Mikael Elfman

Fluid inclusions in magnetite-apatite ore from a cooling magmatic system at El Laco, Chile

Abstract The Pliocene El Laco deposits of magnetite-apatite iron ore of the Kiruna type, situated on the flanks of a volcano in northern Chile, can morphologically and structurally be described as extrusive and intrusive magmatic orebodies with hydrothermal overprinting. Fluid inclusions in pyroxene and apatite record different stages in the transition from a late-magmatic remnant fluid, probably exsolved during crystallization of an ore magma, to hydrothermal fluids of successively lower temperature and salinity. Hydrous saline Na-K chloride melt inclusions with anhydrite daughter crystals in pyroxene intergrown with magnetite from ore lava at Laco Sur and ore breccia in a dike-vein system at Cristales Grandes were formed at >800°C. Pyroxene-magnetite veins in the Laco Sur ore indicate crystallization in fissures during degassing of a flow emplaced at still higher temperatures. Melt inclusions like those in pyroxene also occur in an early generation of apatite from San Vicente Bajo, a subvolcanic orebody...

PIXE and ionoluminescence — A synergetic analytical combination

The purpose of this paper is to demonstrate that ionoluminescence and PIXE are genuinely complementary techniques and that the combination represents a powerful analytical tool, particularly in geochemistry. Ionoluminescence can be used for imaging and qualitative analysis of elements and chemical compounds. The quantification of ionoluminescence data, however, requires an improved understanding of luminescence physics. The trace element properties of PIXE may be of major importance in this development.

A NEW DETECTOR FOR HYDROGEN ANALYSIS WITH A NUCLEAR MICROPROBE

Abstract A new detector for hydrogen analysis of thin samples has been designed for utilization at a nuclear microprobe. An annular surface barrier detector is divided into two halves that are read out individually, and the two protons resulting from p-p scattering are detected in each half. Coincidence technique is applied in order to suppress the background. The minimum detection limit is 20 pg/cm2 for an integrated beam charge of 1 μC. The depth profiling properties are discussed, and three-dimensional images with a resolution of 1 μm or less are considered to be attainable. The detector can be employed in conjunction with other detectors to simultaneously analyze light elements with optimal nuclear reactions and large solid angles.

Complex life histories of fishes revealed through natural information storage devices: case studies of diadromous events as recorded by otoliths

Abstract Diadromous fishes – species that move across salinity gradients as part of their life repertoire – form a major part of coastal and inland fisheries. Conventional mark–recapture techniques have long been used to track their movements, but give incomplete information at best. On the other hand, otoliths (ear-stones) of fishes can provide a complete record of major life history events, as reflected both in their microstructure and elemental composition. Strontium, which substitutes for calcium in the aragonite matrix of otoliths, is a powerful tracer of salinity histories in many migratory fishes. We measured Sr and Ca with a nuclear microprobe (PIXE) and show examples (eel, Anguilla anguilla ; brown trout, Salmo trutta ; American shad, Alosa sapidissima ) of how the technique has solved several mysteries within fisheries biology.

IONOLUMINESCENCE AND PIXE STUDY OF INORGANIC MATERIALS

Abstract The combined use of IL and PIXE is promising in characterizing the inorganic materials. IL is sensitive to the condition of chemical binding and ion valence state, crystallinity and defects. IL can also provide a unique way to monitor and study the ion-beam induced effects in samples. PIXE can provide quantitative information on the elemental distribution of major and trace elements in samples, which in turn helps to understand IL results. The combination of the two techniques provides a new tool for studying the intrinsic and extrinsic luminescence phenomena and is capable of micro-characterizing various inorganic materials, including the ones of geological and synthetic origins.

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

Abstract 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.

Calibration of a new chamber using GUPIX software package for PIXE analysis

A new chamber has been designed and constructed for the second beam line at the Lund Nuclear Microprobe facility, Sweden. The aim with the chamber is to perform standardized analyses with most of the nuclear analytical techniques (proton induced X-ray emission, particle elastic scattering analysis, proton induced gamma emission, nuclear reaction analysis, etc.) with a millimetre size beam. The beam line and chamber constructions are described in this paper. The possibility to run samples in batch. and the special arrangement developed for this is described. A mass calibration of the PIXE set-up has been done with MicroMatter thin film standards and other thick standards. The spectra were acquired with CAMAC based data acquisition system with Kmax interfacing software. The GUPIX software package recently installed in our laboratory has been used to process the PIXE spectra and the results are compared with the certified values. For standardization the instrumental constant H (solid angle and correction factor) is determined relying completely on the GUPIX data base (cross-sections, fluorescence and Coster-Kronig probabilities, stopping powers and attenuation coefficients) for a large set of elements. These H values are saved inside the GUPIX library, to be used in future analysis. (Less)

IONOLUMINESCENCE TECHNIQUE FOR NUCLEAR MICROPROBES

Abstract Ionoluminescence (IL) produced by MeV/amu particles in the Nuclear Microprobe carries rich information on the nature of the chemistry and physics in the various types of materials, such as the molecular structure and ions valence, etc. IL/PIXE methods offer unique ways to study the general luminescence phenomenon by directly relating the trace element information provided by PIXE to IL spectroscopic results. The IL can also be used to identify the organic molecular structure, hence, the combination of the IL data with the PIXE elemental data provide a new tool for biology and medicine studies. One example is the epidermis from the human skin, which exhibits a clear IL. IL is very sensitive to the local chemical environment conditions of the excitation point, therefore, it can be very effective to study the beam modification and beam damage effects. The beam damage problem in the Nuclear Microprobe applications is discussed.

Elemental analysis of single phytoplankton cells using the Lund nuclear microprobe

Abstract The occurrence of annual marine phytoplankton blooms is becoming a global problem. In Europe, the NUTOX project supported by the EC investigates if unbalanced nutrient compositions in the water promote the dominance of harmful phytoplankton species. One of the tasks is the determination of the elemental composition of single phytoplankton cells. This is carried out using the Lund Nuclear Microprobe with a special focus on C, N, P and K. The overall aim is to understand the mechanism leading to toxin production, model it and eventually propose a counteracting method. The preparative method, used to isolate single living cells while reducing their salt environment, is an important part of the analytical procedure. A comparison of light element detection using backscattering from protons and nuclear reaction analysis using deuterons is made.

BORON DISTRIBUTIONS IN SINGLE CRYSTALS INVESTIGATED WITH NUCLEAR REACTION MICRO ANALYSIS

Abstract Crystals synthesised in the laboratory in B-rich fluxes were analysed with a nuclear microprobe and nuclear reaction techniques for boron distribution and concentration determination. The synthesis technique and the principles of the elemental analysis are discussed and some analytical examples are shown. The geological problem, a B-Si substitution, is described with some conclusions. The zonal B-pattern observed in Mn 3+ -substituted diopside clearly demonstrate that the present analyses represent structurally bound B and the observed variation in Na- and B-concentration ratios provide evidence for a decoupling of the suggested substitution mechanisms in clinopyroxene.