The microscopic feshbach optical potential for a schematic coupled channel example

Rawitscher, George

doi:10.1016/0375-9474(87)90076-5

Cited by 50 publications

(97 citation statements)

References 44 publications

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“…Other results from the calculations of Ref. [11], which are in some ways more realistic, have a bearing on the nonlocality considerations of this paper.…”

Section: Calculating the Dppmentioning

confidence: 78%

Dynamic polarization potential and dynamical nonlocality in nuclear potentials: Nucleon-nucleus potential

Keeley

Mackintosh

2014

Phys. Rev. C

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Background: Of the two sources of nonlocality in nucleon-nucleus and nucleus-nucleus interactions, knock-on exchange and dynamically generated, almost all papers referring to nonlocality mention only the first. Purpose: Our purpose is threefold: to demonstrate a method for including dynamical nonlocality, for which a simple prescription (like the Perey factor for exchange nonlocality) is unknown, within distorted wave Born approximation (DWBA) calculations; to identify signatures of dynamic nonlocality and illuminate the extent to which the presence of such nonlocality can influence the extraction of spectroscopic information from direct reactions, and more generally, to increase our understanding of nucleus-nucleus interactions. Methods: After reviewing existing indications of dynamically induced nonlocality, DWBA transfer calculations are presented which compare results involving dynamically nonlocal potentials with those involving their local equivalents. The dynamical nonlocal potentials are generated in situ by the presence of channel coupling and the local equivalents are generated by inversion of the corresponding coupled channel elastic S matrix. This method obviates the need for solving integro-differential equations for including nonlocal potentials in DWBA. Results: The coupling of nucleons to collective states of the target nucleus induces dynamical nonlocality in the nucleon-nucleus interaction that has a significant effect on (p,d) reactions at energies relevant to spectroscopic studies. Conclusions: A method for studying the contribution of dynamically induced nonlocality in nuclear interactions has been demonstrated. Dynamically induced nonlocality should not be overlooked in the analysis of direct reactions. The method can also be applied to dynamic nonlocality due to projectile excitation.

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“…Other results from the calculations of Ref. [11], which are in some ways more realistic, have a bearing on the nonlocality considerations of this paper.…”

Section: Calculating the Dppmentioning

confidence: 78%

Dynamic polarization potential and dynamical nonlocality in nuclear potentials: Nucleon-nucleus potential

Keeley

Mackintosh

2014

Phys. Rev. C

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“…The highly nonlocal and l-dependent nature of the contribution of phonon coupling is indicated in the work of Rawitscher [27] and others, e.g., Ref. [24], who begin with the Feshbach expressions [28].…”

Section: Discussionmentioning

confidence: 98%

Phonon coupling effects in proton scattering fromCa40

Mackintosh

Keeley

2014

Phys. Rev. C

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Background: Formal optical model theory shows that coupling to vibrational nuclear states generates a nonlocal and l-dependent dynamical polarization potential (DPP). Little is established concerning the DPP, yet its properties are crucial for explaining the departures of optical model potentials (OMPs) from global behavior and for the rigorous extraction of spectroscopic information from direct reactions. Purpose: To appraise the application of channel coupling followed by S-matrix inversion for the systematic exploration of the contribution of the coupling of collective states to the nucleon OMP and to identify properties of nuclear potentials indicative of l-dependence. Methods: S-matrix to potential, S lj → V (r) + l · s V SO (r), inversion provides local potentials that precisely reproduce the elastic channel S-matrix from coupled channel (CC) calculations. Subtracting the elastic channel uncoupled (bare) potential yields a local and l-independent representation of the DPP. The dependence of this local DPP upon the nature of the coupled states and upon other parameters can be studied. Results: All components of the DPP arising from coupling to vibrational states are substantially undulatory with a point-by-point magnitude therefore disproportionate to their contribution to volume integrals. Information relating to dynamical nonlocality is found. The proton charge leads to a substantial difference between DPPs for protons and neutrons. Conclusions: Undulatory features in potentials found in precision fits to elastic scattering data are significant, are a consequence of coupling to inelastic channels and must be allowed for in phenomenology; they are indirect evidence of l-dependence. Within the model, coupling to excited states magnifies the effect of the proton charge on the difference between proton-nucleus and neutron-nucleus interactions. Coupled channel plus inversion is a procedure of wide applicability, complementary to evaluation of the Feshbach formalism.

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“…Moreover, because the formal DPPs are nonlocal and L dependent (see, e.g., Ref. [14]) it is also desirable that the local equivalents be determined by an inversion procedure that fully captures these features in a local form. We note, for example, that the DPPs presented herein, which precisely reproduce the elastic channel S L , exhibit certain undulatory features.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…[13] that these undulations can be related to the angular momentum dependence of the formal DPP (see Ref. [14]). The significant differences in the DPPs for the two systems are as follows: (i) the magnitudes of the main features of the 6 He DPP are larger than those for 8 He and (ii) the main attractive and absorptive features of the 8 He DPP occur at significantly larger radii than do the corresponding features of the 6 He DPP.…”

Section: The Dynamic Polarization Potentialsmentioning

confidence: 97%

Influence of single-neutron stripping on near-barrier He6+Pb208 and He
Marquínez-Durán
¹
,
Keeley
²
,
Kemper
³

et al. 2017
Phys. Rev. C
7
7
39
0
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The influence of single-neutron stripping on the near-barrier elastic scattering angular distributions for the 6,8 He + 208 Pb systems is investigated through coupled reaction channels (CRC) calculations fitting recently published data to explore the differences in the absorptive potential found in the scattering of these two neutronrich nuclei. The inclusion of the coupling reduces the elastic cross section in the Coulomb-nuclear interference region for 8 He scattering, whereas for 6 He its major impact is on the large-angle elastic scattering. The real and imaginary dynamic polarization potentials are obtained by inverting the CRC elastic scattering S-matrix elements. These show that the main absorptive features occur between 11 and 12 fm for both projectiles, while the attractive features are separated by about 1 fm, with their main structures occurring at 10.5 fm for 6 He and 11.5 fm for 8 He.

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The microscopic feshbach optical potential for a schematic coupled channel example

Cited by 50 publications

References 44 publications

Dynamic polarization potential and dynamical nonlocality in nuclear potentials: Nucleon-nucleus potential

Dynamic polarization potential and dynamical nonlocality in nuclear potentials: Nucleon-nucleus potential

Phonon coupling effects in proton scattering fromCa40

Influence of single-neutron stripping on near-barrier He6+Pb208 and He
Marquínez-Durán
¹
,
Keeley
²
,
Kemper
³

et al. 2017
Phys. Rev. C
7
7
39
0
View full text Add to dashboard Cite

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The microscopic feshbach optical potential for a schematic coupled channel example

Cited by 50 publications

References 44 publications

Dynamic polarization potential and dynamical nonlocality in nuclear potentials: Nucleon-nucleus potential

Dynamic polarization potential and dynamical nonlocality in nuclear potentials: Nucleon-nucleus potential

Phonon coupling effects in proton scattering fromCa40

Influence of single-neutron stripping on near-barrier He6+Pb208 and HeMarquínez-Durán1, Keeley2, Kemper3 et al. 2017Phys. Rev. C77390View full textAdd to dashboardCite

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About

Influence of single-neutron stripping on near-barrier He6+Pb208 and He
Marquínez-Durán
¹
,
Keeley
²
,
Kemper
³

et al. 2017
Phys. Rev. C
7
7
39
0
View full text Add to dashboard Cite