The new external beam facility of the Oxford scanning proton microprobe

This paper describes the development of a high spatial resolution external beam facility on one of the beamlines of the Oxford scanning proton micropr obe tandem accelerator. Using a ma magnetic quadrupole doublet to focus the beam through the Kapton exit window a beam diameter of < 50 mum full width at half maximum (fwhm) can be achieved on a sample located at 4 mm from th e exit window. The facility is equipped with two Si-Li X-ray detectors for proton-induced X-ray emission (PIXE) analysis of light and trace elements r espectively, a surface barrier detector for Rutherford backscattering spect rometry (RBS) analysis and a HP-Ge detector for gamma -ray detection. The m echanical and beam-optical design of the system is described. (C) 2001 Else vier Science B.V. All rights reserved.