Reflection-asymmetric rotor model of odd<i>A∼</i>219<i>–</i>229 nuclei

Lèander, G.A.; Chen, Y. S.

doi:10.1103/physrevc.37.2744

Cited by 148 publications

(138 citation statements)

References 76 publications

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“…The band structure of 229 Ac has been described fairly well both considering quadrupole deformation plus Coriolis coupling as done in the reaction work [9] or small octupole deformation [10]. The agreement was better when the octupole deformation term was included.…”

Section: Rotational Bandsmentioning

confidence: 56%

“…In 227 Ac only the K=5/2 parity doublet band, observed at 300 keV excitation energy, can be described in terms of static octupole deformation. In the case of 229 Ac the four K=1/2 ± and K=3/2 ± bands observed in (t,α) reactions [9] are interpreted either as normal Nilsson levels or by assuming a weak octupole coupling, β 3 = 0.07 [10]. In summary, the low energy properties of the 223,225,227 Ac isotopes have been accounted for using the reflection asymmetric rotor-plus-quasiparticle model [10] and, in this context, the 219,229 Ac isotopes have been described as shape transitional nuclei.…”

Section: Introductionmentioning

confidence: 99%

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Nuclear structure of 231Ac

Boutami¹,

Borge²,

Mach³

et al. 2008

Nuclear Physics A

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The low-energy structure of 231 Ac has been investigated by means of γ ray spectroscopy following the β − decay of 231 Ra. Multipolarities of 28 transitions have been established by measuring conversion electrons with a mini-orange electron spectrometer. The decay scheme of 231 Ra → 231 Ac has been constructed for the first time. The Advanced Time Delayed βγγ(t) method has been used to measure the half-lives of five levels. The moderately fast B(E1) transition rates derived suggest that the octupole effects, albeit weak, are still present in this exotic nucleus.

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Section: Rotational Bandsmentioning

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Nuclear structure of 231Ac

Boutami¹,

Borge²,

Mach³

et al. 2008

Nuclear Physics A

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“…[35,36], neutron configurations are proposed. Comparisons with neighboring isotones and odd-and even-mass isotopes are discussed, where the following quantities are presented in a systematic way: relative energies between band structures, spin alignments, B(E1)/B(E2) and B(M1)/B(E2) ratios, and parity splittings.…”

Section: Discussionmentioning

confidence: 99%

“…[35,36] investigated the low-spin structure of reflection-asymmetric, odd-mass nuclei in the light-actinide region in the framework of the microscopic-macroscopic mean-field approach. Both sets of calculations focus on the band-head configurations of octupole bands and lead to the same interpretation for the lowest one-quasiparticle state (yrast) in each nucleus.…”

Section: Discussionmentioning

confidence: 99%

Characterization of octupole-type structures inTh221

et al. 2014

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A detailed level scheme for 221 Th has been established in an experiment using the 18 O + 207 Pb reaction at 96 MeV. The evaporation residues from this fissile system were selected with the HERCULES detector array and residue-gated γ rays were measured with Gammasphere. Three band structures of interlinked, alternating-parity levels are observed, two of which are non-yrast. In addition, several high-lying excitations are found. The yrast band is seen up to spin-parity 37/2 − and 39/2 + , beyond which a high-spin feeding transition is observed. The non-yrast sequences are interpreted as parity-doublet structures, based on a configuration similar to that of the yrast band in 223 Th (K = 5/2). The key properties of even-odd nuclei in this mass region [B(E1)/B(E2) and B(M 1)/B(E2) ratios, spin alignments, parity splittings] are reviewed.

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“…Parity doublets have been observed in several odd-mass Ra, Ac and Pa nuclei [12][13][14][15]. An example [14] is shown in Fig.…”

Section: Octupole Deformation the Actinide Regionmentioning

confidence: 99%

Reflection-Asymmetric Shapes in Nuclei

Ahmad¹,

Carpenter²,

Emling

et al. 1990

Exotic Nuclear Spectroscopy

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Soon after the collective nuclear model [1,2] was established, low-lying negative parity states were observed [3] in even-even Ra and Th nuclei from alpha-particle spectroscopic studies. These negative parity levels formed a rotational band with spin sequence 1, 3, 5, and K quantum number 0. Since these states had energies much lower than the expected two quasi-particle states, these were interpreted as octupole vibrations about a spheroidal equilibrium shape. Ever since the discovery of the octupole vibrations, scientists have been thinking about the possibility of octupole deformations in nuclei, that is, nuclei with octupole equilibrium shape. These octupole shapes are symmetric about the Z axis but reflection asymmetric about the XY plane and resemble a Pear.• --. w i : , . £ ,,,.,.. -, ' ; ,.,,_• , T he submitted manutcnpt has been authored bv a contractor of the U. S. Government under contract Na. W-31-109-ENG-3S. Accordingly, the U. S. Government retains a nonexclusive, royalty-free license \n publish or reproduce the published form of this contribution, or allow others to do so, for IK S. Government purposes. MASTERThe octupole deformation or octupole vibration is produced by the long range octupole-octupole correlations. These correlations depend on the r 3 Y3*r^Y3 matrix elements between single particle states with A2. = Aj -3 and the energy difference between them. A look at the shell states ( Fig. 1 with the binding energy of ~10 MeV due to the quadrupole deformation (Fig. 2).It is well known that the rotation of symmetric and asymmetric molecules generate different rotational bands. In the case of the former, the band has 0 + , 2 + , 4 + --level sequence and the latter has 0 + , 1", 2 + , 3", --sequence.Thus the rotation of reflection symmetric and reflection asymmetric nuclei will produce different spectra and these can be used as signature of octupole shape. OCTUPOLE DEFORMATION THE ACTINIDE REGIONIn odd mass nuclei, the two members of the parity doublet have very similar wave functions except the parity. Thus one would expect similar properties for both bands. The data on odd mass nuclei in the mass 224 region can be summarized as follows:1. Parity doublets have been observed in several odd-mass Ra, Ac and Pa nuclei [12][13][14][15]. An example [14] is shown in Fig. 4. The members of the doublets are connected by fast El transitions [15].The B(E1) values in these nuclei are larger than l.OxlO" 3 Weisskopf units (see Fig. 5).3. Alpha decay rates are enhanced to the parity doublet partner of the favored band.4. Coriolis matrix elements and Ml transition rates are attenuated.5. Octupole deformation has also been found at moderate spins [16] in 221 Th and 223 Th.In even-even nuclei, levels with alternating parity have been observed in several Ra and Th nuclei. In general, these are connected by fast El transitions. OCTUPOLE DEFORMATION IN N-88, Z-56 NUCLEIAs shown in Fig. 1, octupole correlations are also expected in the Z~56, N~8Snuclei. However, in these nuclei, spacings for the A2. = 3, Aj =3 le...

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Reflection-asymmetric rotor model of oddA∼219–229 nuclei

Cited by 148 publications

References 76 publications

Nuclear structure of 231Ac

Nuclear structure of 231Ac

Characterization of octupole-type structures inTh221

Reflection-Asymmetric Shapes in Nuclei

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