Hemispherical analyser with 2-D PSD for zero-degree Auger projectile spectroscopy

Details of a new high gain zero-degree Auger projectile electron spectrogra ph using a hemispherical analyser and a 2-dimensional position sensitive de tector (PSD) with multichannel plates and a resistive anode encoder are pre sented. A four-element lens mounted at the entrance of the analyser, provid es a virtual slit for the incoming electrons by focusing them while at the same time decelerating them to improve their energy resolution. Electrons e nter through an aperture at a position Ro which is displaced (along the ene rgy dispersion axis) with respect to the commonly used central entrance pos ition at 1/2 (R-1 + R-2) The analyser has an acceptance energy range of 20% and an energy resolution of 0.9%. An ion-optics trajectory simulation indi cates improved focusing properties for this off-center position thus avoidi ng the need for cumbersome fringing field correction schemes. Test measurem ents of high resolution projectile Anger spectra produced in 21.7 MeV colli sions of F8+ and F7+ projectiles with H-2 and He are presented.