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The masses of ten proton-rich nuclides, including the N=Z+1 nuclides 85-Mo and 87-Tc, were measured with the Penning trap mass spectrometer SHIPTRAP. Compared to the Atomic Mass Evaluation 2003 a systematic shift of the mass surface by up to 1.6 MeV is observed causing significant abundance changes of the ashes of astrophysical X-ray bursts. Surprisingly low alpha-separation energies for neutron-deficient Mo and Tc are found, making the formation of a ZrNb cycle in the rp process possible. Such a cycle would impose an upper temperature limit for the synthesis of elements beyond Nb in the rp process., Comment: Link to online abstract: http://link.aps.org/doi/10.1103/PhysRevLett.106.122501

Changes in the mean-square nuclear charge radii along the lithium isotopic chain were determined using a combination of precise isotope shift measurements and theoretical atomic structure calculations. Nuclear charge radii of light elements are of high interest due to the appearance of the nuclear halo phenomenon in this region of the nuclear chart. During the past years we have developed a new laser spectroscopic approach to determine the charge radii of lithium isotopes which combines high sensitivity, speed, and accuracy to measure the extremely small field shift of an 8 ms lifetime isotope with production rates on the order of only 10,000 atoms/s. The method was applied to all bound isotopes of lithium including the two-neutron halo isotope Li-11 at the on-line isotope separators at GSI, Darmstadt, Germany and at TRIUMF, Vancouver, Canada. We describe the laser spectroscopic method in detail, present updated and improved values from theory and experiment, and discuss the results., Comment: 34 pages, 24 figures, 14 tables

Penning trap mass measurements on neutron-deficient Cd isotopes (99-109)Cd have been performed with the ISOLTRAP mass spectrometer at ISOLDE/CERN, all with relative mass uncertainties below 3*10^8. A new mass evaluation has been performed. The mass of 99Cd has been determined for the first time which extends the region of accurately known mass values towards the doubly magic nucleus 100Sn. The implication of the results on the reaction path of the rp process in stellar X-ray bursts is discussed. In particular, the uncertainty of the abundance and the overproduction created by the rp-process for the mass A = 99 is demonstrated by reducing the uncertainty of the proton-separation energy of 100In Sp(100In) by a factor of 2.5., Comment: 14 pages, 9 figures

High-precision mass measurements on neutron-rich zinc isotopes 71m,72-81Zn 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. As a consequence, 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 farther from stability., Comment: 4 pages, 3 figures

The masses of very neutron-deficient nuclides close to the astrophysical rp- and nu p-process paths have been determined with the Penning trap facilities JYFLTRAP at JYFL/Jyv\"askyl\"a and SHIPTRAP at GSI/Darmstadt. Isotopes from yttrium (Z = 39) to palladium (Z = 46) have been produced in heavy-ion fusion-evaporation reactions. In total 21 nuclides were studied and almost half of the mass values were experimentally determined for the first time: 88Tc, 90-92Ru, 92-94Rh, and 94,95Pd. For the 95Pdm, (21/2^+) high-spin state, a first direct mass determination was performed. Relative mass uncertainties of typically $\delta m / m = 5 \times 10^{-8}$ were obtained. The impact of the new mass values has been studied in nu p-process nucleosynthesis calculations. The resulting reaction flow and the final abundances are compared to those obtained with the data of the Atomic Mass Evaluation 2003., Comment: 21 pages, 12 figures, 2 tables, submitted to Phys. Rev. C

Isotope shifts in dielectronic recombination spectra were studied for Li-like ^{A}Nd^{57+} ions with A=142 and A=150. From the displacement of resonance positions energy shifts \delta E^{142,150}(2s-2p_1/2)= 40.2(3)(6) meV (stat)(sys)) and \delta E^{142,150}(2s-2p_3/2) = 42.3(12)(20) meV of 2s-2p_j transitions were deduced. An evaluation of these values within a full QED treatment yields a change in the mean-square charge radius of ^{142,150}\delta = -1.36(1)(3) fm^2. The approach is conceptually new and combines the advantage of a simple atomic structure with high sensitivity to nuclear size., Comment: 10 pages, 3 figures, accepted for publication in Physical Review Letters

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, as recently introduced for the excitation of the ion motion in a Penning trap, was applied. A comparison with the conventional method of a single continuous excitation demonstrates its advantage of up to ten times shorter measurements. The new mass values of 26,27Al clarify conflicting data in this specific mass region. In addition, the resulting mass values of the superallowed beta-emitter 38Ca as well as of the groundstate of the beta-emitter 26Al m confirm previous measurements and corresponding theoretical corrections of the ft-values., Comment: 7 pages, 9 figures

Accurate atomic mass measurements of neutron-deficient and neutron-rich nuclides around the doubly-magic 208Pb and of neutron-rich cesium isotopes were performed with the Penning trap mass spectrometer ISOLTRAP at ISOLDE/CERN. The masses of 145,147Cs, 181,183Tl, 186Tlm, 187Tl, 196Tlm, 205Tl, 197Pbm, 208Pb, 190 to 197Bi, 209,215,216Bi, 203,205,229Fr, and 214,229,230Ra were determined. The obtained relative mass uncertainty in the range of $2 \cdot 10^{-7}$ to $2 \cdot 10^{-8}$ is not only required for safe identification of isomeric states but also allows mapping the detailed structure of the mass surface. A mass adjustment procedure was carried out and the results included into the Atomic Mass Evaluation. The resulting separation energies are discussed and the mass spectrometric and laser spectroscopic data are examined for possible correlations., Comment: 40 pages, 20 figures, accept. for publication in Nucl. Phys. A

An overview and status report of the new trapping facility for highly charged ions at the Gesellschaft fuer Schwerionenforschung is presented. The construction of this facility started in 2005 and is expected to be completed in 2008. Once operational, highly charged ions will be loaded from the experimental storage ring ESR into the HITRAP facility, where they are decelerated and cooled. The kinetic energy of the initially fast ions is reduced by more than fourteen orders of magnitude and their thermal energy is cooled to cryogenic temperatures. The cold ions are then delivered to a broad range of atomic physics experiments., Comment: 8 pages, 11 figures

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., Comment: 8 pages, 4 figures

Trapping and cooling techniques have become very important for many fundamental experiments in atomic physics. When applied to highly charged ions confined in Penning traps, these procedures are very effective for testing quantum electrodynamics in extreme electromagnetic fields produced by heavy highly charged ions such as uranium U$^{91+}$. In addition, fundamental constants or nuclear ground state properties can be determined with high accuracy in these simple systems. Finally, by studying a single trapped radioactive ion, its nuclear decay can be studied in detail by observing the disappearance of the signal of the mother and the appearance of that of the daughter isotope. Such experiments on highly charged ions at extremely low energy will become possible by the HITRAP facility which is currently being built up at GSI. Also the future Facility for Antiproton and Ion Research (FAIR) will be briefly described which is expected to be operational by 2014., Comment: 8 pages, 5 figures, 1 table. accepted for Journal of Physics Conference Series (2006)

First on-line mass measurements were performed at the SHIPTRAP Penning trap mass spectrometer. The masses of 18 neutron-deficient isotopes in the terbium-to-thulium region produced in fusion-evaporation reactions were determined with relative uncertainties of about $7\cdot 10^{-8}$, nine of them for the first time. Four nuclides ($^{144, 145}$Ho and $^{147, 148}$Tm) were found to be proton-unbound. The implication of the results on the location of the proton drip-line is discussed by analyzing the one-proton separation energies.

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., Comment: 14 figures

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., Comment: 5 pages, 4 figures, 0 tables

The nuclear charge radius of Li-11 has been determined for the first time by high precision laser spectroscopy. On-line measurements at TRIUMF-ISAC yielded a Li-7 - Li-11 isotope shift (IS) of 25101.23(13) MHz for the Doppler-free 2s - 3s transition. IS precision for all other bound Li isotopes was also improved. Differences from calculated mass-based IS yield values for change in charge radius along the isotope chain. The charge radius decreases monotonically from Li-6 to Li-9, and then increases from 2.217(35) fm to 2.467(37) fm for Li-11. This is compared to various models, and it is found that a combination of halo neutron correlation and intrinsic core excitation best reproduces the experimental results., Comment: 5 pages, 2 figures

The FRS-ESR facility at GSI provides unique conditions for precision measurements of large areas on the nuclear mass surface in a single experiment. Values for masses of 604 neutron-deficient nuclides (30<=Z<=92) were obtained with a typical uncertainty of 30 microunits. The masses of 114 nuclides were determined for the first time. The odd-even staggering (OES) of nuclear masses was systematically investigated for isotopic chains between the proton shell closures at Z=50 and Z=82. The results were compared with predictions of modern nuclear models. The comparison revealed that the measured trend of OES is not reproduced by the theories fitted to masses only. The spectral pairing gaps extracted from models adjusted to both masses, and density related observables of nuclei agree better with the experimental data., Comment: Physics Review Letters 95 (2005) 042501 http://link.aps.org/abstract/PRL/v95/e042501

An ion beam cooler and buncher has been developed for the manipulation of radioactive ion beams. The gas-filled linear radiofrequency ion trap system is installed at the Penning trap mass spectrometer ISOLTRAP at ISOLDE/CERN. Its purpose is to accumulate the 60-keV continuous ISOLDE ion beam with high efficiency and to convert it into low-energy low-emittance ion pulses. The efficiency was found to exceed 10% in agreement with simulations. A more than 10-fold reduction of the ISOLDE beam emittance can be achieved. The system has been used successfully for first on-line experiments. Its principle, setup and performance will be discussed.