Microprobe Facility Research Articles

The layout and performance of the Lund nuclear microprobe trigger and data acquisition system

Recently a new data acquisition system has been installed at the Lund nuclear microprobe facility. The trigger layout for this beam scanning and data acquisition system that support a great variety of simultaneously techniques (PIXE, STIM, RBS, and NRA) is presented in detail. The technical status, total trigger throughput and data flow is described. Examples of typical system performance for PIXE, STIM and RBS obtained during routine runs are discussed. Details on hardware and software specifications are given.

The stand-alone microprobe at Livermore

Lawrence Livermore National Laboratory (LLNL) and Sandia National Laboratories/California have jointly constructed a new stand-alone microprobe facility. Although the facility was built to develop a method to rapidly locate and determine elemental concentrations of micron scale particulates on various media using PIXE, the facility has found numerous applications in biology and materials science. The facility is located at LLNL and uses a General Ionex Corporation Model 358 duoplasmatron negative ion source, a National Electrostatics Corporation 5SDH-2 tandem accelerator, and an Oxford triplet lens. Features of the system include complete computer control of the beam transport using LabVIEW™ for Macintosh, computer controlled beam collimating and divergence limiting slits, automated sample positioning to micron resolution, and video optics for beam positioning and sample observation. Data collection is accomplished with the simultaneous use of as many as four EG&G Ortec IGLET-X™ X-Ray detectors, digital amplifiers made by X-Ray Instruments and Associates (XIA), and LabVIEW™ for Macintosh acquisition software.

Nuclear microprobe applications to radioactive waste management basic research

Radioactive waste management is one of the major technical and scientific challenge to be solved by industrialized countries near the beginning of the 21st century. Relevant questions arise about the extrapolation of the long term-behavior of materials from waste package, engineered barriers and near field repository. Whatever the strategical option might be, wet atmosphere or water intrusion through the different barriers constitute the two main remobilization factors for radionuclides in the geosphere and the biosphere. The study of solid alteration processes and elemental sorption phenomena on mineral surfaces is one of the most efficient basic research approaches to assess the long term performance of waste materials. Ion beam analysis and more recently nuclear microprobe techniques have been applied to investigate exchange mechanisms near representative solid/liquid interfaces such as glass/deionized water, uranium dioxide/granitic or clay water or mineral surface/aqueous solution doped with chemical elements analogue to actinide or fission products. This paper intends to describe the different works that have been carried out in Saclay using the nuclear microprobe facility. The coupling of μRBS, μPIXE and μNRA permits to determine the evolution of the surface composition induced by chemical reactions involved. Complementary observation of solid morphology and solution analysis allows to obtain a complete elemental balance on exchange processes.

The Laboratori Nazionali di Legnaro proton microprobe as a tool for mineralogical investigation

The LNL Proton Microprobe has recently been used in performing micro-PIXE analysis of geological samples. Major and trace-element concentrations of one reference standard typical of petrological research and of some igneous rock minerals from the Mount Etna 1910 flow are shown. Comparison with other analytical techniques, accuracy and MDL of the elemental concentrations confirm that micro-PIXE is a powerful technique in mineralogical investigation and prove that the Legnaro Proton Microprobe (LPM) facility can produce reliable quantitative results.

Analysis of glassy spherules extracted from Carpathian Mesozoic lime stone by μPIXE method

Twenty-four glassy spherules collected from three Mesozoic sites of the Carpathian Basin have been analysed for major, minor and trace element composition using the scanning proton microprobe facility of the Institute of Nuclear Research (ATOMKI) in Debrecen. μPIXE analyses revealed surprisingly high Ca and Ba concentrations (CaO ∼40%, BaO ∼2.5%) which have never been reported before. Samples proved to be homogeneous for the major elements (Si, Ca). From geological considerations it may be inferred that these spherules are terrestrial impact products, though, the details of the impact events have not been fully cleared yet.

Ion microprobe analyses of ancient human bone

At the Rossendorf nuclear microprobe facility, a beam of protons with MeV energy was used to analyse ancient human bones of the Merowingian period (6–8th century AD). Emitted X-rays were detected to determine the elemental composition of the bones and to estimate the influence of the burial environment on the elemental content of the skeletons. In cross sections of human femora, a different behaviour of the radial distributions of the main and trace elements like P, Ca, Mn, Fe, Zn, Br, and Sr was observed using lateral-resolved μPIXE. This result indicates post mortem mineral exchange processes and diagenetic alteration during burial of bone tissue in soil.

Application of grazing exit angle in RBS microprobe measurements

Alpha backscattering measurements have been used successfully at the Debrecen nuclear microprobe facility for material analysis. Some of the examples are presented here in detail. Contrary to the traditional RBS technique the scanning RBS microprobe with the detector at grazing exit angle is capable of studying surface topography. This effect is demonstrated by RBS mapping images taken with 2.0 and 2.5 MeV 4He + beams on test samples of different surface patterns containing only one element, Si. The observed effects are discussed.

High Resolution—High Transmission Secondary on Mass Spectrometry (SIMS) for in situ Microanalysis of Lead Isotope Ratios in Minerals and Melt Inclusions

Large format high resolution high transmission SIMS instruments, which include the Anutech SHRIMP and Cameca IMS 1270 ion microprobes, were designed to have the mass resolution and sensitivity required for in situ U/Pb dating of individual zircon crystals. This capability has been applied to other types of geochronology, including the U-Th-Pb dating of monazite (Harrison et al., 1995). Application of the IMS 1270 at the WHOIbased Northeast Regional Ion Microprobe Facility (NERIMF) has also been successfully extended to the measurement of Pb isotope ratios in other mineral and glass phases. These include phases such as plagioclase and basalt glass which contain very low total Pb concentrations (0.1-2 ppm). Zircon (ZrSiO4) commonly contains 1-2% Hf substituting for Zr. Consequently, accurate measurement of Pb isotope ratios in zircon requires a mass resolving power (MRP) of 5000-6000 to sufficiently resolve molecular Hf species such as HfSi + from the isotopes of Pb (Schuhmacher et al., 1993). However, isobaric interferences in feldspars and basalt glass generally require MRPs of only 1850 and 3500, respectively, for SIMS analysis. For plagioclase, the most substantial isobaric interferences, tentatively identified as complexes of Na~CawAlxSiyO +, are easily resolved from the Pb isotopes at MRP 1850 or greater. This much lower MRP requirement is extremely advantageous since the inherent sensitivity for Pb in plagioclase is distinctly inferior to that for Pb in zircon, and because the natural Pb contents of magmatic plagioclases tend to be a maximum of only a few ppm. In plagioclase with a total Pb concentration of 1 3 ppm the ratios 2~176 and 2~176 can easily be determined with a precision of better than 0.5% (1 sigma) for a one hour analysis. K-feldspars have a higher range of natural Pb concentrations often hundreds of ppm and appear to possess an inherently better relative sensitivity factor for Pb than plagioclase. Consequently, precisions are much higher than in plagioclase for 2~176176 analysis, and it is generally p o s s i b l e to e x t e n d the m e a s u r e m e n t to 2~176176176 while still maintaining precisions better than 0.5-1%. Interferences on Pb peaks include + NavKwAl,,SlyOz complexes on the low mass sides and as yet unidentified species (possibly Li,,AlxSiyOz +) on the high mass sides. Both sets of isobars are sufficiently resolved at 1800-2000 MRP to allow accurate Pb isotope analysis. Analysis of basalt glasses requires a minimum MRP of 3500 to sufficiently resolve REEO~ and HfO~ species from the Pb peaks. Although basalt glass requires higher MRP, the intrinsic sensitivity for Pb in basalt under Obombardment is more than five times higher than that for plagioclase. Consequently, the transmission of the IMS 1270 is still sufficiently high to produce 2~176176 analyses with precisions of better than 0.4% (1 sigma) from homogeneous basalt glass for typical one hour analyses of materials with 1 ppm Pb. R e a s o n a b l y p r e c i s e m e a s u r e m e n t s o f 2~176176176 can also be produced at these same resolutions with a concomitant increase in the analytical time. Pyrite (FeS2) and chalcopyrite (CuFeS2) also require only modest MRP for Pb isotope analysis. The only substantial isobaric interferences appear to be Fe3S § complexes on 2~176176 and 56Fe232S ~ on 2~ Both isobars require a nominal MRP of only 1000-1100. Due to inherently high natural Pb concentrations (typically 50-100 ppm), chalcopyrite can readily be analysed for 2~176 and 2~176 with precisions of better than 0.3%, and 2~176176176 can be determined with precisions of better than 0.7% for typical 30 to 60 minute analyses. A lateral spatial resolution of 20-30 micrometers can be maintained for most analyses. This allows studies of zoned minerals, exsolved phases, individual melt inclusions and even crystallized daughters

New CAMAC based data acquisition and beam control system for Lund nuclear microprobe

A new CAMAC based data acquisition system has been installed at the Lund Nuclear Microprobe facility. This paper reports on the development and present status of the data acquisition system. The system is a true multiparameter CAMAC based system with fast Fera bus readout and in crate memory buffer. The user interface is based on Sparrow Kmax software for a Power Macintosh platform. The system read out and tag the event data with position on-line, which make fast on-line monitoring of spectra or element maps possible.Simultaneously, all data can be saved event by event for off-line analysis. The beam scanning part is software controlled through a timed D/A converter, this allows fast scanning of the beam. With a CCD-camera and video card the area to be analysed could be defined directly from the image, and the sample position can be moved. Any kind of irregular scan patterns could be defined.

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

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.

ADVANCES OF NUCLEAR MICROPROBES AND THEIR APPLICATIONS

This paper reviews the recent progress of the nuclear microprobe technology in both micro-analysis and micro-imaging. Some features of the nuclear microprobe facilities established at the Shanghai Institute of Nuclear Research and Fudan University are described Four examples of recent applications are enclosed to show the potentialities of the technique for a variety of scientific studies.

Analytical techniques in nuclear microprobes

A selection of analytical techniques available for implementation in a nuclear microprobe facility has been reviewed. New methods and development of established techniques are emphasised.

Analytical techniques in nuclear microprobes

A selection of analytical techniques available for implementation in a nuclear microprobe facility has been reviewed. New methods and development of established techniques are emphasised.

The NAC nuclear microprobe facility

The NAC NMP facility is discussed, showing that it is a well characterised analytical tool, and some novel features are incorporated, such as on-demand beam deflection and a new lid for the sample chamber.

Light elements analysis using 3He microbeam

Coatings containing light elements such as carbon, nitrogen or oxygen play actually an important role in surface engineering as a means to improve the tribological performance. In this paper, we have studied the wear tracks on a diamond coating after a fretting test against a Cr steel ball. The microprobe facility of the LARN has been used to determine light elements concentration in the wear tracks because the size of the tracks was less than 100 μm and the transfer layer from the Cr steel counterbody was not uniform. Quantitative analysis of oxygen has been performed using the 2.392 MeV resonance of the 16O( 3He , α 0) 15O reaction at 90°, while carbon has been measured simultaneously with the 12C( 3He, p 1) 14N ∗ reaction at 175°. The cross sections and the Q-value of this reaction are so high that an absorber is not required, so we can also measure the backscattered 3He particles in the same detector. A correlation between carbon, oxygen and iron has been made to investigate the possibility of interdiffusion between the diamond coating and the transferred material due to the fretting test.

PIXE microprobe for geoscience applications

Microprobe analysis with PIXE (proton induced X-ray emission) is a well known analytical method with detection limits at the ppm level. It is frequently used for geoscience applications. To improve the versatility and reliability, the Bochum microprobe facility has been reconstructed incorporating a new data acquisition system, a beam dose monitor, and a new slit system.

Microcharacterizing zircon mineral grain by ionoluminescence combined with PIXE

When MeV ions impinge on certain materials, UV, visible and/or near IR light is emitted. In an on-going project this process, ionoluminescence (IL), is combined with μ-PIXE at the Lund nuclear microprobe facility, and applied to microcharacterization of geological materials. The IL method is unique in obtaining chemical information that is not readily available with other IBA techniques. Use of IL microscopy and spectroscopy is demonstrated in this paper. The origin of intrinsic and extrinsic ionoluminescence, especially IL from rare earth elements (REE) are discussed. The possibility of performing IL microscopy to study mineral growth zoning structures and to locate inherited core assisting ion-probe for detailed age dating is discussed. We intend to demonstrate that combined with other IBA methods ionoluminescence is a powerful microcharacterization method in geosciences.

The KFUPM scanning nuclear microprobe facility

The scanning nuclear microprobe facility recently installed on the tandetron accelerator of King Fahd University of Petroleum & Minerals in Dhahran, Saudi Arabia is described. The design is based on the Oxford magnetic quadrupole triplet lens system and can focus a beam of 2.5 MeV protons to a spot of about 1 μm diameter with a current of about 100 pA. Maximum scanning area is at present limited to 130 μm by 100 μm. Acceptance tests performed during the commissioning of the facility are discussed. Elemental maps of a catalyst by PIXE measurements are given to demonstrate the performance of the system.

Nuclear microprobe analysis of 14N and 15N in soybean leaves

A combination of two nuclear microprobe exploitation modes of spectroscopy has been developed to detect 14N and 15N in plant tissues. 14N was determined by proton elastic scattering analysis (PESA) and 15N by proton induced gamma ray emission (PIGE). The advantages of each mode are outlined. The preparation method of the soybean samples which allows the preservation of the tissue structure is described. After checking the linearity of the quantitative evaluations using calibration curves, we have studied the irradiation damages, evaluating the nitrogen mass loss with the nuclear microprobe facilities of Bruyères-le-Châtel. An experimental approach for quantitative 14N and 15N analysis by these nuclear methods in cryofixed and resin embedded soybean leaves is proposed.

The Zagreb nuclear microprobe facility

The nuclear microprobe facility at the Laboratory for Nuclear Microanalysis, of the Ruder Bošković Institute in Zagreb is described. The microbeam system is positioned at one of the beam lines of the EN tandem accelerator. The system consists of the Oxford design magnetic quadrupole doublet and the scattering chamber constructed by ourselves. A general description of the facility is given, together with a more detailed description of chamber design. Few recent examples of microbeam applications in geology, environmental and biomédical research are given.