GB1302144A - - Google Patents

Abstract

1302144 Mass spectrometers EUROPEAN ATOMIC ENERGY COMMUNITY 11 June 1971 [29 June 1970] 27565/71 Heading H1D An ion-sensitive plate for taking mass spectrograms comprises an insulating base 1 on which are mounted a plurality of electrodes (one only shown) each comprising a semi-conductive layer 4 having two opposite edges between which an accelerating voltage can be applied to deflect electrons released from the layer by incident ions to one collector edge. The layer 4, e.g. of gold-doped silicon, is mounted on a base strip 5 which is slidably supported by two clips 6 on two rails 7 fixed to the base 1 and connected to two of a series of contacts 2 along one edge 3 of the base 1 through which accelerating voltages of e.g. -1 KV and -100 V are respectively applied to the rails. A conductive collector strip 8 adjacent the collector edge of the layer 4 is connected by a wire 9 to a contact 2 and thence to an evaluation circuit (not shown). The plate is located so that the upper edge of the layer 4 is opposite the magnet slit 10 of a mass spectrometer having a collimator screen 11 at a potential such as to deflect electrons from the layer 4 back to the layer to a position displaced by the accelerating voltage towards the collector edge to produce secondary electrons. The process is repeated until the secondary electrons reach the collector strip 8. The plate is suitable for use in a focal-plane mass spectrometer already adapted for photographic recording since the existing plate holder and plate change mechanism can be used.