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新井 正敏*; Andersen, K. H.*; Argyriou, D. N.*; Schweika, W.*; Zanini, L.*; Harjo, S.; 神山 崇*; 原田 正英
Journal of Neutron Research, 23(4), p.215 - 232, 2021/12
The general performance of diffractometers at the first long pulse spallation source ESS, is compared with their counterparts at J-PARC, a short pulse spallation source. The difference in the inherent pulse structure of these neutron sources presents opportunities for new concepts for instrumentation, where performance does not scale simply with source power. The article describes advantages and disadvantages of those diffractometers, adapting to the very different source characteristics. We find that the two sources offer comparable performance in flux and resolution when operating in high-resolution mode. ESS offers significant advantages in tunability and flexibility, notably in the ability to relax resolution in order to increase flux for a given experiment. On the other hand, J-PARC instruments perform very well in spite of the lower source power and allow better access to epithermal neutrons, of particular interest for PDF analysis of diffraction data.
原田 正英; 勅使河原 誠; 大井 元貴; Klinkby, E.*; Zanini, L.*; Batkov, K.*; 及川 健一; 藤 暢輔; 木村 敦; 池田 裕二郎
Nuclear Instruments and Methods in Physics Research A, 903, p.38 - 45, 2018/09
被引用回数:10 パーセンタイル:67.52(Instruments & Instrumentation)At the J-PARC pulsed spallation neutron source, liquid hydrogen moderators composed of 99.8% parahydrogen associated with light-water premoderator have been providing high intensity cold and thermal neutron beams. In the design stage, simulations have shown not only high total neutron intensity in the coupled moderator but also a local neutron-brightness increase at the edges. The edge-effect-brightness increase is also exploited in the design of the European Spallation Source (ESS) moderators, which are based on 99.8% parahydrogen, but thin (thickness: 3 cm) to enhance the neutron brightness. In this study, the spatial distribution of the neutron brightness at the surface of the coupled moderator in the J-PARC pulsed spallation neutron source was directly measured with the pinhole geometry to validate the calculated edge-brightness enhancement. The brightness distribution at the moderator surface was clearly observed as predicted by a Monte Carlo simulation, proving the validity of the simulation tools used in the design-optimization process of the J-PARC and ESS moderator.
Thiolliere, N.*; David, J.-C.*; Eid, M.*; Konobeyev, A. Y.*; Eikenberg, J.*; Fischer, U.*; Grschel, F.*; Guertin, A.*; Latg, C.*; Lemaire, S.*; et al.
Proceedings of International Conference on the Physics of Reactors, Nuclear Power; A Sustainable Resource (PHYSOR 2008) (CD-ROM), 8 Pages, 2008/09
MEGAPIE計画では、鉛ビスマスターゲットから放出された放射性ガスの測定が行われた。測定値と複数の計算コードによる結果の比較を行い、鉛ビスマスターゲットからの放射性ガスの放出率を評価した。また、MCNPX2.5.0, FLUKA, SNTコードと放射化評価コードを結合し、ターゲットと構造材の放射化を評価した。これにより、運転中、照射後試験、そして、ターゲット廃棄時の安全や被爆評価にかかわるデータベースを構築した。