Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Harada, Masahide; Teshigawara, Makoto; Oi, Motoki; Klinkby, E.*; Zanini, L.*; Batkov, K.*; Oikawa, Kenichi; Toh, Yosuke; Kimura, Atsushi; Ikeda, Yujiro
Nuclear Instruments and Methods in Physics Research A, 903, p.38 - 45, 2018/09
Times Cited Count：10 Percentile：70.71(Instruments & Instrumentation)Kai, Tetsuya; Harada, Masahide; Teshigawara, Makoto; Watanabe, Noboru; Kiyanagi, Yoshiaki*; Ikeda, Yujiro
Nuclear Instruments and Methods in Physics Research A, 550(1-2), p.329 - 342, 2005/09
Times Cited Count：18 Percentile：74.82(Instruments & Instrumentation)Neutronic study was performed on coupled hydrogen moderators to maximize time-integrated and pulse-peak intensities of slow neutrons when a large number of beams was required. The total increased with the number of beams, although the average decreased due to a reflector-missing by the beam extraction holes in the reflector. At a large beam extraction angle (25 degree), the spatial distribution of the vector-flux of neutrons was undesirable for a rectangular shape moderator. As an alternative we proposed a cylindrical shape one, resulting in a much improved spatial distribution. In addition, neutronic performance was calculated as a function of the diameter, indicating the optimal diameter was about 140 mm. The cylindrical one gave higher pulse-peak intensities with narrower pulse widths without penalty in time-integrated intensities and pulse decay characteristics, providing a more uniform angle-dependence. Some explanations are given for the difference in the pulse characteristics between the two. We decided to adopt the cylindrical one for the Japanese spallation neutron source.
Kai, Tetsuya; Harada, Masahide; Teshigawara, Makoto; Watanabe, Noboru; Ikeda, Yujiro
Nuclear Instruments and Methods in Physics Research A, 523(3), p.398 - 414, 2004/05
Times Cited Count：36 Percentile：89.19(Instruments & Instrumentation)Neutronic performance of a coupled hydrogen moderator was studied as a function of para hydrogen concentration, moderator thickness, height and premoderator thickness. It was found that a thick (120
140mm) moderator with 100% para hydrogen was optimal to provide the highest time- and energy- integrated neutron intensity below 15 meV together with the highetst possible pulse-peak intensity. Low-energy neutron distribution on the moderator viewed surface was found to exhibit an intensity-enhanced region at a picture frame part near premoderator. The rather peculiar distribution suggested that the moderator and the viewed surface must be designed so as to take the brighter region near premoderator in use.
Kai, Tetsuya; Harada, Masahide; Teshigawara, Makoto; Watanabe, Noboru; Ikeda, Yujiro
Proceedings of ICANS-XVI, Volume 3, p.657 - 666, 2003/07
Neutronic design studies were carried out on the J-PARC coupled H
moderator. The highest time- and energy- integrated intensity below 15 meV, pulse peak intensity at 2 meV and 10 meV, were given by 100% para-H moderators, but the optimal moderator thickness was different for each: more than 220 mm, about 120 mm and 80 mm, respectively. Finally, we concluded 140 mm was the optimal thickness for the 100% para-H coupled moderator. Cold neutron distributions on the moderator viewed surface were found to exhibit an intensity-enhanced region at a picture frame part near premoderator. This rather peculiar distribution suggested that the moderator and the viewed surface must be designed so as to take the brighter region near premoderator in use. The intensity decreases along with beam-extraction angle to the normal direction down to about 70% at 25.4
. Then, we propose a cylindrical shape coupled moderator which brings about a slight intensity decrease for 0 but a increase in the averaged intensity over the angles of interest.
