Oblate collectivity in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Pb</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>197</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>

Kuhnert, A.; Stoyer, M. A.; Becker, J. A.; Henry, E. A.; Brinkman, M. J.; Yates, S. W.; Wang, T. F.; Cizewski, J. A.; Stephens, F. S.; Deleplanque, M. A.; Diamond, R. M.; Macchiavelli, A. O.; Draper, J. E.; Azaiez, F.; Kelly, W.H.; Körten, W.

doi:10.1103/physrevc.46.133

Cited by 57 publications

(29 citation statements)

References 16 publications

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“…In particular, long cascades of M1 transitions were observed first in neutron deficient Pb nuclei in the early 1990s [8][9][10]. Later, in 1997, the lifetime measurements based on the Doppler-shift attenuation method (DSAM) for four M1 bands in the nuclei 198 Pb and 199 Pb provided a clear evidence * sqzhang@pku.edu.cn † mengj@pku.edu.cn for magnetic rotation [11].…”

Section: Introductionmentioning

confidence: 99%

Magnetic rotations in198Pb and199Pb within covariant density functional theory

Zhao

Zhang

et al. 2012

Phys. Rev. C

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Well-known examples of shears bands in the nuclei 198 Pb and 199 Pb are investigated within tilted axis cranking relativistic mean-field theory. Energy spectra, the relation between spin and rotational frequency, deformation parameters and reduced M1 and E2 transition probabilities are calculated. The results are in good agreement with available data and with calculations based on the phenomenological pairing plus-quadrupole-quadrupole tilted-axis cranking model. It is shown that covariant density functional theory provides a successful microscopic and fully self-consistent description of magnetic rotation in the Pb region showing the characteristic properties as the shears mechanism and relatively large B(M1) transitions decreasing with increasing spin.

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Section: Introductionmentioning

confidence: 99%

Magnetic rotations in198Pb and199Pb within covariant density functional theory

Zhao

Zhang

et al. 2012

Phys. Rev. C

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“…The collective rotation is traditionally understood as the motion of the deformed nucleus. However, during the past two decades, lively research has sprung up in the regular sequence consisting of enhanced M1 transitions in near-spherical nuclei, called the magnetic rotational band, which was first observed in Pb isotopes [1][2][3]. The magnetic rotational band can be generated by the alignment of the h 11/2 neutron-particle and g 9/2 proton-hole shear blades in the A ∼ 100 mass region, namely, the "shears mechanism."…”

Section: Introductionmentioning

confidence: 99%

High-spin level structure of the doubly odd nucleus104Ag

et al. 2013

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The high-spin level structure of the doubly odd nucleus 104 Ag has been investigated via the 97 Mo( 11 B, 4n) 104 Ag reaction at a beam energy of 50 MeV. The newly established level scheme includes lower-lying two-quasiparticle states and several higher-lying bands. Two positive-parity bands associated with the πg −1 9/2 ⊗ νd 5/2 and πg −1 9/2 ⊗ νg 7/2 configurations are extended significantly. Based on the comparison with the analogous structures in neighboring nuclei and the features of nuclear chirality, the negative parity bands are suggested as candidate chiral doublet bands with the πg −1 9/2 ⊗ νh 11/2 configuration.

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“…A number of collective bands involving rather regular sequences of dipole transitions have recently been observed in 194'196-2~ [1][2][3][4][5][6][7][8], 193Hg [9], and 2~ [10]. All these bands have similar characteristics, e.g.…”

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confidence: 95%

First evidence of the magnetic character of dipole transitions in the “oblate bands” of199Pb

Duprat

Vieu

Azaiez

et al. 1994

Z. Physik A - Hadrons and Nuclei

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Internal conversion coe~cients have been determined feom on-line measurement of electron-and 7-ray emission related to the dipole transitions in the sovariation of the level spacings , it)no signature splitting, ill)small dynamical moments of inertia close to those observed in the oblate bands of the mercury nuclei, iv) large B(M1)/B(E2) ratios. The dipole (AI=I) assignments were established on the basis of angular distributions and/or DCO data. Furthermorc, the inferred M1 multipolarities were deduced from -y-rays intensity balances taking into account the theoretical internal conversion contributions.These different properties were interpreted assuming collective oblate structures built on multi-quasiparticle excitations involving high-K proton orbitals (h9/2 or it3/2) coupled to rotation-aligned i13/~ neutrons, the high-K proton orbitals being responsible for the oblate deformation. An interpretation of these oblate bands has been given in the framework of the "tilted-axis-cranking" model [11] where angular momentum within a band is generated partly by the collective rotation and partly by continuous Mignmcnt of protons and neutrons angular momenta along the tilted axis.In order to experimentally specify in a unambiguous way the nature (electric or magnetic) of the transitions in the dipole bands in 199pb, the determination of conversion coefficients was desirable. For that purpose, an experiment was performed at the Orsay MP Tandem with the e--7 spectrometer [12]. The reaction lS6w(aSO,fn)199pbwas used with a 95 MeV 180 beam and a 300 #g/cm ~ self-supported isotopically enriched target (provided by the GSI Darmstadt laboratory). The prompt electrons were analysed with a Khinheins magnetic lens oriented at 900 with respect to the beam direction. This lens, operating with a swept current, focused the electrons on a cooled Si(Li) detector (active area = 2x7.5 cm 2, thickness = 0.4 cm, FWHM = 1.7 keV at 600 keV). The large electron momentum window of the lens (ABp/Bp= +_ 15%)compensates its rather small transmission (T~_7%). It should be mentionned that a serious drawback of the 900 lens configuration was the relatively important Doppler broadening, the recoil velocity for the above mentionned reaction, fi/, ~1%, leading to < AEDop >_~3 keV. 7-rays were measured simulteanously with a Comptonsuppressed Ge detector(20% efficiency, FWHM~ 2 keV at i MeV) opposite to the lens, 15 cm from the target. An array of six BaF2 crystals (2" • 2", time resolution < 1 ns), operating in coincidence with the pulsed ion beam (FWHM=2 ns, AT=200 ns), was used to trigger the electron and gamma detector signals with the burst of prompt transitions following each nuclear fusion reaction. This trigger condition, added to a two-dimensional F_,-Bp filter, reduces sharply the strong electron background due to 6-rays and scattered electrons in the lowenergy part of the internal conversion electron spectra. The use of a thin target together with the different filters allowed the selection of prompt transitions above

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Oblate collectivity inPb197

Cited by 57 publications

References 16 publications

Magnetic rotations in198Pb and199Pb within covariant density functional theory

Magnetic rotations in198Pb and199Pb within covariant density functional theory

High-spin level structure of the doubly odd nucleus104Ag

First evidence of the magnetic character of dipole transitions in the “oblate bands” of199Pb

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