NOP: a new software tool for neutron optics

The neutron optics package (NOP) is a collection of codes for the computation of reactor spectra, neutron reflectivity of crystals, mirrors and multilayers and other quantities as cross-sections, attenuation in materials and refractive index. These calculations rely on the use of a database of materials cross-sections and crystal structures. NOP is freely distributed as an extension of the X-ray package XOP (Sanchez del Rio, Dejus, SPIE Proceedings 3448 (1998) 340), from which it inherits the user interface and code structure. The NOP package can be used for estimating the reflectivity of optical elements as crystals and multilayers. The NOP output can also be used as an input for neutron instrument ray-tracing modules