A Precision Measurement of the Neutron Scattering Length of He-4 Using Neutron Interferometry

Abstract

We report a 0.08 % measurement of the bound neutron scattering length of ${}^4$He using neutron interferometry. The result is $b = (3.0982 \pm 0.0021 \mbox{ [stat]} \pm 0.0014 \mbox{ [sys]}) \mbox{ fm}$. The corresponding free atomic scattering length is $a = (2.4746 \pm 0.0017 \mbox{ [stat]} \pm 0.0011 \mbox{ [sys]}) \mbox{ fm}$. With this result the world average becomes $b=(3.0993\pm 0.0025)$ fm, a 2 % downward shift and a reduction in uncertainty by more than a factor of six. Our result is in disagreement with a previous neutron interferometric measurement but is in good agreement with earlier measurements using neutron transmission.

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Cited by in corpus (7)

• Pendellösung Interferometry Probes the Neutron Charge Radius, Lattice Dynamics, and Fifth Forces
• Five-body calculation of $s$-wave $n$-${}^4$He scattering at next-to-leading order pionless effective field theory
• A new approach to search for free neutron-antineutron oscillations using coherent neutron propagation in gas
• Neutron interference from a split-crystal interferometer
• General features and contact modeling of $N$-body isolated resonances near threshold
• Few-Nucleon Systems within Finite-Cutoff Pionless EFT
• Fundamental Neutron Physics: a White Paper on Progress and Prospects in the US