Soudan laboratory is clean, safe and back in business

The cleanup of the MINOS cavern and the rest of the Soudan Underground Laboratory is complete.

Two months after a fire broke out in the access shaft of the Soudan mine, the Soudan Underground Laboratory is again open for operation. Safety officers inspected the mine and laboratory last week and issued a permit for normal occupancy. The officers identified a short list of additional repairs, which will be carried out in the upcoming months. Work also continues on the Soudan mine shaft.

“The cleanup of the laboratory is complete, and the MINOS far detector is ready to take beam data with full magnetic field,” said Fermilab physicist Rob Plunkett, co-spokesperson for the MINOS neutrino experiment. “The small number of components we had to replace was consistent with a normal power outage.”

The 5,000-ton MINOS far detector is located a half mile underground in the Soudan laboratory. In March, fire-fighting foam covered parts of the detector and the lowest part of the magnet coil was partially immersed in water. Laboratory staff gently heated the coil over the past two weeks to dry it out.

The CDMS experiment, located in a cavern adjacent to the MINOS detector, experienced no damage to its equipment except to a backup generator. Its cryogenic system recovered unscathed from the power outage triggered by the fire. CDMS scientists have removed the new particle detectors they were testing before the fire, and they will begin operation of an expanded experiment with more dark-matter detectors in September.

University of Minnesota building code inspectors and ES&H personnel from the university and Fermilab inspected the laboratory last Wednesday. The University of Minnesota manages the Soudan Underground Laboratory.

Kurt Riesselmann