Some Properties of a Modified Solenoid β Spectrometer with Zero Field at the Source

Abstract

The resolving power of a long magnetic lens using a field that rises linearly from a zero value at the source and becomes constant at a distance z₀ has been calculated as a function of z₀ for two emission angles 26.5° and 31°. For z₀ smaller than the radius of the spectrometer the resolving power remains nearly equal to that of a uniform field lens and then deteriorates quickly for values of z₀ greater than the radius of the spectrometer. The first‐order spherical aberrations as well as the location of the ring focus and the detector are given graphically as functions of z₀.