Shimming of High Resolution Magnetic Spectrographs. A New Analytical and Numerical Method

摘要

In the construction of SPEG, a high resolution, energy-loss spectrometer for the GANIL accelerator, we used successfully a one-step procedure with simple analytical calculations to realize the corrections of high order aberrations. This procedure is described below. We shall assume that the layout of the optics has been defined in the phase of design. The next step will be the optimization of this system, in order to reduce as far as possible the optical aberrations, due to deviations of the measured magnetic field from the theoretical magnet as well as higher order terms that were not corrected in the initial design. We shall restrict the discussion to the horizontal plane, where aberrations are most relevant for the resolution.