R x B Drift Momentum Spectrometer

We propose a new type of momentum spectrometer, which uses the R×B drift effect to disperse the charged particles in a uniformly curved magnetic field. This kind of R×B spectrometer is designed for the momentum analyses of the decay electrons and protons in the PERC (Proton and Electron Radiation Channel) beam station, which provides a strong magnetic field to g uide the charged particles in the instrument. Instead of eliminating the guiding field, the R×B spectrometer evolves the field gradually to the analysing field, and the charged particles can be adiabatically transp orted during the dispersion and detection. The drifts of the particles have similar properties as their dis persion in the normal magnetic spectrometer. Besides, the R×B spectrometer is especially ideal for the measurements of pa rticles with low momenta and relative large incident angles. We present a design of the R×B spectrometer, which can be used in PERC. The resolution of the momentum spectra can reach 14.4 keV/c, if the particle position measurements have a resolution of 1 mm.