SuperCDMS: An end and a beginning

Dan Bauer

Dan Bauer

One year ago, the Cryogenic Dark Matter Search (CDMS) collaboration warmed up its apparatus at the Soudan Underground Laboratory in northern Minnesota, after 12 years of successful operation. The CDMS II and SuperCDMS Soudan experiments produced many world-leading limits on dark matter particle detection during that time, covering masses from a few GeV to a few TeV. However, the sensitivity was limited by backgrounds and by environmental noise from the design of the facility.

Meanwhile, based on the success of the CDMS experiments at Soudan, DOE and NSF selected the SuperCDMS collaboration to develop a next-generation experiment to be based at SNOLAB, a deeper and cleaner environment located near Sudbury in Ontario, Canada. The focus of the new experiment will be a search for dark matter particles with masses less than 10 GeV/c2, based on the demonstrated SuperCDMS Soudan detector technologies. Such light dark matter is a feature of theoretical models that postulate a “dark sector” of particles that interact only very weakly with normal matter. The ultimate goal for SuperCDMS SNOLAB is to search for such light dark matter to sensitivities where the experiment will begin to see elastic scattering of solar neutrinos with its germanium and silicon targets.

Thus, to focus its attention on developing the new experiment, the collaboration took the painful step of turning off a running experiment at Soudan, saying goodbye to the incredibly helpful staff from the University of Minnesota and recovering its equipment, much of which will be reused for SuperCDMS SNOLAB. To facilitate the recovery of equipment from Soudan, and provide a space for SuperCDMS SNOLAB to be built, PPD renovated an existing hall at Fermilab with the rather pedestrian designation Lab G. Lighting, HVAC and other utilities have been modernized, and a large cleanroom has been installed. The photographs shows this new clean space, which will be the temporary home for SuperCDMS SNOLAB over the next couple of years.

This panoramic view shows the new SuperCDMS SNOLAB cleanroom at Lab G, with SuperCDMS spokesperson Dan Bauer and senior technical specialist Mark Ruschman. Photo: Reidar Hahn

This panoramic view shows the new SuperCDMS SNOLAB cleanroom at Lab G, with SuperCDMS spokesperson Dan Bauer and senior technical specialist Mark Ruschman. Photo: Reidar Hahn

The cleanroom in Lab G will be used in the development of SuperCDMS detectors. Photo: Reidar Hahn

The cleanroom in Lab G will be used in the development of SuperCDMS detectors. Photo: Reidar Hahn

Starting in 2017, with the arrival of a large new dilution refrigerator, the SuperCDMS group at Fermilab will build and commission the cryogenic apparatus that will allow SuperCDMS SNOLAB to cool its detectors to less than 30 milliKelvin. In 2019, the experiment will be installed at SNOLAB and will begin operations starting in 2020. If light dark matter particles exist, SuperCDMS SNOLAB should detect them sometime in the next decade.

Dan Bauer is the spokesperson for SuperCDMS and the deputy head of the Fermilab Center for Particle Astrophysics.