Energy dependence of neutron scattering from<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Pb</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>208</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>in the energy range 7—50 MeV

Finlay, R.W.; Annand, J. R. M.; Cheema, T.S.; Rapaport, J.; Dietrich, F. S.

doi:10.1103/physrevc.30.796

Cited by 50 publications

(26 citation statements)

References 26 publications

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“…Except for the levels with E x = 3708.45 and 4037.44 keV, at least one γ -transition was observed to decay from every excited level up to 4.3 MeV excitation energy over the incident neutron energy range from threshold to 10-13 MeV. 3 The maximum observed excited level has an energy of 5.563 MeV. The only reason for not observing all the levels between 4.3 MeV and 5.5 MeV is their low cross section.…”

Section: Discussionmentioning

confidence: 92%

“…These experiments identified a limited number of neutron energy groups. Finlay et al [3] and Bainum et al [4] only measured the differential level cross sections. The (n, n γ )-technique was applied by the authors of Refs.…”

Section: Introductionmentioning

confidence: 99%

“…In Refs. [2][3][4] the (n, n )-technique was employed. These experiments identified a limited number of neutron energy groups.…”

Section: Introductionmentioning

confidence: 99%

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A measurement of cross sections for 208Pb from threshold up to 20 MeV

Mihăilescu¹,

Borcea²,

Baumann³

et al. 2008

Nuclear Physics A

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Section: Discussionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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A measurement of cross sections for 208Pb from threshold up to 20 MeV

Mihăilescu¹,

Borcea²,

Baumann³

et al. 2008

Nuclear Physics A

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“…The (n,n) data are from Refs. [52,[67][68][69][70], the (p,n) data -from Refs. [15,36,37] and (p,p) -from Refs.…”

Section: B Data Choicementioning

confidence: 99%

Symmetry energy III: Isovector skins

2017

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Isoscalar density is a sum of neutron and proton densities and isovector is a normalized difference.Here, we report on the experimental evidence for the displacement of the isovector and isoscalar surfaces in nuclei, by ∼0.9 fm from each other. We analyze data on quasielastic (QE) charge exchange (p,n) reactions, concurrently with proton and neutron elastic scattering data for the same target nuclei, following the concepts of the isoscalar and isovector potentials combined into Lane optical potential. The elastic data largely probe the geometry of the isoscalar potential and the (p,n) data largely probe a relation between the geometries of the isovector and isoscalar potentials.The targets include 48 Ca, 90 Zr, 120 Sn and 208 Pb and projectile incident energy values span the range of (10-50) MeV. In our fit to elastic and QE charge-exchange data, we allow the values of isoscalar and isovector radii, diffusivities and overall potential normalizations to float away from those in the popular Koning and Delaroche parametrization. We find that the best-fit isovector radii are consistently larger than isoscalar and the best-fit isovector surfaces are steeper. Upon identifying the displacement of the potential surfaces with the displacement of the surfaces for the densities in the Skyrme-Hartree-Fock calculations, and by supplementing the results with those from analysing excitation energies to isobaric analog states in the past, we arrive at the slope and value of the symmetry energy at normal density of 70 < L < 101 MeV and 33.5 < a V a < 36.4 MeV, respectively.

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“…A first application of the method to reaction cross sections on 208 Pb was presented in [3], using total cross sections from [4] and angular distributions from [5]. It was found that the uncertainties of approximately 5% in cross sections at 7, 20, 22, and 24 MeV using direct subtraction via Eq.…”

Section: Applicationsmentioning

confidence: 99%

A New Method for Estimating Neutron Reaction Cross Sections Based on Wick’s Limit

Dietrich¹,

Anderson²,

Bauer³

et al. 2005

AIP Conference Proceedings

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Wick's limit is an inequality that relates the zero-degree differential elastic scattering cross section to the total cross section. The deviation of Wick's limit from an exact equality is small over a wide range of incident energies and target masses. Under these circumstances we show that Wick's limit can be used to correlate the uncertainties in the two terms of the reaction (nonelastic) cross section expressed as the difference between the total and angle-integrated elastic cross sections. When suitable elastic angular distributions are available, we show that the reaction cross section may be obtained with small errors (typically 1.5-3%). Examples are shown for 208 Pb, 54 56 Fe, 232 Th, and 238 U. WICK'S LIMITwhere f´0 o µ is the zero-degree scattering amplitude, σ tot is the total cross section, and k is the center-of-mass wave number. The zero-degree differential elastic cross section σ 0 is given byThus the zero-degree differential elastic cross section σ 0 must be equal to or exceed Wick's limit which isWe define the fractional deviation of the zero-degree differential cross section from Wick's limit asWick's limit is a useful concept when η is small. Figure 1 shows the fractional deviation η vs. energy for several nuclei, using the global optical potential of Koning and Delaroche [2]. For all nuclei shown, there is a significant energy range (approximately 5-60 MeV) in which the deviation from Wick's limit does not exceed a few percent.Insight into this behavior is provided by the Ramsauer model, a simple single-phase-shift model that reproduces FIGURE 1. Fractional deviation η using the optical potential of [2].total cross sections at the 1% level from 5-60 MeV [3]. We define a quantity resembling an S-matrix element in terms of the forward scattering amplitude by S 1 · 2i f´0 o µ k´R ·λ µ 2 (5)

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Energy dependence of neutron scattering fromPb208in the energy range 7—50 MeV

Cited by 50 publications

References 26 publications

A measurement of cross sections for 208Pb from threshold up to 20 MeV

A measurement of cross sections for 208Pb from threshold up to 20 MeV

Symmetry energy III: Isovector skins

A New Method for Estimating Neutron Reaction Cross Sections Based on Wick’s Limit

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