Elastic Scattering of 61.4-MeV Protons

Fulmer, C.B.; Ball, J.B.; Scott, A.; Whiten, M.L.

doi:10.1103/physrev.181.1565

Cited by 135 publications

(49 citation statements)

References 24 publications

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“…Fig. 5 compares the calculated differential elastic scattering cross sections for the p+ 58 Ni system in the 20-60 MeV range with the experimental data from ( Van Hall et al, 1977;Fricke et al, 1967;Fulmer et al, 1969;Sakaguchi et al, 1982) and with the data predicted by CH89. A good agreement has been attained at low and intermediate energies.…”

Section: Calculation Of the Scattering And Bound State Datamentioning

confidence: 98%

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Nucleon–nucleus real potential of Woods–Saxon shape between 60 and 60 MeV for the 40 A 208 nuclei

Беспалова

Romanovsky

Spasskaya

2003

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

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The nucleon differential elastic scattering cross sections, the total proton reaction cross sections, and the single-particle energies of nucleon bound states for 40 Ca, 90 Zr, and 208 Pb nuclei are reanalyzed in terms of the dispersive optical model at energies ranging from -75 MeV to 60 MeV. The resultant real effective Woods-Saxon potential, which corresponds to the dispersive potential, is studied as dependent on A, Z, and E and on projectile specie (proton or neutron). For the first time, a parameterization of the Woods-Saxon real part of the nucleonnucleus optical potential is proposed for the 208 40 A nuclei at energy ranging from -60 MeV to +60 MeV, including a range near the Fermi energy. The parameterization reflects the dispersion relation between the real and imaginary parts of the optical model potential through the energy dependence of the radius parameter of the real part of the potential. The method to determine the imaginary part of the optical model potential, which is symmetrical relative to the Fermi energy, is also proposed for the 208 40 A nuclei. The differential elastic scattering cross sections, the total neutron interaction cross sections, the total proton reaction cross sections, and the single-particle energies of the nucleon bound states calculated in terms of the proposed nucleon-nucleus potential parameterization for some of the n,p+A ( 40 A) systems are compared with the available experimental data, yielding a fairly good agreement.

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Section: Calculation Of the Scattering And Bound State Datamentioning

confidence: 98%

“…The broken curve shows the cross sections predicted by CH89. The markers are the experimental data of Van Hall et al (1977) (the black circles), of Fricke et al (1967) (the light circles), of Fulmer et al (1969) (the black squares), and of Sakaguchi et al (1982) (the light squares). (2,10,(15)(16)(17)(18)20,21).…”

Section: Panel Bmentioning

confidence: 99%

Nucleon–nucleus real potential of Woods–Saxon shape between 60 and 60 MeV for the 40 A 208 nuclei

Беспалова

Romanovsky

Spasskaya

2003

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

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“…2 is the result of distorted-wave calculations with the computer code 14 DWBA70 using wave functions of Cohen and Kurath 15 and Wildenthal, 16 the G-matrix interaction of Bertsche£aZ., 17 and optical model parameters of Fulmer etal. 18 and Bray. 19 The indicated N factors correspond to the normalization of the interaction after normalizing the wave functions to the experimental B(]\dH).…”

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confidence: 98%

Isovector and Gamow-Teller Strength from Small-Angle (n, p) Reactions at 60 MeV

Brady¹,

Casteneda²,

Needham³

et al. 1982

Phys. Rev. Lett.

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The fyi,p) reactions to the analog giant magnetic dipole states, the inverse of the transitions in allowed Gamow-Teller £ decay, have been measured for 6 Li, 12 C, and 28 Si for forward angles using 59.6-MeV neutrons. With use of a relation between a(0°) and the /idecay matrix elements, there results v oT c (0) =157± 11 MeV fm 3 for the / =0, isovector part of the effective spin-flip nucleon-nucleon interaction. Comparison with 120-MeV (p,n) reactions indicates that v oT c has a small energy dependence in the range 60 to 120 MeV.PACS numbers: 24.50.+g, 25.40.Fq, 27.20.+ n, 27.30.+ t Direct charge-exchange reactions 1 " 3 are important tools for the study of transitions which are induced by isovector interactions, which involve a transfer of one unit of isospin to the target nucleus. Charge-exchange reactions excite states in the target isobars and allow the isovector modes to be isolated from the isoscalar. 4 This can be particularly important in the study of giant-resonance excitations where the width of the resonances often causes the overlapping of isoscalar and isovector modes in the target nucleus, Furthermore, direct reactions between nuclear states of definite spin and parity provide selectivity to particular components of the nucleon-nucleon interaction. This is an important feature of charge-exchange reactions which can provide information to supplement that obtained from free n-p scattering.Of particular interest here is the fact that these charge-exchange reactions can produce transitions which are the inverse of those in Fermi (F) and Gamow-Teller (GT) /3 decay. In earlier experimental work 5 ' 6 with the (p,n) reaction at lower energies, the relation between the I =0 contribution to the cross sections and the F and GT matrix elements for the corresponding weak-interaction transitions was used to establish that the ratio of v oT c tot> T c , the volume integrals of the / = 0 isovector components of the effective central nucleon-nucleon interaction for spin-flip and spinnonflip, respectively, was nearly independent of energy.More recent (p,n) work 7 at 120 MeV has led to a theoretical relation 8 " 10 between the 0° (p,n) cross section and the F and GT matrix elements and showed that the ratio v oT c '/v' a° was considerably larger than at low energies. This relation allowed the determination of values for v oT c (q) and v T c (q) at q = 0 for 120-MeV incident energy. In this paper we present for the first time results from the (n,p) reaction of 6 Li, 12 C, and 28 Si at neutron beam energy of 59.6± 0.3 MeV, which provide a measure of the strength of the spinflip part of the isovector interaction at small momentum transfer. The (n,p) reaction, even at 60 MeV, because of its less negative Q value, has as small momentum transfer as (p 9 n) at higher energies, or smaller, thus fulfilling the assumptions of the theoretical analysis. 8 " 10 In addition, the (n,p) reaction for N> Z has the feature of being very selective in that it excites only T 0 + 1 states for T Q targets. The (p 9 n) reaction favors T 0 -l...

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“…The parameters of the DOM were fit for both 40 Ca and 48 Ca from a large set of data covering both positive and negative proton energies. For 40 Ca, 14 experimental elastic-scattering angular distributions for energies from 18 to 135 MeV [8,9,10,11,12,13] and seven data sets for the analyzing power measured at energies from 21 to 80 MeV [12,14,15,16,17,18] were included. For 48 Ca the fitted data included 14 angular distributions and seven sets of analyzing power at energies from 8 to 65 MeV [12,13,19,20].…”

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confidence: 99%

Asymmetry Dependence of Proton Correlations

2006

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A dispersive optical model analysis of p+ 40 Ca and p+ 48 Ca interactions has been carried out. The real and imaginary potentials have been constrained from fits to elastic scattering data, reaction cross sections, and level properties of valence hole states deduced from (e, e ′ p) data. The surface imaginary potential was found to be larger overall and the gap in this potential on either side of the Fermi energy was found to be smaller for the neutron-rich p+ 48 Ca system. These results imply that protons with energies near the Fermi surface experience larger correlations with increasing asymmetry.PACS numbers: 21.10. Pc,24.10.Ht,11.55.Fv In the independent-particle model, nucleons in the nucleus move in a mean-field potential generated by the other nucleons. All nucleon levels up until the Fermi energy (E F ) are fully occupied, while those above are empty. Although this model enables an understanding of various aspects of nuclear structure, a full description of nuclei and nuclear matter requires consideration of the correlations between the nucleons. These include short-range, central and tensor interactions and longer range correlations associated with low-lying collective excitations [2]. As a result, for closed-shell nuclei, singleparticle (sp) levels below E F have an occupancy of only 70-80% and the levels at higher energy have a nonzero occupancy [3]. The strength of the sp levels are spread over energy, with narrow peaks or broad distributions (depending on their separation from E F ). In addition, there is strength at very high momentum [4].Although there are numerous studies of the effect of correlations on the properties of sp levels for nuclei near stability, there are only a few studies for very neutron or proton-rich nuclei. From neutron knock-out reactions, Gade et al. [5] infer the occupancy of the 0d 5/2 neutron hole state in the proton-rich 32 Ar nucleus is considerably reduced relative to those for stable nuclei.An alternate method to study sp strength is through the use of the dispersive optical model (DOM) developed by Mahaux and Sartor [6]. This description employs the Kramers-Kronig dispersion relation that links the imaginary and real parts of the nucleon self-energy [7]. This procedure links optical-model (OM) analyses of reaction data at positive energies to structural information at negative energies. In the present work, the properties of proton levels in Ca nuclei as a function of asymmetry δ= N −Z A are investigated with the DOM. Previously measured elastic-scattering and reaction-cross-section data for protons on 40 Ca and 48 Ca as well as level properties of hole states in these nuclei, inferred from (e, e ′ p) reactions, were simultaneously fit. The dependence on δ is extracted and used to predict level properties of 60 Ca.In the DOM, the complex energy-dependent potential felt by the protons is comprised of a real V, volume W v and surface W s imaginary components, plus spin-orbit V so and Coulomb V c potentials,are used. The real part of the nuclear potential is assumed...

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Elastic Scattering of 61.4-MeV Protons

Cited by 135 publications

References 24 publications

Nucleon–nucleus real potential of Woods–Saxon shape between 60 and 60 MeV for the 40 A 208 nuclei

Nucleon–nucleus real potential of Woods–Saxon shape between 60 and 60 MeV for the 40 A 208 nuclei

Isovector and Gamow-Teller Strength from Small-Angle (n, p) Reactions at 60 MeV

Asymmetry Dependence of Proton Correlations

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