Design Technique for High Speed Pulse Circuitry for Surface Mass Spectrometer

A high speed amplifier/discriminator has been designed and built for use with an electron multiplier as part of a surface ionization mass spectrometer. This amplifier/discriminator permits low loss system operation up to 2 × 106 cps average count rate with random pulses. The design technique uses clipping, differentiation, and staggered quiescent operating points to achieve wide dynamic range and high equivalent frequency response. RF stripline technique and partial neutralization provide excellent stability over the required bandwidth. Pulse height discrimintion is accomplished through use of a monostable tunnel diode circuit.