A COMBINED MASS GATE-ENERGY DISCRIMINATOR

A mass gate allows transmitting a selected mass in a time-of-flight ma ss spectrometer and to block other masses. The conventional stopping-p otential mass gate does not discriminate against spontaneous fragments , which are generated in the drift tube. We present a simple improved version of a mass gate, which discriminates against fragments by using the fact that their kinetic energy is lower than that of the parent i on. (C) 1997 American Institute of Physics.