| 1. |
- Cocolios, T. E., et al.
(författare)
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Early onset of deformation in the neutron-deficient polonium isotopes
- 2012
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Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 381:1, s. 012072-
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Tidskriftsartikel (refereegranskat)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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| 2. |
- Cocolios, T. E., et al.
(författare)
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Early Onset of Ground State Deformation in Neutron Deficient Polonium Isotopes
- 2011
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 106:5, s. 052503-
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Tidskriftsartikel (refereegranskat)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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| 3. |
- Cocolios, T. E., et al.
(författare)
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Structure of Pb-191 from alpha- and beta-decay spectroscopy
- 2010
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Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 37:12, s. 125103-
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Seliverstov, M. D., et al.
(författare)
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Charge radii of odd-A Po191-211 isotopes
- 2013
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 719:4-5, s. 362-366
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Tidskriftsartikel (refereegranskat)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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| 5. |
- Seliverstov, M. D., et al.
(författare)
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Electromagnetic moments of odd-A Po-193-203,Po-211 isotopes
- 2014
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 89:3, s. 034323-
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Tidskriftsartikel (refereegranskat)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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| 6. |
- Pauwels, D., et al.
(författare)
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Gamow-Teller decay population of Ni-64 levels in the decay of 1(+) Co-64
- 2012
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 86:6, s. 064318-
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Tidskriftsartikel (refereegranskat)abstract
- The Co-64 beta-decay feeding levels in the well-studied Ni-64 nucleus were investigated. Whereas the previously known Co-64 decay scheme merely contained 2 gamma rays, the decay scheme established in this work contains 18, of which 5 are observed in this work and 6 were previously observed in an (n, gamma) study but not placed in the Ni-64 level scheme. Surprisingly, one additional level-placed at an excitation energy of 3578.7 keV-could be determined. The observed beta-decay paths involve allowed nu f(5/2) -> pi f(7/2) and nu p(1/2) -> pi p(3/2) transitions. Three strongly fed levels around 4 MeV are interpreted to possess possible proton-intruder character.
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| 7. |
- Radulov, D., et al.
(författare)
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beta decay of Mn-61 to levels in Fe-61
- 2013
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Ingår i: Physical Review C. Nuclear Physics. - : American Physical Society. - 0556-2813 .- 1089-490X. ; 88:1, s. 014307-
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Tidskriftsartikel (refereegranskat)abstract
- A detailed beta-decay study of Mn-61 is presented, yielding extended information on the level structure of Fe-61. Pure beams were obtained at ISOLDE, CERN, after selective laser ionization and mass separation of fission products from the bombardment of a UCx target by 1.4-GeV protons. The beta and gamma information was detected by two MiniBall clusters and three Delta E plastic scintillators. The new Mn-61 decay scheme reveals 48 gamma transitions, distributed over 20 excited states. A comparison to the decay scheme of Mn-59 and excited states in Fe-59 is made. Shell-model calculations with two different interactions are performed in order to compare the nuclear structure of the two neighboring odd-A iron isotopes. Tentative spin and parities of several excited states in Fe-61 are assigned on the basis of beta-decay feeding patterns in both Fe-59,Fe-61 and of results from the theoretical shell-model calculations.
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| 8. |
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| 9. |
- Koester, U., et al.
(författare)
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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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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 84:3, s. 034320-
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Tidskriftsartikel (refereegranskat)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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| 10. |
- Marsh, B. A., et al.
(författare)
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The ISOLDE RILIS pump laser upgrade and the LARIS Laboratory
- 2010
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Ingår i: Hyperfine Interactions. - : Springer Nature. - 0304-3843 .- 1572-9540. ; 196:1-3, s. 129-141
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Tidskriftsartikel (refereegranskat)abstract
- On account of its high efficiency, speed and unmatched selectivity, the Resonance Ionization Laser Ion Source (RILIS) is the preferred method for ionizing the nuclear reaction products at the ISOLDE on-line isotope separator facility. By exploiting the unique electronic energy level 'fingerprint' of a chosen element, the RILIS process of laser step-wise resonance ionization enables an ion beam of high chemical purity to be sent through the mass selective separator magnet. The isobaric purity of a beam of a chosen isotope is therefore greatly increased. The RILIS, comprising of up to three frequency tunable pulsed dye lasers has been upgraded with the installation of a Nd:YAG pump laser as a replacement for the old Copper Vapor Laser (CVL) system. A summary of the current Nd:YAG pumped RILIS performance is given. To accompany the RILIS pump laser upgrade, a new ionization scheme for manganese has been developed at the newly constructed LAser Resonance Ionization Spectroscopy (LARIS) laboratory and successfully applied for on-line RILIS operation. An overview of the LARIS facility is given along with details of the ionization scheme development work for manganese.
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