Production of a nanosecond-pulsed He ++ beam from a standard 5.5 MV Van de Graaff accelerator

Abstract

A standard HVEC† 5.5 MV Van de Graaff accelerator and ion source have been used to produce an average beam current of 20 nA of He ++ ions with a pulse width less than 2.5 nsec at a repetition rate of 2 MHz. A time pickoff located on the mass 2 port of the 90° analyzing magnet was used to provide a signal from the He + beam component to trigger the beam deflection system of the Mobley magnet and to stop the time to amplitude converter (TAC) used to measure the neutron time-of-flight in a nuclear scattering experiment.