Volume 107, Issue 3, 01 February 2010
Index of content:
107(2010); http://dx.doi.org/10.1063/1.3298440View Description Hide Description
Dark-field neutron tomography was applied to obtain three-dimensional volumetric data representing the distribution of micrometer and submicrometer sized structures in bulk samples. This is a size range that complements the range of direct spatial resolution. A phase grating setup implemented in a conventional imaging instrument enables corresponding tomographic investigations on reasonable time scales. Different samples were investigated and demonstrate the applicability of the method for the investigation of structural materials. Local variations in the small-angle scattering in BiSn, AlSi, and aluminum samples were mapped and the results are discussed with respect to the contrast formation of the method.
Jump properties of the tip magnetic field of a notch in a melt-processes yttrium-barium-copper-oxide bulk107(2010); http://dx.doi.org/10.1063/1.3291116View Description Hide Description
We report on a direct measurement of the magnetic field properties at the tip of a notch in melt-processed bulks. In the case of the fixed notch angle, when the notch length increases and reaches a critical value, the tip magnetic field will increase and exceed the initial value of the sample without a notch. In the case of fixed notch length which is equal to the radius of superconducting bulk, the tip magnetic field increases at first and then decreases as the notch angle is over 90°. In addition, the rules of the change in the interaction force between the bulk superconductor and magnet are also reported. A simple physical model is used to interpret these experimental phenomena qualitatively.