Last week I attended the inauguration of SNOLAB. This underground facility in Ontario, Canada has been used now for more than two decades, starting with the enormously successful Sudbury Neutrino Observatory. SNO was a daring experiment that borrowed several hundred tons of extremely valuable heavy water from the Canadian nuclear establishment and resulted in the most precise understanding of neutrinos from the sun. Over the years additional experiments joined SNO to take advantage of the deep underground location. In the last few years the underground facilities have been expanded with several large caverns and experiments, resulting in the world’s deepest, largest clean-area laboratory.
We at Fermilab have several dark-matter experiments either running or planned to be located at SNOLAB. The COUPP 4-kilogram bubble chamber has been operating for more than a year. We will commission the next device, a 60-kilogram chamber, later this year. Assuming all goes well with the 60-kilogram chamber, we are planning for a 500-kilogram chamber. The Cryogenic Dark Matter Search (CDMS), currently running with 10 kilograms of germanium detectors in the Soudan mine in Minnesota, is seeking support from the DOE and NSF to install 100 kilograms of cryogenic germanium detectors at SNOLAB. CDMS will also compete with other dark-matter proposals in the Generation 2 (G2) funding competition next year. We will soon move the DAMIC prototype detector to SNOLAB. DAMIC uses very low-noise CCDs to detect dark-matter particles with a very low threshold, which makes it sensitive to much lighter dark-matter particles than other current experimental technologies.
Visiting SNOLAB is an interesting and unusual experience. To reach the lab, you shoot down the lift some 6,800 feet into the earth, walk through a mile-long drift that is part of a working nickel mine on muddy, uneven ground, and then arrive in the ultra-clean facilities at the laboratory itself. You enter the lab after leaving your clothes behind, taking a shower and donning clean Tyvek suits. Over the years, SNOLAB has developed much experience in keeping out any materials that could bring low-level radioactive backgrounds into the laboratory.
A special feature of SNOLAB is the remarkable collaboration between public and private entities. Support for the laboratory comes from the Canadian federal government, the Ontario provincial government and the Vale Company that owns the mine. It is impressive to see what this collaboration has achieved over time. Perseverance and great physics results do pay off!
|VIP tour of underground facilities at the entrance of the SNOLAB at a depth of 6800 feet. Click to enlarge. Photo: SNOLAB|