Considerations On Quality Factors From Super Mirrors And He-3 Spin Filters For Polarization Analyzers On Wide Q-Range Instrumentation

Polarization analysis will be needed on modern neutron scattering instrumentation designed to measure wide dynamic Q-ranges. These instruments will often use large area detectors and potentially multiple neutron wavelength bands or pulsed sources. This will place high demands on the method used for the polarization analysis. Two methods, super mirrors and He-3 neutron spin filters, are often considered as the only solutions. In this paper we will discuss the basic differences in these two methods for applications measuring a wide dynamic Q-range via the use of large area detectors. First we will present the simplified theory for conceptual understanding of how both wide angle SM and wide angle He-3 analyzer devices perform. Then we discuss how the properties of each method will effect neutron performance taking into account practical considerations. Such a conceptual understanding of the basics of design, performance and limitations of the two main options for such wide angle polarization analysis is timely given the growing momentum toward the use of such techniques as an extension of capability on current neutron instrumentation and for the planing of the many new instruments that will be designed in the near future, e.g. the future ESS source in Sweden.