I. Rajta

The new ATOMKI scanning proton microprobe

Abstract The scanning proton microprobe of the institute of nuclear research (ATOMKI) in Debrecen is based on an Oxford Microbeams coupled quadrupole doublet focussing system built up to the 0° beam line of the 5 MV single ended Van de Graaff accelerator. With the setup described here PIXE analysis, Rutherford backscattering spectrometry and detection of backscattered secondary electrons can be carried out simultaneously. A modified version of the PIXYKLM computer program developed in the institute is used for the evaluation of the PIXE spectra. Applications discussed are related to investigations performed on metal archaeological samples and individual aerosol particles.

Proton beam micromachining on PMMA, Foturan and CR-39 materials

In this paper we investigate further the potential of proton beam micromachining (PBM) on three different materials: the polymers PMMA and CR-39, and the photowritable glass Foturan. A focused beam of 2 MeV protons delivered by the nuclear microprobe of ATOMKI was used to pattern these materials. The parameters of PBM and the obtained structures are presented.

Realization of the simultaneous micro-PIXE analysis of heavy and light elements at a nuclear microprobe

Abstract A new in-vacuum micro-PIXE experimental set-up has been realised at an Oxford-type scanning nuclear microprobe facility. It is based on the simultaneous use of an ultra thin windowed detector and a conventional Be-windowed one for the measurement of the characteristic X-rays of light and heavier elements in the E≈0.2–6 keV and E>4 keV energy ranges, respectively. Complete analytical characterisation of samples from carbon to uranium is possible in a single irradiation process. Performance and technical developments are described in detail.

Fe-Mn micronodules born in the metalliferous sediments of two spreading centres: the East Pacific Rise and Mid-Atlantic Ridge

Abstract A geochemical study of Fe–Mn micronodules associated with the metalliferous sediments at two spreading centres has shown that their composition depends on the site of micronodule formation. Close to the hydrothermal mounds they exhibit significant variation in elemental content related to the type of hydrothermal discharge (low- or high-temperature), the nature of primary hydrothermal matter (plume fall-out, oxidised sulfides), and the extent of diagenesis. In this environment three types of micronodules can be distinguished although not observed as pure end-members: (1) diagenetic micronodules; (2) micronodules formed generally from the plume fall-out of oxyhydroxide matter; and (3) micronodules grown on the oxidised sulfide grains supplied to the sediments by slumping or fall-out of nearby buoyant plume. Away from the active spreading centre, the hydrothermal signatures of primary precipitates are gradually masked and hydrogenous/diagenetic processes lead the micronodule formation. Composition of micronodules becomes less variable. Well-pronounced, deep rift valleys confine the hydrothermal plume, which brings the hydrothermal suspension into contact with restricted volumes of seawater and, consequently, weakens the hydrogenous influence on the primary hydrothermal matter. Shallow rift valleys do not confine hydrothermal plumes, which are scattered over hundreds of kilometres by bottom currents. This brings the hydrothermal suspended matter into contact with large volumes of seawater. Extensive scavenging occurs, which masks the hydrothermal signal away from the spreading axis and enhances the hydrogenous one. Thus, the ridge crest morphology, defined by the spreading rate, is supposed to play a certain role, though indirect, in the chemical composition of the primary precipitates and, consequently, in the composition of the micronodules formed.

Geochemical analysis of radiolarite samples from the Carpathian basin

Abstract A very important raw material of the prehistoric age, radiolarite was investigated in this work. Samples from geological and archaeological sites of the Carpathian basin, Greece and Austria were analyzed by ion beam methods, namely proton-induced gamma-ray emission (PIGE) and proton-induced X-ray emission (PIXE) techniques. Our aim was to study to what extent we are able to classify the specimens with various macroscopical features and different source areas. In order to answer this question, a cluster analysis was carried out on the concentration data set deduced from the analysis. Correlations between the elemental compositions and the source regions are established.

Analysis of single aerosol particles collected in urban and cave environment by proton microprobe

Abstract Quantitative PIXE analysis was performed on several single aerosol particles collected with cascade impactor by the scanning proton microprobe of Debrecen. The cascade impactor samples were collected at an urban location in Debrecen and in a speleotherapeutic cave situated under Budapest during the winter of 1998. The aerosol samples have already been analysed by bulk PIXE technique. Elemental concentrations for 23 elements and also the size of the particles were determined. Cluster analysis was carried out to identify the different particle groups. The contribution of the different types of particles to each size fraction were investigated with special regard to the smaller size fractions which are interesting from the point of view of the speleotherapy. Traces of anthropogenic pollution were also shown in the cave aerosol, and the possible composition of particles containing these pollutants is given. Comparison of the urban and cave aerosol particles is also discussed.

Characterization of individual aerosol particles from the eruption of Lonquimay volcano in Chile

Abstract A set of aerosol samples collected during major volcanic activities around the Chilean site Lonquimay in the years 1988–1990 has been subjected to measurements in conventional and microPIXE modes in the Debrecen institute. The aim of the study was the completion of the earlier results with comparative PIXE data and microPIXE measurements for the characterization of individual particles. Results have been obtained on separate particles in terms of their elemental composition, on separate particle groups of different composition by statistical dissimilarity analysis. Si/Al and K/Si elemental ratios have been used for a comparison with published data from other volcanic locations.

STUDY OF WHITE LEAD PAINT LAYERS BY THE DEBRECEN NUCLEAR MICROPROBE

Abstract The white colours of cross-section samples taken from 10 paintings and 3 different kinds of modern white lead pigments were examined by PIXE using the Debrecen nuclear microprobe. Elemental concentrations of impurities relative to Pb were determined. A comparison with EDAX on the same samples is made.

The Debrecen scanning proton microprobe facility and its applications to geological samples

Abstract The recently installed scanning proton microprobe of the Institute of Nuclear Research (ATOMKI) in Debrecen is supplied with proton beam from a home-made 5 MV single ended Van de Graaff accelerator, while focusing and scanning the beam is achieved by the commercially available system from Oxford Microbeams Ltd. including quadrupole doublet focusing lenses, slits, scanning coils and a PC-based data acquisition package. Its first PIXE application was made in micromineralogy, in the study of spherules. Spherules in different geological and geographical situations may have various extraterrestrial origin. Several of these objects uncovered in the western part of Hungary have been analysed. Cosmic origin can be supposed for the majority of the findings.

Micro-RBS as a technique for the determination of the surface topography of Bi film prepared by pulsed laser deposition

Abstract Particulate deposition on Bi film prepared by pulsed laser deposition (PLD) was studied by Rutherford backscattering spectrometry (RBS) using a 2 MeV 4 He + scanning microbeam with a lateral resolution of 2 μm. Droplets and particulate-free areas could be detected and separated in the analysis, which offers the possibility of independent measurement of the chemical composition of the thin film and the micron-sized droplets. Tomographic images illustrated thickness inhomogeneities and cross-sectional thickness profile of particulates and gave more detailed information about the surface topography than the RBS spectra themselves. An example is discussed where thicknesses larger than the probing depth could be measured. This unique combination of possibilities makes micro-RBS a powerful technique for the complete analysis of particulate thin films.