<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>n</mml:mi><mml:mo>−</mml:mo><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">He</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>4</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>Elastic Scattering near 20 MeV

Niiler, A.; Drosg, M.; Hopkins, J.C.; Seagrave, J.D.; Kerr, E.C.

doi:10.1103/physrevc.4.36

Cited by 13 publications

(23 citation statements)

References 14 publications

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“…4 He(n, n) 4 He differential cross section at an incident neutron energy of 17.6 MeV to the experimental data of Drosg et al [54,55]. For all three Hamiltonians, we find good agreement at the angles where data are available.…”

Section: Cross Sections and Analyzing Powerssupporting

confidence: 80%

Ab initiomany-body calculations of nucleon-4He scattering with three-nucleon forces

et al. 2013

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We extend the ab initio no-core shell model/resonating-group method to include three-nucleon (3N ) interactions for the description of nucleon-nucleus collisions. We outline the formalism, give algebraic expressions for the 3N -force integration kernels, and discuss computational aspects of two alternative implementations. The extended theoretical framework is then applied to nucleon-4 He scattering using similarity-renormalization-group (SRG) evolved nucleon-nucleon plus three-nucleon potentials derived from chiral effective field theory. We analyze the convergence properties of the calculated phase shifts and explore their dependence upon the SRG evolution parameter. We include up to six excited states of the 4 He target and find significant effects from the inclusion of the chiral 3N force, e.g., it enhances the spin-orbit splitting between the 3/2 − and 1/2 − resonances and leads to an improved agreement with the phase shifts obtained from an accurate R-matrix analysis of the five-nucleon experimental data. We find remarkably good agreement with measured differential cross sections at various energies, while analyzing powers manifest larger deviations from experiment for certain energies and angles.

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Section: Cross Sections and Analyzing Powerssupporting

confidence: 80%

Ab initiomany-body calculations of nucleon-4He scattering with three-nucleon forces

et al. 2013

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“…Interaction of neutrons with 4 He is of interest in primordial and stellar nucleosynthesis, in nuclear fusion reactions, and in ab initio theory of light ion reactions [1]. Recently, it has been shown [2] that multiple-scattering corrections made earlier by means of the Aldermaston Monte Carlo technique MAGGIE-2 [3] to measurements of elastic scattering of neutrons from 3 He had been significantly overestimated.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, it has been shown [2] that multiple-scattering corrections made earlier by means of the Aldermaston Monte Carlo technique MAGGIE-2 [3] to measurements of elastic scattering of neutrons from 3 He had been significantly overestimated. In the present paper, similar corrections made to the measurement of elastic scattering of neutrons from 4 He in the energy range near 20 MeV [4] are re-evaluated. Unlike other experimental n- 4 He data in this energy range that measure the energy of the associated recoil α particle [5][6][7], the present re-evaluated differential crosssectional data are based on direct measurement of the scattered neutron.…”

Section: Introductionmentioning

confidence: 99%

“…In the present paper, similar corrections made to the measurement of elastic scattering of neutrons from 4 He in the energy range near 20 MeV [4] are re-evaluated. Unlike other experimental n- 4 He data in this energy range that measure the energy of the associated recoil α particle [5][6][7], the present re-evaluated differential crosssectional data are based on direct measurement of the scattered neutron.…”

Section: Introductionmentioning

confidence: 99%

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Re-evaluation of neutron-He4elastic scattering data near 20 MeV

2011

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Measured differential elastic-scattering cross sections of 17.72-, 20.97-, and 23.72-MeV neutrons from liquid helium-4 were re-evaluated and were corrected for sample-size and multiple-scattering effects by means of a Monte Carlo technique implemented in a more recent code (MCNPX). Results indicate that earlier corrections via the code MAGGIE-2 overestimated the size of multiple-scattering effects by an order of magnitude. The corrected differential cross sections and Legendre coefficients obtained by least-squares fits are given.

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“…Figure 1 shows the corrections applied to the 17.71-MeV experimental angular distribution of 4 He(n,n) 4 He. The curve represents the original, exaggerated sample-size correction [2], the open dots the improved sample-size correction, and the full dots the present (sample-size + angular resolution) corrections. As discussed in Sec.…”

mentioning

confidence: 99%

Erratum: Re-evaluation of neutron-4He elastic scattering data near 20 MeV [Phys. Rev. C83, 064616 (2011)]

Drosg¹,

Ortiz²,

Hoop³

2012

Phys. Rev. C

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Correction for finite angular resolution in measurements of elastic scattering of neutrons from 3 He was found to be significant [1]. Therefore, the prematurely published data of reanalyzed measurements of elastic scattering of neutrons from 4 He are corrected for finite angular resolution. In the original experiment in question [2], a close geometry was chosen to result in high neutron flux incident upon the sample. That is, the distance of neutron source to center of the 4 He scatterer was 11.5 cm, resulting in a mean incoming angular spread of ±6.6 • . The opening angle of detected neutrons was 1.0 • . Because neutron yield as a function of angle is not linear, the effect of finite angular spread is a shift from geometric mean of the scattering angle. The correct angle can be obtained by weighting the yield distributions over the subtended solid angles. Incoming and outgoing angular resolution corrections are dealt with separately. Instead of shifting the angle, a correction of the yield at the mean angle was applied. These corrections were determined by simulations under very small acceptance angles and also under actual experimental geometries. The original modeling of the experiment by the Monte Carlo code accounted just for the angle dependence of the intensity of the incoming neutrons over the acceptance angle but not for the finite angular resolution resulting from the incoming angular spread. Besides, this time the correct incoming energy of 17.71 MeV is used throughout rather than 17.72 MeV, as done in the original paper. TABLE I. Differential cross cections for elastic neutron scattering from 4 He (angles in degrees, cross sections, and uncertainties in mb/sr) E n = 17.71 ± 0.06 MeV E n = 20.97 ± 0.05 MeV E n = 23.72 ± 0.04 MeV lab c.m. σ c.m. σ c.m. c.m. σ c.m. σ c.m. c.m. σ c.m. σ c.m.

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n−He4Elastic Scattering near 20 MeV

Cited by 13 publications

References 14 publications

Ab initiomany-body calculations of nucleon-4He scattering with three-nucleon forces

Ab initiomany-body calculations of nucleon-4He scattering with three-nucleon forces

Re-evaluation of neutron-He4elastic scattering data near 20 MeV

Erratum: Re-evaluation of neutron-4He elastic scattering data near 20 MeV [Phys. Rev. C83, 064616 (2011)]

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