TRANSIT DETECTOR FOR INTERMEDIATE MONITORING IN TIME-OF-FLIGHT MASS ANALYZERS

We present a particle detector for intermediate monitoring of beams of ion bunches (e.g., in time-of-flight mass analyzers). Its principle i s secondary electron emission from a thin wire whose cross section is small (i.e., <5%) compared with the cross section of the primary ion b eam. By means of a special experimental setup, anionic, cationic, or n eutral particle beams can be formed; in addition, a tandem arrangement of our transit detector and a second detector at the end of the ion f light region allows us to test this transit detector. The influence on mass resolution, reliability of ion peak heights, dependence on kinet ic energy and charge of the primary particles, and linearity have been investigated. This new detector may be useful for tandem mass spectro metric experiments, e.g., in time-of-flight analyzers with secondary e xcitation by collisions or photon absorption.