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    DN 200CF (12''OD)  

Electron Spin Detector

DN 100CF (6''OD)

New compact classical 40 kV Mott polarimeter
V.N. Petrov, V.V. Grebenshikov, B.B. Grachev, A.S. Kamochkin
Rev. Sci. Instrum. 74 (3), 1278 (2003).


    A compact classical electron spin detector (polarimeter) based on Mott scattering has been developed. The design of the polarimeter goes back to the classical 100 kV Mott detector. Since the polarimeter is compact, it can be combined with conventional electron energy analyzers. In this Mott polarimeter an electrostatic acceleration voltage up to 40 kV can be applied. The electron detectors are energy sensitive silicon diodes (PIPS detectors) operated in reverse bias with variable discriminator threshold. The detectors and amplifiers are floated on the top of the acceleration voltage and allow field-free travel of the electrons from the scattering gold foil to the detectors. Such features reduce the sensitivity of the polarimeter to slight motion or changes in the shape of the incoming beam.

Technical Data

Measurement of two spin projections of electrons at the same time.

Maintenance free, before and during operation.

Efficiency 5.6*10-4.

Maximum counting rate 500 kcps.

Operating voltage 40 kV.

Mounted on DN 100CF (6”OD).

Maximal sizes of the complete polarimeter:
Length 25cm, diameter 15cm.

The protection shield (if necessary) increases the length and the diameter by an additional 3 and 5 cm, respectively.

The counting signals are passed to ground potential by a fiber-optical system.

The polarimeter is controlled by a special compact stabilized power supply for up to 50 kV with sizes:
30x26x18 cm.

Performance of the polarimeter

    Spin Resolved Auger Electron Spectrum (non derivative) of FeNi alloy measured with Cylindrical Mirror Analyzer. The full time of data accumulation of the spectrum is 35 min with a primary beam current of
4 mA. Statistical uncertainties are less than the size of triangles on the graphs.
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