| 1. |
- Barzakh, A., et al.
(author)
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Large Shape Staggering in Neutron-Deficient Bi Isotopes
- 2021
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In: Physical Review Letters. - 0031-9007. ; 127:19
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Journal article (peer-reviewed)abstract
- The changes in the mean-square charge radius (relative to Bi209), magnetic dipole, and electric quadrupole moments of Bi187,188,189,191 were measured using the in-source resonance-ionization spectroscopy technique at ISOLDE (CERN). A large staggering in radii was found in Bi187,188,189g, manifested by a sharp radius increase for the ground state of Bi188 relative to the neighboring Bi187,189g. A large isomer shift was also observed for Bi188m. Both effects happen at the same neutron number, N=105, where the shape staggering and a similar isomer shift were observed in the mercury isotopes. Experimental results are reproduced by mean-field calculations where the ground or isomeric states were identified by the blocked quasiparticle configuration compatible with the observed spin, parity, and magnetic moment. © 2021 authors.
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| 2. |
- Illana, A., et al.
(author)
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Coulomb excitation of 74,76Zn
- 2023
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In: Physical Review C. - 2469-9985. ; 108:4
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Journal article (peer-reviewed)abstract
- The first experiment using radioactive beams post-accelerated by the HIE-ISOLDE facility has enabled to obtain a precise set of B(E2) transition probabilities in neutron-rich 74,76Zn isotopes. The resulting B(E2; 2+1→0+1) values are consistent with those determined in earlier REX-ISOLDE measurements. While the B(E2; 4+1→2+1) transition probability in 76Zn is also in agreement with earlier Coulomb-excitation results, the value obtained for 74Zn is considerably lower. For the first time, a spectroscopic quadrupole moment of the 2+1 state was measured for an exotic nucleus in this mass region. A detailed comparison is presented with large-scale shell-model and Monte Carlo shell-model calculations.
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| 3. |
- Andel, B., et al.
(author)
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β -delayed fission of isomers in Bi 188
- 2020
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In: Physical Review C. - 2469-9985. ; 102:1
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Journal article (peer-reviewed)abstract
- β-delayed fission (βDF) decay of a low-spin (ls) and a high-spin (hs) isomer in Bi188 was studied at the ISOLDE facility at CERN. Isomer-selective laser ionization and time gating were employed to investigate each isomer separately and their βDF partial half-lives were determined: T1/2p,βDF(188Bihs)=5.6(8)×103 s and T1/2p,βDF(188Bils)=1.7(6)×103 s. This work is the first βDF study of two states in one isotope and allows the spin dependence of low-energy fission to be explored. The fission fragment mass distribution of a daughter nuclide Pb188, following the β decay of the high-spin isomer, was deduced and indicates a mixture of symmetric and asymmetric fission modes. Experimental results were compared with self-consistent mean-field calculations based on the finite-range Gogny D1M interaction. To reproduce the measured T1/2p,βDF(188Bihs), the calculated fission barrier of Pb188 had to be reduced by ≈30%. After this reduction, the measured T1/2p,βDF(188Bils) was in agreement with calculations for a few possible configurations for Bils188. Theoretical βDF probabilities for these configurations were found to be lower by a factor of 4-9 than the βDF probability of Bihs188. The fission fragment mass distribution of Pb188 was compared to the scission-point model SPY and the calculations based on the finite-range liquid-drop model. The first observation of βDF for Bi190 is also reported. © 2020 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
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| 4. |
- Cocolios, T. E., et al.
(author)
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Early Onset of Ground State Deformation in Neutron Deficient Polonium Isotopes
- 2011
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 106:5, s. 052503-
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Journal article (peer-reviewed)abstract
- In-source resonant ionization laser spectroscopy of the even-A polonium isotopes Po-192-210,Po-216,Po-218 has been performed using the 6p(3)7s S-5(2) to (6)p(3)7p P-5(2) (lambda = 843.38 nm) transition in the polonium atom (Po-I) at the CERN ISOLDE facility. The comparison of the measured isotope shifts in Po200-210 with a previous data set allows us 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.
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| 5. |
- Cocolios, T. E., et al.
(author)
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Early onset of deformation in the neutron-deficient polonium isotopes
- 2012
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In: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 381:1, s. 012072-
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Journal article (peer-reviewed)abstract
- In-source laser spectroscopy has been performed at CERN-ISOLDE with the RILIS laser ion source on 191-204,206,208-211,216,218Po. New information on the β decay of 199Po were extracted in the process, challenging previous results. Large-scale atomic calculations were performed to extract the changes in the mean-square charge radius δr 2 from the isotope shifts. The δ«r» 2 for the even-A isotopes reveal a large deviation from the spherical droplet model for N < 116.
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| 6. |
- Cocolios, T. E., et al.
(author)
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Structure of Pb-191 from alpha- and beta-decay spectroscopy
- 2010
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In: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 37:12, s. 125103-
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Journal article (peer-reviewed)abstract
- Complementary studies of Pb-191 have been made in the beta decay of Bi-191 at LISOL (CRC) and in the alpha decay of Po-195 at ISOLDE (CERN). Fine structures in the alpha decay of the low-spin and high-spin isomers of 195Po have been fully resolved. Identification of the parent state is made possible via isomer selection based on narrow-band laser frequency scanning. The alpha-particle and gamma-ray energies have been determined with greater precision. New alpha-particle and. gamma-ray energies are identified. Branching ratios in the decay of Po-195 and Pb-191 have been examined.
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| 7. |
- Flanagan, K. T., et al.
(author)
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Nuclear Spins and Magnetic Moments of Cu-71,Cu-73,Cu-75 : Inversion of pi 2p(3/2) and pi 1f(5/2) Levels in Cu-75
- 2009
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 103:14, s. 142501-
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Journal article (peer-reviewed)abstract
- We report the first confirmation of the predicted inversion between the pi 2p(3/2) and pi 1f(5/2) nuclear states in the nu g(9/2) midshell. This was achieved at the ISOLDE facility, by using a combination of in-source laser spectroscopy and collinear laser spectroscopy on the ground states of Cu-71,Cu-73,Cu-75, which measured the nuclear spin and magnetic moments. The obtained values are mu(Cu-71)=+2.2747(8)mu(N), mu(Cu-73)=+1.7426(8)mu(N), and mu(Cu-75)=+1.0062(13)mu(N) corresponding to spins I=3/2 for Cu-71,Cu-73 and I=5/2 for Cu-75. The results are in fair agreement with large-scale shell-model calculations.
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| 8. |
- Seliverstov, M. D., et al.
(author)
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Charge radii of odd-A Po191-211 isotopes
- 2013
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In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 719:4-5, s. 362-366
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Journal article (peer-reviewed)abstract
- Isotope shifts have been measured for the odd-A polonium isotopes Po191-211 and changes in the nuclear mean square charge radii delta < r(2 >) have been deduced. The measurements were performed at CERN-ISOLDE using the in-source resonance-ionization spectroscopy technique. The combined analysis of these data and our recent results for even-A polonium isotopes indicates an onset of deformation already at Po-197,Po-198, when going away from stability. This is significantly earlier than was suggested by previous theoretical and experimental studies of the polonium isotopes. Moreover and in contrast to the mercury isotopes, where a strong odd-even staggering of the charge radii of the ground states was observed by approaching the neutron mid-shell at N = 104, no such effect is present in polonium down to Po-191. Consequently the charge radii of both isomeric and ground states of the odd-A polonium isotopes follow the same trend as the even-A isotopes.
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| 9. |
- Seliverstov, M. D., et al.
(author)
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Electromagnetic moments of odd-A Po-193-203,Po-211 isotopes
- 2014
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 89:3, s. 034323-
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Journal article (peer-reviewed)abstract
- Hyperfine splitting parameters have been measured for the neutron-deficient odd-mass polonium isotopes and isomers Po-193-203(g,m), Po-209,Po-211. The measurement was performed at the ISOLDE (CERN) online mass separator using the in-source resonance ionization spectroscopy technique. The magnetic dipole moments mu and spectroscopic electric quadrupole moments Q(S) have been deduced. Their implication for the understanding of nuclear structure in the vicinity of the closed proton shell at Z = 82 and the neutron mid-shell at N = 104 is discussed. For the most neutron-deficient nuclei (A = 193,195,197), a deviation of mu and QS from the nearly constant values for heavier polonium nuclei was observed. Particle-plus-rotor calculations with static oblate deformation describe the electromagnetic moments for these nuclei well, provided a gradual increase of a mean deformation when going to lighter masses is assumed for the polonium nuclei with A < 198.
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| 10. |
- Koester, U., et al.
(author)
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In-source laser spectroscopy of (75,77,78)Cu : Direct evidence for a change in the quasiparticle energy sequence in (75,77)Cu and an absence of longer-lived isomers in (78)Cu
- 2011
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 84:3, s. 034320-
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Journal article (peer-reviewed)abstract
- This paper describes measurements on the isotopes (75,77,78)Cu by the technique of in-source laser spectroscopy, at the ISOLDE facility, CERN. The role of this technique is briefly discussed in the context of this and other, higher resolution, methods applied to copper isotopes in the range (57-78)Cu. The data, analyzed in comparison with previous results on the lighter isotopes (59,63)Cu, establish the ground-state nuclear spin of (75,77)Cu as 5/2 and yield their magnetic dipole moments as +1.01(5)mu(N) and +1.61(5)mu(N), respectively. The results on (78)Cu show no evidence for long-lived isomerism at this mass number and are consistent with a spin in the range 3-6 and moment of 0.0(4) mu(N).
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