Lest anyone be tempted to think of Stanley Hall’s giant magnet as a $5 million toy for fun-starved quantitative scientists, Jeff Pelton is eager to set the record straight. Pelton, a spectroscopist who manages the nuclear magnetic resonance (NMR) facility in the building’s basement, takes a decidedly no-nonsense view of the 7-ton, 900 MHz device, which produces a magnetic field of 21 Tesla — 400,000 times that of Earth.