MAS Soudan Underground Laboratory Tour
August 26th, 2000

Soudan, MN

For those who don't know MN Astro Society arranged a tour of the Neutrino experiment area at the Tower-Soudan ex-iron mine way up on 'da-range. At the Soudan Underground Mine State Park

Projects currently being worked on there are: the Soudan 2 Detector which is currently taking data.

Visitors Brochure for Soudan Underground Laboratory @ U-MN (good intro stuff)

Soudan2 is a US/UK experiment on the 27th level of the Soudan Iron Mine in Northern Minnesota. The Mine is run as a State Park by the Department of Natural Resources of the State of Minnesota. The Iron Calorimeter comprises 1000 tonnes of material held under constant watch, night and day, by sensitive electronics which is able to picture the interaction of any neutrino, or any other ‘intruder’, in the mass shielded from cosmic radiation deep underground.

Some Results and Sample Soudan 2 Data @ OXFORD Physics Dept.

MINOS Project , Minos Map Sending neutrinos from Chicago to the range 'UNDER' WI.
Minos side view and Minos Images @ U of MN, and CDMS are currently under construction.

004-008: misc shots in the power / mine elevator winch house

009: loading the elevator (not our group)

010: MAS group starts assembling

013: physics area. Note that everything in this area had to go down in the elevators; aprox 1 meter square x 1.2 high. The elevators are 2-level & the floor of the top level can be removed, so tall things can fit.

014: Our guide, Prof Marvin Marshak from the U/MN

015-018: MAS group

019: "Active" shield surrounding the detector. (A giant-but-thin detector which catches stray muons entering the area around the detector. Hits in the detector can be disregarded for a short time if the shield finds a muon.

021-022: A module from the detector (under repair) The grey things are ribbon connectors to get MANY signals out.

024: The detector. 8 modules wide, at least 8 long, 2 high. The corregated walls and ceiling are parts of the active shield.

025-029: Wires, high voltage power supplies, signal detector preamps, 031 etc.

030: Whole thing sits on I-beams

033-035: An electronics detail from the active shield. The camera kept trying to focus on the protective grill. The grill protects the electronics from people, nach.

036: Reverse view of the room. Yes the fork lift went down in the elevator.

039-042: Excavation under way for a second, larger, experiment chamber.

043: -689 feet altitude

(Click on any thumbnail to see a larger 640x480 JPEG image)

3-D mine map

3-D mine map

3-D mine map

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Welcome to Level 27

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Our guide, Dr. Marvin Marshak from the U/MN Physics

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Some notes:

Suplimental lead shielding is used at some labs. New lead fresh from the foundry has way too many short-lived radioactive isotopes. The best stuff comes from recovered ballast of sunken Spanish galleons.

  1. It has had a few hundred years for the radioactivity to subside
  2. Water has shielded the lead from cosmic rays, which would have pumped some lead atoms into radioactive new isotopes/new elements.

Standard fiberglass printed circuit board (see pix 021) is too radioactive; they use kevlar boards inside the detector.

Of particular interest to folks from Wisconsin. The Chicago ==> Tower/Soudan neutrino beam isn't up and running yet, but it will make a beeline under Wisconsin. The beam will be aprox 1 km diameter at the detector. 99.9x% of the beam will emerge from the Earth in a remort part of the Superior Nat'l Forest and head out into space.

Neutrinos, they are very small.           <==OK
  They have no charge, they have no mass  <==OK,oops
And do not interact at all                <==oops

The Earth is just a silly ball
  To them, through which they simply pass
Like dustmaids down a drafty hall
  Or photons through a sheet of glass.
(The only thing I learned in college, now obsolete.)

Neutrinos by John Updike

--- Rich Brown --- rab --- http://FreeMars.org ---

Photos by Rich Brown

HTML by Ben Huset

Last revision August 26, 2000 by Rich
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