Precision measurement of the electromagnetic dipole strengths in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Be</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>11</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>

Kwan, E.; Wu, C. Y.; Summers, N. C.; Hackman, G.; Drake, T.E.; Andreoiu, C.; Ashley, Robert; Ball, G. C.; Bender, P. C.; Boston, A. J.; Boston, H. C.; Chester, A.; Close, Alex; Cline, D.; Cross, D. S.; Dunlop, R.; Finlay, A.; Garnsworthy, A. B.; Hayes, A. B.; Laffoley, A. T.; Nano, T.; Navrátil, Petr; Pearson, C. J.; Pore, J. L.; Quaglioni, Sofia; Svensson, C. E.; Starosta, K.; Thompson, I. J.; Voss, P.; Williams, Spencer J.; Wang, Z.M.

doi:10.1016/j.physletb.2014.03.049

Cited by 25 publications

(42 citation statements)

References 37 publications

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“…It has one of the largest known reduced dipole transition probabilities between the first excited state at E x = 0.32 MeV and the ground state (B(E1) = 0.116(12) e 2 fm 2 [138]). This observation is corroborated by the recent high precision measurement of the electromagnetic dipole strengths performed at the TRI-UMF Isotope Separator and Accelerator (ISAC II) [139]. The unusual features of this halo nucleus strongly affect the interaction with both light and heavy targets at low bombarding energies.…”

Section: Reactions With 11 Besupporting

confidence: 60%

Elastic scattering, fusion, and breakup of light exotic nuclei

2016

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Abstract. The present status of fusion reactions involving light (A < 20) radioactive projectiles at energies around the Coulomb barrier (E < 10 MeV per nucleon) is reviewed, emphasizing measurements made within the last decade. Data on elastic scattering (providing total reaction cross section information) and breakup channels for the involved systems, demonstrating the relationship between these and the fusion channel, are also reviewed. Similarities and differences in the behavior of fusion and total reaction cross section data concerning halo nuclei, weakly-bound but less exotic projectiles, and strongly-bound systems are discussed. One difference in the behavior of fusion excitation functions near the Coulomb barrier seems to emerge between neutron-halo and proton-halo systems. The role of charge has been investigated by comparing the fusion excitation functions, properly scaled, for different neutron-and proton-rich systems. Possible physical explanations for the observed differences are also reviewed.

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Section: Reactions With 11 Besupporting

confidence: 60%

Elastic scattering, fusion, and breakup of light exotic nuclei

2016

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“…Works along these lines for 4 He suggest a slight reduction of the dipole strength [52,53]. A similar effect would bring the calculated E1 transition in better agreement with the experiment [7].…”

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confidence: 52%

“…The phenomenological energy adjustment only slightly influences the asymptotic behavior of the S wave, as seen by comparing the solid and dashed black curves, while other partial waves are even indistinguishable on the plot resolution. The corresponding spectroscopic factors for the NCSMC-pheno approach, obtained by integrating the squared cluster form factors in reproduces the strong E1 transition, albeit the latest measurement [7] is slightly overestimated, even after the phenomenological energy adjustment. There might be small effects arising from a formally necessary SRG evolution of the transition operator.…”

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confidence: 82%

“…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.…”

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confidence: 99%

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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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“…The angular distributions of the elastic, inelastic scattering and break-up cross sections of the one neutron halo 11 Be on a heavy-mass target ( 197 Au) have been measured at laboratory energies below (31.9 MeV) and around (39.6 MeV) the Coulomb barrier (V b ∼ 40 MeV). The elastic, inelastic channel and break-up channels of the 11 Be + 197 Au reaction have been experimentally separated for the first time in this energy range.…”

Section: Pos(inpc2016)207mentioning

confidence: 99%

Scattering Of The Halo Nucleus 11Be On A 197Au Target At Energies Around The Coulomb Barrier

Borge¹,

Pesudo²,

Nácher³

et al. 2017

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

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The angular distributions of the elastic, inelastic scattering and break-up cross sections of the one neutron halo 11 Be on a heavy-mass target ( 197 Au) have been measured at laboratory energies below (31.9 MeV) and around (39.6 MeV) the Coulomb barrier (V b ∼ 40 MeV). The elastic, inelastic channel and break-up channels of the 11 Be + 197 Au reaction have been experimentally separated for the first time in this energy range. The experiment was performed at TRIUMF, using four Silicon detectors in telescope configuration to separate the 11 Be from the 10 Be fragments and the High-Purity Germanium Detector Array TIGRESS for γ-ray detection. The break-up and inelastic scattering contributions are observed to be relevant even at energies well below the Coulomb barrier. Data are compared with different models of increasing degree of sophistication: semiclassical, inert-core continuum discretised coupled channel (CDCC) calculations and CDCC including core deformation and excitations (XCDCC). XCDCC calculations are necessary to reproduce simultaneously elastic, inelastic and break-up scattering data. The results show that the reaction mechanism is sensible to the entanglement of core and halo degrees of freedom in 197 Au.

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Precision measurement of the electromagnetic dipole strengths in Be11

Cited by 25 publications

References 37 publications

Elastic scattering, fusion, and breakup of light exotic nuclei

Elastic scattering, fusion, and breakup of light exotic nuclei

CanAb InitioTheory Explain the Phenomenon of Parity Inversion inBe11?

Scattering Of The Halo Nucleus 11Be On A 197Au Target At Energies Around The Coulomb Barrier

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