Spectroscopic study of 11Be through β-delayed neutron- and γ-decays of spin-polarized 11Li

Hirayama, Y.; Shimoda, T.; Izumi, H.; Yano, H.; Yagi, Masashi; Hatakeyama, A.; Lévy, C.; Jackson, K. P.; Miyatake, H.

doi:10.1016/j.nuclphysa.2004.04.032

Cited by 8 publications

(3 citation statements)

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“…[48,49]. For the N 2 LO SAT interaction the resonance energy is close to the one predicted by the Gamow shell model [50], although our ab initio calculations predict a broader width.…”

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confidence: 74%

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CanAb InitioTheory Explain the Phenomenon of Parity Inversion inBe11?

et al. 2016

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The weakly bound exotic 11 Be nucleus, famous for its ground-state parity inversion and distinct n+ 10 Be halo structure, is investigated from first principles using chiral two-and three-nucleon forces. An explicit treatment of continuum effects is found to be indispensable. We study the sensitivity of the 11 Be spectrum to the details of the three-nucleon force and demonstrate that only certain chiral interactions are capable of reproducing the parity inversion. With such interactions, the extremely large E1 transition between the bound states is reproduced. We compare our photodisintegration calculations to conflicting experimental data and predict a distinct dip around the 3/2 − 1 resonance energy. Finally, we predict low-lying 3/2 + and 9/2 + resonances that are not or not sufficiently measured in experiments.The theoretical understanding of exotic neutron-rich nuclei constitutes a tremendous challenge. These systems often cannot be explained by mean-field approaches and contradict the regular shell structure. The spectrum of 11 Be has some very peculiar features. The 1/2 + ground state (g.s.) is loosely bound by 502 keV with respect to the n+ 10 Be threshold and is separated by only 320 keV from its parity-inverted 1/2 − partner [1, 2], which would be the expected g.s. in the standard shell-model picture. Such parity inversion, already noticed by Talmi and Unna [3] in the early 1960s, is one of the best examples of the disappearance of the N = 8 magic number with an increasing neutron to proton ratio. The next (n+n+ 9 Be) breakup threshold appears at 7.31 MeV [4], such that the rich resonance structure at low energies is dominated by the n+ 10 Be dynamics. Peculiar also is the electricdipole transition strength between the two bound states, which has attracted much attention since its first measurement in 1971 [5] and was remeasured in 1983 [6] and 2014 [7]. It is the strongest known transition between low-lying states, attributed to the halo character of 11 Be.An accurate description of this complex spectrum is anticipated to be sensitive to the details of the nuclear force [8], such that a precise knowledge of the nucleon-nucleon (NN) interaction, desirably obtained from first principles, is crucial. Moreover, the inclusion of three-nucleon (3N) effects has been found to be indispensable for an accurate description of nuclear systems [9,10]. The chiral effective field theory constitutes one of the most promising candidates for deriving the nuclear interaction. Formulated by Weinberg [11][12][13], it is based on the fundamental symmetries of QCD and uses pions and nucleons as relevant degrees of freedom. Within this theory NN, 3N and higher many-body interactions arise in a natural hierarchy [11][12][13][14][15][16][17]. The details of these interactions depend on the specific choices made during the construction. In particular the way the interactions are constrained to experimental data can have a strong impact [18].In this work we tackle the question if ab initio calculations can provide an accurate des...

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“…[48,49]. For the N 2 LO SAT interaction the resonance energy is close to the one predicted by the Gamow shell model [50], although our ab initio calculations predict a broader width.…”

supporting

confidence: 74%

“…In addition to the resonances observed in the experiment all theoretical spectra predict a low-lying 9/2 + resonance suggested in Refs. [48,49]. For the N 2 LO SAT interaction the resonance energy is close to the one predicted by the Gamow shell model [50], although our ab initio calculations predict a broader width.…”

supporting

confidence: 74%

CanAb InitioTheory Explain the Phenomenon of Parity Inversion inBe11?

et al. 2016

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“…they also stress the presence of a 5/2 − state which is not completely consistent with Refs. [36,37,38]. However, we can not rule out the possibility of a low-lying intruder 2 Ω-dominated state, which would avoid detection in our study.…”

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confidence: 70%

Large basisab initioshell model investigation ofBe9andBe11
Forssén
¹
,
Navrátil
²
,
Ormand
³

et al. 2005
Phys. Rev. C
114
5
138
1
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We present the first ab initio structure investigation of the loosely bound 11 Be nucleus, together with a study of the lighter isotope 9 Be. The nuclear structure of these isotopes is particularly interesting because of the appearance of a parity-inverted ground state in 11 Be. Our study is performed in the framework of the ab initio no-core shell model. Results obtained using four different, high-precision two-nucleon interactions, in model spaces up to 9h , are shown. For both nuclei, and all potentials, we reach convergence in the level ordering of positive-and negative-parity spectra separately. Concerning their relative position, the positive-parity states are always too high in excitation energy, but a fast drop with respect to the negative-parity spectrum is observed when the model space is increased. This behavior is most dramatic for 11 Be. In the largest model space we were able to reach, the 1/2 + level has dropped down to become either the first or the second excited state, depending on which interaction we use. We also observe a contrasting behavior in the convergence patterns for different two-nucleon potentials and argue that a three-nucleon interaction is needed to explain the parity inversion. Furthermore, large-basis calculations of 13 C and 11 B are performed. This allows us to study the systematics of the position of the first unnatural-parity state in the N = 7 isotone and the A = 11 isobar. The 11 B run in the 9h model space involves a matrix with dimension exceeding 1.1 × 10 9 , and is our largest calculation so far. We present results on binding energies, excitation spectra, level configurations, radii, electromagnetic observables, and 10 Be + n overlap functions.

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Excited Nuclear States for Be-11 (Beryllium)

Sukhoruchkin¹,

Soroko²

2012

Nuclei With Z = 1 - 29

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Spectroscopic study of 11Be through β-delayed neutron- and γ-decays of spin-polarized 11Li

Cited by 8 publications

References 0 publications

CanAb InitioTheory Explain the Phenomenon of Parity Inversion inBe11?

CanAb InitioTheory Explain the Phenomenon of Parity Inversion inBe11?

Large basisab initioshell model investigation ofBe9andBe11
Forssén
¹
,
Navrátil
²
,
Ormand
³

et al. 2005
Phys. Rev. C
114
5
138
1
View full text Add to dashboard Cite

Excited Nuclear States for Be-11 (Beryllium)

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Spectroscopic study of 11Be through β-delayed neutron- and γ-decays of spin-polarized 11Li

Cited by 8 publications

References 0 publications

CanAb InitioTheory Explain the Phenomenon of Parity Inversion inBe11?

CanAb InitioTheory Explain the Phenomenon of Parity Inversion inBe11?

Large basisab initioshell model investigation ofBe9andBe11Forssén1, Navrátil2, Ormand3 et al. 2005Phys. Rev. C11451381View full textAdd to dashboardCite

Excited Nuclear States for Be-11 (Beryllium)

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Product

Resources

About

Large basisab initioshell model investigation ofBe9andBe11
Forssén
¹
,
Navrátil
²
,
Ormand
³

et al. 2005
Phys. Rev. C
114
5
138
1
View full text Add to dashboard Cite