Soudan 2

Soudan 2 was a particle detector located in the Soudan Mine in Northern Minnesota, United States, that operated from 1989 to 2001. It was a 960-ton iron tracking calorimeter whose primary purpose was to search for proton decay, although its data was also used to investigate the properties of neutrinos. It found no evidence of proton decay, but it did help confirm Super-Kamiokande's atmospheric neutrino result, supporting the theory of neutrino oscillation.

The Soudan Mine was also home to the MINOS and CDMS detectors.