Editor's note: This article was originally published in the University of Minnesota Physics and Astronomy Newsletter, January 2008. Reprinted here with permission.
The I-35W bridge that collapsed Wednesday, August 1st was very close to the School of Physics and Astronomy's Williams Laboratory, known as the "Tandem Lab." The bridge was twenty feet from the building's loading dock. There were no University staff, faculty, or students in the laboratory at the time of the collapse.
The laboratory was built in 1965 as a combined project of the Atomic Energy Commission (AEC), the National Science Foundation (NSF) and the University of Minnesota to supplement and eventually replace the 68 MeV linear accelerator which had been constructed and operated by the physics department since the middle 1950s. The new machine, although of lower energy (20 MeV), provided a considerably more monochromatic particle beam better suited to the developing area of nuclear structure physics. The facility continued in this area with AEC and Department of Energy (DOE) funding until 1978. At this time proposals were made to transfer the complete facility to the Argonne National Laboratory, the Lawrence Livermore National Laboratory, and to Shanghai, China. As these proposals, each of which involved considerable logistics, were unsuccessful, the University, at the suggestion of Dean R. Staehle, then requested that the facility be operated for applied science.
Professor John Broadhurst of the School of Physics and Astronomy was director of the laboratory from 1972-1978 when it was operating as a particle accelerator. Since the lab predates the bridge, he recollected that the bridge and the lab always had an uneasy coexistence. "We were having trouble with the building sinking because they were building the bridge and excavating the footings." Broadhurst also said that the wall built by the Army Corps of Engineers to contain sand from the annual dredging of the Mississippi River protected the building from the majority of the debris from the bridge collapse.
Although the accelerator was decommissioned in 1978, the laboratory has been repurposed and retrofitted in recent years. Roger Rusack's Compact Muon Solenoid APD Long Term Gamma Study was in the building until the accident. Bill Gilbert, Electromechanical Systems Specialist, said that the experiment was undamaged but was moved out in late August. Professor Bruce Hammer of the Department of Radiology, who shared the Tandem Facility with Physics, said that his experiment survived the accident. He has removed his equipment from the lab.
The building still houses accelerator equipment. Plans for Williams Laboratory are under discussion.