Lifetimes of intruder states in 186Pb, 188Pb and 194Po

Grahn, T.; Dewald, Α.; Möller, O.; Julin, R.; Beausang, C. W.; Christen, Stephan; Darby, I. G.; Eeckhaudt, S.; Greenlees, P. T.; Görgen, A.; Helariutta, K.; Jolie, J.; Jones, P.; Juutinen, S.; Kettunen, H.; Kroll, Thilo; Krücken, R.; Coz, Y. Le; Leino, M.; Leppänen, A. P.; Maierbeck, P.; Meyer, D. A.; Melon, B.; Nieminen, P.; Nyman, M.; Page, R. D.; Pakarinen, J.; Petkov, P.; Rahkila, P.; Saha, Bidhan C.; Sandzelius, M.; Sarén, J.; Scholey, C.; Uusitalo, J.; Bender, M.; Heenen, P. H.

doi:10.1016/j.nuclphysa.2008.01.002

Cited by 49 publications

(43 citation statements)

References 49 publications

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“…9 in Ref. [54]) and does not explain the observed quadrupole moments in adjacent odd-A polonium nuclei. It should be noted that at the same time the deduced mean-squared deformations for these ground-state wave function are sufficiently large β 2 2 1/2 ≈ 0.15 to describe qualitatively the deviation from sphericity in charge radii of polonium isotopes with A<198 [10,11].…”

Section: B Deformation Of Neutron-deficient Polonium Isotopes In Conmentioning

confidence: 85%

“…As in Refs. [50,54], at least for 194,196 Po (core nuclei for 195,197 Po) the ground-state wave function, calculated by this model (employing the Skyrme interaction SLy6 and a density-dependent pairing interaction), is nearly equally distributed around the spherical point at small prolate and oblate deformations, with a slight enhancement on the oblate side. The resulting ground-state mean deformation β 2 < 0.05 for 194,196 Po (see Fig.…”

Section: B Deformation Of Neutron-deficient Polonium Isotopes In Conmentioning

confidence: 94%

See 1 more Smart Citation

Electromagnetic moments of odd-APo193–203,211isotopes

Seliverstov¹,

Cocolios²,

Dexters³

et al. 2014

Phys. Rev. C

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Hyperfine splitting parameters have been measured for the neutron-deficient odd-mass polonium isotopes and isomers [193][194][195][196][197][198][199][200][201][202][203] Po g,m , 209,211 Po. The measurement was performed at the ISOLDE (CERN) online mass separator using the in-source resonance ionization spectroscopy technique. The magnetic dipole moments μ 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 μ and Q S 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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Section: B Deformation Of Neutron-deficient Polonium Isotopes In Conmentioning

confidence: 85%

Section: B Deformation Of Neutron-deficient Polonium Isotopes In Conmentioning

confidence: 94%

Electromagnetic moments of odd-APo193–203,211isotopes

Seliverstov¹,

Cocolios²,

Dexters³

et al. 2014

Phys. Rev. C

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show abstract

“…1) indicated a break in the energy scale observed for the heavier masses, where the energy of the 2 period have been performed at the Department of Physics at the University of Jyväskylä using the recoil-decay-tagging (RDT) technique, studying prompt and delayed γ rays down to mass A = 190 [110,111]. Moreover, lifetimes could be derived making use of the RDT technique in recoil distance Doppler-shift experiments for masses A = 194 [112,113] and A = 196 [114]. The experimental situation for the Po isotones down to A = 190 has been summarized by Julin et al [8].…”

Section: Experimental Data: Situation In the Po Nucleimentioning

confidence: 99%

“…The above results were confirmed later by Smirnova et al [126], this time using a self-consistent Hartree-Fock-Bogoliubov approach using the SLy4 Skyrme force [26], indicating rather wide minima in A = 196-194, a lowest oblate minimum at A = 192 and A = 190, and a turning into prolate at A = 188. Triggered by the new data on masses A = 196 and A = 194, more detailed beyond-mean-field studies were carried out [112][113][114], highlighting a detailed comparison on energy spectra and E2 properties, indicating the interplay of an oblate and a more spherical structure (vibrational). In their analysis, the authors point towards a rather pure intruder character of the whole yrast band, including the ground state.…”

Section: Theoretical Approaches: the Evolving Situation In The Pmentioning

confidence: 99%

Nuclear shape coexistence in Po isotopes: An interacting boson model study

García-Ramos

Heyde

2015

Phys. Rev. C

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Background:The lead region, Po, Pb, Hg, and Pt, shows up the presence of coexisting structures having different deformation and corresponding to different particle-hole configurations in the shell-model language. Purpose: We intend to study the importance of configuration mixing in the understanding of the nuclear structure of even-even Po isotopes, where the shape coexistence phenomena are not clear enough. Method: We study in detail a long chain of polonium isotopes, [190][191][192][193][194][195][196][197][198][199][200][201][202][203][204][205][206][207][208] Po, using the interacting boson model with configuration mixing (IBM-CM). We fix the parameters of the Hamiltonians through a least-squares fit to the known energies and absolute B(E2) transition rates of states up to 3 MeV. Results: We obtained the IBM-CM Hamiltonians and we calculate excitation energies, B(E2)'s, electric quadrupole moments, nuclear radii and isotopic shifts, quadrupole shape invariants, wave functions, and deformations. Conclusions: We obtain a good agreement with the experimental data for all the studied observables and we conclude that shape coexistence phenomenon is hidden in Po isotopes, very much as in the case of the Pt isotopes.

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“…This work has shown a departure from a spherical charge distribution as it is predicted by the finiterange droplet model (FRDM). Self-consistent (beyond) mean field calculations conclude that towards the neutron midshell, the isotopes remain essentially spherical but with an increasingly collective contribution to the wave function: eventually in the lightest isotopes of polonium (N < 104) the wave functions shift towards an oblate deformed minimum [15]. A low energy two-particle twohole (2p-2h) intruder ðs…”

mentioning

confidence: 99%

Collinear Resonance Ionization Spectroscopy of Neutron-Deficient Francium Isotopes

et al. 2013

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The magnetic moments and isotope shifts of the neutron-deficient francium isotopes [202][203][204][205] Fr were measured at ISOLDE-CERN with use of collinear resonance ionization spectroscopy. A production-todetection efficiency of 1% was measured for 202 Fr. The background from nonresonant and collisional ionization was maintained below one ion in 10 5 beam particles. There are surprisingly few nuclear observables with which theorists can elucidate the nuclear force and interacting many-fermion problem. The laser spectroscopy technique reported here has measured two of these (the magnetic moment and mean-square charge radius) via the hyperfine interaction and isotope shift. This is achieved without introducing assumptions associated with any particular approach, making these measurements suitable for testing modern nuclear models. A variety of laser spectroscopy techniques now exists for studying shortlived radioactive isotopes, which broadly focus on either high resolution (< 100 MHz linewidth) or high sensitivity (< 1 atom=s) [1,2].We report here the first measurements of 202;203;205 Fr, reaching 11 neutrons from the N ¼ 126 shell closure. This has been made possible by a new highly sensitive, highresolution technique of bunched collinear-beam resonance ionization spectroscopy (CRIS). The CRIS technique combines for the first time velocity bunching (provided by the collinear geometry [3,4]) and time bunching (to eliminate the duty loss of required pulsed laser systems). The high sensitivity is reached through a combination of the excellent overlap of laser and beam, and the high quantum efficiency of ion detectors. This new technique may be applied generally to all nuclides, but it is at the limits of nuclear stability that it will manifest its particular advantages.The CRIS method was first proposed more than 30 years ago [5], and its sub-Doppler resolution was demonstrated by Schultz et al., who measured the radioactive isotopes of ytterbium [6]. Since these isotopes were produced as a continuous beam, the duty cycle losses associated with pulsed lasers introduced a loss in efficiency by a factor of 30, which contributed to a low total experimental efficiency of 0.001%. With the installation of a gas-filled radio frequency quadrupole ion trap (ISCOOL) at ISOLDE, bunched ion beams that match the duty cycle of the pulsed lasers are now available [7]. This motivated the development of a dedicated experiment to exploit the CRIS technique applied to time-bunched beams. In the present case it allowed for the first time measurements of the neutrondeficient francium isotopes with half-lives as short as 300 ms and production rates below 100 atoms=s.In our work the francium isotopes were produced through spallation reactions induced by 1.4 GeV protons, incident on a high temperature uranium carbide target (2000 C) and surface ionized (ionization potential 4.07 eV [8]) with use of a tantalum ionizer tube. A schematic of the experiment is presented in Fig. 1. The beam was accelerated to 50 keV, mass separated, and sub...

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Lifetimes of intruder states in 186Pb, 188Pb and 194Po

Cited by 49 publications

References 49 publications

Electromagnetic moments of odd-APo193–203,211isotopes

Electromagnetic moments of odd-APo193–203,211isotopes

Nuclear shape coexistence in Po isotopes: An interacting boson model study

Collinear Resonance Ionization Spectroscopy of Neutron-Deficient Francium Isotopes

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