The new confocal heavy ion microprobe beamline at ANSTO: The first microprobe resolution tests and applications for elemental imaging and analysis
| Autor: | Zeljko Pastuovic, S. Long, M. Ionescu, Michael Mann, Rainer Siegele, David Button, David D. Cohen |
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| Rok vydání: | 2017 |
| Předmět: |
Nuclear and High Energy Physics
Microprobe 010308 nuclear & particles physics Aperture business.industry Chemistry Ion current 02 engineering and technology Microbeam 021001 nanoscience & nanotechnology 01 natural sciences Collimated light Optics Beamline 0103 physical sciences 0210 nano-technology business Instrumentation Image resolution Beam (structure) |
| Zdroj: | Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms. 404:1-8 |
| ISSN: | 0168-583X |
| Popis: | The Centre for Accelerator Science facility at ANSTO has been expanded with the new NEC 6 MV “SIRIUS” accelerator system in 2015. In this paper we present a detailed description of the new nuclear microprobe–Confocal Heavy Ion Micro-Probe (CHIMP) together with results of the microprobe resolution testing and the elemental analysis performed on typical samples of mineral ore deposits and hyper-accumulating plants regularly measured at ANSTO. The CHIMP focusing and scanning systems are based on the OM-150 Oxford quadrupole triplet and the OM-26 separated scan-coil doublet configurations. A maximum ion rigidity of 38.9 amu-MeV was determined for the following nuclear microprobe configuration: the distance from object aperture to collimating slits of 5890 mm, the working distance of 165 mm and the lens bore diameter of 11 mm. The overall distance from the object to the image plane is 7138 mm. The CHIMP beamline has been tested with the 3 MeV H+ and 6 MeV He2+ ion beams. The settings of the object and collimating apertures have been optimized using the WinTRAX simulation code for calculation of the optimum acceptance settings in order to obtain the highest possible ion current for beam spot sizes of 1 μm and 5 μm. For optimized aperture settings of the CHIMP the beam brightness was measured to be ∼0.9 pA μm−2 mrad−2 for 3 MeV H+ ions, while the brightness of ∼0.4 pA μm−2 mrad−2 was measured for 6 MeV He2+ ions. The smallest beam sizes were achieved using a microbeam with reduced particle rate of 1000 Hz passing through the object slit apertures several micrometers wide. Under these conditions a spatial resolution of ∼0.6 μm × 1.5 μm for 3 MeV H+ and ∼1.8 μm × 1.8 μm for 6 MeV He2+ microbeams in horizontal (and vertical) dimension has been achieved. The beam sizes were verified using STIM imaging on 2000 and 1000 mesh Cu electron microscope grids. |
| Databáze: | OpenAIRE |
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