| 1. |
- Backis, A., et al.
(författare)
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Time- and energy-resolved effects in the boron-10 based multi-grid and helium-3 based thermal neutron detectors
- 2021
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Ingår i: Measurement science and technology. - : IOP PUBLISHING LTD. - 0957-0233 .- 1361-6501. ; 32:3
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Tidskriftsartikel (refereegranskat)abstract
- The boron-10 based multi-grid detector is being developed as an alternative to helium-3 based neutron detectors. At the European Spallation Source, the detector will be used for time-of-flight neutron spectroscopy at cold to thermal neutron energies. The objective of this work is to investigate fine time- and energy-resolved effects of the Multi-Grid detector, down to a few mu eV, while comparing it to the performance of a typical helium-3 tube. Furthermore, it is to characterize differences between the detector technologies in terms of internal scattering, as well as the time reconstruction of similar to mu s short neutron pulses. The data were taken at the Helmholtz Zentrum Berlin, where the Multi-Grid detector and a helium-3 tube were installed at the ESS test beamline, V20. Using a Fermi-chopper, the neutron beam of the reactor was chopped into a few tens of mu s wide pulses before reaching the detector, located a few tens of cm downstream. The data of the measurements show an agreement between the derived and calculated neutron detection efficiency curve. The data also provide fine details on the effect of internal scattering, and how it can be reduced. For the first time, the chopper resolution was comparable to the timing resolution of the Multi-Grid detector. This allowed a detailed study of time- and energy resolved effects, as well as a comparison with a typical helium-3 tube.
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| 2. |
- Kirstein, Oliver, et al.
(författare)
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Neutron position sensitive detectors for the ESS
- 2014
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Ingår i: Proceedings of Science. - : Proceedings of Science (PoS). ; Vertex2014, s. 029-029
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Konferensbidrag (refereegranskat)abstract
- The European Spallation Source (ESS) in Lund, Sweden will become the world's leading neutron source for the study of materials. It will be a long pulse source, with an average beam power of 5 MW delivered to the target station. The ESS is in the construction phase, which started in 2013 with the completion of the Technical Design Report (TDR). The instruments are being selected from conceptual proposals submitted by groups from around Europe. These instruments present numerous challenges for detector technology in the absence of the availability of Helium-3, which is the default choice for detectors for instruments built until today and due to the extreme rates expected across the ESS instrument suite. Additionally a new generation of source requires a new generation of detector technologies to fully exploit the opportunities that this source provides. To meet this challenge at a green-field site, the detectors will be sourced from partners across Europe through numerous in-kind arrangements; a process that is somewhat novel for the neutron scattering community. This contribution presents briefly the current status of detectors for the ESS, and outlines the timeline to completion. For a conjectured instrument suite based upon instruments recommended for construction, a recently updated snapshot of the current expected detector requirements is presented. A strategy outline as to how these requirements might be tackled by novel detector developments is shown. In terms of future developments for the neutron community, synergies should be sought with other disciples, as recognized by various recent initiatives in Europe, in the context of the fundamentally multi-disciplinary nature of detectors. This strategy has at its basis the in-kind and collaborative partnerships necessary to be able to produce optimally performant detectors that allow the ESS instruments to be world-leading. This foresees and encourages a high level of collaboration and interdependence at its core, and rather than each group being all-rounders in every technology, the further development of centres of excellence across Europe for particular technologies and niches.
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| 3. |
- Birch, J., et al.
(författare)
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Multi-Grid boron-10 detector for time-of-flight spectrometers in neutron scattering science
- 2015
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Ingår i: 2015 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2015. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781467398626
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Konferensbidrag (refereegranskat)abstract
- The Multi-Grid (MG) detector has been introduced at ILL and developed by a collaboration between ILL, ESS and Linkoping University. This detector design addresses the severely decreased availability of He3, in particular for neutron scattering instruments with large-area detectors, such as time-of-flight neutron spectrometers at ESS and other facilities. The MG detector is based on thin converter films of boron-10 carbide arranged in layers orthogonal to the incoming neutrons. The design of the detector provides position resolution, efficiency competitive with He3 and a strong gamma rejection capability. This paper presents the MG large-area (2.4m2) demonstrator and the progress made in order to meet the needs of production of B4C-coated layers, mechanical parts and assembly on a scale similar to that of the final detectors for ESS. A particular effort was made to produce aluminium detector parts with a low alpha background, successfully reducing the background rate to acceptable levels. Following the IN5 demonstrator, a compact prototype has been designed in order to finalise the electronic readout to be used at the ESS instruments equipped with the MG.
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| 4. |
- Jailin, C., et al.
(författare)
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Fast Tracking of Fluid Invasion Using Time-Resolved Neutron Tomography
- 2018
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Ingår i: Transport in Porous Media. - : Springer Science and Business Media LLC. - 0169-3913 .- 1573-1634. ; 124:1, s. 117-135
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Tidskriftsartikel (refereegranskat)abstract
- Water flow in a sandstone sample is studied during an experiment in situ in a neutron tomography setup. In this paper, a projection-based methodology for fast tracking of the imbibition front in 3D is presented. The procedure exploits each individual neutron 2D radiograph, instead of the tomographic-reconstructed images, to identify the 4D (space and time) saturation field, offering a much higher time resolution than more standard reconstruction-based methods. Based on strong space and time regularizations of the fluid flow, with an a priori defined space and time shape functions, the front shape is identified at each projection time step. This procedure aiming at a fast tracking the fluid advance is explored through two examples. The first one shows that the fluid motion that occurs during one single 180(Formula presented.) scan can be resolved at 5 Hz with a sub-pixel accuracy whereas it cannot be unraveled with plain tomographic reconstruction. The second example is composed of 42 radiographs acquired all along a complete fluid invasion in the sample. This experiment uses the very same approach with the additional difficulty of large fluid displacement in between two projections. As compared to the classical approach based on full reconstructions at each invasion stage, the proposed methodology in the studied examples is roughly 300 times faster offering an enhanced time resolution.
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| 5. |
- Pfeiffer, D., et al.
(författare)
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First measurements with new high-resolution gadolinium-GEM neutron detectors
- 2016
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Ingår i: Journal of Instrumentation. - : IOP PUBLISHING LTD. - 1748-0221. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- European Spallation Source instruments like the macromolecular diffractometer (NMX) require an excellent neutron detection efficiency, high-rate capabilities, time resolution, and an unprecedented spatial resolution in the order of a few hundred micrometers over a wide angular range of the incoming neutrons. For these instruments solid converters in combination with Micro Pattern Gaseous Detectors (MPGDs) are a promising option. A GEM detector with gadolinium converter was tested on a cold neutron beam at the IFE research reactor in Norway. The mu TPC analysis, proven to improve the spatial resolution in the case of B-10 converters, is extended to gadolinium based detectors. For the first time, a Gd-GEM was successfully operated to detect neutrons with a measured efficiency of 11.8% at a wavelength of 2 angstrom and a position resolution better than 250 mu m.
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