151 research outputs found
Calculation of francium hyperfine anomaly
The Dirac-Hartree-Fock plus many-body perturbation theory (DHF+MBPT) method
has been used to calculate hyperfine structure constants for Fr. Calculated
hyperfine structure anomaly for hydrogen-like ion has been shown to be in good
agreement with analytical expressions. It has been shown that the ratio of the
anomalies for and states is weakly dependent on the principal
quantum number. Finally, we estimate Bohr--Weisskopf corrections for several Fr
isotopes. Our results may be used to improve experimental accuracy for the
nuclear factors of short-lived isotopes.Comment: 5 pages, 3 tables, 2 figures. arXiv admin note: text overlap with
arXiv:1703.1004
The Bohr-Weisskopf effect in the potassium isotopes
The magnetic hyperfine structure constants have been calculated for low-lying
levels in neutral potassium atom taking into account the Bohr--Weisskopf (BW)
and Breit--Rosenthal (BR) effects. According to our results the
state of K~I is free from both BR and BW corrections on the level of the
current theoretical uncertainties. Using this finding and the measured values
of the constants, we corrected the nuclear magnetic moments for
several short-lived potassium isotopes. The BW correction is represented as a
product of atomic and nuclear factors. We calculated the atomic factor for the
ground state of K I, which allowed us to extract nuclear factors for potassium
isotopes from the experimental data. In this way the
application range of the single-particle nuclear model for nuclear-factor
calculation in these isotopes has been clarified
In-source laser spectroscopy with the laser ion source and trap: first direct study of the ground-state properties of Po-217,Po-219
D. A. Fink et al.; 15 págs.; 17 figs.; 3 tabs.; Open Access funded by Creative Commons Atribution Licence 3.0A Laser Ion Source and Trap (LIST) for a thick-target, isotope-separation on-line facility has been
implemented at CERN ISOLDE for the production of pure, laser-ionized, radioactive ion beams. It offers
two modes of operation, either as an ion guide, which performs similarly to the standard ISOLDE
resonance ionization laser ion source (RILIS), or as a more selective ion source, where surface-ionized ions
from the hot ion-source cavity are repelled by an electrode, while laser ionization is done within a radiofrequency
quadrupole ion guide. The first physics application of the LIST enables the suppression of
francium contamination in ion beams of neutron-rich polonium isotopes at ISOLDE by more than 1000
with a reduction in laser-ionization efficiency of only 20. Resonance ionization spectroscopy is performed
directly inside the LIST device, allowing the study of the hyperfine structure and isotope shift of 217Po for
the first time. Nuclear decay spectroscopy of 219Po is performed for the first time, revealing its half-life, α-
to-β-decay branching ratio, and α-particle energy. This experiment demonstrates the applicability of the
LIST at radioactive ion-beam facilities for the production and study of pure beams of exotic isotopes. Published by the American Physical SocietyThis work was supported by the Bundesministerium für Bildung und
Forschung (BMBF, Germany) within the Wolfgang-
Gentner programme as well as through the consecutive
project fundings of 06Mz9181I, 06Mz7177D, and
05P12UMCIA, by FWO-Vlaanderen (Belgium), by
GOA/2010/010 (BOF-KULeuven), by the IUAP-Belgian
State Belgian Science Policy (BRIX network P7/12), by the
U.K. Science and Technology Facilities Council (STFC),
by the European Union within FP7 (ENSAR No. 262010),
by the Slovak Research and Development Agency
(Contract No. APVV-0105-10), by the Slovak grant agency
VEGA, and the Reimei Foundation of JAEA (Contract
No. 1/0576/13). T. E. C. was supported by STFC Ernest
Rutherford Grant No. ST/J004189/1.Peer Reviewe
Early onset of ground-state deformation in the neutron-deficient polonium isotopes
In-source resonant ionization laser spectroscopy of the even- polonium
isotopes Po has been performed using the
to ( nm) transition in the polonium atom
(Po-I) at the CERN ISOLDE facility. The comparison of the measured isotope
shifts in Po with a previous data set allows to test for the first
time recent large-scale atomic calculations that are essential to extract the
changes in the mean-square charge radius of the atomic nucleus. When going to
lighter masses, a surprisingly large and early departure from sphericity is
observed, which is only partly reproduced by Beyond Mean Field calculations.Comment: As submitted to PR
Changes in mean-squared charge radii and magnetic moments of Tl 179-184 measured by in-source laser spectroscopy
Hyperfine structure and isotope shifts have been measured for the ground and isomeric states in the neutron-deficient isotopes Tl179-184 using the 276.9-nm transition. The experiment has been performed at the CERN-Isotope Separator On-Line facility using the in-source resonance-ionization laser spectroscopy technique. Spins for the ground states in Tl179,181,183 have been determined as I=1/2. Magnetic moments and changes in the nuclear mean-square charge radii have been deduced. By applying the additivity relation for magnetic moments of the odd-odd Tl nuclei the leading configuration assignments were confirmed. A deviation of magnetic moments for isomeric states in Tl182,184 from the trend of the heavier Tl nuclei is observed. The charge radii of the ground states of the isotopes Tl179-184 follow the trend for isotonic (spherical) lead nuclei. The noticeable difference in charge radii for ground and isomeric states of Tl183,184 has been observed, suggesting a larger deformation for the intruder-based 9/2- and 10- states compared to the ground states. An unexpected growth of the isomer shift for Tl183 has been found
Detailed α-decay study of 180Tl
International audienceA detailed -decay spectroscopy study of has been performed at ISOLDE (CERN). -selective ionization by the Resonance Ionization Laser Ion Source (RILIS) coupled to mass separation provided a high-purity beam of . Fine-structure decays to excited levels in the daughter were identified and an -decay scheme of was constructed based on an analysis of - and -- coincidences. Multipolarities of several -ray transitions deexciting levels in were determined. Based on the analysis of reduced -decay widths, it was found that all decays are hindered, which signifies a change of configuration between the parent and all daughter states
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