Development of a capillary microprobe for MeV ion beams

Energy spectrum of a 1 MeV proton beam which was transmitted through a self made capillary with an outlet diameter of about 2 micron.

M.J. Simon (PhD thesis), M. Döbeli

In this thesis project conical microcapillaries are used to develop a microprobe for MeV ion beams. The focused beam is used as a raster ion probe for Scanning Transmission Ion Microscopy (STIM) and Particle Induced X-ray Emission (PIXE) imaging. Measurements are performed at atmospheric pressure. The application of the capillary microprobe for MeV ion beam lithography is being investigated. The capillaries of very regular conical shape are produced in-house.

The collimating and focusing properties of capillaries are determined and the physical phenomena leading to the focusing effect are investigated by measuring the compression factor and the change in phase space volume occupied by the beam. The compression factor is the ratio of the number of transmitted particles to the number of incident particles divided by the geometric ratio of exit and entrance cross section of the capillary. Trannsmission experiments  for ions of different energy, mass and initial charge state are performed. The experimental data are compared to Monte Carlo simulations.

Homemade glass capillary of regular conical shape