Bragg diffraction optics on neutron diffractometers

Abstract

Basic formulae for optimization of double and three axis diffractometers using bent-perfect-crystal (BPC) monochromators and analyzers are introduced with emphasis on momentum space focusing. The formulae have been derived for slit-like samples as well as plane-like ones and enable an easy implementation of the BPC-elements on conventional diffraction devices. The use of the BPC-elements permits one in many cases to benefit from focusing in real and momentum space simultaneously when working with open beams without Soller collimators.