Master defence by Mads Bertelsen – Niels Bohr Institute - University of Copenhagen

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Master defence by Mads Bertelsen

Optimizing neutron guides using the minimalist principle and guide_bot

Today almost every neutron scattering experiment have the neutron beam delivered by a guide. The guide is an optical component that uses neutron mirrors where the neutron can be totally reflected if the angle of incidence is sufficiently low. The geometry of neutron guides is important for the performance, and actively researched as large gains in performance are still possible.

In this master thesis it is investigated how appropriate constrictions on the neutron intake of a guide can be calculated from a description of the required beam. The neutron intake should be minimized without significant performance losses to reduce background.

A program which facilitates automatic optimization of neutron guides called guide_bot is introduced. This program enables users without prior knowledge of Monte Carlo ray tracing simulations to describe a guide to be optimized for a specific set of demands in a matter of minutes. The program is demonstrated by testing the derived constrictions, where it is found that using appropriate assumptions, they provide a tool for properly balancing neutron intake with performance.