A PRECISE ELECTRON-BEAM ENERGY CALIBRATION FOR USE IN NUCLEAR-PHYSICS

An accurate calibration of the MIT-Bates electron beam energy has been achieved. The electron beam was injected into the MIT-Bates South Hal l Ring and the spin-precession frequency, Omega(s), was measured. From the spin-precession frequency the equilibrium energy of the ring was determined to be 370.3115+/-0.0021+/-0.0004 MeV, where the first error is statistical and the second is systematic. The energy of the beam d elivered by the linac was determined to be 369.954+/-0.023+/-0.300 MeV . This provides a rigorous check on the accuracy of the facility's ene rgy analyzing magnets. The first moment of the energy distribution was also measured. By observing the time constant of the spin diffusion w ith zero power in the South Hall Ring RF cavity, we obtained a value o f sigma(gamma)/gamma = (3.7+/-0.5) x 10(-4). We provide a lower limit to the polarization lifetime. At a beam energy of 370 MeV no measurabl e decrease in the polarization was observed up to 2 ms after injection .