A new hemispherical analyser with 2-D PSD and focusing lens for use in 0 degrees electron spectroscopy

A new electron spectrograph has been developed to study electron emission i n ion-atom collisions and in particular for use in 0 degrees Auger projecti le spectroscopy. It incorporates a hemispherical analyser, a 2-dimensional position-sensitive detector (PSD) with multichannel plates and a resistive anode encoder. A novel feature of this analyser is the use of an asymmetric entrance aperture and a non-zero entrance potential to improve focusing by correcting for fringing field effects. A four-element lens mounted at the entrance of the analyser, provides a virtual slit, focusing and deceleratin g incoming electrons for improved enery resolution and reduction of the ion beam scattering at the spectrometer entrance. The analyser has an acceptan ce energy range of 20%. As a first test of the apparatus, the production of Binary Encounter electrons from 20 MeV F-9+,F-8+ + H-2 collisions was meas ured. The bare F9+ results were used for an in situ calibration of the 2D-P SD overall efficiency. The F8+ data were found to be in good agreement with the elastic electron scattering model. (C) 1998 Elsevier Science B.V. All rights reserved.