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  • The Definitive Search for Dark Matter Axions

    The experimental insert within the magnet showing (top to bottom) the thermal shielding, liquid helium reservoir and microwave cavity.


    The ADMX cryostat/magnet ready to be installed into the experiment hall at the University of Washington.

    Experiment


    The Axion Dark Matter eXperiment (ADMX) detects the very weak conversion of dark matter axions into microwave photons. Axion conversion into photons is stimulated by an apparatus consisting of an 8 tesla magnet and a cryogenically cooled high-Q tunable microwave cavity (shown at the upper right). When the cavity's resonant frequency is tuned to the axion mass, the interaction between nearby axions in the Milky Way halo and ADMX's magnetic field is enhanced. This results in the deposit of a very tiny amount of power (less than a yoctowatt) into the cavity.

    An extraordinarily sensitive microwave receiver allows the very weak axion signal to be extracted from the noise. The experiment receiver features quantum-limited noise delivered by an exotic Superconducting QUantum Interference Device (SQUID) amplifier and lower temperatures from a 3He refrigerator.

    ADMX is the first experiment sensitive to realistic dark-matter axion masses and couplings and the improved detector allows an even more sensitive search.