DMRadio 50 Liter

By Kent Irwin 

Director, Hansen Experimental Physics Laboratory (HEPL), Professor of Physics, of Particle Physics and Astrophysics and of Photon Science

One of the deepest puzzles left in the Standard Model of particle physics is the Strong CP problem. Experimentally, this shows up as the neutron’s electric dipole moment being ten orders of magnitude smaller than expected. The only widely recognized solution is the axion, a hypothetical particle that not only resolves this theoretical mystery, but also could have been produced in just the right abundance in the early universe to account for the dark matter that dominates the universe. In other words: solve one “Holy Grail” problem in physics, and you might solve two.

At Stanford, the search for axions is advancing with the Dark Matter Radio (DMRadio) suite of experiments. At its heart, DMRadio is like the world’s most sensitive AM radio placed inside a superconducting shield, and tuned to listen for a signal that should not exist. Such a signal can only appear in the presence of a powerful magnetic field, and if we hear it, it would be the faint whisper of dark matter itself.

Closing 40K shield to prepare for the initial cooldown.

This year marks a major milestone: the commissioning of DMRadio-50L, a 50-liter superconducting detector now being brought online in the basement of the Physics and Astrophysics Building. Supported by the Gordon and Betty Moore Foundation, the Heising-Simons Foundation, and the Department of Energy’s QuantISED program, and built in collaboration with colleagues at MIT, UC Berkeley, and Princeton, DMRadio-50L positions Stanford physicists at the forefront of one of the most exciting frontiers in fundamental physics.

View of the interior of cryostat with coldfinger from 

dilution refrigerator sticking into DMRadio-50L cryostat.