Does quantum entanglement invalidate contrast variation practices in neutron scattering?

A surprising observation of the anomalous deep inelastic neutron scattering from liquid H2O-D2O mixtures was reported recently in PRL. It has also bee n suggested that such anomalous scattering can manifest itself as a deviati on of the neutron scattering length density Nb from the conventional theory , based upon the assumption that the molecular volumes of the constituents are additive in the mixture. For H2O-D2O mixtures deviations as much as 5-1 0% are predicted from the conventionally expected value Nb. This fact would result in serious consequences for the widely used technique of contrast v ariation in neutron scattering. We have used an advanced neutron interferom etry technique in order to verify these predictions and confirmed the exper imental practice of isotopic contrast variation with high precision. (C) 20 00 Elsevier Science B.V. All rights reserved.