A focusing‐geometry small‐angle neutron scattering instrument with a magnetic neutron lens

We have constructed a focusing‐geometry small‐angle neutron scattering (FSANS) instrument, SANS‐J‐II, with two kinds of neutron focusing device: a series of compound refractive lenses made of MgF 2 and a magnetic neutron lens based on an extended Halbach‐type sextupole magnet. In this study, we investigated the performance of the FSANS instrument with the magnetic neutron lens. The intensity distribution of a direct neutron beam focused on the detector plane by the magnetic neutron lens had a ratio of the peak height to the background level of for a polarized neutron beam with a polarization degree of . It is found that a minimum value of the measurable range [where is the modulus of the scattering vector and is defined as , where is the scattering angle and is the neutron wavelength], , of  Å −1 can be achieved by the FSANS instrument with the magnetic neutron lens using neutrons with  Å and for the full width at half maximum.