ENERGY-DISTRIBUTIONS FROM A RACETRACK MICROTRON MEASURED WITH A MAGNETIC SPECTROMETER

Energy spectra of accelerated electron beams from a racetrack microtro n were measured using a magnetic spectrometer. The spectrometer utiliz ed a 90-degrees dipole magnet. A ray-tracing program was developed to determine the slit positions of the spectrometer based on a detailed m ap of the magnetic field measured at field strengths corresponding to about 20 and 50 MeV. The total a priori uncertainty (previously often called systematic or class B uncertainty) of the measured most probabl e energy E(p) is 0.22% (one approximate standard deviation) and the a posteriori uncertainty (previously often called random or class A unce rtainty) is 0.04% (1sigma). The estimated energy resolution (DELTAE/E) of the spectrometer is 4 X 10(-4). Spectral energy distributions of t he electron beam were measured at a E(p)=21.1 and 51.6 MeV, and the ob tained full width at half-maximum of the energy distributions were 53 and 34 keV, respectively. All the measurements were performed in vacuu m to minimize the influence of electron energy loss and scatter.