Neutron spin manipulation optics: basic principles and possible applications

A number of basic elements for neutron spin manipulation optics (NSMO) based on Larmor and non-Larmor (quantum) precessions under reflection are considered. It is concluded that transition to 3D in neutron polarization optics may bring additional instrumental possibilities. New neutron optical devices will include spin turners (particularly, π/2-turners and π- turners, or flippers), spin precessors and antiprecessors, 3D-polarizers, 3D-analyzers, 3D- rotators, spin manipulators, hyper-polarizers. The innovative neutron optics is directly applicable to developing 3D polarization and polarimetry techniques, such as reflectometry with 3D- polarimetry, Neutron optical Spin Echo (NoSE), including compact NoSE and TOF NoSE schemes. A hyper-polarizer is a device which not only separates neutrons with the opposite spins, but also flips the 'wrong' spins. Thus, hyper-polarizers can double the intensity of polarized neutron beams, although a gain in the intensity can be achieved only with the increase either in the angular divergence or in the width of the beam, in full accordance with the Liouville theorem. The tasks to be solved for implementation of the NSMO concepts are discussed.