ADMX Phase II : Relocation and Millikelvin Cooling

Abstract

Low mass axions are an attractive candidate for making up dark matter. While there are several models for how the Axion couples with other matter, were they to be the majority of the local galactic dark matter halo, they would have a number density on the order of 1014 cm−3. The Axion Dark Matter eXperiment (ADMX) is a microwave cavity experiment searching for axion Dark Matter via the axion’s electromagnetic coupling. While the original ADMX did not see evidence of axions, the experiment is planned to go through two phases of upgrades to expand its sensitivity and provide a definitive search for axion dark matter. The first phase established the use of a SQUID amplifier which can reduce the amplifier noise temperature to the 100 mK range. In the second phase we will first move the experiment from LLNL to CENPA at the University of Washington. Once the experiment has been moved successfully we will install a dilution refrigerator to cool the cavity to the 100 mK range thus increasing the sensititivity to the level required to scan the remainder of the allowed model space.