Neutron-proton and neutron-neutron quasifree scattering in the<i>n-d</i>breakup reaction at 26 MeV

Siepe, A.; Deng, J. K.; Huhn, V.; Wätzold, L.; Weber, C.; Witsch, W. von; Witała, H.; Glöckle, W.

doi:10.1103/physrevc.65.034010

Cited by 38 publications

(43 citation statements)

References 20 publications

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“…The cross section for nn quasifree (QFS) scattering is one such anomaly. Two recent experiments reported cross sections for this particular nd breakup configuration that exceed theoretical calculations by almost 20% at incident neutron energies of 26 and 25 MeV [1,2]. The theoretical values can be brought into agreement with these results by increasing the strength of the 1 S 0 nn potential matrix element by roughly 10%.…”

Section: Introductionsupporting

confidence: 76%

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Neutron-neutron quasifree scattering inndbreakup at 10 MeV

Malone

Crowe

Crowell

et al. 2016

EPJ Web of Conferences

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Abstract.The neutron-deuteron (nd) breakup reaction provides a rich environment for testing theoretical models of the neutron-neutron (nn) interaction. Current theoretical predictions based on rigorous ab-initio calculations agree well with most experimental data for this system, but there remain a few notable discrepancies. The cross section for nn quasifree (QFS) scattering is one such anomaly. Two recent experiments reported cross sections for this particular nd breakup configuration that exceed theoretical calculations by almost 20% at incident neutron energies of 26 and 25 MeV [1,2]. The theoretical values can be brought into agreement with these results by increasing the strength of the 1 S 0 nn potential matrix element by roughly 10%. However, this modification of the nn effective range parameter and/or the 1 S 0 scattering length causes substantial charge-symmetry breaking in the nucleon-nucleon force and suggests the possibility of a weakly bound di-neutron state [3]. We are conducting new measurements of the cross section for nn QFS in nd breakup. The measurements are performed at incident neutron beam energies below 20 MeV. The neutron beam is produced via the 2 H(d, n) 3 He reaction. The target is a deuterated plastic cylinder. Our measurements utilize time-of-flight techniques with a pulsed neutron beam and detection of the two emitted neutrons in coincidence. A description of our initial measurements at 10 MeV for a single scattering angle will be presented along with preliminary results. Also, plans for measurements at other energies with broad angular coverage will be discussed.

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Section: Introductionsupporting

confidence: 76%

“…Measurements of the neutron-proton QFS a e-mail: rm216@phy.duke.edu cross section are in good agreement with theoretical calculations. However, recent measurements of the nn QFS cross section exceed theoretical predictions by almost 20% [1,2] (see Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Neutron-neutron quasifree scattering inndbreakup at 10 MeV

Malone

Crowe

Crowell

et al. 2016

EPJ Web of Conferences

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“…The measurement of QFS np cross sections have shown good agreement of data with theory [9], confirming thus good knowledge of the np force. For nn QFS it was found that theory underestimates the data by ≈20 % [9].…”

Section: The Dineutron and Its Influence On Nd Observablessupporting

confidence: 66%

“…For nn QFS it was found that theory underestimates the data by ≈20 % [9]. The large stability of the QFS cross sections to the underlying dynamics, implies that the present day 1 S 0 nn interaction is probably incorrect.…”

Section: The Dineutron and Its Influence On Nd Observablesmentioning

confidence: 99%

Calculations of Three-Nucleon Reactions

et al. 2013

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Faddeev calculations using the chiral three-nucleon force in next-to-next-to-next-to-leading-order show that this force is too weak to provide an explanation for the low-energy A y puzzle. The large discrepancy between data and theory for the neutron-neutron quasi-free-scattering cross section in low energy neutrondeuteron breakup requires a modification of the 1 S 0 neutron-neutron force. We discuss the consequences that a bound 1 S 0 state of two neutrons has on neutron-deuteron scattering observables. At higher energies we compare the solutions of the non-relativistic three-nucleon Faddeev equations with three-nucleon force included to the solutions of its Poincaré invariant version.

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“…The experimental cross sections obtained at 25 -26 MeV exceed the theoretical estimates by about 18% [1,2]. At the same time, the theory describes well the cross sections obtained for quasifree np scattering at these energies.…”

Section: Introductionsupporting

confidence: 59%

Determination of Energy of n n-Singlet Virtual State in $$\varvec{d+{{}^{2}}}\hbox {H}\varvec{\rightarrow p+p+n+n}$$ d + 2

et al. 2017

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Determination of energy of nn-singlet virtual state in d+ 2 H  p+ p +n+n reactionAbstract The nn final state interaction has been investigated in d+ 2 H(pp) S +(nn) S p+p+n+n reaction going through a formation and breakup of singlet diproton and dineutron in the intermediate state.In the kinematically complete experiment performed at Ed =15 MeV two proton and neutron were detected at angles close to those of emission of (pp) S and (nn) S systems. Simulation of the reaction showed that the shape of neutron energy (timing) spectrum depends on εnn − the energy of virtual 1 S0 state of nn-system. The most likely value εnn = 0.076 ± 0.006MeV was obtained by fitting procedure using the experimental data and simulations. This low value of εnn evidently indicates on effective enhancement of nn-interaction in the intermediate state of studied reaction.

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Neutron-proton and neutron-neutron quasifree scattering in then-dbreakup reaction at 26 MeV

Cited by 38 publications

References 20 publications

Neutron-neutron quasifree scattering inndbreakup at 10 MeV

Neutron-neutron quasifree scattering inndbreakup at 10 MeV

Calculations of Three-Nucleon Reactions

Determination of Energy of n n-Singlet Virtual State in $$\varvec{d+{{}^{2}}}\hbox {H}\varvec{\rightarrow p+p+n+n}$$ d + 2

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