| 1. |
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| 2. |
- Cooper-Jensen, Carsten, et al.
(författare)
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"m=1" coatings for neutron guides
- 2014
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Ingår i: International Workshop on Neutron Optics and Detectors (NOP&D 2013) 2–5 July 2013, Munich, Germany. - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 528, s. 012005-012005
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Konferensbidrag (refereegranskat)abstract
- A substantial fraction of the price for a supermirror neutron guide system is the shielding, which is needed because of the gamma radiation produced as a result of neutron absorption in the supermirror layers. Traditional coatings have been made of nickel-titanium heterostructures, but Ni and Ti also have a fairly high absorption cross section for cold and thermal neutrons. We examine a number of alternatives to Ni as part of a study to reduce the gamma radiation from neutron guides. Materials such as diamond and Be have higher neutron scattering density than Ni, smaller absorption cross section, and when a neutron is absorbed they emit gamma photons with lower energies. We present reflectivity data comparing Ni with Be and preliminary results from diamond coatings showing there use as neutron guide coatings. Calculations show that Be and diamond coatings emit two orders of magnitude fewer gamma photons compared to Ni, mainly because of the lower absorption cross section.
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| 3. |
- Dijulio, Douglas D., et al.
(författare)
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Characterization of the radiation background at the Spallation Neutron Source
- 2016
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Ingår i: VI European Conference On Neutron Scattering (ECNS2015). - : IOP Publishing. ; 746:1
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Konferensbidrag (refereegranskat)abstract
- We present a survey of the radiation background at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, TN, USA during routine daily operation. A broad range of detectors was used to characterize primarily the neutron and photon fields throughout the facility. These include a WENDI-2 extended range dosimeter, a thermoscientific NRD, an Arktis He-4 detector, and a standard Nal photon detector. The information gathered from the detectors was used to map out the neutron dose rates throughout the facility and also the neutron dose rate and flux profiles of several different beamlines. The survey provides detailed information useful for developing future shielding concepts at spallation neutron sources, such as the European Spallation Source (ESS), currently under construction in Lund, Sweden.
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| 4. |
- Hall-Wilton, Richard, et al.
(författare)
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Detectors for the European Spallation Source
- 2012
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Ingår i: 2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC). - 1082-3654. ; , s. 4283-4289
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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 by 2025. First neutrons will be produced in 2019. It will be a long pulse source, with an average beam power of 5 MW delivered to the target station. The pulse length will be 2.86 ms and the repetition rate 14 Hz. The ESS is presently in a design update phase, which ends in February 2013 with a Technical Design Report (TDR). Construction will subsequently start with the goal of bringing the first seven instruments into operation in 2019 at the same time as the source. The full baseline suite of 22 instruments will be brought online by 2025. 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. Additionally a new generation of source requires a new generation of detector technologies to fully exploit the opportunities that this source provides. This contribution presents briefly the current status of the ESS, and outlines the timeline to completion. The number of instruments and the framework for the decisions on which instruments should be built are shown. For a conjectured full instrument suite, which has been chosen for demonstration purposes for the TDR, a snapshot of the current expected detector requirements is presented. An outline as to how some of these requirements might be tackled is shown. Given that the delivery of the ESS TDR is only a few months away, this contribution reflects strongly the content of the TDR.
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| 5. |
- Kanaki, Kalliopi, et al.
(författare)
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A novel small-angle neutron scattering detector geometry
- 2013
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Ingår i: Journal of Applied Crystallography. - 1600-5767. ; 46, s. 1031-1037
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Tidskriftsartikel (refereegranskat)abstract
- A novel 2 pi detector geometry for small-angle neutron scattering (SANS) applications is presented and its theoretical performance evaluated. Such a novel geometry is ideally suited for a SANS instrument at the European Spallation Source (ESS). Motivated by the low availability and high price of 3 He, the new concept utilizes gaseous detectors with B-10 as the neutron converter. The shape of the detector is inspired by an optimization process based on the properties of the conversion material. Advantages over the detector geometry traditionally used on SANS instruments are discussed. The angular and time resolutions of the proposed detector concept are shown to satisfy the requirements of the particular SANS instrument.
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| 6. |
- Kanaki, Kalliopi, et al.
(författare)
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Statistical Energy Determination in Neutron Detector Systems for Neutron Scattering Science
- 2012
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Ingår i: 2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC). - 1082-3654. ; , s. 162-166
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Konferensbidrag (refereegranskat)abstract
- This contribution evaluates the feasibility and potential of a statistical determination of the neutron energy for thermal and cold neutrons in the new generation of neutron detectors. For the European Spallation Source (ESS), sited in Lund, Sweden, which is planned to be operational in 2019, and the world's leading source for the study of materials with neutrons by 2025, novel neutron detectors represent a critical technology that needs to be developed. The discussion here is based upon B-10 based thin-film detectors for neutron scattering science; however such a development is generalisable to other converter materials and potentially relevant to applications outside of neutron scattering science.
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| 7. |
- Kearley, Gordon J., et al.
(författare)
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Inelastic Neutron Scattering and Density Functional Theory- Molecular Dynamics Study of Si Dynamics in Ti3SiC2
- 2014
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Ingår i: Journal of the American Ceramic Society. - : Wiley. - 1551-2916 .- 0002-7820. ; 97:3, s. 916-922
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Tidskriftsartikel (refereegranskat)abstract
- Observed differences between measured and calculated elastic constants for Ti3SiC2 are investigated using Density Functional Theory and Inelastic Neutron Scattering. The agreement between the calculated lattice dynamics and the dynamics measured by inelastic neutron scattering is considered good except at energies below similar to 20meV where discrepancies suggest anharmonic potentials. This suggestion is confirmed by Density Functional TheoryMolecular Dynamics simulation which shows multiple site occupancy of the Si atoms within the basal plane at finite temperature and produces a calculated inelastic spectrum in better agreement with the measured spectrum in the low-energy region. The highly anharmonic potential energy surface of the Si atoms offers an explanation for the failure of elastic constants, calculated based on the harmonic approximation, to agree with initial experimental measurements.
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| 8. |
- 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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| 9. |
- Kirstein, Oliver
(författare)
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The European spallation source and future opportunities for materials science
- 2015
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Ingår i: State-of-the-Art Developments in Materials Characterization. - : Springer Science and Business Media LLC. - 9781605117317 ; 1754, s. 111-122
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Konferensbidrag (refereegranskat)abstract
- The European Spallation Source is Europe's next generation high-power neutron source utilising a linear accelerator and a rotating tungsten target to produce neutrons that will be used for fundamental research and industrial applications. The facility is co-hosted by the states of Denmark and Sweden, and while the main site will be placed in Lund, Sweden, the Data Management and Software Centre will be located in Copenhagen, Denmark. The facility will cover a broad range of scientific applications in the fields of physics, chemistry, biology, or life sciences. A focus will also be materials science and engineering, and dedicated instruments will gradually become available to the user community once neutrons will be produced neutrons from 2019 onwards.
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| 10. |
- Lee, Wai Tung, et al.
(författare)
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Polarisation Development at the European Spallation Source
- 2023
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Ingår i: EPJ Web of Conferences. - 2100-014X. ; 286, s. 03004-03004
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Tidskriftsartikel (refereegranskat)abstract
- To meet the ever-increasing user demand, eleven of the fifteen European Spallation Source (ESS) instruments under construction aim to offer polarised neutrons for user experiments. They include an imaging instrument, a SANS instruments, two reflectometers, three diffractometers, and four spectrometers. In conjunction with in-kind contributions and instrumentation grants, the ESS Polarisation Project will support the incorporation of polarisation analysis on eight of the eleven instruments. The project aims to deliver polarised neutrons for first-science experiments as instruments enter operation. Different polariser and polarisation analyser techniques will be available to accommodate the specifics of experiments on a given instrument. Polarised 3He neutron spin filter using either Metastable Optical Pumping (MEOP) or Spin-Exchange Optical Pumping (SEOP) techniques will provide shared-use equipment among many instruments, with SEOP’s main application being in situ beam-polarisation. Several instruments will also use polarising-supermirror devices. To provide wide-bandwidth spin-flipping capability to the time-of-flight instruments, Adiabatic Fast Passage (AFP) neutron spin flippers, also known as gradient-field radiofrequency spin flippers will be the main method of choice. Devices based on the same AFP principle will also be used to flip 3He nuclear spins. We are constructing our first 3He polariser setup, including field coils to produce highly uniform magnetic field. Monte Carlo simulations are being done for the supermirror polarisers. To ensure science-focused development, we are working with university partners in doing scientific experiments with polarised neutrons. These are some of the activities developing polarisation analysis for ESS instruments in our project.
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