Direct Evidence for Octupole Deformation in 
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 and the Origin of Large 
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 Moment Variations in Reflection-Asymmetric Nuclei

Bucher, B.; Zhu, S. J.; Wu, C. Y.; Janssens, R. V. F.; Bernard, R.; Robledo, L. M.; Rodríguez, T. R.; Cline, D.; Hayes, A. B.; Ayangeakaa, A. D.; Buckner, M. Q.; Campbell, C. M.; Carpenter, M. P.; Clark, J. A.; Crawford, H. L.; David, H. M.; Dickerson, Clayton; Harker, J.; Hoffman, C. R.; Kay, B. P.; Kondev, F. G.; Lauritsen, T.; Macchiavelli, A. O.; Pardo, R. C.; Savard, G.; Seweryniak, D.; Vondrasek, R.

doi:10.1103/physrevlett.118.152504

Cited by 100 publications

(69 citation statements)

References 39 publications

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“…The SCMF (β 2 , β 3 ) deformation energy surfaces for the even-even Ba nuclei exhibit a transition from a weakly deformed quadrupole shape of 142 Ba to moderately quadrupole and octupole deformed shapes of 144,146 Ba, characterized by β 3 -soft potentials. The resulting sdf IBM energy spectra display a signature of octupole collectivity in the pronounced E3 transitions between the low-lying negative-parity band and the groundstate band, in agreement with recent spectroscopic data [5,6]. The sdf -IBFM reproduces the experimental lowenergy excitation spectra in the considered odd-mass Ba isotopes fairly well.…”

Section: Basupporting

confidence: 87%

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Signatures of octupole correlations in neutron-rich odd-mass barium isotopes

2018

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Octupole deformation and the relevant spectroscopic properties of neutron-rich odd-mass barium isotopes are investigated in a theoretical framework based on nuclear density functional theory and the particle-core coupling scheme. The interacting-boson Hamiltonian that describes the octupole-deformed even-even core nucleus, as well as the single-particle energies and occupation probabilities of an unpaired nucleon, are completely determined by microscopic axially-symmetric (β2, β3)-deformation constrained self-consistent mean-field calculations for a specific choice of the energy density functional and pairing interaction. A boson-fermion interaction that involves both quadrupole and octupole degrees of freedom is introduced, and their strength parameters are determined to reproduce selected spectroscopic data for the odd-mass nuclei. The model reproduces recent experimental results both for the even-even and odd-mass Ba isotopes. In particular, for 145,147 Ba our results indicate, in agreement with recent data, that octupole deformation does not determine the structure of the lowest states in the vicinity of the ground state, and only becomes relevant at higher excitation energies.

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Section: Basupporting

confidence: 87%

“…A number of new experiments are either running or being planned at major RIB facilities around the world. Recently, experimental evidence for permanent octupole deformation in radioactive nuclei has been reported, e.g., 224 Ra and 220 Rn at CERN [4] and 144 Ba [5] and 146 Ba [6] at Argonne National Laboratory.…”

Section: Introductionmentioning

confidence: 99%

Signatures of octupole correlations in neutron-rich odd-mass barium isotopes

2018

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“…On the other hand, a number of new E2 and E3 matrix elements were well-determined from the new Coulomb excitation yields; the full set of which are reported in Ref. [19]. The most significant result is the ground-state E3 matrix element 3 − 1 M (E3) 0 + 1 determined to be 0.65( +14 −20 ) eb 3/2 which reflects the amplitude of octupole deformation present in the ground state [2].…”

Section: Resultsmentioning

confidence: 93%

“…[14]). Once the χ 2 minimum was found, the rigid-rotor constraint was removed to properly determine the full uncertainties, including correlations between matrix elements [19].…”

Section: Discussionmentioning

confidence: 99%

First Direct Observation Of Enhanced Octupole Collectivity In 144,146Ba

Bucher¹,

Zhu²,

Wu³

et al. 2017

Proceedings of the 26th International Nuclear Physics Conference — PoS(INPC2016)

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The octupole strength present in the neutron-rich, radiocative nucleus 146 Ba has been experimentally determined for the first time using Coulomb excitation. To achieve this, A=146 fission fragments from CARIBU were post-accelerated by the Argonne Tandem Linac Accelerator System (ATLAS) and impinged on a thin 208 Pb target. Using the GRETINA γ-ray spectrometer and the CHICO2 heavy-ion counter, the reduced transition probability B(E3; 3 − →0 +) was determined as 48(+21 −29) W.u. The new result provides further experimental evidence for the presence of a region of octupole deformation surrounding the neutron-rich barium isotopes.

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“…The 140 Ba nucleus is particularly interesting because it is located at the onset of octupole correlations. Two neighbouring isotopes, the neutron-rich 144,146 Ba isotopes, were recently studied experimentally in terms of their B(E3) values [1,2], using radioactive beams and Coulomb excitation. The respective B(E3) values, although featuring large uncertainties, were found to be significantly larger than any theoretical prediction.…”

Section: Introductionmentioning

confidence: 99%

Investigating the structure of the low-lying states in 140Ba

Khaliel

Mertzimekis²,

Bracco³

et al. 2020

hnps

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The neutron-rich 144,146Ba isotopes have been studied recently in terms of their experimental B(E3) values [1,2]. Although featuring large uncertainties, the results were found to be significantly larger than any theoretical calculation. Similar questions exist for the slightly lighter isotope 140Ba, which is particularly interesting since it is located at the onset of octupole correlations. The lifetimes of the lower-lying states are completely unknown, with the sole exception of the first 2+ state [3].In this work, we report on the outcome of a short test run, attempting to populate the states of interest using the 138Ba(18O,16O)140Ba reaction. The experiment was carried out at IFIN-HH using a specially manufactured natBa target sandwiched between two Au layers. This was considered imperative due to Barium's quick oxidation in air. Four beam energies (61,63,65,67 MeV) below the Coulomb barrier have been tested. The subsequent decay was measured using the Bucharest ROSPHERE array, consisting of 15 Ge detectors and 10 LaBr3(Ce) scintillators.The preliminary results from the test run report on the level population strengths and the limits in lifetime measurements, which are expected to provide new information on the structural effects in neutron-rich barium isotopes, especially regarding quadrupole and octupole degrees of freedom. The _ndings are also expected to act as stringent tests to theoretical modeling in this mass regime.

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Direct Evidence for Octupole Deformation in Ba146 and the Origin of Large E1 Moment Variations in Reflection-Asymmetric Nuclei

Cited by 100 publications

References 39 publications

Signatures of octupole correlations in neutron-rich odd-mass barium isotopes

Signatures of octupole correlations in neutron-rich odd-mass barium isotopes

First Direct Observation Of Enhanced Octupole Collectivity In 144,146Ba

Investigating the structure of the low-lying states in 140Ba

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