The elastic scattering of intermediate energy protons from 40Ca and 208Pb

Hutcheon, D. A.; Olsen, W.C.; Sherif, H. S.; Dymarz, R.; Cameron, J.M.; Johansson, J.I.; Kitching, P.; Liljestrand, P.R.; McDonald, W. J.; Miller, C. A.; Neilson, G.C.; Sheppard, D.M.; McDaniels, D.K.; Tinsley, J. R.; Schwandt, P.; Swenson, L.W.; Stronach, C. E.

doi:10.1016/0375-9474(88)90078-4

Cited by 80 publications

(29 citation statements)

References 22 publications

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“…In the case of p+ 208 Pb, the data at 400 MeV were taken from Ref. [30]. The full and dashed curves represent results for the Paris potential and corresponding inversion respectively.…”

Section: A Sensitivity To Off-shell Effects In Na Scatteringmentioning

confidence: 99%

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Sensitivity of nucleon-nucleus scattering to the off-shell behavior of on-shell equivalentNNpotentials

et al. 1996

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The sensitivity of nucleon-nucleus elastic scattering to the off-shell behavior of realistic nucleon-nucleon interactions is investigated when on-shell equivalent nucleon-nucleon potentials are used. The study is based on applications of the full-folding optical model potential for an explicit treatment of the offshell behavior of the nucleon-nucleon effective interaction. Applications were made at beam energies between 40 and 500 MeV for proton scattering from 40 Ca and 208 Pb. We use the momentum-dependent Paris potential and its local on-shell equivalent as obtained with the Gelfand-Levitan and Marchenko inversion formalism for the two nucleon Schrödinger equation. Full-folding calculations for nucleon-nucleus scattering show small fluctuations in the corresponding observables. This implies that off-shell features of the NN interaction cannot be unambiguously identified with these processes. Inversion potentials were also constructed directly from NN phase-shift data (SM94) in the 0-1.3 GeV energy range. Their use in proton-nucleus scattering above 200 MeV provide a superior description of the observables relative to those obtained from current realistic NN potentials. Limitations and scope of our findings are presented and discussed.

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“…In the case of p+ 208 Pb, the data at 400 MeV were taken from Ref. [30]. The full and dashed curves represent results for the Paris potential and corresponding inversion respectively.…”

Section: A Sensitivity To Off-shell Effects In Na Scatteringmentioning

confidence: 99%

“…[33] at 400 MeV and from Ref. [30] at 500 MeV. Certainly, applications of the Paris (or its inverse) potential at 400 MeV and above constitute an extrapolation of the model.…”

Section: Na Scattering From Nn Phase-shiftsmentioning

confidence: 99%

Sensitivity of nucleon-nucleus scattering to the off-shell behavior of on-shell equivalentNNpotentials

et al. 1996

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“…All theoretical models use the same exact scattering formalism, but vary only in their value for R 208 skin , as indicated in the legend. The experimental data is from Ref [55]. (reprinted from Ref [25],.…”

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confidence: 99%

Neutron skins of atomic nuclei: per aspera ad astra

Thiel¹,

Sfienti²,

Piekarewicz³

et al. 2019

J. Phys. G: Nucl. Part. Phys.

133

127

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The complex nature of the nuclear forces generates a broad range and diversity of observational phenomena. Heavy nuclei, though orders of magnitude less massive than neutron stars, are governed by the same underlying physics, which is enshrined in the nuclear equation of state. Heavy nuclei are expected to develop a neutron-rich skin where many neutrons collect near the surface. Such a skin thickness is strongly sensitive to the poorly-known density dependence of the symmetry energy near saturation density. An accurate and model-independent determination of the neutron-skin thickness of heavy nuclei would provide a significant first constraint on the density dependence of the nuclear symmetry energy.The determination of the neutron-skin thickness of heavy nuclei has far reaching consequences in many areas of physics as diverse as heavy-ion collisions, polarized electron and proton scattering off nuclei, precision tests of the standard model using atomic parity violation, and nuclear astrophysics.While a systematic and concerted experimental effort has been made to measure the neutron-skin thickness of heavy nuclei, a precise and model-independent determination remains elusive. The measurement of parity-violating asymmetries provides a clean and model-independent determination of the weak form factor of the nucleus which is dominated by the neutron distribution. However, measuring parity-violating asymmetries of the order of a part per million is both challenging and time-consuming. Alternative observables sensitive to the symmetry energy have been proposed and measured succesfully in recent experimental campaigns. These data are valuable, but interpretations contain implicit model dependence that hinder the clean determination of the neutron-skin thickness. How to move forward at a time when many new facilities are being commissioned and how to strengthen the synergy with other areas of physics are primary goals of this review.

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“…Similar calculations for the related (e,e n) reaction indicate that final-state charge exchange may be appreciable, but it is only a small effect in the (e,e p) reaction [14,15]. It has been shown, however, that real differences can exist between relativistic and nonrelativistic calculations for the same processes [16][17][18][19][20][21]. Therefore, we have done a relativistic calculation for the final-state charge exchange contribution to (γ ,n) reactions that is built on our relativistic direct knockout formalism for (γ ,N) reactions [7,8].…”

Section: Introductionmentioning

confidence: 76%

On the calculation of charge-exchange effects in a relativistic model for (γ n) reactions

Lotz¹,

Sherif²

2001

Can. J. Phys.

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The charge-exchange contribution to photoneutron emission is calculated in a relativistic model. The emission is regarded as a two-step process consisting of a direct electromagnetic knockout of a proton followed by a (p,n) charge-exchange reaction. The latter step is effected by the isovector components of the scalar and vector mean field optical potentials. A novel procedure, in which the pertinent integral is reduced to a simpler integral in combination with a differential equation, is adopted to evaluate the transition amplitude. We find that the charge-exchange contribution is comparable in magnitude to the direct contribution over a range of photon energies. There is some dependence on the optical and binding potentials used to calculate nucleon wave functions. As expected, the sum of direct and charge-exchange contributions is not sufficient to account for the observed cross sections, confirming the importance of including meson exchange and isobar currents. PACS Nos.: 25.20Lj, 25.40Kv, 24.10Jv Résumé : Nous utilisons un modèle relativiste pour calculer la contribution de l'échange de charge lors de l'émission de photoneutrons. Cette émission est vue comme un processus à deux étapes consistant en une expulsion (knockout) directe électromagnétique d'un proton, suivie d'une réaction d'échange de charge (p,n). Cette dernière étape est due à la composante isovecteur des potentiels optiques scalaire et vecteur en champ moyen. Nous utilisons une nouvelle procédure pour calculer l'amplitude de transition, où l'intégrale appropriée est réduite à une intégrale simple associée à une équation différentielle. Nous trouvons que la contribution d'échange de charge est comparable en grandeur à la contribution directe sur une plage d'énergie du photon. Le résultat dépend un peu des potentiels optiques et de liaison utilisés pour calculer les fonctions d'onde nucléoniques. Comme on pouvait s'y attendre, la somme des contributions directe et d'échange n'est pas suffisante pour expliquer les sections efficaces observées, ce qui confirme le besoin d'inclure l'échange de mésons et les courants isobariques.[Traduit par la Rédaction]

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The elastic scattering of intermediate energy protons from 40Ca and 208Pb

Cited by 80 publications

References 22 publications

Sensitivity of nucleon-nucleus scattering to the off-shell behavior of on-shell equivalentNNpotentials

Sensitivity of nucleon-nucleus scattering to the off-shell behavior of on-shell equivalentNNpotentials

Neutron skins of atomic nuclei: per aspera ad astra

On the calculation of charge-exchange effects in a relativistic model for (γ n) reactions

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