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

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supplied from the high pressure bombe and cooled down to about 20K in the cryostat maintaining the catalyst. Here, we get para concentration of equilibrium at temperature. We controlled the para concentration by the temperature at the catalyst since we supposed that the para concentration became equilibrium value at that temperature. The gas is transferred to a moderator chamber and condensed there. Figure 1. Flow diagram of the hydrogen gas to convert ortho to para. The para rich gas was sampled from the line to measure the ortho/para ratio. We used a simple method using a principle measuring the voltage caused by the difference of the thermal transmission between different para ratio hydrogen gasses in the Pirani gauges. The system is shown in Fig. 2 and the procedure is as follows: 10� 1� 10� V 1k� normal H2 gas sampling 200mA Figure 2. Equipment for measuring ortho/para ratio 170 LN para rich H2 gas
Step 1: Normal gas is filled in both Pirani gauges and the bridge circuit was adjusted so as to diminish the electromotive force.� Step 2: Normal gas in one of the Pirani gauges is exchanged by sample gas.� Step 3: V is measured. The voltage measurement was performed at a hydrogen pressure of 5.3x103 Pa. We have to make calibration curve of voltage vs. para-ratio before hand. The accuracy of this measurement is not clear now but it may be less than 2-3%. We intended to check the accuracy by using Raman spectroscopy. Neutron measurements were performed at Hokkaido linac facility. The target-moderator-reflector system (TMRS) is shown in Fig. 3. Pb was used as a target and graphite as a reflector. The moderator size was 5 cm thick, 12 cm wide and 12 cm high. For a coupled moderator a 15 mm thick polyethylene pre-moderator was placed instead of Cd decoupler. Temperature of the hydrogen moderator was about 17 K. We measured the energy spectra for a coupled and a decoupled moderators with the time of flight method. Liquid N2 Moderator (5 � 12 � 12) Pb Target (7 � 8 � 15 cm) Figure 3. Experimental setup of TMRS. Heat Exchanger Decoupler(Cd 0.5mm) For the simulation we used the MCNPX code with using the ENDF-B/V and VI cross section data, and the TMRS model for simulation included the main part of the experimental setup which affected the neutronic performance. 3. EXPERIMENTAL RESULTS AND COMPARISON WITH SIMULATION n Reflector (Graphite) Collimator Energy spectra from the decupled moderator are shown in Fig. 4 as well as the simulation results. The para ratios examined were 35 and 99%. The simulation results give higher intensities than the experimental ones. The intensity is different around 0.005-0.3 eV. The intensity ratio is shown in Fig. 5. The intensity ratio is defined here (Intensity at any para concentration)/(Intensity at 35% para concentration). The overall tendency of the simulation is almost the same as that of the experiment. The intensity ratio around 0.01-0.1 eV agrees well although the absolute intensity around there was different, and little bit different below 0.01 eV. One of the reasons of the difference would be the difference between temperatures of experiment and calculation. We only have cross section data at 20K but the experiment performed at 17K. Therefore, we took into account only the density change of the hydrogen in the calculation. Error in the measurement of the para concentration may also be another reason. 171
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ACoM - 6 6th 6 International Worksh
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Forschungszentrum Jülich GmbH Inst
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Preface These are the Proceedings o
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List of participants, cont’d. Kü
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Pepe M. 43 Petriw S. 43 Picton D.J.
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Experimental background, results an
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• Light water ice as H(H2O) at T
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In Table 2 a survey is given about
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sigma-T in barns/molecule Figure 4.
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2.3 Liquid water Compared to the so
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presented. The corresponding experi
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3.2 Gaseous hydrogen and deuterium
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Rho(Omega) normalised 160 140 120 1
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elatively free and can also suffer
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Figure 16. Heat Capacity for Solid
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o-D2 and p-H2 at 5K for an ucn ener
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Figure 22. UCN Upscattering Rates i
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ho(omega) normalised 40 35 30 25 20
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derived from Walker [52]. The neutr
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Since there is only a small gain of
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7. CALCULATION OF SCATTERING LAW DA
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For the validation of these data se
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[36] Nielsen, M.: Phonons in Solid
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2. THE CASE OF MOLECULAR SOLIDS An
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γ r ( 0) ≅ 2 2 2 T erf e ( ) / 2
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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
Page 124 and 125: 3.2 Moderator performance The resul
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Page 128 and 129: Figure 2. The methane pelletizer, m
Page 130 and 131: Figure 5. The cryogenic hopper fill
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Page 134 and 135: ture
Page 136 and 137: The charging device scheme could be
Page 138 and 139: Table 1. Data of irradiation of met
Page 140 and 141: 5. METHODS OF PROCESSING OF RAW EXP
Page 142 and 143: of radicals, that is, before a burp
Page 144 and 145: 6.2 Condition for thermally stimula
Page 146 and 147: Table 4. Estimated values of an ene
Page 148 and 149: • Nine spontaneous burps were obs
Page 150 and 151: APPENDIX Some useful relations and
Page 152 and 153: APPENDIX. Graphs of burps. 148
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Page 160 and 161: 2. EXPERIMENTAL SETUP Fig. 1 will g
Page 162 and 163: All these parameters are kept const
Page 164 and 165: 4. CONCLUSIONS We demonstrated that
Page 166 and 167: JESSICA (Juelich Experimental Spall
Page 168 and 169: The moderator system consists of th
Page 170 and 171: to change the temperatures and to p
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Page 176 and 177: 10 9 10 8 10 7 10 6 Para35%[Experim
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Page 180 and 181: 2. TIME OF FLIGHT SPECTRA AND ENERG
Page 182 and 183: When applying this transformation t
Page 184 and 185: data were analyzed in more detail.
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Page 188 and 189: First of all, we should conclude th
Page 190 and 191: The equation (a) may also describe
Page 192 and 193: Even at h=0.01 mm which is too smal
Page 194 and 195: model and some consequences of its
Page 196 and 197: methane and 0.7-1.5% for water ice
Page 198 and 199: case: the sample of infinite size.
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Page 216 and 217: Phase Diagram of the CH4-H20 system
Page 218 and 219: Reaction Chamber for Hydrate Produc
Page 220 and 221: Analysis: X-ray diffraction pattern
Page 222 and 223: 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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Druck-Materie 20b.qxd - JUWEL - Forschungszentrum Jülich

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