Novel three stage double directional focusing neutron monochromator

Neutron focusing monochromator consisting of three stages of Si-single crystals (with two slabs at each stage), which can provide us continuously variable curvatures in the vertical plane and the bending in the scattering plane, respectively, has been designed and constructed. Each stage can independently be tilted as well as bended by two kinds of mechanical gear systems. The adjustment of both horizontal and vertical curvatures is remotely controlled. The two-axis crystal diffractometer dedicated to strain scanning and installed at supermirror neutron guide tube in KUR has been equipped with this monochromator. By introducing the vertical focusing the detector signal has increased by a factor of two with respect to the previous one-stage version. Design and performance tests are presented. (author)