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

More documents

Recommendations

Info

ABSTRACT ACoM - 6 6 th Meeting of the Collaboration on Advanced Cold Moderators <strong>Jülich</strong>, 11 – 13 September 2002 Neutron cross section of methane hydrate Y. Kiyanagi, S. Date, T. Horikawa, J. Takamine, H. Iwasa and T. Kamiyama Graduate School of Eng., Hokkaido University Kita-13, Nishi-8, Kita-ku, Sapporo 060-8628, Japan T. Uchida, T. Ebinuma and H. Narrita National Institute of Advanced Industrial Science Tsukisamu, Toyohira-ku, Sapporo 062-8517, Japan S. M. Bennington ISIS Department, Rutherford Appleton Chilton, Didcot, Oxon, UK To estimate the neutronic characteristics of methane hydrate and also to synthesize cross section data for simulation we need neutron scattering data ranging wide energy and momentum region. We performed inelastic neutron scattering experiments to get information about the neutron cross section on methane hydrate. It was found that at high momentum transfer region rotational mode as well as vibration mode showed recoil like behavior. On the other hand, at low momentum region, as well known, free rotation like energy levels were observed. The energy level of ice in methane hydrate was very similar to normal ice. The results suggest that the rough expression of the cross section of the methane hydrate is presented by linear combination of the methane and ice. 1. INTRODUCTION It has been proved that methane is the best material for the cold moderator[1]. On the other hand ice at 20K gives higher neutron intensity around the thermal neutron region[1]. Methane hydrate consists of these tow materials. So, it is expected that the methane hydrate moderator give the higher intensity for a wide energy region ranging from cold to thermal neutron energy. Therefore, the methane hydrate has been proposed as a new cold moderator material. To evaluate the neutronic characteristics of methane hydrate it is necessary to perform moderator experiments as well as to obtain the cross section data for understanding the characteristics and also to perform the simulation since in the experiments we get information under the restrict conditions. However, there exist very small number of cross section data and they aimed at knowing the dynamics of methane in the hydrate. Furthermore, the energy range studied was concentrated at low energy[2-4]. To know the moderator neutronics we should know the neutron scattering cross section in the wide energy and momentum region and also the total neutron cross section. For this purpose we performed neutron inelastic scattering experiments. Here, we briefly mention about the preliminary consideration on the results of the scattering experiment. 97
Page 1 and 2:
ACoM - 6 6th 6 International Worksh
Page 3 and 4:
Forschungszentrum Jülich GmbH Inst
Page 5:
Preface These are the Proceedings o
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
Page 54 and 55: [5] Meeting on Moderator Concepts a
Page 56 and 57: state. Conversely, the monatomic hy
Page 58 and 59: Note that the equilibrium trihydrog
Page 60 and 61: para hydrogen system under irradiat
Page 62 and 63: [12] T. E. Fessler and J. W. Blue,
Page 64 and 65: tion of neutron intensities, partic
Page 66 and 67: varied between calculations but the
Page 68 and 69: 5. THE OPTIMISATION OF MULTIPLY GRO
Page 70 and 71: Figure 7. A comparison of time dist
Page 72 and 73: 4.8 cm hydrogen slab in front of a
Page 75 and 76: ACoM - 6 6 th Meeting of the Collab
Page 77 and 78: the moderator is annealed every 12
Page 79 and 80: The method requires two additional
Page 81 and 82: ABSTRACT ACoM - 6 6 th Meeting of t
Page 83 and 84: Heat transfer processes across phas
Page 85 and 86: 3. TWO-PHASE FLOW PATTERN IN THE MO
Page 87 and 88: continuous phase dominating, and a
Page 89 and 90: Also the velocity pattern has chang
Page 91 and 92: Figure 8. Methane pellets concentra
Page 95 and 96: sample volume and the nominal densi
Page 97 and 98: The results presented in this paper
Page 99: Table 10. Summary of energy transfe
Page 103 and 104: the formula also to the libration m
Page 105 and 106: By fitting this function to the exp
Page 107 and 108: ABSTRACT ACoM 6 6 th Meeting of the
Page 109 and 110: mesitylene-D0, and the IINS spectra
Page 111 and 112: The intensity of scattered neutrons
Page 113 and 114: Intensity of scattered neutrons - I
Page 115 and 116: otations seem to be weaker and the
Page 119 and 120: Water ice may still be a candidate
Page 121 and 122: �� 5 K � 20 K ��
Page 123 and 124: Figure 6. Inelastic spectra from ic
Page 125 and 126: The wealth of low lying energy leve
Page 127 and 128: ABSTRACT ACoM - 6 6 th Meeting of t
Page 129 and 130: After passing through the sub-cooli
Page 131 and 132: Figure 6. The 1.5 liter Amock moder
Page 135 and 136: Main results: Radiation effects in
Page 137 and 138: Irradiation cavity inside the capsu
Page 139 and 140: Table 2. Data of irradiation of ice
Page 141 and 142: eleased energy, J/g 120 110 100 90
Page 143 and 144: methane) an energy storing rate R i
Page 145 and 146: as adiabatic one. Then, solution of
Page 147 and 148: 4÷÷÷÷5K (see Fig. 8). Saturatio
Page 149 and 150: Due to insufficient number of irrad
Page 151 and 152:
4. S. Ikeda, N. Watanabe, S. Satoh
Page 153 and 154:
149
Page 155 and 156:
151
Page 157 and 158:
153
Page 159 and 160:
ACoM - 6 6 th Meeting of the Collab
Page 161 and 162:
3. PROTON BEAM MONITORING To normal
Page 163 and 164:
performed with 1 mm layers of cadmi
Page 165 and 166:
Page 167 and 168:
During beam time the target which i
Page 169 and 170:
The moderator vessel including its
Page 171 and 172:
materials. This is possible because
Page 173 and 174:
Page 175 and 176:
Step 1: Normal gas is filled in bot
Page 177 and 178:
Figure 6. Experimental energy spect
Page 179 and 180:
Page 181 and 182:
Similar time of flight spectra were
Page 183 and 184:
Table 1. Real moderator temperature
Page 185 and 186:
etween 4 . 10 -3 eV and 2 . 10 -1 e
Page 187 and 188:
Page 189 and 190:
tered radicals. But in more sophist
Page 191 and 192:
Due to high dose rate and big volum
Page 193 and 194:
Figure 4. Recommended values of max
Page 195 and 196:
where Ď is absorbed dose rate. Now
Page 197 and 198:
It is interesting to note that σ 2
Page 199 and 200:
11. V.I. Goldanski, E.N. Rumanov, E
Page 201 and 202:
Appendix 197
Page 203 and 204:
Page 205 and 206:
201
Page 207 and 208:
203
Page 209 and 210:
205
Page 211 and 212:
207
Page 213 and 214:
209
Page 215 and 216:
Page 217 and 218:
Experimental Set up 213
Page 219 and 220:
Reaction Path 215
Page 221 and 222:
Comparison with non-hydrate forming
Page 223 and 224:
Mechanical Tests: Conditions 219
Page 225 and 226:
Mechanical Tests: Results 221
Page 227 and 228:
Conclusion • SKD approach is a vi
Page 229 and 230:
Schriften des Forschungszentrums J
Page 231:
Forschungszentrum Jülich in der He
show all

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

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?