Druck-Materie 20b.qxd - JUWEL - Forschungszentrum Jülich

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Bibliographic information published by Die Deutsche Bibliothek. Die Deutsche Bibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data are available in the Internet . Publisher and Forschungszentrum Jülich GmbH Distributor: Zentralbibliothek 52425 Jülich Phone +49 (0) 2461 61-5368 · Fax +49 (0) 2461 61-6103 e-mail: zb-publikation@fz-juelich.de Internet: http://www.fz-juelich.de/zb Cover Design: Grafische Betriebe, Forschungszentrum Jülich GmbH Printer: Grafische Betriebe, Forschungszentrum Jülich GmbH Copyright: Forschungszentrum Jülich 2004 The editor cannot accept any responsibility or liability for the accuracy of any statements or information given in the papers. Schriften des Forschungszentrums Jülich Reihe Materie und Material / Matter and Materials Band / Volume 20 ISSN 1433-5506 ISBN 3-89336-363-7 Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming, and recording, or by any information storage and retrieval system, without permission in writing from the publisher.
Preface These are the Proceedings of the 6th Meeting of the International Collaboration on Advanced Cold Moderators. We apologize for the long delay in publishing these lecture notes, which is mainly the editor’s fault. On the other hand, despite the long time since our meeting, it was not possible to obtain all contributions to the Proceedings in full text version. Like in the editor’s case this is certainly due to the many other duties of our colleagues. In order to nevertheless present a complete account of the meeting we have included in an Appendix copies of what was collected from the authors during the meeting. The collaboration on Advanced Cold Moderators was initiated during a meeting at Forschungszentrum Jülich in July of 1997, when a small working group of experts from numerous institutions was established. After this inaugural meeting we had the second one, arranged by Renate Bercher and Günter Bauer of the Paul-Scherrer-Institut in Villigen (Switzerland) in February of 1998. The third meeting, ACoM-3, took place in Oak Ridge under the supervision of Trevor Lukas in June of the same year. The fourth meeting was organized by Heidrun Barnert-Wiemer of Forschungszentrum Jülich and held there in February of 1999. The fifth meeting took place in Berlin in connexion with a general workshop on moderator concepts for spallation sources organized by Thomas Gutberlet, then at the Hahn-Meitner-Institut in Berlin. Of the first three meetings only minutes were written up and supplemented with copies of a few presentations, which were available. The first “formal” proceedings were printed and distributed among the collaboration members and meeting participants for ACoM-4. Our sixth meeting, the proceedings of which we deliver here, was attended by thirtyfour colleagues from eight countries on three continents – a small but impressive assembly of experts in the field. They presented their latest results in theory, numerical computation and experiments on advanced cold moderator media like methane-hydrate, tri-methyl-benzene or ammonia. With the sponsorship of Forschungszentrum Jülich and the support of members of the project team of the European Spallation Source (ESS) we were able to have a pleasant and fruitful meeting on site in the seminar room of the ESS project building. Taking care of transportation and hotel accommodation of the external participants, the ladies Julia Philippen and Andrea Fournier warranted a smooth course of the meeting. Lunches were served in one of Forschungszentrum’s Cafeterias and coffee and snacks during the breaks were provided next to the lecture hall. Günter Mank and Alf Bauer from the ESS project team efficiently assisted with technical support regarding computers and beamer facilities. The European Spallation Source project is unfortunately dormant for an unspecified term and the two major megawatt spallation facilities in Japan and the US are in a very advanced stage of construction employing conventional cryogenic moderators only. Nevertheless, the performance prospects of advanced cold sources (if we consider an all para-hydrogen moderator a conventional one) are so intriguing that we can expect their development to continue. In this respect we are looking forward to our next meeting. Harald Conrad, editor March 2004
Page 1 and 2: ACoM - 6 6th 6 International Worksh
Page 3: Forschungszentrum Jülich GmbH Inst
Page 8 and 9: List of participants, cont’d. Kü
Page 10 and 11: Pepe M. 43 Petriw S. 43 Picton D.J.
Page 12 and 13: Experimental background, results an
Page 14 and 15: • Light water ice as H(H2O) at T
Page 16 and 17: In Table 2 a survey is given about
Page 18 and 19: sigma-T in barns/molecule Figure 4.
Page 20 and 21: 2.3 Liquid water Compared to the so
Page 22 and 23: presented. The corresponding experi
Page 24 and 25: 3.2 Gaseous hydrogen and deuterium
Page 26 and 27: Rho(Omega) normalised 160 140 120 1
Page 28 and 29: elatively free and can also suffer
Page 30 and 31: Figure 16. Heat Capacity for Solid
Page 32 and 33: o-D2 and p-H2 at 5K for an ucn ener
Page 34 and 35: Figure 22. UCN Upscattering Rates i
Page 36 and 37: ho(omega) normalised 40 35 30 25 20
Page 38 and 39: derived from Walker [52]. The neutr
Page 40 and 41: Since there is only a small gain of
Page 42 and 43: 7. CALCULATION OF SCATTERING LAW DA
Page 44 and 45: For the validation of these data se
Page 46 and 47: [36] Nielsen, M.: Phonons in Solid
Page 48 and 49: 2. THE CASE OF MOLECULAR SOLIDS An
Page 50 and 51: γ r ( 0) ≅ 2 2 2 T erf e ( ) / 2
Page 52 and 53: 4. PRELIMINARY APPLICATION Solid Me
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[5] Meeting on Moderator Concepts a
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state. Conversely, the monatomic hy
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Note that the equilibrium trihydrog
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para hydrogen system under irradiat
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[12] T. E. Fessler and J. W. Blue,
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tion of neutron intensities, partic
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varied between calculations but the
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5. THE OPTIMISATION OF MULTIPLY GRO
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Figure 7. A comparison of time dist
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4.8 cm hydrogen slab in front of a
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ACoM - 6 6 th Meeting of the Collab
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the moderator is annealed every 12
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The method requires two additional
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ABSTRACT ACoM - 6 6 th Meeting of t
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Heat transfer processes across phas
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3. TWO-PHASE FLOW PATTERN IN THE MO
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continuous phase dominating, and a
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Also the velocity pattern has chang
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Figure 8. Methane pellets concentra
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ACoM - 6 6 th Meeting of the Collab
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sample volume and the nominal densi
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The results presented in this paper
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Table 10. Summary of energy transfe
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2. EXPERIMENTAL Methane hydrate was
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Figure 4. Energy levels of methane
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102
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phase transitions from phase II to
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After melting phase I in the cryost
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4. SOLID PHASES OF MESITYLENE-D0 AN
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G(ν) [a.u.] 8 6 4 2 Phase II Phase
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112
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A not quite as perfect cold spectru
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2.2 Inelastic neutron scattering Th
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Figure 4. Inelastic spectra at the
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3.2 Moderator performance The resul
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122
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Figure 2. The methane pelletizer, m
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Figure 5. The cryogenic hopper fill
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128
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ture
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The charging device scheme could be
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Table 1. Data of irradiation of met
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5. METHODS OF PROCESSING OF RAW EXP
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of radicals, that is, before a burp
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6.2 Condition for thermally stimula
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Table 4. Estimated values of an ene
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• Nine spontaneous burps were obs
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APPENDIX Some useful relations and
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APPENDIX. Graphs of burps. 148
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150
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152
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154
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2. EXPERIMENTAL SETUP Fig. 1 will g
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All these parameters are kept const
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4. CONCLUSIONS We demonstrated that
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JESSICA (Juelich Experimental Spall
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The moderator system consists of th
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to change the temperatures and to p
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168
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supplied from the high pressure bom
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10 9 10 8 10 7 10 6 Para35%[Experim
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174
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2. TIME OF FLIGHT SPECTRA AND ENERG
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When applying this transformation t
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data were analyzed in more detail.
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182
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First of all, we should conclude th
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The equation (a) may also describe
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Even at h=0.01 mm which is too smal
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model and some consequences of its
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methane and 0.7-1.5% for water ice
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case: the sample of infinite size.
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196
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198
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200
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202
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210
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Phase Diagram of the CH4-H20 system
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Reaction Chamber for Hydrate Produc
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Analysis: X-ray diffraction pattern
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Comparison with non-hydrate forming
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Mechanical Tests: Apparatus 220
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Morphology of Indium Jacket 222
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Schriften des Forschungszentrums J
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Schriften des Forschungszentrums J
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