The Nuclear Microprobe

Each of the two beamlines are focussed by a single electromagnetic quadrupole doublet, and a beam size of about 1 pm2 is achieved with a beam current of approximately 50 pA. Electrostatic deflectors are mounted to permit beam sweeping on the sample both to produce images and to limit heating effects. 

The analysis chamber is such that PIXE, RBS, PIGE, NRA and ERDA are routinely performed simultaneously with the microprobe. A 4-axis micron-level goniometer permits precise positioning. The radioactive beamline enters a shielded 

We will first consider, however, Secondary Ion Mass Spectroscopy (SIMS) in which both neutral and charged species are sputtered from the surface, and detected by means of a mass spectrometer. This involves ion beams of lower energy than in the techniques described previously. 

Wilson, Stevie, and Magee (1989) list the advantages and disadvantages of SIMS as follows  

Detection limits of parts per million (ppm) atomic for most elements and parts per billion (ppb) atomic for favourable elements, lppm is 0.0001%. 

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The basis of the nuclear microprobe (NMP) is a source of energetic ions from a particle accelerator. These... 

The first nuclear microbeam with a spatial resolution of 1 pm was built by Watt et al. (1981), and the first sub-micron instrument was built by Grime et al. (1987). Khodja et al. (2001) have published a description of the nuclear microprobe at the Pierre Sue Laboratory in France, which is a national facility dedicated to microbeam analysis. Its unique facility is that it is capable of analysing radioactive samples by means of a dedicated beamline. Figure 4.1 shows a schematic diagram of the apparatus. 

Ryan, C.G. 2000. Quantitative trace element imaging using PIXE and the nuclear microprobe. International Journal of Imaging Systems and Technology, 11, 219-230. 

Ryan C G 1995 The nuclear microprobe as a probe of earth structure and geological processes Nud. Instrum. Methods B 104 69... 

In geology, there is such a wide variety of applications that a few laboratories with a microprobe use their accelerator exclusively for this type of research. Fundamental geological studies, not only work on fluid inclusions, zonation in several minerals, etc., but also the search for precious metals in ores, are issues amenable to micro-PIXE. Extraterrestrial material has also been investigated with the nuclear microprobe. The lateral resolution and the... 

Using a combination of analytical techniques, the nuclear microprobe can provide simultaneous multi-elemental analysis over the entire Periodic Table with a spatial resolution of 1 pm, a minimum detection limit of 1-100 ppm depending on the conditions and a quantitative accuracy of 5-20% depending on the type of analysis. Although the penetration depth of MeV protons can be in the region of 100 pm in some materials, the nuclear microprobe is a surface-biased technique since signals are detected preferentially from the near surface region ( 10 pm depth). 

Figure 4.1. Schematic diagram of the Pierre Sue nuclear microprobe (Khodja et al. 2001).

Swann, C. P. (1997). Recent applications of nuclear microprobes to the study of art objects and archaeological artifacts. Nuclear Instruments and Methods in Physics Research B 130 289-296. 

See the proceedings of the following International Conferences appeared in special issues of Nuclear Instruments and Methods in Physics Research Section B Nucl. Instrum. Methods Phys. Res. B 2002, 193, Proc. of the 19th Intern. Conf. on Atomic Collisions in Solids Nucl. Instrum. Methods Phys. Res. B 2002,190, Proc. of the I5th Intern. Conf. on Ion Beam Analysis Nucl. Instrum. Methods Phys. Res. B 2001, 175-177, Proc. of the 12th Intern. Conf. on Ion Beam Modification of Materials Nucl. Instrum. Methods Phys. Res. B 2001,18I, Proc. of the 7th Intern. Conf. on Nuclear Microprobe Technology and Applications. 

Llabador, Y. Moretto, P. Applications of Nuclear Microprobes in the Life Sciences—An Efficient Analytical Technique for Research in Biology and Medicine, World Scientific Singapore, 1998. Cookson, J.A. Ferguson, A.T.G. Pilling, F. J. Radioanal. Chem. 1972,12, 39. 

Figure 3 View of the external nuclear microprobe beam line of the AGLAE accelerator.

Michelet, C. and Moretto, P., Applications of Nuclear Microprobes in the Life Sciences, World Scientific Publisher, Singapore, 1999. 

Kristiansson, P. et al., Photon-tagged nuclear reaction analysis — evaluation of the technique for a nuclear microprobe, Nucl. Instr. Meth. B, 136-138, 362, 1998. 

Megaelectron volt (MeV) ion beam techniques offer a number of non-destructive analysis methods that allow to measure depth profiles of elemental concentrations in material surfaces. Elements are identified by elastic scattering, by specific nuclear reaction products or by emission of characteristic X-rays. With nuclear microprobes raster images of the material composition at the surface can be obtained. Particle-induced gamma-ray emission (PIGE) is especially suited for fluorine detection down to the ppm concentration level. 

G.E. Coote, I.C. Vickridge, Application of a nuclear microprobe to the study of calcified tissues, Nucl. Instr. Meth. B30 (1988) 393-397. 

D.N. Jamieson, B. Rout, R. Szymanski, P. Spizzirri, A. Sakellariou, W. Belcher, C.G. Ryan, The new Melbourne nuclear microprobe system, Nucl. Instr. Meth. B190 (2002) 54-59. 

N. Boscher-Barre, P. Trocellier, Nuclear microprobe study of a woman s skeleton from the sixth century, Nucl. Instrum. Methods Phys. Res. B 73 (1993) 413-416. 

Figure 7.68 PIXE elemental maps of Ca of The images were obtained at the Nuclear micro-regions (approx. 250 pm2) of selected Microprobe (NMP) facility of iThemba LABS,...

Ryan, C.G., van Achterbergh, E., Yeats, C.J., Win, T.T., and Cripps, G. (2002) Quantitative PIXE trace element imaging of minerals using the new CSIRO-GEMOC nuclear microprobe. Nucl. Instrum. Methods Phys. Res., Sect. B. 189, 400-407. 

Some relevant terms for activation analysis are activation analysis, neutron activation analysis (NAA), instrumental neutron activation analysis (INAA), neutron activation analysis with radiochemical separation (RNAA), photon activation, neutron capture prompt gamma activation analysis (PGAA), charged particle activation, autoradiography, liquid scintillation counting, nuclear microprobe analysis, radiocarbon (and other element) dating, radioimmunoassay, nuclear track technique, other nuclear and radiochemical methods. Briefly, the salient features of some of the more popular techniques are as follows ... 

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