Optimization studies on the target station for the high-brilliance neutron source HBS based on Monte Carlo simulations

The importance of neutrons as scientific probes is undisputed. The High-Brilliance Neutron Source (HBS), planned by Forschungszentrum Jülich, shall serve as a precursor for a network of low- and medium-flux neutron sources throughout Europe and will make use of the neutron-producing reaction Be(p,n) or Be(d,n) in the sub-spallation regime with E_ion < 100MeV. Subject of this thesis is the development and optimization of the target-moderator-reflector system of the HBS. The dependence of the brilliance and temporal pulse structure of the generated neutrons on the geometry, the materials, and the accelerator parameters is examined in multi-dimensional parameter studies. The investigations are conducted by means of the Monte Carlo method. The simulation studies indicate that a combination of a compact thermal moderator with a high slowing-down power ξ Σ_el , for example PE or light water, and a high-volume reflector with a low capture cross section σ(n,γ) << σ_H(n,γ), e.g., beryllium or graphite, exhibits an exceptionally high thermal neutron flux within the moderator-reflector assembly. The neutrons can effectively be extracted by exploiting the streaming effect using newly developed flux channels from the center of the moderator, whereby the peak brilliance is increased significantly. Cold moderators should be implemented in the flux maximum inside the thermal moderator to additionally increase the peak brilliance of cold neutrons. For the mechanical engineering of the target-moderator-reflector assembly a design of all components as compact as possible is strongly advised. A further subject of this thesis is the design and optimization of a moderator prototype for measurements at the AKR-2 training reactor in Dresden, by which the conclusions of the simulations are verified