Ordering of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>0</mml:mn><mml:msub><mml:mi>d</mml:mi><mml:mrow><mml:mn>5</mml:mn><mml:mo>/</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>1</mml:mn><mml:msub><mml:mi>s</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>proton levels in light nuclei

Hoffman, C. R.; Kay, B. P.; Schiffer, J. P.

doi:10.1103/physrevc.94.024330

Cited by 18 publications

(16 citation statements)

References 38 publications

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“…The lowest states 0 − and 1 − in 16 terises the 2 − and 3 − states. The widths of all four states are consistent with single-proton states [21]. Population of d-states in 16 F have larger probability than s-states for light targets, while in reactions in the lead target mainly s-states are populated.…”

Section: Relative Energy Spectrasupporting

confidence: 65%

Comparison of electromagnetic and nuclear dissociation of Ne17

Wamers¹,

Marganiec²,

Aksouh³

et al. 2018

Phys. Rev. C

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The Borromean dripline nucleus 17 Ne has been suggested to possess a two-proton halo structure in its ground state. In the astrophysical rp process, where the two-proton capture reaction 15 O(2p, γ) 17 Ne, plays an important role, the calculated reaction rate differs by several orders of magnitude between different theoretical approaches. To add to the understanding of 17 Ne structure we have studied nuclear and electromagnetic dissociation. A 500 MeV/u 17 Ne beam was directed towards lead, carbon and polyethylene targets. Oxygen isotopes in the final state were measured in coincidence with one or two protons. Different reaction branches in the dissociation of 17 Ne were disentangled. The relative populations of s-and d-states in 16 F were determined for light and heavy targets. The differential cross section for electromagnetic dissociation (EMD) shows a continuous internal energy spectrum in the three-body system 15 O+2p. The 17 Ne EMD data were compared to current theoretical models. None of them yields, however, satisfactory agreement with the experimental data presented here. These new data may facilitate future development of adequate models for description of the fragmentation process.

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Section: Relative Energy Spectrasupporting

confidence: 65%

Comparison of electromagnetic and nuclear dissociation of Ne17

Wamers¹,

Marganiec²,

Aksouh³

et al. 2018

Phys. Rev. C

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confidence: 60%

“…Such effects had already been noted by Bohr and Mottelson [9]. The bulk features of the dramatic variations in the separation of the proton and neutron 1s and 0d orbitals between He and O can be attributed to weak-binding effects on the s states, with the tensor and spin-orbit components of the residual two-body protonneutron interaction accounting for only a small fraction of the total change [7,8].The 'lingering' effect means that the rate at which the eigenstate moves with changing radius of the potential, changes as the state approaches zero binding. Hamamoto and Sagawa [10] explored the splitting between the 1p 3/2 -1p 1/2 states for a generic A = 44 system using a finite nuclear potential and observed a substantial decrease in the splitting as the 1p 1/2 moved close to threshold.…”

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confidence: 63%

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Effect of Weak Binding on the Apparent Spin-Orbit Splitting in Nuclei

2017

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The apparent splitting between orbitals that are spin-orbit partners can be substantially influenced by the effects of finite binding. In particular, such effects can account for the observed decrease in separation of the neutron 1p 3/2 and 1p 1/2 orbitals between the 41 Ca and 35 Si isotopes. This behavior has been the subject of recent experimental and theoretical works and cited as evidence for a proton "bubble" in 34 Si causing an explicit weakening of the spin-orbit interaction. The results reported here suggest that the change in the separation between the 1p 3/2 and 1p 1/2 partners occurs dominantly because of the behavior of the energies of these 1p neutron states near zero binding.To describe the ordering of levels in nuclei and the pattern of magic numbers a spin-orbit interaction had to be added to the nuclear Hamiltonian which is the basis of the very successful nuclear shell-model [1]. The magnitude of the spin-orbit interaction is determined empirically and is not fully understood quantitatively. The spin-orbit coupling must be a surface term, and is usually included in the one-body mean field as a potential proportional to the derivative of the nuclear density.Recent works have postulated the presence of a proton "bubble" in 34 Si [2,3], suggesting that the central depletion in the proton density results in an 'interior' contribution to the spin-orbit interaction, opposite in sign to that of the outer surface, causing a factor of approximately two reduction in the spin-orbit splitting of the neutron 1p orbitals. In this work we show that the low binding energy of the neutron states considered, quantitatively accounts for the reduction. The effects of finite binding must be taken into account before other explanations are considered.Data [4] from neutron-adding (d,p) reactions on 40 Ca, 38 Ar, 36 S, and most recently 34 Si using a radioactive ion beam [2], provide information on the location of the 1p 3/2 and 1p 1/2 single-particle strength outside of the N = 20 closed neutron shell. This information is reasonably complete. Using the dominant fragments of the neutron 1p 3/2 and 1p 1/2 strength as a measure of the single-particle energies it was shown [2] that the spin-orbit splitting between the neutron 1p 3/2 and 1p 1/2 states decreases by almost 1 MeV from 41 Ca to 35 Si, with most of that decrease happening between 37 S and 35 Si. To first order the use of the dominant fragments is a fair approximation, although the actual centroids, which can be determined from the available experimental data [5] (and see Supplemental Information [6]), lie at slightly different energies. In Fig. 1 between S and Si for the centroids. The 1p 1/2 state is close to the separation threshold at 35 Si. It was recently emphasized [7,8] that bound states with low angular momentum, especially s states, linger below threshold, showing a reluctance to become unbound. Such effects had already been noted by Bohr and Mottelson [9]. The bulk features of the dramatic variations in the separation of the proton and neutron 1s an...

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“…The conventional shell model and magic numbers are obtained by solving the Schrödinger equation in a mean field potential. In the light nuclei region, especially approaching the neutron or proton drip line, many factors could contribute to the change or disappearance of the conventional shells, such as the monopole interaction between proton and neutron [1], the weak binding of the nucleons approaching the drip line [2][3][4], and the three-body force in nuclei [5]. As a well-recognized example, the ground state (1/2 + ) and the first excited state (1/2 − ) of the halo nucleus 11 Be are inverted with respect to the predictions from conventional independent particle shell model.…”

Section: Introductionmentioning

confidence: 99%

Low-lying states in Be12 using one-neutron transfer reaction

Chen¹,

Lou²,

Ye³

et al. 2018

Phys. Rev. C

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A new one-neutron adding reaction on 11 Be was performed at 26.9A MeV. The elastic scattering data was measured simultaneously to determine the target component and optical potentials for the entrance channel. A special isomer-tagging method was used to determine the cross sections for the 0 + 2 state. Based on the ratio of the s−wave spectroscopic factors of the 0 + 1 and 0 + 2 states, along with the previously reported p−wave intensities, the s− and d−wave components of these two states were obtained and compared with shell model calculations using various interactions. The result shows a dominant d−wave strength in the ground state of 12 Be, and reveals the dominance of sd-and sp-single-particle configurations in the 2 + and 1 − state of 12 Be, respectively. Together with the configuration mixing analysis, the relative spectroscopic factors, which are shown to be less sensitive to the different choice of optical potentials, provide important insights on the wave functions for the low-lying states of 12 Be.

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Ordering of the0d5/2and1s1/2proton levels in light nuclei

Cited by 18 publications

References 38 publications

Comparison of electromagnetic and nuclear dissociation of Ne17

Comparison of electromagnetic and nuclear dissociation of Ne17

Effect of Weak Binding on the Apparent Spin-Orbit Splitting in Nuclei

Low-lying states in Be12 using one-neutron transfer reaction

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