Soudan 1 was a particle detector located in the

Soudan Mine The Lake Vermilion-Soudan Underground Mine State Park is a Minnesota state park at the site of the Soudan Underground Mine, on the south shore of Lake Vermilion, in the Vermilion Range (Minnesota). The mine is known as Minnesota's oldest, deep ...

in Northern Minnesota, United States, which operated for a year in 1981–82. It was a 30-ton tracking calorimeter whose primary purpose was to search for

proton decay In particle physics, proton decay is a hypothetical form of particle decay in which the proton decays into lighter subatomic particles, such as a neutral pion and a positron. The proton decay hypothesis was first formulated by Andrei Sakha ...

. It set a lower limit on the lifetime of the proton of 1.6×10³⁰ years as well as upper limits on the density of magnetic monopoles. It also served as a prototype for the following

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 w ...

and

MINOS In Greek mythology, Minos (; grc-gre, Μίνως, ) was a King of Crete, son of Zeus and Europa. Every nine years, he made King Aegeus pick seven young boys and seven young girls to be sent to Daedalus's creation, the labyrinth, to be eat ...

experiments.

Design and operation

Soudan 1 was installed 590 meters below the surface and brought into routine operation in August 1981 by high-energy physics research groups from the

University of Minnesota The University of Minnesota, formally the University of Minnesota, Twin Cities, (UMN Twin Cities, the U of M, or Minnesota) is a public university, public Land-grant university, land-grant research university in the Minneapolis–Saint Paul, Tw ...

and

Argonne National Laboratory Argonne National Laboratory is a science and engineering research national laboratory operated by UChicago Argonne LLC for the United States Department of Energy. The facility is located in Lemont, Illinois, outside of Chicago, and is the lar ...

. The detector was a 3×3×2m³ block of

iron oxide Iron oxides are chemical compounds composed of iron and oxygen. Several iron oxides are recognized. All are black magnetic solids. Often they are non-stoichiometric. Oxyhydroxides are a related class of compounds, perhaps the best known of w ...

-loaded concrete instrumented with 3456 gas proportional tubes. It was surrounded on five sides by a veto shield of solid

scintillator A scintillator is a material that exhibits scintillation, the property of luminescence, when excited by ionizing radiation. Luminescent materials, when struck by an incoming particle, absorb its energy and scintillate (i.e. re-emit the absorbe ...

, which was completed in October 1981. This allowed events which might otherwise have looked like proton decay, but were actually caused by

cosmic rays Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our ow ...

, to be discarded. It had a total running time of 0.97 years.

References

{{Proton decay experiments Particle experiments

Design and operation

See also

References