News Archive 2008

Prof. Dr. Klaus Blaum has been elected a fellow of the American Physical Society. Read more ... >

In this article a novel Penning trap is introduced, which we call the hybrid Penning trap: a combination of cylindrical electrodes and electrodes of non-cylindrical shape, e.g. toroidal or hyperbolic, as opposed to purely cylindrical traps consisting of cylindrical electrodes only. A quasi-Green's function method renders possible the analytical calculation of any hybrid Penning trap allowing for the analytical calculation of the entire electrostatic properties. In a toroidal hybrid trap with the ring electrode made out of ferromagnetic material, the magnetic bottle field is enhanced by more than an order of magnitude which enables the use of the continuous Stern-Gerlach effect for our planned measurement of the proton g-factor. Detailed analytical expressions for the design of a toroidal hybrid Penning trap for are given simplifying the development of such traps for high-precision experiments. Read more ... >

A just in Physical Review C published article reports on accurate mass measurements of very neutron-deficient nuclides below tin to ascertain their impact on the nucleosynthesis. The data were obtained within joint experiments at the Penning trap facilities JYFLTRAP at JYFL/Jyväskylä and SHIPTRAP at GSI/Darmstadt. In total, 21 nuclides from yttrium to palladium were studied, and almost half of the mass values were experimentally determined for the first time. Many of the studied nuclides play a role in two astrophysical nucleosynthesis processes, the rp- and the recently discovered νp-process. Their proton-capture rates and finally the isotonic abundance ratios are influenced by the obtained mass data. The data obtained at both facilities agree within their uncertainties, and their weighted averages were given as the final results. Relative mass uncertainties of typically dm/m = 5E-8 have been achieved corresponding to a reduction by more than a factor of ten. The impact of the new mass values has been studied in νp-process nucleosynthesis calculations. The resulting reaction flow and the final abundances were compared with those obtained with the data of the Atomic Mass Evaluation AME2003. Read more details in the article ... >

The neutron-rich isotope 11Li has an exceptionally large radius. Its nuclear system consists of a core with two loosely bound neutrons around it. This is the concept of the so called halo nuclei. By comparing the quadrupole moment of the 11Li halo nucleus to that of its 9Li core, one can investigate the influence of halo neutrons on the core. In a recently in PRL published article R. Neugart et al. report the measurement of the electric quadrupole moment and the magnetic moment of the 11Li halo nucleus with a precision improved by an order of magnitude. The measurements have been performed at ISOLDE/CERN, Geneva using an improved experimental method which is based on the nuclear magnetic resonance (NMR) technique. A 8.8(1.5)% increase of the 11Li quadrupole moment relative to that of 9Li was found. While modern nuclear theories have difficulties simultaneously reproducing the charge radii and quadrupole moments of both Li isotopes, the simple halo picture allows to illustrate the relationship between both quantities. Read more ... >

The Max Planck Institute for Nuclear Physics is celebrating its 50th anniversary with an open house on 28. September 2008 from 10 a.m. until 5 p.m..

At the Research Reactor TRIGA Mainz  currently a setup for high-precision mass measurements and laser spectroscopy on heavy and neutron-rich nuclides is built. A just published article gives a survey of the experimental setup and the physical objective of TRIGA-SPEC (J.Ketelaer et al., Nucl. Instr. Meth. A 594 (2008) 162 ). At beam tube B of the reactor the Penning trap mass spectrometer TRIGA-TRAP has already been set up and is currently commissioned. Moreover we build a collinear laser spectroscopy beamline and an on-line ion source with a magnetic mass separator as coupling to the reactor.