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Some experimental and simulation results on the grooved moderators and so on. Y. Kiyanagi, Fujio Hiraga, Takashi Kamiyama. ( Supplement for previous talk form Hokkaiido University). Example of experimental data of a grooved moderator ( Hydrogen moderator) Multi grooves Single groove.
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Some experimental and simulation results on the grooved moderators and so on Y. Kiyanagi, Fujio Hiraga, Takashi Kamiyama (Supplement for previous talk form Hokkaiido University)
Example of experimental data of a grooved moderator(Hydrogen moderator) Multi grooves Single groove
Multi-grooves moderator assembly Energy spectrum measurement Experimental setup Pulse measurement
A coupled solid methane moderator with a groove • Optimization of size of a groove • Check experiments of neutron intensity distribution on the moderator surface • Simulation of pulse shapes and comparison with results of a flat moderator • Improvement of thermal neutron intensity
Grooved Moderator and flat moderator Premoderator Premoderator Grooved Moderator Flat Moderator T Target Target T=50mm
Comparison of the spatial distributions of neutrons on both moderator surfaces at various neutron energies L=15mm h=30mm d=50mm X=0mm
Spatial distributions depending on the groove height h 2.2-4.4meV L=10mm W=80mm d=50mm X=0mm
Spatial distributions of intensity ratios depending on the groove height h 2.2-4.4meV Ratio=Groove/Flat L=10mm W=80mm d=50mm X=0mm
Spatial distribution depending on the groove position from the bottom h=30mm W=80mm d=50mm X=0mm
Increase of neutron intensity as a function of groove height hat various distance of groove L W=80mm d=50mm X=0mm
Increase of intensity as a function of groove depth d h=80mm L=3mm W=80mm X=0mm
Optimum width of groove w h=80mm L=3mm d=70mm X=0mm
Optimum target position h=80mm L=3mm d=70mm w=100mm
Optimum size of a groove Height h=80 [mm] Distance from the bottom L= 3 [mm] Depth d=70 [mm] Width w= 100[mm] Target position x= 0 [mm]
Comparison of spatial distribution with experimental results (cold)
Comparison of spatial distribution with experimental results (thermal)
Simulation of pulse shapes from a groove and from a corresponding area of a flat moderator
Structure of Be filter-reflector hydrogen moderator chamber Al pieces Be piece Be folder
Beam hole angle q Beam position ー + H2O premoderator Graphite reflector Top view of the moderator assembly
neutron intensity (arb. units) ○With Be ●Without Be Neutron energy (eV)
Intensity ratio ○ q=0 ● q=30 (to Be) Electorn beam positon (cm) (tomoderator)
Mesitylene is the best moderator among the non-explosive moderator material
Comparison of spectra fromcoupledmoderators Methane Hydrogen(~normal) Our old data for reference Phase 1 Phase 3 Mesitylene Phase 1: slow cooling <2K/min Integrated intensity (0.8~5meV) 40% of Methane 44% of Hydrogen
Full width at half maximum of emission time 10 3 Mesitylene Hydrogen 10 2 Methane Methane Hydrogen 10 1 メシチレン Mesitylene 固体メタン 液体水素 10 0 1 10 100 Energy[meV] Comparison among decoupled moderators Pulse shape (3.3meV) FWHM of mesitylene is wider below 10 meV and almost the same above 10 meV compared with hydrogen (~normal). (Phase1data)