The National University of Singapore high energy ion nano-probe facility: Performance tests

摘要

The Research Centre for Nuclear Microscopy, National University of Singapore incorporates three state-of-the-art beam lines, connected to a high brightness High Voltage Engineering Europa 3.5 MV Singletron accelerator. One of these lines is a NEC (National Electrostatics Corporation, USA) ion channeling facility, utilising broad beam ion beam analysis techniques for advanced materials research. The other two lines are microbeam facilities; one is designed for nuclear microscopy of biomedical samples and advanced materials, where relatively high currents (>50 pA) are required, and the other for proton beam micromachining (PBM) and materials modification, where lower currents can be utilised. The resolution performances of the two microbeam lines have been measured, and the results are as follows: (1) The nuclear microscope line incorporates the Oxford Microbeams OM2000 endstation with the OM50 quad-rupole lenses configured in the high excitation triplet mode. This line has achieved the world's best performances for analytical applications of 290 x 400 nm for a 50 pA current of 2 MeV protons. (2) The PBM line, which is the first of its kind worldwide, utilizes the new generation of compact (OM52) quadrupole lenses (Oxford Microbeams Ltd.) also configured in a high excitation, triplet configuration. This facility, which has superior demagnification properties, has achieved the world's best performances for low current applications. Spot sizes of 35 x 75 nm have been measured using direct scanning transmission ion microscopy for beam currents of 10,000 protons per second.