Abstract
The European Spallation Source (ESS) is the world's next generation spallation-based neutron source. The research conducted at ESS will yield in the discovery and development of new materials including the fields of manufacturing, pharmaceuticals, aerospace, engines, plastics, energy, telecommunications, transportation, information technology and biotechnology. The spallation source will deliver an unprecedented neutron flux. In particular, the reflectometers selected for construction, ESTIA and FREIA, have to fulfill challenging requirements. Local incident peak rate can reach 105 Hz/mm2. For new science to be addressed, the spatial resolution is aimed to be less than 1 mm with a desired scattering of 10−4 (peak-to-tail ratio). The latter requirement is approximately two orders of magnitude better than the current state-of-the-art detectors. The main aim of this work is to quantify the cumulative contribution of various detector components to the scattering of neutrons and to prove that the respective effect is within the requirements set for the Multi-Blade detector by the ESS reflectometers. To this end, different sets of geometry and beam parameters are investigated, with primary focus on the cathode coating and the detector window thickness.
Highlights
: The European Spallation Source (ESS) is the world’s generation spallation-based neutron source
The trend in figure 7a demonstrates that for wavelengths above 2.5 Å and 4 Å which are the lowest limit for FREIA and ESTIA respectively, a cost-effective choice of converter thickness would be of the order of 7-8 μm, for the fraction of scattered neutrons to stay below 10−3
A parameter scan is performed focusing mainly on the effects related to the converter thickness and the detector window
Summary
The Multi-Blade detector is a novel neutron detector currently being designed at ESS (see figure 1a). Its development was initiated at Institute Laue-Langevin (ILL) [35, 37, 41, 42]. It consists of a set of successive Multi-Wire Proportional Chambers [43], with 10B4C-coated cathodes and Ar/CO2 (80/20 by volume) as a gas counter mixture. On the other side of the blade a kapton layer and 32 copper strips are located for charge readout. The blades are tilted in a way that the incoming neutron beam hits the converter layer with an incident angle of 5◦, as shown in figure 1b. Several cassettes are assembled together forming a fan-like arrangement to achieve the area coverage required for reflectometry
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