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# Precision neutron interferometric measurements of the n-p, n-d, and n-3He zero-energy coherent neutron scattering amplitudes

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### Abstract

We have performed high precision measurements of the zero-energy neutron scattering amplitudes of gas phase molecular hydrogen, deuterium, and $$^{3}$$He using neutron interferometry. We find $$b_{\mathit{np}}=(-3.7384 \pm 0.0020)$$ fm\cite{Schoen03}, $$b_{\mathit{nd}}=(6.6649 \pm 0.0040)$$ fm\cite{Black03,Schoen03}, and $$b_{n^{3}\textrm{He}} = (5.8572 \pm 0.0072)$$ fm\cite{Huffman04}. When combined with the previous world data, properly corrected for small multiple scattering, radiative corrections, and local field effects from the theory of neutron optics and combined by the prescriptions of the Particle Data Group, the zero-energy scattering amplitudes are: $$b_{\mathit{np}}=(-3.7389 \pm 0.0010)$$ fm, $$b_{\mathit{nd}}=(6.6683 \pm 0.0030)$$ fm, and $$b_{n^{3}\textrm{He}} = (5.853 \pm .007)$$ fm. The precision of these measurements is now high enough to severely constrain NN few-body models. The n-d and n-$$^{3}$$He coherent neutron scattering amplitudes are both now in disagreement with the best current theories. The new values can be used as input for precision calculations of few body processes. This precision data is sensitive to small effects such as nuclear three-body forces, charge-symmetry breaking in the strong interaction, and residual electromagnetic effects not yet fully included in current models.

### Most cited references2

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### Quantum Monte Carlo Calculations of Light Nuclei

(2001)
Accurate quantum Monte Carlo calculations of ground and low-lying excited states of light p-shell nuclei are now possible for realistic nuclear Hamiltonians that fit nucleon-nucleon scattering data. At present, results for more than 30 different (J^pi;T) states, plus isobaric analogs, in A \leq 8 nuclei have been obtained with an excellent reproduction of the experimental energy spectrum. These microscopic calculations show that nuclear structure, including both single-particle and clustering aspects, can be explained starting from elementary two- and three-nucleon interactions. Various density and momentum distributions, electromagnetic form factors, and spectroscopic factors have also been computed, as well as electroweak capture reactions of astrophysical interest.
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### Neutron scattering lengths: A survey of experimental data and methods

(1991)
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### Author and article information

###### Journal
2005-08-12
nucl-ex/0508017 10.1016/j.physb.2006.05.185
6 pages, 4 figures, submitted to Physica B as part of the Festschrift honouring Samuel A. Werner at the International Conference on Neutron Scattering 2005
nucl-ex nucl-th

Nuclear physics