A quadrupole-focusing time-of-flight mass spectrometer

A time-of-flight mass spectrometer with a quadrupole doublet in its flight path has been built up at the Bochum Dynamitron Tandem Laboratory (DTL). The quadrupole doublet allows extension of the flight path and thereby improvement of mass resolution and suppression of background radiation. Using a flight path of 2.60 m we get a mass resolution of 0.95% for alpha particles and of 1.1% for 16 O ions; the solid angle of the spectrometer amounts to 0.94 msr. The ion optical properties of the spectrometer are discussed and illustrated by means of a thick-target scattering experiment.