The Multi-Blade is a Boron-10-based gaseous detector introduced to face the challenge arising in neutron reflectometry at pulsed neutron sources. Neutron reflectometers are the most challenging instruments in terms of instantaneous counting rate and spatial resolution. This detector has been designed to cope with the requirements set for the reflectometers at the upcoming European Spallation Source (ESS) in Sweden. Based on previous results obtained at the Institut Laue-Langevin (ILL) in France, an improved demonstrator has been built at ESS and tested at the Budapest Neutron Centre (BNC) in Hungary and at the Source Testing Facility (STF) at the Lund University in Sweden. A detailed description of the detector and the results of the tests are discussed in this manuscript.
Inelastic neutron scattering instruments require very low background; therefore the proper shielding for suppressing the scattered neutron background, both from elastic and inelastic scattering is essential. The detailed understanding of the background scattering sources is required for effective suppression. The Multi-Grid thermal neutron detector is an Ar/CO 2 gas filled detector with a 10 B 4 C neutron converter coated on aluminium substrates. It is a large-area detector design that will equip inelastic neutron spectrometers at the European Spallation Source (ESS). To this end a parameterised Geant4 model is built for the Multi-Grid detector. This is the first time thermal neutron scattering background sources have been modelled in a detailed simulation of detector response. The model is validated via comparison with measured data of prototypes installed on the IN6 instrument at ILL and on the CNCS instrument at SNS. The effect of scattering originating in detector components is smaller than effects originating elsewhere. IntroductionInelastic neutron scattering is a very powerful technique for exploring atomic and molecular motion, as well as magnetic and crystal field excitations [1]. Timeof-Flight (ToF) spectrometers allow a broad phase space to be measured in a single setting; this is typically achieved with a large area detector array [2]. In typical state-of-the-art neutron instruments [2][3][4][5][6][7][8], this detector array can be 10-50 m 2 . One of the main performance criteria of these spectrometers is typically defined by the Signal-to-Background Ratio (SBR), therefore understanding and enhancing the latter is important for the instrument optimisation. In particular, scattered neutrons have a significant contribution to the SBR. The estimation of the SBR is done currently on a series of prescriptions based on observations of historical instrument installation.As a consequence of the recent restructuring of the 3 He market [9], a need for cost effective 3 He-replacing detector solutions is raised [10], especially for inelastic neutron scattering instruments, where large area detectors with high SBR are required. A potent new solution for this type of instruments is the Multi-Grid detector [11; 12], which will be used for the three Time-of-Flight chopper spectrometers at ESS [13][14][15][16]. The Multi-Grid design was invented at the Institut Laue-Langevin (ILL) [17; 18], and the detector now is jointly developed by the ILL and the ESS within the CRISP [19] and BrightnESS [20] projects.The Multi-Grid detector is an Ar/CO 2 -filled proportional chamber with a solid boron-carbide ( 10 B 4 C) neutron converter, enriched in 10 B [21][22][23]. The basic unit of the Multi-Grid detector is the grid, an aluminium frame; thin aluminium lamellas, coated on their both sides with boron-carbide, the so called blades are placed in this frame, parallel with each other and the entrance window of the grid, dividing the grid into cells. In the detector the grids are structured into columns, and this way the cells ...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.