Improved ion beam analysis facilities at the University of Surrey

A number of hardware and software improvements to the Surrey 2 MV Van de Graaff accelerator have enabled the production of a more stable beam, making the microbeam in particular easier to use, as well as a more accurate routine energy calibration, increasing the surface mass resolution. A feedback loop to electrostatic beam steerers before the analysing magnet uses the generating voltmeter (GVM) to fix the entry point of the beam into the analysing magnet. This arrangement fixes the position of the beam in the beam line as well as accurately stabilising the beam energy with a precision of about 100 eV and an accuracy of about 500 eV. Four point energy calibration is determined automatically from specially prepared samples. The electronic gain and offset are determined directly, leading to a precision in the determination of relative signal energies of about 500 eV for 1.5 MeV beam energy. (C) 1998 Elsevier Science B.V.