Helium ray - tracing Simulating the neutral helium atom microscope NEMI using

This thesis investigates the validity of making simulations of neutral matter-wave microscope instrumentation, by modifying the well established McStas neutron ray tracing software. Specifically this thesis models the neutral helium atom microscope, NEMI, located at the University of Bergen. Two new instrument components were written in order to simulate NEMI. The new components were a source with a Lorentzian wavelength distribution and Gaussian spatial distribution, and a Fresnel zone plate. The simulations comply with the physics intended to be simulated, and show a subtle, but important, dependency on wavelength that was not present in previous geometrical calculations done by the NEMI group in Bergen. Dansk resumé Dette bachelorprojekt undersøger gyldigheden af at lave simulationer af neutral stof-bølgemikroskopinstrumentering, ved at modificere det veletablerede McStas neutron ray-tracing software. Konkret handler denne afhandling om at modellere det neutrale helium atom mikroskop, NEMI, der står ved Universitetet i Bergen. To nye instrument komponenter blev skrevet for at simulere NEMI. De nye komponenter var en kilde med en Lorentzfordeling i bølgelængder og en Gaussisk rumlig fordeling, og en Fresnel zone plade. Simuleringerne overholder den kendte fysik bag komponenterne, og viser en subtil, men dog vigtig, afhængighed af bølgelængde, der ikke var til stede i tidligere geometriske beregninger udført af NEMI-gruppen i Bergen.