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Maekawa, Fujio; Oikawa, Kenichi; Harada, Masahide; Teshigawara, Makoto; Kai, Tetsuya; Kasugai, Yoshimi; Meigo, Shinichiro; Oi, Motoki; Futakawa, Masatoshi; Watanabe, Noboru*; et al.
Proceedings of 19th Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-19) (CD-ROM), 8 Pages, 2010/07
Efforts have been made to characterize neutronic performance of JSNS. A NOBORU instrument was mainly used for this purpose while some other instruments were used when needed. The followings were confirmed. (1) Judging from a measured spectral shape, a para-hydrogen fraction in the hydrogen moderator was very close to unity as expected due to introduction of catalyst in a hydrogen circulation system. (2) Measured data for absolute spectral intensity and pulse shapes agreed very well with simulation calculations, and suggested adequacy of the neutron source designs. (3) The world's highest resolution of 0.035 % was recorded at the powder diffractometer SuperHRPD. (4) A total neutron flux of 3 
10
n/s/cm
was confirmed at the chopper instrument 4SEASONS when it was normalized to 1 MW. The flux is the world's highest among existing spallation neutron sources, and is comparable to fluxes at intense reactor sources even in time-averaged value.
Harada, Masahide; Oikawa, Kenichi; Maekawa, Fujio; Meigo, Shinichiro; Futakawa, Masatoshi; Watanabe, Noboru*
Proceedings of 19th Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-19) (CD-ROM), 8 Pages, 2010/07
To validate the neutronics design of JSNS, we measured neutron spectra at all available neutron beam lines by CTOF method. Measured values were in good agreement with evaluated ones for beam lines without guide tubes. Some discrepancies in spectral intensity were found in some of beam lines using a neutron guide tube. This result indicates that the CTOF method is very effective for checking initial installation of beam lines because neutron spectral intensity can be measured systematically in a short time. Furthermore, by measuring neutron spectral intensity with the CTOF method, we studied change of neutronic performance due to changes of operation conditions of JSNS such as incident proton beam conditions (position, profile and energy) and moderator temperature. These operation parameter dependences on neutronic performance were compared with calculated ones, and confirmed good agreements between them. This indicated reliability of neutronics design of JSNS.
Harada, Masahide; Oikawa, Kenichi; Oi, Motoki; Kai, Tetsuya; Sakai, Kenji; Maekawa, Fujio; Watanabe, Noboru*; Shinohara, Takenao; Takata, Shinichi
Proceedings of 19th Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-19) (CD-ROM), 10 Pages, 2010/07
A neutron beam line NOBORU built at MLF in J-PARC is suitable for imaging experiments due to a large beam size, a short distance from the moderator to the sample position and an adequate experimental room. In order to evaluate suitability for the imaging experiments, we measured neutron spectral intensities and flux distributions at the sample position of NOBORU. We also measured those quantities with use of some filters, collimators and slits equipped on NOBORU. As preliminary experiments for imaging, we measured Bragg edge transmission of some alloys and resonance absorption of some elements. The result showed welded and non-welded areas in an alloy could be clearly distinguished by the Bragg edge transmission. It was also found that several elements in the sample could be distinguished clearly by the resonance absorption method. It could be concluded that NOBORU was very suitable for the imaging experiments at J-PARC.
Sakasai, Kaoru; To, Kentaro; Nakamura, Tatsuya; Harjo, S.; Moriai, Atsushi; Ito, Takayoshi; Abe, Jun; Aizawa, Kazuya; Soyama, Kazuhiko; Katagiri, Masaki*; et al.
Proceedings of 19th Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-19) (CD-ROM), 5 Pages, 2010/07
Neutron detectors for Engineering Materials Diffractometer, named TAKUMI, at J-PARC have been developed under international cooperation between Rutherford Appleton Laboratory (RAL) and Japan Atomic Energy Agency (JAEA), and installed successfully at the end of March 2009. The detector size was 8051370217 mm which was about 1.5 times larger than those installed in ENGIN-X, ISIS facility, RAL. Neutrons are detected based on a nuclear reaction of 
Li(n, 
)
H using ZnS/LiF scintillator. The data acquisition electronics and decoding module were also manufactured. The overall performances of the detectors have been tested using various sources. The results showed that the detectors had good performances such as a position resolution of 3 mm, a neutron detection efficiency of more than 50% at 1 
-neutrons, and a 
-ray sensitivity of less than 10
at 1.3 MeV--ray by 
Co source, which met the requirements of TAKUMI, and they will be presented at the meeting.
Aso, Tomokazu; Tatsumoto, Hideki; Otsu, Kiichi; Uehara, Toshiaki; Kawakami, Yoshihiko; Sakurayama, Hisashi; Futakawa, Masatoshi
Proceedings of 19th Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-19) (CD-ROM), 8 Pages, 2010/07
In the J-PARC, the cryogenic hydrogen system for the 1MW pulsed spallation neutron source (JSNS) plays a role in supplying supercritical hydrogen at a temperature of 18 K and pressure of 1.5 MPa to three moderators in which spallation neutrons generated in a mercury target are slowed down to cold neutrons. Through the off-beam commissioning until April 2008, we confirmed that the specifications of the cryogenic system were satisfied as expected, and we could succeed in circulating supercritical hydrogen with the maximum flow rate of about 190 g/s. We have succeeded in generating first neutrons in the mercury target and providing moderated neutrons through the hydrogen moderators without any problems in May 2008. We also confirmed characteristics of the cryogenic hydrogen system with accepting the proton beam on the mercury target as on-beam commissioning.