Improving energy resolution on neutron monochromator arrays

Horizontal focusing properties of a new neutron monochromator geometry are investigated by Monte Carlo simulations. The geometry is based on the Rowland circle, which satisfies ideal focusing conditions, as opposed to standard planar monochromator devices. For asymmetric geometries one can get optimised conditions for both intensity and energy resolution for such a Rowland monochromator, in contrast to standard planar arrays. Energy resolution gains are also found for symmetric geometries, in particular for cold neutrons. Additional advantages include a symmetric beam well centered in energy. No changes are observed in integrated intensities.