate as "one experiment, two sites", sharing expertise, technology, and data. This award will expand the collaboration to accelerate the construction of ADMX-HF as well as dramatically expand its initial capability.
Broader Impacts: ADMX has proven to be a technology driver as components such as the SQUID amplifiers developed for ADMX are already being used for other purposes. Innovations to be developed by ADMX-HF have similarly broad potential. Both PI and Co-PI are committed educators with long experience in involving undergraduate students in their research and engaging the public. The research funded through this award will inform additional education and outreach initiatives with which they are involved.
