206 research outputs found
Q-Value and Half-Lives for the Double-Beta-Decay Nuclide 110Pd
The 110Pd double-beta decay Q-value was measured with the Penning-trap mass
spectrometer ISOLTRAP to be Q = 2017.85(64) keV. This value shifted by 14 keV
compared to the literature value and is 17 times more precise, resulting in new
phase-space factors for the two-neutrino and neutrinoless decay modes. In
addition a new set of the relevant matrix elements has been calculated. The
expected half-life of the two-neutrino mode was reevaluated as 1.5(6) E20 yr.
With its high natural abundance, the new results reveal 110Pd to be an
excellent candidate for double-beta decay studies
Ground-State Electromagnetic Moments of Calcium Isotopes
High-resolution bunched-beam collinear laser spectroscopy was used to measure
the optical hyperfine spectra of the Ca isotopes. The ground state
magnetic moments of Ca and quadrupole moments of Ca were
measured for the first time, and the Ca ground state spin was
determined in a model-independent way. Our results provide a critical test of
modern nuclear theories based on shell-model calculations using
phenomenological as well as microscopic interactions. The results for the
neutron-rich isotopes are in excellent agreement with predictions using
interactions derived from chiral effective field theory including three-nucleon
forces, while lighter isotopes illustrate the presence of particle-hole
excitations of the Ca core in their ground state.Comment: Accepted as a Rapid Communication in Physical Review
Spins, Electromagnetic Moments, and Isomers of 107-129Cd
The neutron-rich isotopes of cadmium up to the N=82 shell closure have been
investigated by high-resolution laser spectroscopy. Deep-UV excitation at 214.5
nm and radioactive-beam bunching provided the required experimental
sensitivity. Long-lived isomers are observed in 127Cd and 129Cd for the first
time. One essential feature of the spherical shell model is unambiguously
confirmed by a linear increase of the 11/2- quadrupole moments. Remarkably,
this mechanism is found to act well beyond the h11/2 shell
Precision Mass Measurements of 129-131Cd and Their Impact on Stellar Nucleosynthesis via the Rapid Neutron Capture Process
Masses adjacent to the classical waiting-point nuclide 130Cd have been
measured by using the Penning- trap spectrometer ISOLTRAP at ISOLDE/CERN. We
find a significant deviation of over 400 keV from earlier values evaluated by
using nuclear beta-decay data. The new measurements show the reduction of the N
= 82 shell gap below the doubly magic 132Sn. The nucleosynthesis associated
with the ejected wind from type-II supernovae as well as from compact object
binary mergers is studied, by using state-of-the-art hydrodynamic simulations.
We find a consistent and direct impact of the newly measured masses on the
calculated abundances in the A = 128 - 132 region and a reduction of the
uncertainties from the precision mass input data
Probing the N = 32 shell closure below the magic proton number Z = 20: Mass measurements of the exotic isotopes 52,53K
The recently confirmed neutron-shell closure at N = 32 has been investigated
for the first time below the magic proton number Z = 20 with mass measurements
of the exotic isotopes 52,53K, the latter being the shortest-lived nuclide
investigated at the online mass spectrometer ISOLTRAP. The resulting
two-neutron separation energies reveal a 3 MeV shell gap at N = 32, slightly
lower than for 52Ca, highlighting the doubly-magic nature of this nuclide.
Skyrme-Hartree-Fock-Boguliubov and ab initio Gorkov-Green function calculations
are challenged by the new measurements but reproduce qualitatively the observed
shell effect.Comment: 5 pages, 5 figure
Calculation of electrostatic fields using quasi-Green's functions: application to the hybrid Penning trap.
Penning traps offer unique possibilities for storing, manipulating and investigating charged particles with high sensitivity and accuracy. The widespread applications of Penning traps in physics and chemistry comprise e.g. mass spectrometry, laser spectroscopy, measurements of electronic and nuclear magnetic moments, chemical sample analysis and reaction studies. We have developed a method, based on the Green's function approach, which allows for the analytical calculation of the electrostatic properties of a Penning trap with arbitrary electrodes. The ansatz features an extension of Dirichlet's problem to nontrivial geometries and leads to an analytical solution of the Laplace equation. As an example we discuss the toroidal hybrid Penning trap designed for our planned measurements of the magnetic moment of the (anti)proton. As in the case of cylindrical Penning traps, it is possible to optimize the properties of the electric trapping fields, which is mandatory for high-precision experiments with single charged particles. Of particular interest are the anharmonicity compensation, orthogonality and optimum adjustment of frequency shifts by the continuous SternGerlach effect in a quantum jump spectrometer. The mathematical formalism developed goes beyond the mere design of novel Penning traps and has potential applications in other fields of physics and engineering
Laser spectroscopy of cadmium isotopes: probing the nuclear structure between the neutron 50 and 82 shell closures
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