| 1. |
- Barrow, Joshua, et al.
(författare)
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Computing and Detector Simulation Framework for the HIBEAM/NNBAR Experimental Program at the ESS
- 2021
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Ingår i: 25<sup>th</sup> International Conference on Computing in High Energy and Nuclear Physics (CHEP 2021). - : EDP Sciences.
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Konferensbidrag (refereegranskat)abstract
- The HIBEAM/NNBAR program is a proposed two-stage experiment at the European Spallation Source focusing on searches for baryon number violation via processes in which neutrons convert to antineutrons. This paper outlines the computing and detector simulation framework for the HIBEAM/NNBAR program. The simulation is based on predictions of neutron flux and neutronics together with signal and background generation. A range of diverse simulation packages are incorporated, including Monte Carlo transport codes, neutron ray-tracing simulation packages, and detector simulation software. The common simulation package in which these elements are interfaced together is discussed. Data management plans and triggers are also described.
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| 2. |
- Batkov, Konstantin, et al.
(författare)
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Unperturbed moderator brightness in pulsed neutron sources
- 2013
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 729, s. 500-505
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Tidskriftsartikel (refereegranskat)abstract
- The unperturbed neutron brightness of a moderator can be defined from the number of neutrons leaving the surface of a moderator completely surrounded by a reflector. Without openings for beam extraction, it is the maximum brightness that can be theoretically achieved in a moderator. The unperturbed brightness of a cylindrical cold moderator filled with pure para-H-2 was calculated using MCNPX; the moderator dimensions were optimised, for a fixed target and reflector geometry corresponding to the present concept for the BS spallation source. This quantity does not depend on openings for beam extraction and therefore can be used for a first-round optimisation of a moderator, before effects due to beam openings are considered. We find that such an optimisation yields to a factor of 2 increase with respect to a conventional volume moderator, large enough to accommodate a viewed surface of 12 x 12 cm(2): the unperturbed neutron brightness is maximum for a disc-shaped moderator of 15 cm diameter, 1.4 cm height. The reasons for this increase can be related to the properties of the scattering cross-section of paraH(2), to the added reflector around the exit surface in the case of a compact moderator, and to a directionality effect. This large optimisation gain in the unperturbed brightness hints towards similar potentials for the perturbed neutron brightness, in particular in conjunction with advancing the optical quality of neutron delivery from the moderator to the sample, where by Lionville theorem the brightness is conserved over the beam trajectory, except for absorption and similar type losses. (C) 2013 Elsevier B.V. All rights reserved
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| 3. |
- Gallimore, Stephen, et al.
(författare)
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Challenges and Design Solutions of the Liquid Hydrogen Circuit at the European Spallation Source
- 2014
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Ingår i: Advances in Cryogenic Engineering: Transactions of the Cryogenic Engineering Conference - CEC (AIP Conference Proceedings). - : AIP Publishing LLC. - 1551-7616 .- 0094-243X. ; 1573, s. 659-664
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Konferensbidrag (refereegranskat)abstract
- The European Spallation Source (ESS), Lund, Sweden will be a 5MW long-pulse neutron spallation research facility and will enable new opportunities for researchers in the fields of life sciences, energy, environmental technology, cultural heritage and fundamental physics. Neutrons are produced by accelerating a high-energy proton beam into a rotating helium-cooled tungsten target. These neutrons pass through moderators to reduce their energy to an appropriate range (< 5 meV for cold neutrons); two of which will use liquid hydrogen at 17 K as the moderating and cooling medium. There are several technical challenges to overcome in the design of a robust system that will operate under such conditions, not least the 20 kW of deposited heat. These challenges and the associated design solutions will be detailed in this paper.
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| 4. |
- Klinkby, Esben, et al.
(författare)
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In-Pile He-4 Source for UCN Production at the ESS
- 2014
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Ingår i: Advances in High Energy Physics. - : Hindawi Limited. - 1687-7357 .- 1687-7365.
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Tidskriftsartikel (refereegranskat)abstract
- ESS will be a premier neutron source facility. Unprecedented neutron beam intensities are ensured by spallation reactions of a 5 MW, 2.0 GeV proton beam impinging on a tungsten target equipped with advanced moderators. The work presented here aims at investigating possibilities for installing an ultra cold neutron (UCN) source at the ESS. One consequence of using the recently proposed flat moderators is that they take up less space than the moderators originally foreseen and thus leave more freedom to design a UCN source, close to the spallation hotspot. One of the options studied is to place a large He-4 UCN source in a through-going tube which penetrates the shielding below the target. First calculations of neutron flux available for UCN production are given, along with heat-load estimates. It is estimated that the flux can give rise to a UCN production at a rate of up to 1.5 . 10(8) UCN/s. A production in this range potentially allows for a number of UCN experiments to be carried out at unprecedented precision, including, for example, quantum gravitational spectroscopy with UCNs which rely on high phase-space density.
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| 5. |
- Schonfeldt, T., et al.
(författare)
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Broad spectrum moderators and advanced reflector filters using (208)pb
- 2015
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 769, s. 1-4
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Tidskriftsartikel (refereegranskat)abstract
- Cold and thermal neutrons used in neutrons scattering experiments are produced in nuclear reactors and spallation sources. The neutrons are cooled to thermal or cold temperatures in thermal and cold moderators, respectively. The present study shows that it is possible to exploit the poor thermalizing property of Pb-208 to design a broad spectrum moderator, i.e. a moderator which emits thermal and cold neutrons from the same position. Using Pb-208 as a reflector filter material is shown to be slightly less efficient than a conventional beryllium reflector filter. However, when surrounding the reflector filter by a cold moderator it is possible to regain the neutrons with wavelengths below the Bragg edge, which are suppressed in the beryllium reflector filter. In both the beryllium and lead case surrounding the reflector filter with a cold moderator increases the cold brightness significantly compared to a conventional reflector filter. (C) 2014 Elsevier B.V. All rights reserved.
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