Testing the Perey effect

Titus, L. J.; Nunes, F. M.

doi:10.1103/physrevc.89.034609

Cited by 39 publications

(138 citation statements)

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“…This dynamical nonlocality is unrelated to exchange nonlocality that generates most of the energy dependence of the nucleon OMP and is responsible for the well-known Perey effect; see Refs. [25,26]. The cases in Table III reveal consequences of the underlying nonlocality such as the different degrees of departure of the real and imaginary DPPs and their volume integrals from the proportionality to deformation length squared, δ 2 , that would be expected for the formal nonlocal DPP for phonon coupling.…”

Section: More General Vibrational Couplingmentioning

confidence: 99%

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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Section: More General Vibrational Couplingmentioning

confidence: 99%

Phonon coupling effects in proton scattering fromCa40

Mackintosh

Keeley

2014

Phys. Rev. C

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“…As shown in [16], this factor does not provide an accurate description of non-locality in transfer reactions. Given that the study of [16] focused exclusively on the Perey-Buck interaction, which has a rather simple form, it was unclear to us whether these results could be generalized.…”

Section: Introductionmentioning

confidence: 99%

“…A standard way to take care of the non-local effects on the wavefunction, without solving a non-local equation, is through the introduction of the so-called Perey factor [17,18]. As shown in [16], this factor does not provide an accurate description of non-locality in transfer reactions. Given that the study of [16] focused exclusively on the Perey-Buck interaction, which has a rather simple form, it was unclear to us whether these results could be generalized.…”

Section: Introductionmentioning

confidence: 99%

“…Motivated by earlier work [7], we recently performed a systematic study of the effects of non-locality in the nucleon-nucleus effective interactions in (p, d) transfer reactions used for studying single-particle states [16] . All calculations in [16] were based on the Perey-Buck (PB) optical potential and compared with local-phaseequivalents obtained for this interaction.…”

Section: Introductionmentioning

confidence: 99%

“…All calculations in [16] were based on the Perey-Buck (PB) optical potential and compared with local-phaseequivalents obtained for this interaction. Consistent with what had been found before [17,18], we found that nonlocality affects the scattering wave functions in the nuclear interior out to the surface region.…”

Section: Introductionmentioning

confidence: 99%

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Effects of nonlocal potentials on(p,d)transfer reactions

et al. 2015

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Background: Although local phenomenological optical potentials have been standardly used to interpret nuclear reactions, recent studies suggest the effects of non-locality should not be neglected. Purpose: In this work we investigate the effects of non-locality in (p, d) transfer reactions using non-local optical potentials. We compare results obtained with the dispersive optical model to those obtained using the Perey-Buck interaction. Method: We solved the scattering and bound-state equations for the non-local version of the dispersive optical model. Then, using the distorted wave Born approximation, we calculate the transfer cross section for (p, d) on 40 Ca at Ep=20, 35 and 50 MeV. Results: The inclusion of non-locality in the bound state has a larger effect than on the scattering states. The overall effect on the transfer cross section is very significant. We found an increase due to non-locality in the transfer cross section of ≈ 30 − 50% when using the Perey-Buck interaction and ≈ 15 − 50% when using the dispersive optical potential. Conclusions: Although the details of the non-local interaction can change the magnitude of the effects, our study shows that qualitatively the results obtained using the dispersive optical potential and the Perey-Buck interaction are consistent, in both cases the transfer cross sections are significantly increased.

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Transfer reaction code with nonlocal interactions

Titus

Ross

Nunes

2016

Computer Physics Communications

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We present a suite of codes (NLAT for nonlocal adiabatic transfer) to calculate the transfer cross section for single-nucleon transfer reactions, $(d,N)$ or $(N,d)$, including nonlocal nucleon-target interactions, within the adiabatic distorted wave approximation. For this purpose, we implement an iterative method for solving the second order nonlocal differential equation, for both scattering and bound states. The final observables that can be obtained with NLAT are differential angular distributions for the cross sections of $A(d,N)B$ or $B(N,d)A$. Details on the implementation of the T-matrix to obtain the final cross sections within the adiabatic distorted wave approximation method are also provided. This code is suitable to be applied for deuteron induced reactions in the range of $E_d=10-70$ MeV, and provides cross sections with $4\%$ accuracy.Comment: 35 pages, 6 figure

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Testing the Perey effect

Cited by 39 publications

References 39 publications

Phonon coupling effects in proton scattering fromCa40

Phonon coupling effects in proton scattering fromCa40

Effects of nonlocal potentials on(p,d)transfer reactions

Transfer reaction code with nonlocal interactions

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