There is a specific instrument to analyze the distribution of the electrons flying out of the experimental device. It consists of two semicircles of R = 20cm radius, with a magnetic field between them. A half of the cut edge of the semicircle is the detector, while in the second half, there is, in the distance d = 15cm from the center, a crevice through which the electrons are ejected into the space with magnetic field. Assume the electrons are moving at nonrelativistic speed. Derive the ratio η of maximal and minimal velocity of the electrons, measurable with this device.
[Figure: Analyzer diagram showing semicircular geometry with magnetic field B, radius R, distance d, and crevice position]