Phase-shift analysis of<i>NN</i>scattering below 160 MeV: Indication for a strong tensor force

Henneck, R.

doi:10.1103/physrevc.47.1859

Cited by 25 publications

(13 citation statements)

References 118 publications

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“…2, Henneck's recent phaseshift analysis [22] at 25 MeV is also consistent with our values. His conclusion that the tensor force is strong below 160 MeV is therefore not applicable in our energy range.…”

Section: A^(tt)-iv(n)supporting

confidence: 93%

Measurements of polarized-neutron–polarized-proton scattering: Implications for the triton binding energy

et al. 1993

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Measurements have been made of ACTT for polarized neutrons incident on a polarized proton target from 3.65 to 11.60 MeV. In the energy range near 10 MeV, ACTT is very sensitive to the nucleon-nucleon tensor interaction. Comparison of the data to potential-model predictions indicate that the tensor interaction is weak, resulting in values of the ^Si-^Di mixing parameter €i which are smaller than predicted by any nucleon-nucleon potential model. A smaller tensor force will bring the predictions of local potential models for the triton binding energy into closer agreement with the experimental value.PACS numbers: 25.40.Dn, 13.75.Cs, 21.30.+y, 25.10.+S A long-standing problem in nuclear physics has been the theoretical prediction of the triton binding energy [1]. All realistic and local nucleon-nucleon (NN) potentials predict too little binding. Many mechanisms have been proposed to increase the triton binding energy, among which are three-body forces and relativistic effects. Recent theoretical work, however, suggests that neither mechanism can contribute significantly [2,3]. In contrast, it is well established that the strength of the NN tensor force below 50 MeV has a large influence on the triton binding energy [4]. A^A^ parameters above 50 MeV are not important for this problem as this is approximately the Fermi energy of the nucleons in the triton. Calculations [5] show that a weak tensor force at low energies will bring potential model predictions into closer agreement with the experimentally determined value.In spite of its importance, both in the binding of fewnucleon systems and in the saturation of nuclear matter [5], the strength of the NN tensor force is only loosely constrained by the existing data [6]. We have measured the spin-dependent difference in total cross section, Aor, for the scattering of transversely polarized neutrons from transversely polarized protons below 12 MeV. These measurements cover a significant fraction of the energy range important to the triton binding energy. Our measurements indicate that the tensor force is indeed weak at low energies, possibly resolving the triton binding energy problem.At low energies, the strength of the tensor interaction is parametrized by the isoscalar ^Si-^Di phase-shift mixing parameter ei. Aar exhibits a large sensitivity to ei for neutron energies from 5 to 35 MeV [7]. In addition, ACT is insensitive to most other phase-shift parameters. The only significant sensitivity is to the ^SQ and ^Si phase shifts which are constrained by experiment. In contrast, other observables sensitive to the tensor interaction such as the spin transfer parameter, K^ , and the spin-correlation coefficient, Ayy{9)^ are sensitive to the P waves, which are much less well determined. Only in the special case 9 = 90^ is Ayy independent of the -^Pi phase shift.ACT is measured using a polarized neutron beam incident upon a polarized proton target and is defined to be the total cross section with the spins antiparallel minus the total cross section with the spins parallel [8]:A...

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Section: A^(tt)-iv(n)supporting

confidence: 93%

Measurements of polarized-neutron–polarized-proton scattering: Implications for the triton binding energy

et al. 1993

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“…This is in contradiction to the result obtained by the Basel group with an experiment performed at Villigen [22,23], where ∆σ L has been measured at 66 MeV incident neutron energy and the analysis made by Henneck [24]. In these works the authors conclude that the tensor component of NN potential below 100 MeV must be stronger than predicted by the models.…”

Section: The Mixing Parameter ǫcontrasting

confidence: 54%

Measurement of spin-dependent total cross-section difference $\Delta\sigma_T$ in neutron-proton scattering at 16 MeV

Brož¹,

Černý²,

Doležal³

et al. 1996

Zeitschrift f�r Physik A Hadrons and Nuclei

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A new measurement of ∆σ T for polarized neutrons transmitted through a polarized proton target at 16.2 MeV has been made. A polarized neutron beam was obtained from the 3 H(d, n) 4 He reaction; proton polarization over 90% was achieved in a frozen spin target of 20 cm 3 volume. The measurement yielded the value ∆σ T = (−126 ± 21 ± 14) mb. The result of a simple phase shift analysis for the 3 S 1 − 3 D 1 mixing parameter ǫ 1 is presented and compared with the theoretical potential model predictions.

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“…In addition, we show figures of some of the more interesting phases and compare to the Nijmegen multienergy partial-wave analysis [16], the single-energy analysis from SAID [28], and recent single-energy analyses by Bugg and Bryan [30], and by Henneck [31]. In Fig.…”

Section: Data Fittingmentioning

confidence: 96%

Accurate nucleon-nucleon potential with charge-independence breaking

1995

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We present a new high-quality nucleon-nucleon potential with explicit charge dependence and charge asymmetry, which we designate Argonne v 18 . The model has a charge-independent part with fourteen operator components that is an updated version of the Argonne v 14 potential. Three additional chargedependent and one charge-asymmetric operators are added, along with a complete electromagnetic interaction. The potential has been fit directly to the Nijmegen pp and np scattering data base, low-energy nn scattering parameters, and deuteron binding energy. With 40 adjustable parameters it gives a 1 χ 2 per datum of 1.09 for 4301 pp and np data in the range 0-350 MeV.

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Phase-shift analysis ofNNscattering below 160 MeV: Indication for a strong tensor force

Cited by 25 publications

References 118 publications

Measurements of polarized-neutron–polarized-proton scattering: Implications for the triton binding energy

Measurements of polarized-neutron–polarized-proton scattering: Implications for the triton binding energy

Measurement of spin-dependent total cross-section difference $\Delta\sigma_T$ in neutron-proton scattering at 16 MeV

Accurate nucleon-nucleon potential with charge-independence breaking

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