Results 1 - 10 of 335686
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[en] The importance of isotopic anomalies in refractory inclusions in meteorites is well established. Measurements of the anomalies using conventional mass spectrometry are often rendered difficult, however, by isobarically interfering isotopes: for example, 48Ti and 48Ca. Resonance ionization mass spectrometry (RIMS) can substantially reduce isobaric interferences in a number of systems. We have employed RIMS for the in situ detection of Ti atoms sputtered from pure Ti metal and from several terrestrial oxides containing both Ti and Ca. Tunable lasers were employed to resonantly ionize neutral Ti atoms. We have chosen Ti specifically because of the importance of Ti isotopic anomalies in cosmochemistry
[en] Full text: o-TOF ICPMS was used for inorganic analysis of environmental, food and biological samples. The method validity was proved by analysis of spiked samples, reference materials, by determination without/with internal standards and the standard addition technique. The technique was shown to be powerful, and reliable for analysis of the samples mentioned, and high sample throughput enables environmental or biological screening studies. Independent of the number of elements analyzed, complete analysis and whole mass spectra are gained from a small sample amount in a very short time. (author)
[en] There has been significant progress in the field of mass spectrometry in the last two decades which has led to the advent of new ion sources, improvements in existing mass analysers and introduction of hybrid mass analysers. The technique continues to advance with new developments in related fields and many new applications have emerged, particularly in health sciences and for forensic applications. The expectation from users are determination of single atom/molecule with highest possible specificity. The present symposium will focus on different aspects of mass spectrometry such as use of mass spectrometry in the nuclear industry, nano structures and fundamental chemical processes, biological aspects, inter-cluster reactions, advanced instrumentation etc. Papers relevant to INIS are indexed separately
[en] Concentrations of 239+249Pu in environmental samples were determined by ICP-MS and α spectrometry, showing consistent results, which suggests an applicability of ICP-MS to 239Pu and 240Pu measurement. The activity ratios of 238Pu/239+240Pu and 240Pu/239Pu were significantly different in samples from the general environment and near Sellafield reprocessing plants, indicating the usefulness of these ratios for identification of the Pu contamination source. (author)
[en] Applications of Time-of-Flight Mass Spectrometer (TOF -MS) for RIMS are quite well known. Enhancement in mass resolution of RIMS signals is expected by replacing the TOF-MS with RTOF -MS. We have designed such a RTOF instrument as part of our RIMS set up. The mass spectrometer designed is based on optimization using an ion simulation software with improved resolution and sensitivity. The mass spectrometer consists of electrodes for ion accelerator with two stages of homogeneous electric fields, and an ion reflector with a single stage of homogeneous electric field. The ions after acceleration can be focused as well as steered in both vertical and horizontal directions with the ion optics incorporated in the system. A novel grid design for uniform electric field and high transmission at extraction, acceleration and reflectron stages is included. The accelerator and ion reflector are separated by the first field free drift space. The ion reflector and the micro channel plate (MCP) ion detector are separated by a second field free drift space. Optimized electric fields on the electrodes ensure that a spatial distribution of ions initially at rest in the ion extraction zone are brought to a temporal focusing of first and second orders in the detector plane. Simultaneous energy focusing is also possible along with spatial focusing. Therefore, mass resolution is enhanced over the linear TOF-MS that provides only for longitudinal focusing of first order, while the optimized novel grid design ensures that ion transmission and instrument sensitivity are improved
[en] For the purpose of analyzing the interactive mechanisms between hyperthermal particles and a solid surface, a formal expression describing the dependency of surface effective mass upon the incident angle of the oncoming particle is presented. The formulation is deduced based on the interrelationships among the surface effective mass, the distance of impulse propagation and the non-conservative tangential momentum of the oncoming particle. Following the deduction, some reasoning is attempted toward the viewpoint adopted frequently by the exiting works where the mass is assumed to be constant
[en] We present a compact theorem which reveals the fact that static spatially regular massive scalar fields with nonminimal coupling to gravity cannot form spherically symmetric asymptotically flat horizonless matter configurations. In particular, the no-go theorem rules out the existence of boson stars made of static scalar fields with generic values of the physical parameter ξ which quantifies the coupling between the spacetime curvature and the massive bosonic fields. (orig.)
[en] Electrostatic time-of-flight spectrometers are commonly used in atomic physics as charge or mass analyzers. Various specialized schemes designed to minimize the time dispersion of the measured signal have been designed and implemented. However, little attention has been paid either to the general scaling rules underlying the design and operation of these devices, or to their properties when viewed as optical systems. In this work, a general approach to the analysis and design of multisegment time-of-flight spectrometers is presented and then applied to the optimization of both time focusing and transverse space focusing in a typical device. (orig.)
[en] High-precision nuclear mass data is required for several scientific applications like calculations on the astrophysical r-process, nuclear structure studies and tests of nuclear mass models. Such data is gained for example by the double Penning trap mass spectrometer TRIGA-TRAP, one branch of the TRIGA-SPEC experiment, which has recently been set up in order to investigate the neutron-rich as well as the long-lived transuranium area of the chart of nuclides. The nuclides of interest are either produced by thermal neutron-induced fission of a uranium target or ionized off-line in a laser ablation ion source. Mass measurements on rare-earth nuclides were already performed and deviations from the literature values were discovered. In this talk the present status of the TRIGA-TRAP experiment is outlined, and the influence of the latest mass measurement results on the Atomic-Mass Evaluation is presented.
[en] The lightest mass eigenvalue of a six-dimensional theory compactified on a torus is numerically evaluated in the presence of the brane-localized mass term. The dependence on the cutoff scale Λ is non-negligible even when Λ is two orders of magnitude above the compactification scale, which indicates that the mass eigenvalue is sensitive to the size of the brane, in contrast to five-dimensional theories. We obtain an approximate expression of the lightest mass in the thin brane limit, which well fits the numerical calculations, and clarifies its dependence on the torus moduli parameter τ. We find that the lightest mass is typically much lighter than the compactification scale by an order of magnitude even in the limit of a large brane mass.