BPM for Spectrometry Design Concept

The resolution required for the spectrometer is at least 100 nm. The only BPM type proved to have a resolution better than 100 nm is a microwave cavity BPM [1]. The supression of the undesired symmetric cavity modes with coupling slots is also well established [2], [3]. This means a substantial improvement in the stability and the accuracy of the beam position measurement vs. a standard technique utilizing two feedthroughs per axis for coupling with a following 180 hybrid canceling out the monopole modes [4]. The recent progress in the waveform processing and analysis tools and cheap microwave electronic components available on the market also played a certain role in the choice of the technology in favor of microwave cavity BPMs.