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As neutron simulations packages are used for analysis of the expected performance for practically all newly built neutron instruments, possibilities for simulations with polarized neutrons have been relatively underdeveloped. During the last years we developed a new approach for the representation of time-dependent magnetic fields (both in magnitude and direction) for the VITESS simulation package. This allowed us to simulate the neutron spin dynamics in practically all polarized neutron devices (RF neutron flipper, adiabatic gradient RF flipper, the Drabkin resonator, etc.). In this article the above-mentioned VITESS instrument components (modules) will be presented and the simulated performance of a number of polarized neutron scattering instruments (NRSE, MIEZE, SESANS, etc.) will be demonstrated. Thus, we practically complete the polarized neutron suite of the VITESS, which seems sufficient for the simulation of performance of any existing polarized neutron scattering instrument. Future work will be concentrated on developments of dedicated sample modules (kernels) to allow for virtual experiments with VITESS.

Handling of polarization became very important in simulations of neutron scattering. One of the very comprehensive and open-source neutron simulation package, VITESS, has been intensely involved in polarized neutron simulations. Several examples will be shown here. Another similar package NISP also contains polarization tools. McStas has implemented an initial set of routines handling polarization, as our examples will also show.

The neutron spin-echo (NSE) method, which is the most powerful tool of high-resolution neutron spectroscopy, is known in two versions: with the long solenoids and short alternating fields. Here we consider an alternative version that makes use of spin flippers consisting of thin magnetic foils (TMF) with an in-plane rotating magnetic field vector. MNCP simulations show the perfect performance of the NSE spectrometer build upon such flippers. The requirements for TMF are estimated. Some possible applications of such technique are discussed. This approach can be considered as an alternative to the present day NSE techniques.

Soller-type collimators with supermirror coating may be used for polarisation of neutron beams. The disadvantage of such devices is a high level of gamma background and fast neutrons in the case of pulsed neutron sources. In order to increase the neutron flux, the collimator was made convergent. Generally, benders make it possible to suppress the fast neutron and gamma background completely. The combination of a bender and a convergent Soller collimator (convergent or focusing bender) is proposed for polarisation of the neutron beam for future NSE spectrometers at the cold source of ESS. Simulations and optimisation of convergent benders as neutron polarisers for NSE spectrometers are presented. The VITESS software package proved to be a powerful tool for the optimisation of polarising devices.