Browsing by Author "Andersen, KH"

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    (3)He polarization for ISIS TS2 phase I instruments
    (Elsevier, 2011-06-01) Beecham, CJ; Boag, S; Frost, CD; McKetterick, TJ; Stewart, JR; Andersen, KH; Bentley, PM; Jullien, D
    Here we report on the development of polarization analysis (PA) techniques to be employed at the ISIS pulsed neutron source second target station. Both spin exchange optical pumping and metastability exchange optical pumping techniques are being developed at ISIS to produce polarized neutron spin filters for use as neutron polarizers and analysers. We focus on the developments of a polarization solution on the LET spectrometer, including the updated design of the PASTIS XYZ coil set and single crystal silicon analyser cell. We also report on the construction of a combined polarizer/analyser solution for the WISH diffractometer. (C) 2010 Elsevier B.V.
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    The ABC of powder diffractometer detector coverage
    (Wiley-Blackwell, 2011-04-01) Andersen, KH; Bentley, PM; Cussen, LD
    This article addresses the question of the most effective detector configuration for neutron spectrometers using a discussion of a particular case - constant-wavelength powder diffractometers at continuous neutron sources. A first variation uses an essentially one-dimensional `banana' detector coupled with out-of-scattering-plane beam divergence before and after the sample. A second variation uses an incident beam tightly defined both in- and out-of-plane coupled to a `4 pi' detector covering all possible scattering angles after the sample. It is widely believed that the 4 pi arrangement is superior for most varieties of neutron spectrometer but is more difficult and more expensive to implement. Starting from a commonly used overall instrument figure-of-merit, this article presents simple arguments leading to the surprising conclusion that this is untrue for these constant-wavelength powder diffractometers, provided only that the cylindrical samples used with the banana detector have a height greater than 2.4 times their diameter. © 2011, Wiley-Blackwell.
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    Correction of optical aberrations in elliptic neutron guides
    (Elsevier Science BV, 2012-11-21) Bentley, PM; Kennedy, SJ; Andersen, KH; Rodriguez, DM; Mildner, DFR
    Modern, nonlinear ballistic neutron guides are an attractive concept in neutron beam delivery and instrumentation because they offer increased performance over straight or linearly tapered guides. However, like other ballistic geometries they have the potential to create significantly non-trivial instrumental resolution functions. We address the source of the most prominent optical aberration, namely coma, and we show that for extended sources the off-axis rays have a different focal length from on-axis rays, leading to multiple reflections in the guide system. We illustrate how the interplay between coma, sources of finite size, and mirrors with non-perfect reflectivity can therefore conspire to produce uneven distributions in the neutron beam divergence, a source of complicated resolution functions. To solve these problems, we propose a hybrid elliptic-parabolic guide geometry. Using this new kind of neutron guide shape, it is possible to condition the neutron beam and remove almost all of the aberrations, whilst providing the same performance in beam current as a standard elliptic neutron guide. We highlight the positive implications for neutron scattering instruments that this new shape can bring. © 2012, Elsevier Ltd.
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    Global optimization of an entire neutron guide hall
    (Wiley-Blackwell, 2011-06-01) Bentley, PM; Fouquet, P; Bohm, M; Sutton, I; Dewhurst, CD; Andersen, KH
    This paper describes the optimization of an entire neutron guide system, from the moderator to the sample position for several instruments simultaneously, using no more than a desktop computer and a few days of CPU time. This is made possible by merging two relatively advanced computational techniques. Neutron acceptance diagram shading is a fast new method for modelling neutron beams, using an approach based on polygons similar to those featuring in computer games. Optimization algorithms based on swarm intelligence are efficient and reliable ways to maximize numerically calculable figures of merit with many strongly coupled geometry parameters. Recent developments in these methods are described, as well as their combination to optimize the geometry of the H5 beamlines at the Institut Laue-Langevin. The optimization was such that all instruments simultaneously gain as much on-sample flux as possible by taking unused phase space from their neighbours, whilst no instrument suffers any losses in its useful flux. © 2011, Wiley-Blackwell.
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    The instrument suite of the European Spallation Source
    (Elsevier B. V., 2020-01-10) Andersen, KH; Argyriou, DN; Jackson, AJ; Houston, J; Henry, PF; Deen, PP; Toft-Petersen, R; Beran, P; Strobl, M; Arnold, T; Wacklin-Knecht, H; Vivanco, R; Parker, SF; Gussen, A; Kanaki, K; Scionti, G; Olsen, MA; Arai, M; Schmakat, Ph; Lechner, RE; Niedermayer, Ch; Schneider, H; Zanetti, M; Petrillo, C; Moreira, FY; Stepanyan, S; Luna, P; Calzada, E; Stahn, J; Voigt, J; Dupont, T; Hanslik, R; Siemers, DJ; Udby, L; Chowdhury, MAH; Klauser, Ch; Rouijaa, M; Lehmann, E; Heynen, A; Bustinduy, I; Schwaab, A; Raspino, D; Scatigno, C; del Moral, OG; Kiehn, R; Aprigliano, G; Zanatta, M; Huerta, M; Bellissima, S; Lerche, M; Holm-Dahlin, S; Huerta, M; Christensen, NB; Lohstroh, W; Gorini, G; Fenske, J; Hansen, UB; Klauser, C; Rodrigues, S; Müller, M; Gorini, G; Bovo, C; Hall-Wilton, R; Fabrèges, X; Siemers, DJ; Khaplanov, A; Tsapatsaris, N; Taylor, J; Christensen, M; Schefer, J; Woracek, R; Tozzi, P; Müller, M; Carlsen, H; Olsen, MA; Orecchini, A; Di Fresco, L; Paciaroni, A; Bovo, C; Magán, M; Hauback, BC; Elmer, J; Heenan, RK; Piscitelli, F; Masi, F; Bakedano, G; Klimko, S; De Bonis, A; Fedrigo, A; Lukáš, P; Frielinghaus, H; Stahn, J; Schweika, W; Markó, M; Pfeiffer, D; Kirstein, O; Di Fresco, L; Schreyer, A; Orszulik, A; Nowak, G; Butterweck, S; Šaroun, J; Paciaroni, A; Kolevatov, R; Lehmann, EH; Filges, U; Schreyer, A; Koenen, M; Bustinduy, I; Magán, M; Feygenson, M; Cooper, JFK; Abad, E; Senesi, R; Longeville, S; Llamas-Jansa, I; Schulz, M; Birk, JO; Sharp, M; Galsworthy, P; Šaroun, J; Martínez, J; Hiess, A; Holm-Dahlin, S; Filges, U; Pullen, SA; Guyon Le Bouffy, J; Schefer, J; Lukáš, P; Udby, L; Kozielewski, T; Niedermayer, C; Sacchetti, F; Hartl, M; Jaksch, S; Salhi, Z; Brückel, T; Aguilar, J; Aguilar, J; Seifert, M; Bordallo, HN; Robillard, T; Villacorta, FJ; Herranz, I; del Rosso, L; Hauback, BC; Orecchini, A; Fabrèges, G; Fenske, J; Neuhaus, J; Schillinger, B; Abad, E; Kittelmann, T; Lefmann, K; Seifert, M; Neuhaus, J; Herranz, I; Kolevatov, R; Annighöfer, B; Oksanen, E; Morgano, M; Laszlo, G; Freeman, PG; Kennedy, SJ; Bertelsen, M; Bellissima, S; Alba-Simionesco, C; Markó, M; Mezei, F; Chowdhury, M; Halcrow, W; Jestin, J; Lieutenant, K; Babcock, E; Rønnow, HM; Engels, R; del Moral, OG; Vickery, A; Rouijaa, M; Lavie, P; Petersson Årsköld, S; Glavic, A; Désert, S; Mannix, D; Scatigno, C; Petry, W; Christensen, NB; Violini, N; Villacorta, FJ; Porcher, F; Glavic, A; Scionti, G; Zanetti, M; Fernandez-Alonso, F; Rønnow, HM; Mosconi, M; Olsson, M; Stepanyan, S; Petrillo, C; del Rosso, L; Harbott, P; Sacchetti, F; Bertelsen, M; Kämmerling, H; Andreani, C; Schulz, M; Colognesi, D; Luna, P; Loaiza, L; Turner, D; Martínez, JL; Tartaglione, A; Sordo, F; Llamas-Jansa, I; Schmakat, P; Lechner, RE; Poqué, A; Fernandez-Alonso, F; Colognesi, D; Tartaglione, A; Morgano, M; Webb, N; Loaiza, L; Whitelegg, L; Petry, W; Iversen, K; Vivanco, R; Tozzi, P; Goukassov, A; Schillinger, B; Carlsen, H; Masi, F; Christensen, M; Nowak, G; Nightingale, J; Schütz, S; Lopez, CI; Langridge, S; Schütz, S; Nagy, G; Zanatta, M; Andreani, C; Lefmann, K; Lohstroh, W; Mosconi, M; Senesi, R; Stefanescu, I; Bakedano, G; Hagen, ME; Wischnewski, A; Bourges, P; Hansen, UB; De Bonis, A; Kiehn, R; Parker, SF; Iversen, K; Sordo, F; Freeman, PG; Birk, JO; Rodríguez, DM; Ansell, S
    An overview is provided of the 15 neutron beam instruments making up the initial instrument suite of the European Spallation Source (ESS), and being made available to the neutron user community. The ESS neutron source consists of a high-power accelerator and target station, providing a unique long-pulse time structure of slow neutrons. The design considerations behind the time structure, moderator geometry and instrument layout are presented. The 15-instrument suite consists of two small-angle instruments, two reflectometers, an imaging beamline, two single-crystal diffractometers; one for macromolecular crystallography and one for magnetism, two powder diffractometers, and an engineering diffractometer, as well as an array of five inelastic instruments comprising two chopper spectrometers, an inverse-geometry single-crystal excitations spectrometer, an instrument for vibrational spectroscopy and a high-resolution backscattering spectrometer. The conceptual design, performance and scientific drivers of each of these instruments are described. All of the instruments are designed to provide breakthrough new scientific capability, not currently available at existing facilities, building on the inherent strengths of the ESS long-pulse neutron source of high flux, flexible resolution and large bandwidth. Each of them is predicted to provide world-leading performance at an accelerator power of 2 MW. This technical capability translates into a very broad range of scientific capabilities. The composition of the instrument suite has been chosen to maximise the breadth and depth of the scientific impact of the early years of the ESS, and provide a solid base for completion and further expansion of the facility. © 2020 The Authors. Published by Elsevier B.V. Open access article under the CC BY-NC-ND license.
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    The performance of magnetic lens for focusing VCN-SANS
    (Elsevier, 2011-04-01) Yamada, M; Iwashita, Y; Kanaya, T; Ichikawa, M; Tongu, H; Kennedy, SJ; Shimizu, HM; Mishima, K; Yamada, NL; Hirota, K; Carpenter, JM; Lal, J; Andersen, KH; Geltenbort, P; Guerard, B; Manzin, G; Hino, M; Kitaguchi, M; Bleuel, M
    We have developed a prototype rotating-permanent magnet sextupole lens (named rot-PMSx) for more efficient experiments with neutron beams in time of flight (ToF) mode. This lens can modulate the focusing strength over range 1.5 x 10(4)T/m(2) <= g' <= 5.9 x 10(4) T/m(2). Synchronization between the modulation and the beam pulse produces a focused beam without significant chromatic aberration. We anticipate that this lens could be utilized in focusing small angle neutron scattering (SANS) instruments for novel approach to high resolution SANS. We carried out experiments testing the principle of this lens at the very cold neutron (VCN) beamline (PF2) at Institut Laue-Langevin (ILL), France. The focused beam image size at the detector was kept constant at the same beam size as the source (approximate to 3 mm) over a wavelength range of 30 angstrom <= lambda <= 48 angstrom in focal length of approximate to 1.14m. The flux gain was about 12 relative to a beam without focusing, and the depth of focus was quite large. These results show the good performance of this lens and the system. Thereupon we have demonstrated the performance of this test bed for high resolution focusing of VCN-SANS for a well-studied softmatter sample; a deuterium oxide solution of Pluronic F127, an (PEO)(100)(PPO)(65)(PEO)(100) tri-block copolymer in deuterium oxide. The results of the focusing experiment and the focusing VCN-SANS are presented. (C) 2010 Elsevier B.V. All rights reserved.
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    Polarised 3He based neutron polarisers and analysers for magnetism research on ANSTO instruments
    (Australian Institute of Physics, 2012-02-02) Lee, WT; Klose, F; Jullien, D; Andersen, KH
    Polarised 3He based neutron polariser and polarization analyser [1] have become a matured technology for polarised neutron experimental works. A joint project of the Australian Nuclear Science and Technology Organisation (ANSTO) and the Institute Laue Langevin (ILL) is underway to provide 6 OPAL neutron scattering instruments with these important research capabilities. The instruments include SANS Quokka, diffractometer Wombat, thermal triple-axis spectrometer Taipan, reflectometer Platypus, Taipan’s cold-neutron counterpart Sika, and cold neutron time-of-flight spectrometer Pelican. Discussions are underway to further expand the use to more instruments, including the Laue diffractometer Koala and new instruments that are being designed and constructed. The project will produce a 3He gas polarizing station that uses the Metastable Exchange Optical Pumping method [2]. Silicon-window polarised 3He cells will polarize the incident neutron beam on several instruments and analyse the scattered neutrons on Platypus and Quokka. Wide-angle analyser “Pastis” cells [3] will be used for Wombat and Pelican. The polarizers and analysers are housed in magnetio-static cavities “Magic Box” and “Pastis” uniform field coils. The polarizing station has passed major performance requirements. The equipment for use on instruments are being built and tested for 3He polarisation lifetime, and infrastructural changes are being incorporated on ANSTO instruments. This presentation will provide examples illustrating the use of polarised neutrons to study magnetic materials and explain the methodology for using this technique. The latest status of the polarizing station and test results of the instrument components will be presented.