Cross-section measurements of neutron-deuteron breakup at 13.0 MeV

Setze, H. R.; Howell, C. R.; Tornow, W.; Braun, R. T.; Trotter, D. E. González; Hussein, A.; Pedroni, R.; Roper, C. D.; Salinas, F.; Šlaus, I.; Vlahović, Branislav; Walter, R. L.; Mertens, G.; Lambert, J.M.; Witała, H.; Glöckle, W.

doi:10.1103/physrevc.71.034006

Cited by 27 publications

(31 citation statements)

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“…This observable is known to be quite insensitive to changes in the Hamiltonian [33,34]. Indeed, even the effect of the very strong 3N forces U3 and U5 is insignificant and much smaller than the discrepancy between the predictions and experimental data [35][36][37]. Figure 8 presents theoretical results for neutrondeuteron scattering; the corresponding theoretical results for proton-deuteron breakup also strongly disagree with the data, despite the inclusion of Coulomb in the calculations; the proton-deuteron results overpredict the data.…”

Section: A Observations Made In the Parameter Searchmentioning

confidence: 47%

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Three-nucleon system: Irreducible and reducible contributions of the three-nucleon force

Deltuva

Sauer

2015

Phys. Rev. C

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The three-nucleon bound and scattering equations are solved in momentum space for a coupled-channels Hamiltonian. The Hamiltonian couples the purely nucleonic sector of Hilbert space with a sector in which one nucleon is excited to a isobar. The interaction consists of irreducible two-baryon and irreducible three-baryon potentials. The calculation keeps only the purely nucleonic one among the irreducible three-baryon potentials. The coupled-channels two-baryon potential yields additional reducible contributions to the three-nucleon force. The Coulomb interaction between the two protons is included using the method of screening and renormalization. Three-nucleon force effects on the bound-state energies and on observables of elastic nucleon-deuteron scattering and breakup are studied. PACS number(s): 21.30.−x, 21.45.−v, 24.70.+s, 25.10.+s I. MOTIVATIONThe notion of the three-nucleon (3N) force is not a uniquely defined concept for the theoretical description of nuclear phenomena. The 3N force arises in the hadronic picture of nuclear systems, a model developed by theoreticians for calculational convenience. The 3N force is therefore also model dependent and experimentally not measurable.The microscopic degrees of freedom underlying nuclear phenomena are the quarks and gluons of quantum chromodynamics (QCD). However, a direct description of nuclear phenomena in terms of those microscopic degrees of freedom is not available yet; instead, the effective description in terms of quark-gluon clusters, i.e., in terms of hadrons and their interactions among each other and with electroweak probes is a common conceptual and often quantitatively successful approach to nuclear phenomena at low and moderate energies which we also adopt. At low energies, rigid nucleons appear to make up nuclei in bound and scattering states; after all, nuclear bound states have masses which are almost multiples of the one of a single nucleon. At energies above the pion-(π ) production threshold, the isobar and the π meson become additional active degrees of freedom. The interactions between the hadronic constituents of nuclear systems depend on the chosen degrees of freedom, i.e., on the energy range of applicability; they are mediated by exchanged mesons. The dynamics is usually assumed to be controlled by a field theory for the effective hadronic degrees of freedom, originally by a phenomenological field theory with a zoo of mesons [1]. At present, the favorably employed one is the chiral effective field theory (χ EFT) [2-4], which respects the chiral symmetries of QCD and works with the nucleon and π as degrees of freedom, sometimes extended by the inclusion of the isobar [5,6].However, for practical calculations of nuclear systems, the dynamics is chosen to follow quantum mechanics. The forces between the hadrons, arising from field-theoretic processes, have therefore to be cast into the form of Hermitian potentials. That dynamic simplification is achieved by freezing some of the field-theoretic degrees of freedom. The quantum-mechanical kin...

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Section: A Observations Made In the Parameter Searchmentioning

confidence: 47%

“…We choose the irreducible 3N potential U1 as the most reasonable one for a further comparative study of irreducible and reducible contributions to the 3N force; the addition of 034002-7 [35,36] (open and full squares). The proton-deuteron data from Ref.…”

Section: B Overview On Results Obtained With the Additional 3n Potenmentioning

confidence: 99%

Three-nucleon system: Irreducible and reducible contributions of the three-nucleon force

Deltuva

Sauer

2015

Phys. Rev. C

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“…Moreover, precise measurement of the cross section is more difficult than measurement of analyzing powers. Therefore, experiments on nd-SS cross section were performed at only a few laboratories, at Erlangen [34,39], Bochum [37], TUNL [35,36], and Bonn-Beijing [38].…”

Section: Discovery Of Ss Anomaly In Nd Breakupmentioning

confidence: 99%

Experimental Investigations of Discrepancies in Three-Nucleon Reactions

Sagara

2010

Few-Body Syst

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Experiments on pd scattering, pd capture and pd breakup performed by our Kyushu University group since 1988 are reviewed. Various discrepancies between the experimental results and 3N Faddeev calculations have been found, and systematical measurements of the discrepancies have been made. From discrepancies in pd scattering cross section and in 3N binding energy, 2π-exchange 3N force was determined, and the discrepancies were satisfactorily diminished. There are, however, still many discrepancies awaiting theoretical investigation, as described in this report. IntroductionA precise experimental study of three-nucleon (3N) reactions at Kyushu University Tandem Accelerator Laboratory (KUTL) was started in 1988. Before the 3N experiments, high-intensity polarized p-and d-beams had been already developed at KUTL to measure ( d, p) polarization transfer coefficients. These beams were used to obtain high-statistics 3N data. To obtain high-precision and reliable 3N data, experimental facilities were improved.Beam polarization and beam position on the target should be stable in order to obtain reliable data. Also beam intensity should be stable to correctly estimate counting efficiency of detectors. Beam polarization, integrated beam charge, and target thickness (gas pressure and length along the beam axis) should be accurately measured. To obtain high-statistic data, data acquisition speed should be fast enough to accumulate many counts with low counting loss. These requirements were not easily satisfied in a university laboratory.Our purpose for starting 3N experiments at that time was to find 3N forces and to solve A y puzzle. Numerical calculations of Faddeev equations were greatly developed in 1980's. Speeds of computers became faster every year. Koike and Heidenbauer pointed out presence of A y puzzle (1986) [1]. Faddeev calculations with realistic NN potentials instead of separable potentials were made first by Takemiya [2], then by Bochum group [3,4].We decided therefore, to obtain precise and systematic experimental data of 3N reactions. When the precise data were compared with reliable Faddeev calculations, shortage of 2N force (2NF) might appear as a discrepancy between the data and the calculations. The discrepancy might indicate effects of 3NF or other origins which we were looking for. If a discrepancy was confirmed, theoretical investigations would reveal its origin(s), which would be 3NF or others. On this thought, we started precise and systematic experiments on pd system at KUTL in 1988.By 2009 we have made many experiments on (a) pd scattering in a beam energy range of 2-18 MeV,

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“…[1] and [37] for references; the most recent results can be found in Refs. [38] and [39], and in [40] at much higher incident energy). In the region of intermediate energies MeV) only at 65 MeV have several isolated kinematical configurations been investigated with respect to cross sections and analyzing powers [41][42][43][44].…”

Section: Introductionmentioning

confidence: 99%

Systematic study of three-nucleon force effects in the cross section of the deuteron-proton breakup at 130 MeV

Kistryn¹,

Stephan²,

Biegun³

et al. 2005

Phys. Rev. C

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High-precision cross-section data of the deuteron-proton breakup reaction at 130 MeV are presented for 72 kinematically complete configurations. The data cover a large region of the available phase space, divided into a systematic grid of kinematical variables. They are compared with theoretical predictions, in which the full dynamics of the three-nucleon (3N) system is obtained in three different ways: realistic nucleon-nucleon (NN) potentials are combined with model 3N forces (3NF's) or with an effective 3NF resulting from explicit treatment of the -isobar excitation. Alternatively, the chiral perturbation theory approach is used at the next-to-next-to-leading order with all relevant NN and 3N contributions taken into account. The generated dynamics is then applied to calculate cross-section values by rigorous solution of the 3N Faddeev equations. The comparison of the calculated cross sections with the experimental data shows a clear preference for the predictions in which the 3NF's are included. The majority of the experimental data points are well reproduced by the theoretical predictions. The remaining discrepancies are investigated by inspecting cross sections integrated over certain kinematical variables. The procedure of global comparisons leads to establishing regularities in disagreements between the experimental data and the theoretically predicted values of the cross sections. They indicate deficiencies still present in the assumed models of the 3N system dynamics.

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Cross-section measurements of neutron-deuteron breakup at 13.0 MeV

Cited by 27 publications

References 48 publications

Three-nucleon system: Irreducible and reducible contributions of the three-nucleon force

Three-nucleon system: Irreducible and reducible contributions of the three-nucleon force

Experimental Investigations of Discrepancies in Three-Nucleon Reactions

Systematic study of three-nucleon force effects in the cross section of the deuteron-proton breakup at 130 MeV

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