29 research outputs found
Nuclear Charge Radius of Be
The nuclear charge radius of Be was precisely determined using the
technique of collinear laser spectroscopy on the transition in the Be ion. The mean square charge radius increases
from Be to 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 Be. Calculations in the fermionic molecular
dynamics approach show a strong sensitivity of the charge radius to the
structure of Be. The experimental charge radius is consistent with a
breakdown of the N=8 shell closure.Comment: 5 pages, 3 figure
Collinear laser spectroscopy of atomic cadmium
Hyperfine structure and 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 Cd and 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 and nuclear
ground states and isomeric states is evaluated and a linear
relationship is observed for all nuclear states except . 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
Precision Test of Many-Body QED in the Be Fine Structure Doublet Using Short-Lived Isotopes
Absolute transition frequencies of the 2s\; ^2{\rm S}_{1/2} \rightarrow
2p\;^2\mathrm{P}_{1/2,3/2} transitions in Be were measured for the
isotopes Be. The fine structure splitting of the state and its
isotope dependence are extracted and compared to results of \textit{ab initio}
calculations using explicitly correlated basis functions, including
relativistic and quantum electrodynamics effects at the order of
and . Accuracy has been improved in both the theory and
experiment by 2 orders of magnitude, and good agreement is observed. This
represents one of the most accurate tests of quantum electrodynamics for
many-electron systems, being insensitive to nuclear uncertainties.Comment: 5 pages, 2 figure
Nuclear charge radii of potassium isotopes beyond N = 28
We report on the measurement of optical isotope shifts for Âłâž, Âłâč, âŽÂČ, âŽâŽ, âŽâ¶â»â”ÂčK relative to âŽâ·K from which changes in the nuclear mean square charge radii across the N = 28 shell closure are deduced.
The investigation was carried out by bunched-beam collinear laser spectroscopy at the CERN-ISOLDE radioactive ion-beam facility. Mean square charge radii are now known from Âłâ·K to â”ÂčK, covering all Îœ fâ/â-shell as well as all Îœ pâ/â-shell nuclei. These measurements, in conjunction with those of Ca, Cr, Mn and Fe, provide a first insight into the Z dependence of the evolution of nuclear size above the shell closure at N = 28
Structural trends in atomic nuclei from laser spectroscopy of tin
Tin is the chemical element with the largest number of stable isotopes. Its complete proton shell, comparable with the closed electron shells in the chemically inert noble gases, is not a mere precursor to extended stability; since the protons carry the nuclear charge, their spatial arrangement also drives the nuclear electromagnetism. We report high-precision measurements of the electromagnetic moments and isomeric differences in charge radii between the lowest 1/2(+), 3/2(+), and 11/2(-) states in Sn117-131, obtained by collinear laser spectroscopy. Supported by state-of-the-art atomic-structure calculations, the data accurately show a considerable attenuation of the quadrupole moments in the closed-shell tin isotopes relative to those of cadmium, with two protons less. Linear and quadratic mass-dependent trends are observed. While microscopic density functional theory explains the global behaviour of the measured quantities, interpretation of the local patterns demands higher-fidelity modelling. Measurements of the hyperfine structure of chemical elements isotopes provide unique insight into the atomic nucleus in a nuclear model-independent way. The authors present collinear laser spectroscopy data obtained at the CERN ISOLDE and measure hyperfine splitting along a long chain of odd-mass tin isotopes.Peer reviewe
Quadrupole moments of odd-A â”Âłâ»â¶ÂłMn: Onset of collectivity towards N = 40
The spectroscopic quadrupole moments of the oddâeven Mn isotopes between N=28 and N=38 have been measured using bunched-beam collinear laser spectroscopy at ISOLDE, CERN. In order to increase sensitivity to the quadrupole interaction, the measurements have been done using a transition in the ion rather than in the atom, with the additional advantage of better spectroscopic efficiency. Since the chosen transition is from a metastable state, optical pumping in ISOLDEâs cooler and buncher (ISCOOL) was used to populate this state. The extracted quadrupole moments are compared to large-scale shell model predictions using three effective interactions, GXPF1A, LNPS and modified A3DA. The inclusion of both the 1Îœg9/2and 2Îœd5/2orbitals in the model space is shown to be necessary to reproduce the observed increase in the quadrupole deformation from N=36 onwards. Specifically, the inclusion of the 2Îœd5/2orbital induces an increase in neutron and proton excitations across the reduced gaps at N=40and Z=28, leading to an increase in deformation above N=36
Nuclear charge radii of â¶ÂČâ»âžâ°Zn and their dependence on cross-shell proton excitations
Nuclear charge radii of â¶ÂČâ»âžâ°Zn have been determined using collinear laser spectroscopy of bunched ion beams at CERN-ISOLDE. The subtle variations of observed charge radii, both within one isotope and along the full range of neutron numbers, are found to be well described in terms of the proton
excitations across the Z = 28 shell gap, as predicted by large-scale shell model calculations. It comprehensively explains the changes in isomer-to-ground state mean square charge radii of â¶âčâ»â·âčZn, the inversion of the
odd-even staggering around N = 40 and the odd-even staggering systematics of the Zn charge radii. With two protons above Z = 28, the observed charge radii of the Zn isotopic chain show a cumulative effect of different aspects of nuclear structure including single particle structure, shell closure, correlations and deformations near the proposed doubly magic nuclei, â¶âžNi and â·âžNi
Properties of nuclei probed by laser light
Viewing objects as small as atomic nuclei by visible light sounds quite unrealistic. However, nuclei usually appear as constituents of atoms whose excitations are indeed associated with the absorption and emission of light. Nuclei can thus interact with light via the atomic system as a whole