Focusing and polarized neutron small-angle scattering spectrometer (SANS-J-II). The challenge of observation over length scales from an ångström to a micrometre

Abstract

SANS-J (a pinhole small-angle neutron scattering spectrometer at research reactor JRR3, Tokai, Japan) was reconstructed as a focusing and polarized neutron small-angle scattering spectrometer (SANS-J-II). By employing focusing lenses of a biconcave MgF2 crystal or of a sextupole permanent magnet and a high-resolution photomultiplier, the minimum accessible magnitude of the scattering vector q min was improved from 3 × 10-3 Å-1 to an ultra-small-angle scattering (USAS) of 3 × 10-4 Å-1. Compared with a Bonse-Hart double-crystal method, the advantages of focusing USAS are the efficient detection of anisotropic USAS with an area detector, an improvement in q resolution Δq/q at conventional magnitudes of the scattering vector q ∼ 10 -3 Å-1 and a gain in neutron flux in the conventional q region of q ∼ 10-3 Å-1. © International Union of Crystallography 2007.