Overview of the MINOS Areas

The MINOS Areas are the downstream-most portion of the NuMI tunnel complex. The NuMI tunnels start at the Main Injector and extend for about 1.5 km underground, slanted downward at about 3.3 degrees. The MINOS Areas, at the end, are about 350 ft underground, approximately one and a half times the height of the High Rise.

The schematic below shows a side view, through the earth, of the entire length of the NuMI tunnels. "Upstream" and "downstream" reference the direction in which the particle beam travels, in this view from left to right. Primary protons are extracted from the Main Injector, under the High Rise at the left side. They are aimed downward, strike a target in the Target Hall, located by it's access shaft and MI-65 Surface Building. The particles exiting the target pass into the Decay Pipe, and most are stopped in the Absorber, a small enclosure which marks the start of the areas accessed via the MINOS shaft. Pions produced in the target decay to muons and neutrinos while passing through the Decay Pipe, and this is how the neutrino beam is produced.

NuMI Tunnels schematic

The second schematic below is an expansion of the MINOS Areas. Two views are shown together - the upper view is from the side, through the earth; the lower view is looking down from above. The light dotted line in the lower view shows the path of the neutrino beam center-line, where it passes through rock between the Absorber Enclosure and the MINOS Access Tunnel.

MINOS Areas schematic

The MINOS Areas.

The numbered items are -

  1. The MINOS Surface Building
  2. The MINOS Shaft
  3. The MINOS Hall (a) and the NOvA Cavern (b)
  4. The MINOS Access Tunnel
  5. The Absorber Access Tunnel
  6. The Muon Alcoves
  7. The Absorber Enclosure
  8. The Absorber Utility area
  9. The Decay Pipe Tunnel

Particle Physics Division manages installations in the Surface Building, and in the MINOS Hall and Access Tunnel. The Absorber Tunnel, Enclosure and Muon Alcoves are managed by Accelerator Division, however detectors installed in the Muon Alcoves or the Absorber Access Tunnel must follow the same ORC review process applied elsewhere underground. Some space for equipment storage is available in the Surface Building; equipment not in use is not stored underground, following fire protection guidelines. See the Safety Review Section for details.

All the underground areas are accessed via the MINOS Surface Building and Shaft. Nearly all these areas are accessible during beam delivery, except for the Muon Alcoves and the Absorber Enclosure, which are radiation areas interlocked to the NuMI Beam Permit. All of these areas require the checking out of one or more keys for access, and ES&H training to be able to check out keys. Tours are by arrangement. See the Access Section for more information.