Magnetic experiences
Before conversion to a superconducting magnet, the Fermi Chicago Cyclotron Magnet (symmetry, Dec 2006) was used in the Neutrino Area as an analyzing magnet for muons. I worked on the deep inelastic muon scattering experiment E203 in the late 1970s, and we needed to calibrate the magnet for our experiment. At the time, the magnet pole tips were about 4 meters in diameter and the gap was about 80 cm high. For some reason (probably convenience) we decided to put the NMR (nuclear magnetic resonance) probe in the center of the magnet while it was running at about 1.5 Tesla.
I was designated to put the probe in the center of the magnet, so I removed all metal objects from my pockets, watch, belt, wallet, etc., and, crouching over, I stepped over the magnet coils and proceeded into the gap with the probe. After a mishap (fall) due to my Fermilab-issued steel-toed "safety" shoes, I again proceeded into the gap sans shoes.
We needed a non-magnetic stand to position the probe midway in the gap, so my companions scrounged around for pieces of scrap wood or boxes without nails. Finally someone found a 50-cm long, 30-cm high section of aluminum I-beam. It took about 15 seconds to wrestle it through the fringe field. With the probe in place, I exited the magnet slowly so as to minimize whole-body eddy current effects.
Robert Shafer, Fermilab (retired)
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