Wide Angle Polarization Analyzer

Wide Angle Polarization Analyzers (WAPAs) are precision instruments designed to analyze the polarization state of neutrons scattered by a sample. Two distinct neutron optical designs are available:

• rWAPA (reflection geometry), which utilizes spin-selective reflection via polarizing supermirrors.
• tWAPA (transmission geometry), which analyzes the transmitted beam without altering its trajectory.

rWAPAs consist of thin, curved lamellas arranged radially to form channels that gradually widen along the neutron propagation direction. Each lamella is coated on both sides with Fe/Si-based polarizing supermirrors, enabling efficient spin discrimination.

tWAPAs, on the other hand, employ a radial array of V-shaped cavities, either with straight legs or shaped according to a logarithmic spiral. This design allows for high transmission efficiency while preserving the beam path.

Depending on the number of channels and geometry, WAPAs typically cover horizontal angular ranges of 40°–120° and vertical ranges of 10°–20°.
SwissNeutronics WAPAs offer key advantages:

• Stable polarization efficiency over long periods
• Maintenance-free operation
• High transmission efficiency in tWAPA designs

These features make WAPAs ideal for neutron scattering experiments requiring wide angular coverage and high polarization.