The Pappas group, former section Neutron and Positron Methods in Materials (NPM2), focuses on the innovative and complementary use of neutrons and positrons in a broad area of fields relevant to health and energy. Neutron scattering accesses the microscopic and mesoscopic length and time scales whereas positron annihilation probes electronic structures, local structural inhomogeneities and defects. The development of new experimental methods for neutrons and positrons is one of the traditional fields of excellence of our group. The first reactor based positron source worldwide was realized in Delft. The section has a long-standing experience in neutron reflectometry, polarized neutrons and Larmor labeling, which led to the development of new techniques and concepts such as SESANS or Larmor Diffraction.
The main areas of research of Pappas group include the conditions of implementation of self-healing in Al Alloys investigated by positron annihilation. New magnetic phases arising from frustration, magnetoelastic coupling or chirality are studied by polarized neutrons and high resolution inelastic neutron scattering. Colloids, emulsions, gels and drug delivery systems are investigated by SESANS. Neutron reflectometry is used for protein absorption, magnetic thin films, surface modification (polymer brushes) or drug delivery systems.
NPM2 cooperates closely with the Brück group in the area of materials and techniques both for neutrons and positrons.