|
SNOLAB is a Canadian underground physics laboratory at a depth of 2 km in Sudbury, Ontario in Vale's Creighton nickel mine. The original Sudbury Neutrino Observatory (SNO) experiment has ended, but the facilities have been expanded into a permanent underground laboratory. SNOLAB is the world's second-deepest underground lab facility; the deeper Kolar Gold Fields experiments ended with the closing of the mine in 1992, and the planned DUSEL laboratory has been greatly scaled back after the National Science Foundation refused major funding. In 2010, it was surpassed by the China Jinping Underground Laboratory, which achieves a muon flux of less than 0.2 μ/m²/day,〔 compared with SNOLAB's 0.27 μ/m²/day.〔 (For comparison, the rate on the surface, at sea level, is about 15 million μ/m²/day.) Although accessed through a mine, the laboratory proper is maintained as a class-2000 cleanroom, with very low levels of dust and background radiation. The 6800 ft (2070 m) overburden of rock provides 6010 metre water equivalent (MWE) shielding from cosmic rays, providing a low-background environment for experiments requiring high sensitivities and extremely low counting rates. == History == A large deep cavity was originally constructed for the SNO experiment, but other groups were interested in conducting experiments in the very deep location. In 2002 funding was approved by the Canada Foundation for Innovation to expand the SNO facilities into a general-purpose laboratory, and more funding was received in 2007 and 2008. Construction of the major laboratory space was completed in 2009, with the entire lab entering operation as a 'clean' space in March 2011.〔http://www.snolab.ca/public/updates/index.html〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「SNOLAB」の詳細全文を読む スポンサード リンク
|