Publications (44)69.09 Total impact
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Article: New mass data for the rp-process above Z = 32
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ABSTRACT: High-accuracy mass measurements have been performed with the Penning trap mass spectrometer ISOLTRAP at ISOLDE/CERN. The short-lived nuclides 70, 71, 72, 73Se , 72, 73, 74, 75Br , and 98, 99, 100, 101, 103Ag have been measured with an average uncertainty of a few keV. The data are important input for nucleosynthesis calculations of the rp-process beyond Z = 32 .European Physical Journal A 04/2012; 47(6):1-9. · 2.19 Impact Factor -
Article: Cadmium mass measurements between the neutron shell closures at N = 50 and 82
AIP Conf. Proc. 01/2011; 1377(1):332-334. -
Article: Approaching the N= 82 shell closure with mass measurements of Ag and Cd isotopes
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ABSTRACT: Mass measurements of neutron-rich Cd and Ag isotopes were performed with the Penning trap mass spectrometer ISOLTRAP. The masses of 112,114-124Ag and 114,120,122-124,126,128Cd, determined with relative uncertainties between 2×10-8 and 2×10-7, resulted in significant corrections and improvements of the mass surface. In particular, the mass of 124Ag was previously unknown. In addition, other masses that had to be inferred from Q values of nuclear decays and reactions have now been measured directly. The analysis includes various mass differences, namely the two-neutron separation energies, the applicability of the Garvey-Kelson relations, double differences of masses δVpn, which give empirical proton-neutron interaction strengths, as well as a comparison with recent microscopic calculations. The δVpn results reveal that for even-even nuclides around 132Sn the trends are similar to those in the 208Pb region.Phys. Rev. C. 03/2010; 81(3). -
Article: Masses and charge radii of 17-22Ne and the two-proton-halo candidate 17Ne.
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ABSTRACT: High-precision mass and charge radius measurements on ;{17-22}Ne, including the proton-halo candidate 17Ne, have been performed with Penning trap mass spectrometry and collinear laser spectroscopy. The 17Ne mass uncertainty is improved by factor 50, and the charge radii of ;{17-19}Ne are determined for the first time. The fermionic molecular dynamics model explains the pronounced changes in the ground-state structure. It attributes the large charge radius of 17Ne to an extended proton configuration with an s;{2} component of about 40%. In 18Ne the smaller radius is due to a significantly smaller s;{2} component. The radii increase again for ;{19-22}Ne due to cluster admixtures.Physical Review Letters 01/2009; 101(25):252502. · 7.37 Impact Factor -
Article: Mass measurements beyond the major r-process waiting point 80Zn.
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ABSTRACT: High-precision mass measurements on neutron-rich zinc isotopes (71m,72-81)Zn have been performed with the Penning trap mass spectrometer ISOLTRAP. For the first time, the mass of 81Zn has been experimentally determined. This makes 80Zn the first of the few major waiting points along the path of the astrophysical rapid neutron-capture process where neutron-separation energy and neutron-capture Q-value are determined experimentally. The astrophysical conditions required for this waiting point and its associated abundance signatures to occur in r-process models can now be mapped precisely. The measurements also confirm the robustness of the N=50 shell closure for Z=30.Physical Review Letters 01/2009; 101(26):262501. · 7.37 Impact Factor -
Article: Electric and magnetic field optimization procedure for Penning trap mass spectrometers
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ABSTRACT: Significant systematic errors in high-precision Penning trap mass spectrometry can result from electric and magnetic field imperfections. An experimental procedure to minimize these uncertainties is presented for the on-line Penning trap mass spectrometer ISOLTRAP, located at ISOLDE/CERN. The deviations from the ideal magnetic and electric fields are probed by measuring the cyclotron frequency and the reduced cyclotron frequency, respectively, of stored ions as a function of the time between the ejection of ions from the preparation trap and their capture in the precision trap, which influences the energy of their axial motion. The correction parameters are adjusted to minimize the frequency shifts.06/2008; -
Article: Time-separated oscillatory fields for high-precision mass measurements on short-lived Al and Ca nuclides
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ABSTRACT: High-precision Penning trap mass measurements on the stable nuclide 27Al as well as on the short-lived radionuclides 26Al and 38,39Ca have been performed by use of radiofrequency excitation with time-separated oscillatory fields, i.e. Ramsey's method, recently extended to Penning trap mass measurements of radioactive isotopes. A comparison with the conventional method of a single continuous excitation demonstrates the advantage of up to ten times shorter measurements. The new mass values of 26,27Al are compared to literature values and clarify conflicting data in this mass region. In addition, the resulting mass values of the superallowed β-emitter 38Ca as well as of the ground state of the β-emitter 26Alm confirm previous measurements.EPL (Europhysics Letters) 05/2008; 82(5):50005. · 2.17 Impact Factor -
Article: Restoration of the n=82 shell gap from direct mass measurements of 132,134Sn.
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ABSTRACT: A high-precision direct Penning trap mass measurement has revealed a 0.5-MeV deviation of the binding energy of (134)Sn from the currently accepted value. The corrected mass assignment of this neutron-rich nuclide restores the neutron-shell gap at N=82, previously considered to be a case of "shell quenching." In fact, the new shell gap value for the short-lived (132)Sn is larger than that of the doubly magic (48)Ca which is stable. The N=82 shell gap has considerable impact on fission recycling during the r process. More generally, the new finding has important consequences for microscopic mean-field theories which systematically deviate from the measured binding energies of closed-shell nuclides.Physical Review Letters 03/2008; 100(7):072501. · 7.37 Impact Factor -
Article: Evidence for a breakdown of the Isobaric Multiplet Mass Equation: A study of the A=35, T=3/2 isospin quartet
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ABSTRACT: Mass measurements on radionuclides along the potassium isotope chain have been performed with the ISOLTRAP Penning trap mass spectrometer. For 35K T1/2=178ms) to 46K (T1/2=105s) relative mass uncertainties of 2x10-8 and better have been achieved. The accurate mass determination of 35K (dm=0.54keV) has been exploited to test the Isobaric Multiplet Mass Equation (IMME) for the A=35, T=3/2 isospinquartet. The experimental results indicate a deviation from the generally adopted quadratic form.08/2007; -
Article: Ramsey method of separated oscillatory fields for high-precision penning trap mass spectrometry.
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ABSTRACT: Ramsey's method of separated oscillatory fields is applied to the excitation of the cyclotron motion of short-lived ions in a Penning trap to improve the precision of their measured mass values. The theoretical description of the extracted ion-cyclotron-resonance line shape is derived and its correctness demonstrated experimentally by measuring the mass of the short-lived 38Ca nuclide with an uncertainty of 1.1 x 10(-8) using the Penning trap mass spectrometer ISOLTRAP at CERN. The mass of the superallowed beta emitter 38Ca contributes for testing the theoretical corrections of the conserved-vector-current hypothesis of the electroweak interaction. It is shown that the Ramsey method applied to Penning trap mass measurements yields a statistical uncertainty similar to that obtained by the conventional technique but 10 times faster. Thus the technique is a new powerful tool for high-precision mass measurements.Physical Review Letters 05/2007; 98(16):162501. · 7.37 Impact Factor -
Article: High-precision mass measurements of nickel, copper, and gallium isotopes and the purported shell closure at N=40
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ABSTRACT: High-precision mass measurements of more than thirty neutron-rich nuclides around the Z=28 closed proton shell were performed with the triple-trap mass spectrometer ISOLTRAP at ISOLDE/CERN to address the question of a possible neutron shell closure at N=40. The results, for 57,60,64-69Ni (Z=28), 65-74,76Cu (Z=29), and 63-65,68-78Ga (Z=31), have a relative uncertainty of the order of 10^8. In particular, the masses of 72-74,76Cu have been measured for the first time. We analyse the resulting mass surface for signs of magicity, comparing the behavior of N=40 to that of known magic numbers and to mid-shell behavior. Contrary to nuclear spectroscopy studies, no indications of a shell or sub-shell closure are found for N=40.02/2007; -
Article: Separated Oscillatory Fields for High-Precision Penning Trap Mass Spectrometry
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ABSTRACT: Ramsey's method of separated oscillatory fields is applied to the excitation of the cyclotron motion of short-lived ions in a Penning trap to improve the precision of their measured mass. The theoretical description of the extracted ion-cyclotron-resonance line shape is derived out and its correctness demonstrated experimentally by measuring the mass of the short-lived $^{38}$Ca nuclide with an uncertainty of $1.6\cdot 10^{-8}$ using the ISOLTRAP Penning trap mass spectrometer at CERN. The mass value of the superallowed beta-emitter $^{38}$Ca is an important contribution for testing the conserved-vector-current hypothesis of the electroweak interaction. It is shown that the Ramsey method applied to mass measurements yields a statistical uncertainty similar to that obtained by the conventional technique ten times faster.02/2007; -
Article: Towards a magnetic field stabilization at ISOLTRAP for high-accuracy mass measurements on exotic nuclides
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ABSTRACT: The field stability of a mass spectrometer plays a crucial role in the accuracy of mass measurements. In the case of mass determination of short-lived nuclides with a Penning trap, major causes of fluctuations are temperature variations in the vicinity of the trap and pressure changes in the liquid helium cryostat of the superconducting magnet. Thus systems for the temperature and pressure stabilization of the Penning trap mass spectrometer ISOLTRAP at the ISOLDE facility at CERN have been installed. A reduction of the temperature and pressure fluctuations by at least an order of magnitude down to and has been achieved, which corresponds to a relative magnetic field change of ΔB/B=2.7×10-9 and 1.1×10-10, respectively.Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 01/2007; -
Article: Population inversion of nuclear states by a Penning trap mass spectrometer
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ABSTRACT: According to the energy-mass equivalence, E = mc2, excited long-lived nuclear states, so-called isomers, are distinguished from the ground state by their additional mass. The ultra-high accuracy provided by Penning traps now allows to weigh nuclear excitation energies. With the on-line Penning trap mass spectrometer ISOLTRAP, we have developed a mass-separation procedure of sufficient resolving power to isolate particles of a selected isomeric state from an ensemble delivered from the radioactive beam facility ISOLDE at CERN, first demonstrated for 68Cu. The resulting unique form of ion ensembles opens up a large variety of new nuclear-physics experiments. Mass excesses of -65567.0(1.6) keV for the 1+ ground state and -64850.3(1.5) keV for the 6− isomeric state have been determined.EPL (Europhysics Letters) 01/2007; 67(4):586. · 2.17 Impact Factor -
Article: A new Channeltron-detector setup for precision mass measurements at ISOLTRAP
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ABSTRACT: Recent technical developments at ISOLTRAP include the design, installation and characterization of a new Channeltron-detector setup in order to increase the detection efficiency by about a factor of 3. Since a detection efficiency close to 100% is reached, true single-ion experiments can be performed for the first time and exotic nuclides further away from the valley of stability with lower production yields and/or shorter half-lives as compared to previous investigations are accessible.Hyperfine Interactions 10/2006; 173(1):181-193. · 0.21 Impact Factor -
Article: High-Accuracy Mass Measurements for a Test of the Standard Model
10/2006; 637:19. -
Article: High-accuracy mass measurements of neutron-rich Kr isotopes
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ABSTRACT: The atomic masses of the neutron-rich krypton isotopes 84,86-95Kr have been determined with the tandem Penning trap mass spectrometer ISOLTRAP with uncertainties ranging from 20 to 220 ppb. The masses of the short-lived isotopes 94Kr and 95Kr were measured for the first time. The masses of the radioactive nuclides 89Kr and 91Kr disagree by 4 and 6 standard deviations, respectively, from the present Atomic-Mass Evaluation database. The resulting modification of the mass surface with respect to the two-neutron separation energies as well as implications for mass models and stellar nucleosynthesis are discussed.Phys. Rev. C. 09/2006; 74(3). -
Article: ISOLTRAP Mass Measurements for Weak‐Interaction Studies
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ABSTRACT: The conserved‐vector‐current (CVC) hypothesis of the weak interaction and the unitarity of the Cabibbo‐Kobayashi‐Maskawa (CKM) matrix are two fundamental postulates of the Standard Model. While existing data on CVC supports vector current conservation, the unitarity test of the CKM matrix currently fails by more than two standard deviations. High‐precision mass measurements performed with the ISOLTRAP experiment at ISOLDE/CERN provide crucial input for these fundamental studies by greatly improving our knowledge of the decay energy of super‐allowed β decays. Recent results of mass measurements on the β emitters 18Ne, 22Mg, 34Ar, and 74Rb as pertaining to weak‐interaction studies are presented. © 2006 American Institute of PhysicsAIP Conference Proceedings. 04/2006; 831(1):49-54. -
Article: Mass measurements of 56−57Cr and the question of shell reincarnation at N = 32
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ABSTRACT: Binding energies determined with high accuracy provide smooth derivatives of the mass surface for analysis of shell and pairing effects. Measurements with the Penning trap mass spectrometer ISOLTRAP at CERN-ISOLDE were made for 56−57Cr for which an accuracy of 4 × 10−8 was achieved. Analysis of the mass surface for the supposed new N = 32 shell closure rather indicates a sub-shell closure, but of a different nature than known cases such as 94Sr.Journal of Physics G Nuclear and Particle Physics 09/2005; 31(10):S1765. · 4.18 Impact Factor -
Article: ISOLTRAP pins down masses of exotic nuclides
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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.Journal of Physics G Nuclear and Particle Physics 09/2005; 31(10):S1775. · 4.18 Impact Factor
Top co-authors
Top Journals
Institutions
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2006–2012
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GSI Helmholtzzentrum für Schwerionenforschung
Jena, Thuringia, Germany
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2005–2009
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Ernst-Moritz-Arndt-Universität Greifswald
- Institut für Physik
Greifswald, Mecklenburg-Vorpommern, Germany -
Johannes Gutenberg-Universität Mainz
- Institute of Physics
Mainz, Rhineland-Palatinate, Germany
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2004
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KU Leuven
- Section of Nuclear and Radiation Physics (IKS)
Leuven, VLG, Belgium -
European Organization for Nuclear Research
- Physics Department (PH)
Genève, GE, Switzerland
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