Quantum-statistical interference of coincident neutrons from the compound nucleus

Coincident neutrons from the ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ ${+}^{26}$Mg${\to }^{44}$Ca (${\mathit{E}}_{\mathit{x}}$=60 and 71 MeV) compound-nuclear reaction show an anticorrelation at small relative momentum, giving evidence for quantum-statistical interference in analogy to the optical Hanbury-Brown and Twiss effect. An average decay width of 60 keV is extracted from the measured energy correlations. The deduced extension of the neutron wave packets exceeds by far the nn scattering length, in accordance with the observed insignificance of the attractive nn final-state interaction.