Search for Anomalous Scattering of keV Neutrons from ${\mathrm{H}}_2\mathrm{O}\mathrm{\text{−}}{\mathrm{D}}_2\mathrm{O}$ Mixtures

We measured the neutron scattering intensities from pure liquid ${\mathrm{H}}_2\mathrm{O}$ relative to that of pure ${\mathrm{D}}_2\mathrm{O}$ and also relative to ${\mathrm{H}}_2\mathrm{O}\mathrm{\text{−}}{\mathrm{D}}_2\mathrm{O}$ mixtures, at room temperature. This study is relevant to the problem of quantum entanglement. The neutrons were generated from an electron Linac and the final energy of the scattered neutrons was fixed at 24.3 keV using a 20 cm thick pure iron filter. The scattering intensity ratios were found to agree with expected values deduced from the tabulated total cross sections within an accuracy of 3%. Thus no anomaly was observed.

Figure 1

Schematic view of the layout of the experiment. The distance between the Ta target and the ${}^6\mathrm{Li}$-glass $n$ detector is 25.3 m.

Figure 2

Time-of-flight spectrum of the scattered neutrons from a ${\mathrm{H}}_2\mathrm{O}$ sample detected after passing through a 20 cm Fe filter. The $\gamma$ flash is depressed by the effect of the 20 cm iron filter. The 300 keV group is the average energy of neutron lines weighted by the ${}^6\mathrm{Li}$ ($n$, $\alpha$) cross section of the detector.

Figure 3

Measured (squares) and calculated (solid line) scattered intensity ratios versus $X_{\mathrm{D}}$, the ${\mathrm{D}}_2\mathrm{O}$ concentration in the ${\mathrm{H}}_2\mathrm{O}\mathrm{\text{−}}{\mathrm{D}}_2\mathrm{O}$ mixture sample. The dashed line represents calculated ratios obtained by assuming a 40% drop in the $n\mathrm{\text{−}}p$ scattering cross section; it is shown to illustrate the extent of deviation from the measured data that would be caused by such a drop in cross section.