Gesellschaft Fur Strahlen- Und Umweltforschung Mbh (gsf)

Wilfried Szymczak

An apparatus for counting individual particles in time-of-flight mass spectrometry includes a device for producing secondary particles at a high repetition rate by pulsed ion bombardment of a sample from which the secondary particles originate, an accelerator for accelerating the secondary particles, and a detector for detecting arrival of the secondary particles and producing an output signal indicating detection of a secondary particle. The output signal of the detector has a magnitude which is independent of the number of simultaneously impinging secondary particles. A fast pulse amplifier recieves the output signals and amplifies them. A fast discriminator receives the amplified signals and converts them into unit pulses, and supplies the converted signal to a shifting and attenuating device, for shifting and attenuating the unit pulses in a selected time relationship so that a noise-distorted base line of the unit pulses does not lie in a predetermined measuring range, and so that a plateau of the unit pulses lies in the predetermined measuring range. A transient recorder fed by the shifting ad attenuating device produces an output signal at a high voltage level for a short time interval in response to each of the shifted and attenuated unit pulses, representing a mass spectrum of the secondary particles.

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Lohhof, Germany

Wilfried Szymczak