Thermal neutron capture cross section of deuterium

Jurney, E.T.; Bendt, P.J.; Browne, J.C.

doi:10.1103/physrevc.25.2810

Cited by 64 publications

(64 citation statements)

References 7 publications

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“…[26] obtained σ = 0.503±0.003 mb. This is in excellent agreement with the experimental result σ = 0.508 ± 0.015 mb [27]. But the discrepancy would be several standard deviations if we stopped with the universal prediction.…”

Section: Some Results At Nnlosupporting

confidence: 81%

Universality and Beyond

Phillips

2010

EPJ Web of Conferences

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Abstract. I discuss the impact of a finite effective range, r, on systems with a large two-body scattering length, a. In particular, I show how observables can be written as an expansion around the "universal", or large-scatteringlength limit. The parameter governing this expansion is the ratio r/a. In few-nucleon systems the ratio r/a has a value of about 1/3, and so such corrections are essential in producing good agreement between theory and data. Hence, I first show how these effects range play a key role in making the so-called "pionless" effective field theory a successful descriptor of low-energy processes in the NN system. I then move to the NNN system, and review predictions for the energy-dependence of observables there. However, the beautiful Efimov physics associated with the presence of a large scattering length is not fully revealed in the NNN system, precisely because r/a corrections are large. I therefore turn to cold atomic gases and show that there are some important recent experiments where physics "beyond universality" affects the data. In the process I demonstrate that an additional piece of short-distance physics is necessary to renormalize scattering-length-dependent observables in the three-body system once corrections ∼ r are considered. Finally, I discuss recent initial efforts to compute r/a corrections to the predictions of universality for the four-body system.

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Section: Some Results At Nnlosupporting

confidence: 81%

Universality and Beyond

Phillips

2010

EPJ Web of Conferences

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“…[2]. The use of the present MI two-body current operators therefore leads to an estimate closer to the experimental datum σ T = 0.508 ± 015 mb [71]. However, the addition of the three-body currents, which give a rather sizable contribution as can be seen from the row labeled "full-new" in Table IV, brings the total cross section to σ T = 0.556 mb.…”

Section: The 2 H(n γ) 3 H Radiative Capture Reactionmentioning

confidence: 90%

Electromagnetic structure of A=2 and 3 nuclei and the nuclear current operator

et al. 2005

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Different models for conserved two-and three-body electromagnetic currents are constructed from two-and three-nucleon interactions, using either meson-exchange mechanisms or minimal substitution in the momentum dependence of these interactions. The connection between these two different schemes is elucidated. A number of low-energy electronuclear observables, including (i) np radiative capture at thermal neutron energies and deuteron photodisintegration at low energies, (ii) nd and pd radiative capture reactions, and (iii) isoscalar and isovector magnetic form factors of 3 H and 3 He, are calculated in order to make a comparative study of these models for the current operator. The realistic Argonne v18 two-nucleon and Urbana IX or Tucson-Melbourne three-nucleon interactions are taken as a case study. For A=3 processes, the bound and continuum wave functions, both below and above deuteron breakup threshold, are obtained with the correlated hyperspherical-harmonics method. Three-body currents give small but significant contributions to some of the polarization observables in the 2 H(p, γ) 3 He process and the 2 H(n, γ) 3 H cross section at thermal neutron energies. It is shown that the use of a current which did not exactly satisfy current conservation with the two-and three-nucleon interactions in the Hamiltonian was responsible for some of the discrepancies reported in previous studies between the experimental and theoretical polarization observables in pd radiative capture.

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“…The experimental values for σ T and R c are respectively (0.508 ± 0.015) mb from Ref. [6] and −0.42 ± 0.03 from Ref. [30].…”

Section: Electromagnetic Observables At N 2 Lo In A=2-3 Systemsmentioning

confidence: 99%

“…The identity 6) and the analogous one for τ i × τ j allow one to express the magnetic dipole operator in Eq. (7.4) as…”

Section: Electromagnetic Observables At N 2 Lo In A=2-3 Systemsmentioning

confidence: 99%

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Electromagnetic two-body currents of one- and two-pion range

2008

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Nuclear electromagnetic currents are derived in time-ordered perturbation theory within an effective-field-theory framework including explicit nucleons, ∆ isobars, and pions up to one loop, or N 3 LO. The currents obtained at N 2 LO, i.e. ignoring loop corrections, are used in a study of neutron radiative captures on protons and deuterons at thermal energies, and of A=2 and 3 nuclei magnetic moments. The wave functions for A=2 are derived from solutions of the Schrödinger equation with the Argonne v 18 (AV18) or CD-Bonn (CDB) potentials, while those for A=3 are obtained with the hyperspherical-harmonics-expansion method from a realistic Hamiltonian including, in addition to the AV18 or CDB two-nucleon, also a three-nucleon potential. With the strengths of the ∆-excitation currents occurring at N 2 LO determined to reproduce the n-p cross section and isovector combination of the trinucleon magnetic moments, we find that the cross section and photon circular polarization parameter, measured in n-d and n-d processes, are underpredicted by theory, for example the cross section by (11-38)% as the cutoff is increased from 500 to 800 MeV. A complete analysis of the results, in particular their large cutoff dependence, is presented.

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Thermal neutron capture cross section of deuterium

Cited by 64 publications

References 7 publications

Universality and Beyond

Universality and Beyond

Electromagnetic structure of A=2 and 3 nuclei and the nuclear current operator

Electromagnetic two-body currents of one- and two-pion range

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