Sudbury Neutrino Observatory - Detector Description

Detector Description

The SNO detector target consisted of 1,000 tonnes (1,102 short tons) of heavy water contained in a 6-metre (20 ft) radius acrylic vessel. The detector cavity outside the vessel was filled with normal water to provide both buoyancy for the vessel and radioactive shielding. The heavy water was viewed by approximately 9,600 photomultiplier tubes (PMTs) mounted on a geodesic sphere at a radius of about 850 centimetres (335 in). The cavity housing the detector is the largest man-made underground cavity in the world, requiring a variety of high-performance rock bolting techniques to prevent rock bursts.

The observatory is located at the end of a 1.5-kilometre (0.9 mi) long drift, named the "SNO drift", isolating it from other mining operations. Along the drift are a number of operations and equipment rooms, all held in a clean room setting. Most of the facility is Class 3000 (fewer than 3,000 particles of 1 μm or larger per 1 m3 of air) but the final cavity containing the detector is Class 1000.