A NEW SHEAR APPARATUS FOR SMALL-ANGLE NEUTRON-SCATTERING (SANS) MEASUREMENTS

A new shear apparatus for small angle neutron scattering experiments was developed. Compared to other instruments two new experimental degrees of freedom are characteristic for this apparatus: (i) there is only one shear cell and not two as in other shear apparatus, and (ii) the angle α between the incident beam of neutrons and the vector of the velocity gradient of the sheared solution can be changed between 0°and 50°. This gives the possibility to test the anisotropic distribution of nonspherical particles, like micelles, in much more detail than with the other shear apparatuses. For example the symmetry of the scattering pattern of rodlike micelles is reduced from point group 2 mm for α=0 to point group 2 for α≠0, which is shown in an experiment performed with rodlike micelles of Cetylpyridiniumsalicylate.