High-spin parity doublets in the nucleus 151Pm

Urban, W.; Bacelar, J.; Gast, W.; Hebbinghaus, G.; Krämer–Flecken, A.; Lieder, R.M.; Morek, T.; Rza̧ca‐Urban, T.

doi:10.1016/0370-2693(90)90889-e

Cited by 43 publications

(16 citation statements)

References 15 publications

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“…Similar alternating parity bands originating from 5/21413] and 5/2[532] configurations were observed in ~51Pm [23,24] at medium spin and in 155Eu [25] at low spin. Although the existing experimental data do not show the limit of static octupole deformation at experimentally observed spin in 151pm, a tendency towards octupole deformation is clearly seen [4].…”

supporting

confidence: 59%

Octupole correlations at medium spin in odd-proton153Eu nucleus

Afanasjev¹,

Mizutori²

1995

Z. Physik A - Hadrons and Nuclei

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Abstract. Medium-spin experimental data on alternating parity bands in 153Eu are analysed and compared with results of cranking calculations assuming no octupole deformation, dynamic octupole deformation and static octupole deformation. It is concluded that the existence of static octupole deformation is plausible in this nucleus at medium spin.PACS: 27.70.+q; 21.60.Cs Alternating-parity rotational bands linked by the enhanced El-transitions have been observed in the A ~ 150 (N 88, Z ~ 60) mass region. These bands are interesting because they can be considered as parity doublets (PD's) associated with the breaking of the intrinsic reflection symmetry [1,2] On the other hand, the tendency towards octupole deformation can be magnified with increasing spin [8,9]. The deformed shell model indicates that proton number Z = 62 is octupole driving not only at low spin but also at rotational frequency ha; -=-0.3 MeV [9]. While the N = 88 octupole deformed gap, which is clearly seen at ha; = 0, disappears with increasing rotational frequency, the neutron numbers N = 90, 91 become octupole-driving towards moderate octupole deformation/33 ~ 0.05 at rotational frequency hw ~ 0.3 (see Fig. 2 in ref.[9]). Therefore, the neighbouring even-even nuclei 152Sm and 154Gd are calculated octupolesoft at high rotational frequencies [9]. The odd nuclei with an octupole soft core can get octupole deformed in the case when unpaired nucleons in specific orbitals polarize the * Permanent address: Nuclear Research Center, Latvian Academy of Sciences, LV-2169, Salaspils, Miera str. 31, Latvia shape towards static octupole deformation. That can be examplified by the fact that the octupole barriers for low-lying band-heads of the odd-mass nuclei in the A ~ 145 region are calculated significantly larger compared to the ones in the even-even neighbours [10].Recently, the experimental data on the alternating-parity bands with f2 = 5/2 in 153Eu has been expanded to higher spins [11]. Levels of the same spin but opposite parity lie close in energy and strong electric dipole transitions connect appropriate band members. Intrinsic dipole moments Do deduced from B(E1)/B(E2) values do not reveal any pronounced spin dependence. This aspect of the data is consistent with static octupole deformation. At the same time, the difference of magnetic moments of opposite parity bands, obtained from (9K --gR)/Qo values, was considered as evidence in favour of reflection-symmetric description of the intrinsic states of these bands.In this article, we will try to clarify the nature of strong octupole correlations observed at medium spin in this nucleus. Firstly, the analysis of rotational properties of the alternating-parity bands with f2 = 5/2 will be expanded to higher spins compared with ref. [4]. Then, the results obtained within the cranking model with and without inclusion of static and dynamic octupole deformation will be compared with experiment.Both the static and dynamic octupole deformation can be responsible for the existence of the alternating-parity ban...

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supporting

confidence: 59%

Octupole correlations at medium spin in odd-proton153Eu nucleus

Afanasjev¹,

Mizutori²

1995

Z. Physik A - Hadrons and Nuclei

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“…This raised the question if the 322.9-keV level may be due to octupole correlations, which are expected and observed in this part of the nuclear chart [2][3][4][5][6]. The final conclusion about the nature of the 322.9-keV excitation and the presence of octupole correlations in 143 Xe could not be drawn in Ref.…”

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confidence: 98%

Reflection symmetry of the near-yrast excitations in145Ba

et al. 2012

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Excited states in145 Ba, populated in spontaneous fission of 248 Cm, have been studied by means of γ spectroscopy, using high-fold γ coincidences measured with the EUROGAM2 array of Ge detectors. The 507.7-keV level, which has been assigned in this work spin and parity 9/2 + , belongs to the i 13/2 intruder band. We have identified in 145 Ba a new 9/2 − 2 level at 346.3 keV and a band on top of it. The negative parity indicates that it is not due to an octupole excitation. The position of the 5/2 − ground state, relative to the positive-parity band, could be reproduced by calculations with a reflection-symmetric potential and we do not observe a parity doublet to the ground state. Therefore we conclude that octupole excitations in 145 Ba are most likely due to octupole vibrations coupled either to the reflection-symmetric ground state or to the i 13/2 , decoupled neutron configuration.

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“…It would be tempting to assign a negative parity to this state, and hence a spin of 5/2 − , by assuming that the competing transitions feeding it and the ground state are M 1 + E2 in nature and knowing that the nearby 35.1-keV isomeric state has a low B(E1) value. However B(E1) values have been shown to differ by five orders of magnitude in the nearby nucleus 151 Pm [38] and competing M 1 + E2 and E1 decays which both feed the 38.9-keV state cannot be ruled out.…”

Section: Quasi-particle-rotor Model Calculations and State Intermentioning

confidence: 98%

Near-yrast structure of odd-A, neutron-rich Pr isotopes

et al. 2012

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The neutron-rich praseodymium isotopes 151 Pr and 153 Pr have been studied by prompt γ-ray spectroscopy using 248 Cm and 252 Cf spontaneous-fission sources placed inside the EUROGAM-II and Gammasphere germanium arrays, respectively. Rotational bands, based on 3/2 − [541] states, with similar structures, have been assigned to these nuclei. These bands decay by intraband E2 transitions. Interband E1 transitions, reported in other works, were not observed. Delayed conversionelectron and γ-ray spectroscopy of an A = 151 nucleus has been performed at the Lohengrin mass spectrometer. A previously reported 35.1-keV isomer of 151 Pr has been determined to decay by an E1 transition and its half-life of 50(8) µs measured for the first time. Calculations performed using a reflection-symmetric quasi-particle-rotor model successfully reproduce the energies of the excited states of these nuclei and their decay patterns. The spin of the isomer has been assigned to be (1/2 + , 3/2 + ) from a comparison with the calculations. The long half life of this isomer and the lack of intraband E1 transitions show an absence of strong octupole correlations in the observed states of 151,153 Pr. This is explained in terms of increasing quadrupole deformation reducing the number of Nilsson orbitals close to the Fermi surface available to form octupole collectivity.

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High-spin parity doublets in the nucleus 151Pm

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Cited by 43 publications

References 15 publications

Octupole correlations at medium spin in odd-proton153Eu nucleus

Octupole correlations at medium spin in odd-proton153Eu nucleus

Reflection symmetry of the near-yrast excitations in145Ba

Near-yrast structure of odd-A, neutron-rich Pr isotopes

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