The SNOLAB underground laboratory is an expansion of the original SNO facility which consisted of a large experimental cavern 22 m in diameter and 34 m high (72′ dia x 112′ height), ancillary spaces in mining drifts (tunnels) for the experiment and personnel infrastructure. The SNO Detector is located at 46Â° 28’30” N, 81Â° 12’04” W. The main level of the laboratory is located on the 6800 ft level of the mine with 2070 m of granitic rock overburden consisting mainly of norite. The ambient rock temperature at this depth is 42C. The 2km of norite overburden corresponds to 6010m water equivalent. Surface elevation at the site is 309 m (1014 ft) above mean sea level. The surface topology is approximately flat. Access to the 6800 Level and SNOLAB is via #9 Shaft located 1.8 km from the laboratory entrance.
A key feature of the original laboratory was that all the experimental spaces and personnel spaces were maintained as one large clean room. Personnel entering the laboratory would pass through showers and change into clean room clothing. Equipment entering the laboratory is either cleaned in a “carwash” before entering the laboratory or is brought underground in sealed containers that are opened after being washed and brought into the clean space.