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Super-big superconducting magnet to be moved into laboratory Dec. 13

James E. Kloeppel, Physical Sciences Editor
(217) 244-1073; kloeppel@illinois.edu

12/8/2000

CHAMPAIGN, Ill. -- A superconducting magnet 14 feet in diameter and weighing more than 80,000 pounds will be moved into the high-bay area of the Nuclear Physics Laboratory, 23 E. Stadium Drive, Champaign, beginning at 8:30 a.m. Wednesday (Dec. 13).

The delicate operation of unloading and moving the magnet will require three heavy-lift cranes -- two outside the lab and one inside.

Funded by the National Science Foundation, the $2.75 million magnet was designed by University of Illinois researchers for an upcoming experiment at the Thomas Jefferson National Accelerator Facility in Newport News, Va. Constructed by Babcock and Wilcox Technologies in Lynchburg, Va., the magnet required three years to build.

The experiment, called G0 (pronounced "Gee Zero"), involves about 100 scientists from many institutions. UI researchers are leading the effort: Physicist Steve Williamson is experiment coordinator; physicist Doug Beck is spokesman for the project.

Over the next few months, the researchers will meticulously inspect the magnet, cool it to liquid-helium temperatures (-450 degrees Fahrenheit) and turn it on for the first time.

“There is a huge amount of energy stored in the magnetic field --"about the same amount of energy as in two cars colliding at 60 miles per hour," Beck said. "And all of that energy is trying to pull the magnet's coils together." If pieces of the magnet shift too far, the magnet could be destroyed.

Cooling the huge magnet could take up to 10 days, Beck said. Once the magnet is thermally stabilized, the researchers will apply power and watch for any unexpected movements. As the power is gradually increased, a robotic test rig will precisely monitor the growing magnetic-field strength in three-dimensional space, and alert the researchers to potential problems.

Late next year, with testing complete, the magnet is scheduled to be shipped to the Jefferson facility. There it will serve as the centerpiece of the G0 experiment -- a major effort to closely examine the role that the strange quark plays in generating proton structure and nuclear magnetism.

In the experiment, an intense beam of polarized electrons will scatter off liquid hydrogen and deuterium targets located in the magnet's core. Detectors, mounted around the perimeter of the magnet, will record the number, and position, of the scattered particles.

The new magnet will provide a much broader view of the small-scale structure of the proton, compared with earlier “snapshots” obtained with other experiments, Beck said.

"We know that the proton’s structure -- in particular, its magnetic moment -- comes from the up, down and strange quarks inside the proton," Beck said. "But exactly how it is put together is what we are trying to find out."