Precision neutron interferometric measurement of the nd coherent neutron scattering length and consequences for models of three-nucleon forces -: art. no. 192502

We have performed the first high precision measurement of the coherent neutron scattering length of deuterium in a pure sample using neutron interferometry. We find b(nd) = (6.665 +/- 0.004) fm in agreement with the world average of previous measurements using different techniques, b(nd) = (6.6730 +/- 0.0045) fm. We compare the new world average for the nd coherent scattering length b(nd) = (6.669 +/- 0.003) fm to calculations of the doublet and quartet scattering lengths from several modern nucleon-nucleon potential models with three-nucleon force (3NF) additions and show that almost all theories are in serious disagreement with experiment. This comparison is a more stringent test of the models than past comparisons with the less precisely determined doublet scattering length of 2(and) = (0.65 +/- 0.04) fm.