New compact classical 40 kV Mott polarimeter

Abstract

A compact classical electron spin detector based on Mott scattering is described. This Mott polarimeter has an efficiency of Ϸ5.6ϫ10 Ϫ4 , a maximum counting rate of 500 kcps and bulk size 15 cmϫ25 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.

Tuning of the Rashba effect in Pb quantum well states via a variable Schottky barrier

“…The ARPES spectrometer is equipped with two orthogonally mounted Mott detectors operated at an acceleration voltage of 40 kV36 (see Fig. 1(b)).…”

Spin and angle resolved photoemission on non-magnetic low-dimensional systems

“…The first detection scheme is the conventional or classical Mott polarimeter [18] where the electrons are accelerated between two concentric hemispheres to 40-60 kV. The gold foil and the detectors (typically passivated implanted planar silicon (PIPS)) are at the same potential inside the inner hemisphere and the electrons thus travel through field free space between the foil and the detector [19]. The PIPS pulses are discriminated after amplification such that only the elastically scattered electrons are counted.…”

Spin-Resolved Valence Photoemission

“…For this reason, Petrov and coworkers have been active in combining various electron energy analyzers with compact spherical high-energy Mott polarimeters [15,31,45,46]; they have also performed comparative tests of this type of polarimeter with the retarding-potential Mott polarimeter [41].…”

“…The early polarimeters, now generally referred to as "classical" Mott polarimeters, were bulky (typically several cubic meters) as electron energies of around 100 keV were involved for both scattering and detection. A modern classical Mott polarimeter has been developed and fully characterized by Petrov [45,46]. This instrument (which is commercially available; see "Commercially Available Polarimeters") has a spherical geometry and is used, inter alia, for photoemission studies on the Swiss Light Source where it has proved to be very reliable.…”