Study of a ~(10)B-based Multi-Blade detector for Neutron Scattering Science

摘要

The main goal in neutron reflectometry instruments is to achieve a high angular resolution and high counting rates. Although ~3 He shortage affects scientific research in neutron scattering science due to its wide use in detectors as neutron converter; this is not the main issue for neutron reflectometry application where detector sizes are generally moderate. Indeed ~3 He detectors are instead limited in spatial resolution. To reduce the particles traces and thereby increase the spatial resolution those detectors are operated at high quencher gas pressure, resulting in mechanical constraints. A promising alternative, to accomplish these goals, is to exploit solid ~(10)B-films employed in a proportional gas chamber. The challenge with this technique is to attain a suitable detection efficiency. This can be achieved by operating the ~(10) B conversion layer at grazing angle relative to the incoming neutron direction. The Multi-Blade design is based on this operational principle and it is conceived to be modular in order to be adaptable to different applications. A prototype has been developed at ILL and the results obtained on our monochromatic test beam line are presented here. A significant concern in a modular design is the uniformity of detector response: several effects might contribute to degrade the uniformity and they have to be taken into account in the detector concept: overlap between different substrates, coating uniformity, substrate flatness, parallax errors, etc. A simulation has been developed to address these problems.