A neutron optical periscope used for neutron imaging

A standard neutron guide is ill suited for neutron imaging, because reflections in the guide destroy the collimation of the neutron beam and let the cross-section of the neutron guide act as a divergent area source. Good neutron imaging installations use a flight tube instead, but with direct sight they also have a large background of gamma radiation and fast and epithermal neutrons. With the availability of high-m super mirrors, it has now become possible to build a neutron optical periscope that eliminates direct sight with two plain optical reflections only, without destroying the beam collimation ratio. At the FRM II reactor of Technische Universitنt München, several prototypes have been built and tested. Several neutron periscopes will be installed during the upgrade of the ANTARES neutron imaging facility in 2009/2010.