SESAME (Spin Echo Scattering Angle Measurement)
The second LENS beamline, dubbed SESAME (Spin Echo Scattering Angle Measurement), measured its first neutrons on April 21, 2009. Started in the summer of 2006, this beamline has been the vision of IU professor Roger Pynn at CEEM. SESAME uses polarized neutrons to probe in-plane correlations on solid and liquid samples, and it also provides a platform for the development of instrumentation employing polarized neutrons. Instrumentation projects carried out on the uinstrument include the development of a broad-beam cryogenic spin-flipper, a novel compact spin precession decive called a cryo-cup, and several designs for magnetic prisms to be used in the SESAME technique itself. An in-situ 3He analyzer was added to the instruemnt early in 2013 and a new 2-D position sensitive detector is also being installed in 2013.
The SESAME technique relies upon magnetic fields confined into precise geometries to encode the scattering angle of neutrons into the final polarization of the beam. The resulting data give information on the real-space scattering length density correlations in materials over length scales for a few nm to several microns. Several experiments at national labs over the past few years have provided proof-of-principle results for SESAME. The most recent experiments were performed at the NIST Center for Neutron Research and the Los Alamos Neutron Science Center, in which neutron reflectivity was carried out on a nanopatterned silicon stamp. The results have been confirmed through theoretical calculations, and provide a basis for analysis of future experiments on more complicated structures, such as biomembranes and block copolymers. . The instrument at LENS has been used to study real-space correlations in porous alumina and bulk colloidal systems.