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ABSTRACT: A high spin isomer with spin 25(-) and mean lifetime of 220 mu s has been observed at an excitation energy of 4772 keV in At-212. The measured E3 decay rate for the 224 keV transition deexciting this level is enhanced but significantly lower than those observed in the neighboring isotopes or predicted using a multiparticle octupole coupling model. The relatively simple configurations involved in this decay and the close relationship to neighboring states allow a clear association to be made between the occupation of a specific single particle orbital and a blacking of the octupole vibrational correlation.
Physical Review Letters 01/1998; 80(10):2077-2080. · 7.37 Impact Factor
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CS PURRY,
PM WALKER,
GD DRACOULIS,
T KIBEDI, S BAYER,
AM BRUCE,
AP BYRNE,
M DASGUPTA,
W GELLETLY,
F KONDEV,
PH REGAN,
C THWAITES
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ABSTRACT: A T-1/2 = 220 ns, eight-quasiparticle isomer, with four unpaired neutrons and four unpaired protons, has been established at an excitation energy of 6576 keV in the prolate deformed nucleus, W-178. The associated rotational band has also been identified, revealing the collective properties in the presence of blocked pairing correlations, with expected quenching of the nuclear superfluidity. The band retains a small degree of rotational alignment, and has a less-than-rigid dynamic moment of inertia.
Physical Review Letters 01/1995; 75(3):406-409. · 7.37 Impact Factor
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ABSTRACT: Excited states in the nuclei 210At and 211At have been studied using 208Pb(7Li,xn) reactions. Detailed spectroscopy of levels up to 30ℏ has been achieved. New isomeric levels arising from core-excited states were observed, with the highest-lying isomers attributed to a coupling of the π[h9/22i13/2] configuration to double neutron-particle–hole excitations. Clear relationships between the states observed in 210At and 211At were identified. Semiempirical shell-model calculations reproduce very well the yrast states in both nuclei. Uncertainty in the modeling of core-polarization was seen as a limiting factor in the calculation of accurate level energies for core-excited states.
Nuclear Physics A.
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ABSTRACT: Excited states in the odd-odd nucleus 212At have been studied using γ-ray and electron spectroscopy following the 208Pb(7Li,3n) reaction. Levels were identified to spins of 25 and to excitation energies of about 4.8 MeV. New isomeric states which decay by enhanced E3 transitions have been established at spins 18+, 22− and 25−. Shell model calculations reproduce well the main features of the level scheme and show the configuration dependence of certain empirical residual interaction matrix elements.
Nuclear Physics A.
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ABSTRACT: Excited states in 180Ta have been identified using the 176Yb(11B,α3n)180Ta and 176Yb(7Li,3n)180Ta reactions and associated time-correlated γ-ray spectroscopy, including particle-γ coincidences for channel selection. As well as identifying the rotational band based on the 9- two-quasiparticle state at 75 keV, at least eight other low-lying two-quasiparticle states and associated rotational bands have been established. Lifetimes in the few nanosecond region were isolated using γ-γ-time techniques. Most of the observed two-quasiparticle states and some of the band members can be identified with states known from particle transfer studies. The properties of the observed Ωn±Ωp partners of 1+ and 8+ bands from the ν9/2+[624]⊗π7/2+[404] configuration and the 0- and 9- pair from the ν9/2+[624]⊗π9/2-[514] configuration are discussed. High-K structures identified include the band based on the four-quasiparticle 45 μs, 15- isomer, a 32 ns, four-quasiparticle 18(+) isomer, and a six-quasiparticle 19(-) intrinsic state and its band. Configuration assignments are aided by analysis of the in-band decay properties, which confirm, for example, a predominantly νπ3 configuration for the 15- isomer. The results are compared with multiquasiparticle calculations. A number of yrast high-K six- and eight-quasiparticle states which could be accessible in future studies are predicted.
Phys. Rev. C. 58(3).
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C. S. Purry,
P. M. Walker,
G. D. Dracoulis,
T. Kibédi, S. Bayer,
A.M. Bruce,
A. P. Byrne,
M. Dasgupta,
W Gelletly,
F. Kondev,
P. H. Regan,
C. Thwaites
Papers from the Department of Physics.
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Papers from the Department of Physics.
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Phys.Lett. 393B:279.
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Contrib. Nuclear Structure '98;
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Nucl.Phys. A694:3.
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Nucl.Phys. A674:301.
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Contrib. Nuclear Structure '98;
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C S Purry,
P M Walker,
G D Dracoulis,
T Kibedi,
F G Kondev, S Bayer,
A M Bruce,
A P Byrne,
W Gelletly,
P H Regan,
C Thwaites,
O Burglin,
N Rowley
Nucl.Phys. A632:229.
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Nucl.Phys. A672:54.
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Nucl.Phys. A617:91.
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Phys.Rev. C58:1444.
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Phys.Rev. C61:044315.
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Phys.Rev. C53:1205.
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C. J. Pearson,
P. M. Walker,
C. S. Purry,
G. D. Dracoulis, S. Bayer,
A. P. Byrne,
T. Kibédi,
F G Kondev,
T. Shizuma,
R. A. Bark,
G. Sletten,
S. Frauendorf
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ABSTRACT: Tilted-axis rotation, arising from Fermi-aligned configurations, has been observed for the first time to cause backbending in an odd-proton nucleus. In <SUP>181</SUP>Re, two t-bands are found to be energetically favored relative to the usual rotation-aligned s-bands, presenting an alternative form of cold nuclear rotation. Interactions between the bands are weak, and unambiguous comparisons with tilted-axis-cranking calculations can be made.
Nuclear Physics Group.
