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We demonstrate a three phase-grating neutron interferometer as a robust candidate for large area interferometry applications and characterization of materials. This novel far-field moire technique allows for broad wavelength acceptance and relaxed requirements related to fabrication and alignment, circumventing the main obstacles associated with perfect crystal neutron interferometry. Interference fringes were observed with a total interferometer length of four meters, and the effects of an aluminum 6061 alloy sample on the coherence of the system was examined. Experiments to measure the autocorrelation length of samples and the universal gravitational constant are proposed and discussed.

An achromatic cold-neutron microscope with magnification 4 is demonstrated. The image-forming optics is composed of nested coaxial mirrors of full figures of revolution, so-called Wolter optics. The spatial resolution, field of view, and depth of focus are measured and found consistent with ray-tracing simulations. Methods of increasing the resolution and magnification are discussed, as well as the scientific case for the neutron microscope. In contrast to traditional pinhole-camera neutron imaging, the resolution of the microscope is determined by the mirrors rather than by the collimation of the beam, leading to possible dramatic improvements in the signal rate and resolution., Comment: To be published in Applied Physics Letters

The neutron is electrically neutral, but its substructure consists of charged quarks so it may have an internal charge distribution. In fact it is known to have a negative mean square charge radius (MSCR), the second moment of the radial charge density. In other words the neutron has a positive core and negative skin. In the first Born approximation the neutron MSCR can be simply related to the neutron-electron scattering length b_ne. In the past this important quantity has been extracted from the energy dependence of the total transmission cross-section of neutrons on high-Z targets, a very difficult and complicated process. A few years ago S.A. Werner proposed a novel approach to measuring b_ne from the neutron's dynamical phase shift in a perfect crystal close to the Bragg condition. We are conducting an experiment based on this method at the NIST neutron interferometer which may lead to a five-fold improvement in precision of b_ne and hence the neutron MSCR., Comment: 5 pages, 2 figures

We have performed high precision measurements of the zero-energy neutron scattering amplitudes of gas phase molecular hydrogen, deuterium, and $^{3}$He using neutron interferometry. We find $b_{\mathit{np}}=(-3.7384 \pm 0.0020)$ fm\cite{Schoen03}, $b_{\mathit{nd}}=(6.6649 \pm 0.0040)$ fm\cite{Black03,Schoen03}, and $b_{n^{3}\textrm{He}} = (5.8572 \pm 0.0072)$ fm\cite{Huffman04}. When combined with the previous world data, properly corrected for small multiple scattering, radiative corrections, and local field effects from the theory of neutron optics and combined by the prescriptions of the Particle Data Group, the zero-energy scattering amplitudes are: $b_{\mathit{np}}=(-3.7389 \pm 0.0010)$ fm, $b_{\mathit{nd}}=(6.6683 \pm 0.0030)$ fm, and $b_{n^{3}\textrm{He}} = (5.853 \pm .007)$ fm. The precision of these measurements is now high enough to severely constrain NN few-body models. The n-d and n-$^{3}$He coherent neutron scattering amplitudes are both now in disagreement with the best current theories. The new values can be used as input for precision calculations of few body processes. This precision data is sensitive to small effects such as nuclear three-body forces, charge-symmetry breaking in the strong interaction, and residual electromagnetic effects not yet fully included in current models., Comment: 6 pages, 4 figures, submitted to Physica B as part of the Festschrift honouring Samuel A. Werner at the International Conference on Neutron Scattering 2005

We have performed high-precision measurements of the coherent neutron scattering lengths of gas phase molecular hydrogen and deuterium using neutron interferometry. After correcting for molecular binding and multiple scattering from the molecule, we find b_{np} = (-3.7384 +/- 0.0020) fm and b_{nd} = (6.6649 +/- 0.0040) fm. Our results are in agreement with the world average of previous Measurements, b_{np} = (-3.7410 +/- 0.0010) fm and b_{nd} = (6.6727 +/- 0.0045) fm. The new world averages for the n-p and n-d coherent scattering lengths, including our new results, are b_{np} = (-3.7405 +/- 0.0009) fm and b_{nd} = (6.6683 +/- 0.0030) fm. We compare bnd with the calculations of the doublet and quartet scattering lengths of several nucleon-nucleon potential models and show that almost all known calculations are in disagreement with the precisely measured linear combination corresponding to the coherent scattering length. Combining the world data on b_{nd} with the modern high-precision theoretical calculations of the quartet n-d scattering lengths recently summarized by Friar et al., we deduce a new value for the doublet scattering length of ^{2}a_{nd} = [0.645 +/- 0.003(expt) +/- 0.007(theory)] fm. This value is a factor of 4, more precise than the previously accepted value of ^{2}a_{nd} = [0.65 +/- 0.04(expt)] fm. The current state of knowledge of scattering lengths in the related p-d system, ideas for improving by a factor of 5 the accuracy of the b_{np} and b_{nd} measurements using neutron interferometry, and possibilities for further improvement of our knowledge of the coherent neutron scattering lengths of 3H, 3He, and 4He are discussed., Comment: 22 pages, 19 figures

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 nuclear doublet scattering length of a_nd = (0.65 +/- 0.04) fm., Comment: 4 pages, 4 figures