145 research outputs found

    Nuclear Masses in Astrophysics

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    Among all nuclear ground-state properties, atomic masses are highly specific for each particular combination of N and Z and the data obtained apply to a variety of physics topics. One of the most crucial questions to be addressed in mass spectrometry of unstable radionuclides is the one of understanding the processes of element formation in the Universe. To this end, accurate atomic mass values of a large number of exotic nuclei participating in nucleosynthesis are among the key input data in large-scale reaction network calculations. In this paper, a review on the latest achievements in mass spectrometry for nuclear astrophysics is given.Comment: Proceedings of the 10th Symposium on Nuclei in the Cosmos, NIC X - Mackinac Island, Michigan, USA (10 pages, 4 figures

    First-order perturbative calculation of the frequency-shifts caused by static cylindrically-symmetric electric and magnetic imperfections of a Penning trap

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    The ideal Penning trap consists of a uniform magnetic field and an electrostatic quadrupole potential. Cylindrically-symmetric deviations thereof are parametrized by the coefficients Bn and Cn, respectively. Relativistic mass-increase aside, the three characteristic eigenfrequencies of a charged particle stored in an ideal Penning trap are independent of the three motional amplitudes. This three-fold harmonicity is a highly-coveted virtue for precision experiments that rely on the measurement of at least one eigenfrequency in order to determine fundamental properties of the stored particle, such as its mass. However, higher-order contributions to the ideal fields result in amplitude-dependent frequency-shifts. In turn, these frequency-shifts need to be understood for estimating systematic experimental errors, and eventually for correcting them by means of calibrating the imperfections. The problem of calculating the frequency-shifts caused by small imperfections of a near-ideal trap yields nicely to perturbation theory, producing analytic formulas that are easy to evaluate for the relevant parameters of an experiment. In particular, the frequency-shifts can be understood on physical rather than purely mathematical grounds by considering which terms actually drive them. Based on identifying these terms, we derive general formulas for the first-order frequency-shifts caused by any perturbation parameter Bn or Cn.Comment: 18 pages, 1 figure, 0 tables. Accepted manuscript subsequently published. Streamlined the introduction. Optimized choice of summation variable

    Classical calculation of relativistic frequency-shifts in an ideal Penning trap

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    The ideal Penning trap consists of a uniform magnetic field and an electrostatic quadrupole potential. In the classical low-energy limit, the three characteristic eigenfrequencies of a charged particle trapped in this configuration do not depend on the amplitudes of the three eigenmotions. No matter how accurate the experimental realization of the ideal Penning trap, its harmonicity is ultimately compromised by special relativity. Using a classical formalism of first-order perturbation theory, we calculate the relativistic frequency-shifts associated with the motional degrees of freedom for a spinless particle stored in an ideal Penning trap, and we compare the results with the simple but surprisingly accurate model of relativistic mass-increase.Comment: 8 pages, 0 figures, 1 table; Accepted manuscript subsequently published with a slightly extended description of the perturbative metho

    g factor of lithiumlike silicon 28Si11+

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    The g factor of lithiumlike 28Si11+ has been measured in a triple-Penning trap with a relative uncertainty of 1.1x10^{-9} to be g_exp=2.0008898899(21). The theoretical prediction for this value was calculated to be g_th=2.000889909(51) improving the accuracy to 2.5x10^{-8} due to the first rigorous evaluation of the two-photon exchange correction. The measured value is in excellent agreement with the state-of-the-art theoretical prediction and yields the most stringent test of bound-state QED for the g factor of the 1s^22s state and the relativistic many-electron calculations in a magnetic field

    A reservoir trap for antiprotons

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    We have developed techniques to extract arbitrary fractions of antiprotons from an accumulated reservoir, and to inject them into a Penning-trap system for high-precision measurements. In our trap-system antiproton storage times > 1.08 years are estimated. The device is fail-safe against power-cuts of up to 10 hours. This makes our planned comparisons of the fundamental properties of protons and antiprotons independent from accelerator cycles, and will enable us to perform experiments during long accelerator shutdown periods when background magnetic noise is low. The demonstrated scheme has the potential to be applied in many other precision Penning trap experiments dealing with exotic particles.Comment: Article by the BASE-collaboration at CERN. Results from the Antiproton physics run 2014. Submitted to International Journal of Mass Spectrometry, 8th of April 201

    Nuclear Charge Radius of 12^{12}Be

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    The nuclear charge radius of 12^{12}Be was precisely determined using the technique of collinear laser spectroscopy on the 2s1/2→2p1/2,3/22s_{1/2}\rightarrow 2p_{1/2, 3/2} transition in the Be+^{+} ion. The mean square charge radius increases from 10^{10}Be to 12^{12}Be by \delta ^{10,12} = 0.69(5) \fm^{2} compared to \delta ^{10,11} = 0.49(5) \fm^{2} for the one-neutron halo isotope 11^{11}Be. Calculations in the fermionic molecular dynamics approach show a strong sensitivity of the charge radius to the structure of 12^{12}Be. The experimental charge radius is consistent with a breakdown of the N=8 shell closure.Comment: 5 pages, 3 figure

    Long-term monitoring of the internal energy distribution of isolated cluster systems

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    A method is presented to monitor the internal energy distribution of cluster anions via delayed electron detachment by pulsed photoexcitation and demonstrated on Co4−_4{}^- in an electrostatic ion beam trap. In cryogenic operation, we calibrate the detachment delay to internal energy. By laser frequency scans, at room temperature, we reconstruct the time-dependent internal energy distribution of the clusters. The mean energies of ensembles from a cold and a hot ion source both approach thermal equilibrium. Our data yield a radiative emission law and the absorptivity of the cluster for thermal radiation.Comment: Manuscript LaTeX with 6 pages, 4 figures, plus LaTeX supplement with 9 pages, 4 figures and 2 tables. This article has been accepted by Physical Review Letter

    High-precision measurement of the atomic mass of the electron

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    The quest for the value of the electron's atomic mass has been subject of continuing efforts over the last decades. Among the seemingly fundamental constants which parameterize the Standard Model (SM) of physics and which are thus responsible for its predictive power, the electron mass me plays a prominent role, as it is responsible for the structure and properties of atoms and molecules. This manifests in the close link with other fundamental constants, such as the Rydberg constant and the fine-structure constant {\alpha}. However, the low mass of the electron considerably complicates its precise determination. In this work we present a substantial improvement by combining a very accurate measurement of the magnetic moment of a single electron bound to a carbon nucleus with a state-of-the-art calculation in the framework of bound-state Quantum Electrodynamics. The achieved precision of the atomic mass of the electron surpasses the current CODATA value by a factor of 13. Accordingly, the result presented in this letter lays the foundation for future fundamental physics experiments and precision tests of the SM

    Literatur-Rundschau

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    Margreth LĂŒnenborg: Joumalismus als kultureller Prozess (Klaus Arnold)Institut zur Förderung publizistischen Nachwuchses/Deutscher Presserat (Hg.): Ethik im Redaktionsalltag (Horst Pöttker)Elisabeth Hurth: "Gute Nacht, John Boy!". Familien vor und auf dem Bildschirm (Eckhard Bieger)GĂŒnther Mees: Stimme der Stimmlosen. UCIP - Katholische Weltunion der Presse (Ferdinand Oertel)Harald Schleicher/Alexander Urban (Hg.): Filme machen (Michael Harnischmacher)Heike B. Görtemaker: Ein deutsches Leben. Die Geschichte der Margret Boveri 1900-1975 (Verena Blaum)

    Collinear laser spectroscopy of atomic cadmium

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    Hyperfine structure AA and BB factors of the atomic 5s\,5p\,\; ^3\rm{P}_2 \rightarrow 5s\,6s\,\; ^3\rm{S}_1 transition are determined from collinear laser spectroscopy data of 107−123^{107-123}Cd and 111m−123m^{111m-123m}Cd. Nuclear magnetic moments and electric quadrupole moments are extracted using reference dipole moments and calculated electric field gradients, respectively. The hyperfine structure anomaly for isotopes with s1/2s_{1/2} and d5/2d_{5/2} nuclear ground states and isomeric h11/2h_{11/2} states is evaluated and a linear relationship is observed for all nuclear states except s1/2s_{1/2}. This corresponds to the Moskowitz-Lombardi rule that was established in the mercury region of the nuclear chart but in the case of cadmium the slope is distinctively smaller than for mercury. In total four atomic and ionic levels were analyzed and all of them exhibit a similar behaviour. The electric field gradient for the atomic 5s\,5p\,\; ^3\mathrm{P}_2 level is derived from multi-configuration Dirac-Hartree-Fock calculations in order to evaluate the spectroscopic nuclear quadrupole moments. The results are consistent with those obtained in an ionic transition and based on a similar calculation.Comment: 12 pages, 5 figure
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