New compact classical 40 kV Mott polarimeter

A compact classical electron spin detector based on Mott scattering is described. This Mott polarimeter has an efficiency of ≈5.6×10−4, a maximum counting rate of 500 kcps and bulk size 15 cm×25 cm. The design of the polarimeter goes back to the classical Mott detector, operating from 100 to 120 kV but it can be combined with conventional analyzers due to its compactness. In this Mott polarimeter an electrostatic acceleration voltage up to 40 kV can be applied and the detectors are energy sensitive silicon diodes operated in reverse bias with variable discriminator threshold. The detectors with the amplifiers are floated on the top of acceleration voltage to allow a field-free travel of the electrons from the scattering gold foil to the detectors. Such features reduce the polarimeters sensitivity to slight motion or changes in the shape of the incoming beam.