HOLISTIC DESIGN OF A SCANNING NUCLEAR MICROPROBE

A scanning nuclear microprobe (SNM) has been designed to focus high fl ux densities of protons to 1 mu m in vacuum and to 25 mu m in air or c ontrolled atmospheres. The design was constrained by demanding that th e market price of a commercial SNM, including end-station, scanner, au tomated control and data acquisition system, be less than or equal to 1 million US dollars. This goal can be achieved with a single-ended el ectrostatic accelerator delivering proton and alpha beams up to 1.5 Me V. The holistic design not only substantially reduces the cost of the overall system but allows all elements in the system - ion source, vel ocity selector, accelerator, magnetic focusing and scanner - to be opt imized. We find that it should be possible to obtain 2 nA of 1.5 MeV p rotons in a 1 mu m target spot; i.e. an order of magnitude improvement over existing systems. Such beam densities will make the SNM a versat ile tool for studies in the few hundred nanometer range.