Showing papers by "Lutz Schweikhard published in 2005"
TL;DR: The Penning-trap mass spectrometer at the ion trap facility SHIPTRAP is in the final stage of commissioning as discussed by the authors, and the first on-line mass measurements of neutron-deficient radionuclides in the rare-earth region around A = 147 were performed in July 2004.
Abstract: The Penning-trap mass spectrometer at the ion trap facility SHIPTRAP is in the final stage of commissioning. First on-line mass measurements of neutron-deficient radionuclides in the rare-earth region around A = 147 were performed in July 2004. Systematic investigations in order to determine systematic errors are ongoing. Further improvements of the efficiency of the system are in preparation, e.g. improved detection schemes and further optimization of the stopping cell. SHIPTRAP will then address exotic nuclides produced in fusion-evaporation reactions at the velocity filter SHIP. This production technique will give access to nuclei not available at ISOL facilities, especially in the transuranium region.
83 citations
TL;DR: In this article, the use of computational methods is discussed for plasma edge physics and plasma turbulence studies, and the problem of plasma-wall interaction requires multi-scale methods (molecular dynamics, kinetic Monte Carlo).
Abstract: The use of computational methods is discussed for plasma edge physics and plasma turbulence studies. The problem of plasma-wall interaction requires multi-scale methods (molecular dynamics, kinetic Monte Carlo). Plasma transport is studied with quite different methods. For low temperature plasmas it is sometimes still possible to use a full kinetic model, using so-called superparticles representing a large number of real particles. Similar methods are used in the gyro-kinetic description of turbulence in high temperature plasmas or in astrophysical plasmas. For longer length scales fluid models are usually used leading to mixed conduction-convection problems. The concept of local magnetic coordinates allow transport analysis also for ergodic magnetic configurations.
74 citations
TL;DR: In this article, the triple-trap mass spectrometer ISOLTRAP at ISOLDE/CERN has demonstrated the feasibility of in-trap-decay product ions.
Abstract: The triple-trap mass spectrometer ISOLTRAP at ISOLDE/CERN has demonstrated the feasibility of mass spectrometry of in-trap-decay product ions. This novel technique gives access to radionuclides, which are not produced directly at ISOL-type radioactive ion beam facilities. As a proof of principle, the in-trap decay of 37K+ has been investigated in a Penning trap filled with helium buffer gas. The half-life of the mother nuclide was confirmed and the recoiling 37Ar+ daughter ion was contained within the trap. The ions of either the mother or the daughter nuclide were transferred to a precision Penning trap, where their mass was determined.
26 citations
TL;DR: In this paper, it was shown that the dianion yield depends on the size of the fullerenes with more than 10% of the trapped C90- ions forming dianions while the corresponding relative yield was less than 0.1%.
Abstract: Fullerene dianions in the range C702- to C902- have been created by subjecting trapped fullerene monoanions to low energy electrons in a Penning trap. The dianion production was found to be a function of the trapping-potential depth and the time of interaction between the simultaneously stored monoanions and electrons. Under similar conditions the dianion yield depends on the size of the fullerenes with more than 10% of the trapped C90- ions forming dianions while the corresponding relative yield for C702- was less than 0.1%. The large difference can be explained by the repulsive Coulomb barrier and the second electron affinity of the fullerenes.
21 citations
TL;DR: The Penning trap mass spectrometer ISOLTRAP has been used for the determination of close to 300 masses of radionuclides and a relative mass uncertainty of 10-8 can now be reached.
Abstract: The Penning trap mass spectrometer ISOLTRAP has to date been used for the determination of close to 300 masses of radionuclides. A relative mass uncertainty of 10-8 can now be reached. Recent highlights were measurements of rp-process nuclides as for instance 72-74Kr or superallowed β emitters like 22Mg, 74Rb and 34Ar. The heaviest nuclides measured so far with ISOLTRAP are neutron-rich radium and francium isotopes. An overview of ISOLTRAP mass measurements and details about the recent experiment on 229-232Ra and 230Fr are presented.
19 citations
TL;DR: Clusters consisting of a few atoms build the bridge between individual atoms and the condensed phase of matter and they are, thus, of great general interest and ideally suited for the calibration of mass spectrometers and for consistency checks in high-accuracy mass determinations.
Abstract: Clusters consisting of a few atoms build the bridge between individual atoms and the condensed phase of matter and they are, thus, of great general interest. Over the last two decades, considerable progress has been made in the study of their properties and ion storage techniques, in particular the use of ion cyclotron resonance (Penning) traps, are important tools for advanced investigations. Vice versa, cluster ions can serve as probes for the evaluation of ion-trap properties. Furthermore, they are ideally suited for the calibration of mass spectrometers and for consistency checks in high-accuracy mass determinations. Examples from the research areas mentioned, i.e. the investigation of cluster properties and the application of cluster ions for Penning-trap studies and mass calibration, are reported.
16 citations
TL;DR: In this article, the third harmonic of a Nd:YAG laser was used to extract relative dissociation energies from the mass spectra of Au30+α-clusters.
Abstract: Ion trapping allows detailed studies of atomic
clusters with various interactions and over a large range of timescales.
An overview of methods at hand is given and a specific
example is presented in detail where size-selected Au30+
clusters have been stored in a Penning trap and photofragmented by
exposure to the third harmonic of a Nd:YAG laser. The resulting
mass spectra were sampled after reaction periods varying from
10 μs to 1 s. The data are used to extract relative
dissociation energies, which agree well with model-free values
determined previously by other means, albeit with a slightly
larger magnitude of the odd-even effect. Below n≃24
the relative dissociation energies
extracted from the abundance spectra develop very little over the
five orders of magnitude in time covered in the experiments.
This behavior has been predicted, but not tested previously. Above n≃24
both spectra and dissociation energies develop odd-even effects after a storage time
of 10–100 ms. Possible reasons for this behavior are discussed.
14 citations
TL;DR: The ISOLTRAP experiment at the ISOLDE facility at CERN is a Penning trap mass spectrometer for on-line mass measurements on short-lived radionuclides.
13 citations
TL;DR: In this paper, high-precision mass measurements were performed on Ni, Cu, and Ga isotopes at the triple-trap mass spectrometer ISOLTRAP at ISOLDE/CERN.
Abstract: Recently high-precision mass measurements were performed on Ni, Cu, and Ga isotopes at the triple-trap mass spectrometer ISOLTRAP at ISOLDE/CERN. The relative uncertainty was of the order of 10-8. Data indicate a competition between the sub-shell closure N = 40 and the mid-shell region N = 39 between the well-known magic numbers N = 28 and N = 50.
12 citations
TL;DR: The mass of radionuclides contribute to a variety of fundamental studies including tests of the weak interaction and the standard model as discussed by the authors, and the limits of mass measurements on exotic nuclides have been extended considerably by the Penning-trap mass spectrometer ISOLTRAP at the ISOLDE facility at CERN.
Abstract: The mass of radionuclides contribute to a variety of fundamental studies including tests of the weak interaction and the standard model. The limits of mass measurements on exotic nuclides have been extended considerably by the Penning-trap mass spectrometer ISOLTRAP at the ISOLDE facility at CERN. Recent ISOLTRAP measurements are summarized and current technical improvements are outlined.
7 citations
TL;DR: In this article, the reactions of stored ruthenium and osmium cations with oxygen have been studied in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer.
TL;DR: In this article, the authors determined the dissociation energy of V13+ by comparison of the rates of sequential fragmentation and single-step fragmentation of the first fragment, V12+→V 11+.
Abstract: The dissociation energy of V13+ has been determined by comparison of the rates of sequential fragmentation, V13+→V 12+→V 11+, and single-step fragmentation of the first fragment, V12+→V 11+. The dissociation-energy value obtained as D=4.35(13) eV has implications for the amount of radiative cooling of the cluster derived form the data presented earlier [C. Walther et al., Phys. Rev. Lett. 83, 3816 (1999)] and is used to analyze additional results.
TL;DR: In this article, new measurements performed with the Penning trap mass spectrometer ISOLTRAP extend the backbone to short-lived species, and recently obtained mass results are presented.
Abstract: New measurements performed with the Penning trap mass spectrometer ISOLTRAP extend the backbone to short-lived species. Recently obtained mass results are presented.
TL;DR: In this paper, a massenspektrometrie an atomaren Kernen gewinnt die Formel eine greifbare Bedeutung: Die Kernmasse verrat uns die Kernbindungsenergie.
Abstract: E = mc2 ist wohl die meist genannte Gleichung der modernen Physik, und das nicht nur im derzeitigen Einsteinjahr. Im Zusammenhang mit der Massenspektrometrie an atomaren Kernen gewinnt die Formel eine greifbare Bedeutung: Die Kernmasse verrat uns die Kernbindungsenergie. Uber die Massenzunahme lassen sich sogar angeregte Kernzustande identifizieren und massenspektrometrisch voneinander trennen. Dies konnte kurzlich am On-line-Massenseparator ISOLDE am CERN mit der Penning-Fallen-Apparatur ISOLTRAP demonstriert werden.