Neutron Imaging With Bragg Mirrors

Phase-space analysis of neutron optics has revealed that neutron imaging by Bragg reflection from thick bent perfect crystals can be non-dispersive (independent of the neutron wavelength), like with an optical mirror. The corresponding devices, called Bragg mirrors (BM), can be used for neutron imaging at pulsed neutron sources. Using a position sensitive detector (PSD) and time-of-flight analysis (TOF), a BM imaging system will make it possible to collect both real space mapping data and scattering space data simultaneously. Each pixel of PSD will correspond to a point in the sample and will contain a segment of the diffraction pattern (useful for strain, texture or phase analysis), or of an inelastic spectrum. In this paper the resolution and efficiency of BM in TOF diffraction experiments are calculated and compared with the usual sequential method of mapping. Experimental tests performed at steady state neutron sources showed sub-millimeter spatial resolution in the one-dimensional case.