[en] When a solid surface is subjected to a bombardment of energetic ions, material is ejected from the surface in a process known as sputtering. A part of the sputtered material is ionized and these secondary ions can be analyzed with a mass spectrometer according to a technique known as secondary ion mass spectrometry (SIMS). A description is presented of the present status of geochemical and cosmochemical applications of the ion microprobe. Attention is given to the sputtering event, molecular ion interferences, aspects of isotopic fractionation, secondary ion intensities in polycomponent materials, and questions of trace element analysis. Geochemical applications of the ion microprobe are based on certain advantages over other analytical techniques. These advantages are related to high sensitivity, low background, and the capability of in situ analysis of isotopic composition. The distribution of trace elements in minerals is considered, along with isotope anomalies, isotope zoning, diffusion studies, and depth profiling

No abstract available

[en] We report a systematic ion microprobe study of the isotope fractionation effects produced during the sputtering of pure metal targets. The metals studied were B, Mg, Si, Cr, Ni, Cu, Ge, Mo, Ag, Sb, Re, Tl, and Pb; isotopic ratios were determined with typical precisions of 0.1%--0.3%. Detailed studies show that the data are free of possible instrumental biases, interference effects, etc. In all cases, the secondary ions produced by sputtering are enriched in the lighter isotope, and the degree of this enrichment is a function both of the spatial location and the energy of the extracted ions relative to the sputtering site. The maximum observed L/H enrichment factors vary from 6.5%/amu for B to 0.6%/amu for Pb, and are observed to show an approximate M/sub H//M/sub L/ [rather than a (M/sub H//M/sub L/)/sup 1/2/ ] dependence on mass. For masses greater than 50, the mass dependence of this fractionation can be closely described by an ionization model modified after Schroeer et al. [Surf. Sci. 34, 571 (1973)]; it is improbable that the observed fractionation is related to differential sputtering effects. Use of ion microprobes for isotopic research in geochemistry/cosmochemistry will require careful control of this isotopic fractionation process if a precision of better than 1%--2% is sought

[en] Many research and development programs for fast breeder reactors are in progress by Power Reactor and Nuclear Fuel Development Corporation with the cooperation from many establishments in Japan. One of which, Fuel Monitoring Facility, is now under construction next to Joyo at Oarai Engineering Center. The quantity of radioactive materials to be processed will be as much as that of HFEF in US and ADAC in France. Therefore advanced knowhow was required through basic planning, precise designing and construction stages. The specification of FMF building is as follows, (i) structure: reinforced concrete type with four stories and two basements, (ii) building area: 1,920.01m², (iii) floor area: 7,617.72m². The functional features of the facility are as follows; (1) storage of fuel assembly, (2) removing of sodium from fuel assembly, (3) outer view and dimensional inspection, (4) weighing of fuel assembly, (5) dismembering of fuel assembly, (6) weighing of fuel pin, (7) outer view and dimensional inspection of fuel pin, (8) gamma scanning of fuel pin, (9) pacture test of fuel pin, (10) cutting off of fuel pin, (11) dismeating of fuel pin, (12) storage of cut-off pins. These functional sequences are processed in a test cell, and decontaminating cell, clean cell, hot repairing cell and contact-repairing cell are arranged around it. This facility is to be operated with consideration of safe handling of plutonium, maximum radioactivity of 1,000,000 curies and carry-over of sodium contaminating fuel pins. Now final construction is in progress, and reliable operation will be commenced in very near future. (Iwase, T.)

[en] YbB₁₂ is the only Yb-based Kondo insulator. We have succeeded for the first time in growing a large single crystal (6 mm diameter x 50 mm) of YbB₁₂ by floating zone method using a newly developed image-furnace with four xenon lamps. The results of the electrical resistivity, Hall effect and magnetic susceptibility measurements indicate that the quality of this crystal is better than that of the best polycrystal ever reported. (orig.)

[en] We propose a new approach to microscopic derivation of the Interacting Boson Model (IBM) Hamiltonian for general cases, starting from the mean-field model, e.g., the one with Skyrme-type interactions [1]. The multi-fermion dynamics of the surface deformations and the effects of the nuclear force are simulated in terms of bosons. By comparing Potential Energy Surface (PES) of the mean-field model with that of the IBM, the parameters of the IBM Hamiltonian can be obtained as functions of N and Z. Using this method, levels and wave functions of the excited states are computed precisely: Various situations of three dynamical symmetries and quantum shape/phase transitions, including the recently proposed critical-point symmetries [2,3], can be reproduced quite nicely. Moreover, intriguing spectroscopic properties, e.g., unexpectedly large region of the E(5) symmetry, are predicted for experimentally unknown exotic nuclei such as W-Os isotopes with A ≥200. As another application, we will present the results of the systematic calculations for Z ≤50 nuclei such as Ru isotopes. These results contain the predicted energy levels for unexplored territory. Finally, we would like to discuss the uniqueness of the derived IBM parameters with the aid of the wavelet analysis, taking Sm and Ba isotopes as examples.(author)

[en] The use of the ⁸⁷Rb-⁸⁷Sr radiogenic tracer system to study the creation of the continental lithosphere is examined and results obtained by the technique on garnet lherzolite xenoliths from Southern African kimberlites are presented. The geochemical and geodynamical implications of the observations are discussed. (U.K.)

[en] A method for quantitative analysis of silicates with an ion-microprobe has been developed by suppressing the intensities of interfering molecular ion species based on the difference in the kinetic energy distributions between molecular and single-atom ions. Molecular ions drop their intensities rapidly with increasing energy and are virtually eliminated at the energy level 150 eV higher than the energy acquired by acceleration. Outlines of geochemical applications of the technique are given for: (a) analysis of isotopic composition of Pb in galena; (b) analysis of isotopic composition of Mg in anorthite and hibonite in inclusions in the Leoville meteorite; (c) quantitative analysis of major and trace elements in Ca-rich pyroxene, garnet and plagioclase; (d) determination of REE pattern in hornblende; and (e) in-depth profiling of ¹⁸O/¹⁶O ratios to determine oxygen self-diffusion in silicates in hydrothermal conditions. Although the potential capabilities of an ion-microprobe are not well-realised at the present stage, due in part to the lack of well-documented standards for trace elements and a relatively large beam spot size, it is concluded, considering the technical development foreseeable in the near future, that the ion-microprobe should prove extremely useful in geochemistry. (author)

[en] The possibility of using ¹⁴³Nd/¹⁴⁶Nd as a natural tracer was examined by analyzing two Hercynian granitic rocks, one carbonatite, three alkali basalts and nine tholeiites. ¹⁴³Nd/¹⁴⁶Nd ratios ary notable different for these rock types: 0.7068-0.7073 for granitic rocks, 0.7078 for the carbonatite, 0.7080 for alkali basalts and 0.7083 for tholeiites. The isotopic difference between tholeiites and alkali basalts suggests that they are derived from parts of the mantle which have been chemically different. Comparison of the measured ¹⁴³Nd/¹⁴⁶Nd ratio of tholeiites and the isotopic growth in a simple two-stage model system suggests that the source of the tholeiite magmas has had light-REE-depleted pattern, being consistent with Gast's (1968) contention that ridge tholeiites are derived from a part of the mantle which is a residue left after a previous melting event. (Auth.)

[en] Attention is focussed on chronological and chemical aspects of lunar studies in connection with the chronology and chemistry of the achondrites and the Earth. A model for the chemical evolution of the Moon is discussed based on the major element compositions, phase relations and abundances and distributions of rare earth elements. A comparison is made among the planetary objects with respect to their chemical evolution and possible primary composition for rare earth elements. (U.K.)