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Nakajima, Kenji; Kawamura, Seiko; Kikuchi, Tatsuya; Kajimoto, Ryoichi; Takahashi, Nobuaki*; Nakamura, Mitsutaka; Soyama, Kazuhiko; Osakabe, Toyotaka
EPJ Web of Conferences, 83, p.03011_1 - 03011_5, 2015/01
Times Cited Count：4 Percentile：72.07(Physics, Multidisciplinary)We report the design of the beam-transport system (especially the vertical geometry) for a cold-neutron disk-chopper spectrometer AMATERAS at J-PARC. Based on the elliptical shape, which is one of the most effective geometries for a ballistic mirror, the design was optimized to obtain, at the sample position, a neutron beam with high flux without serious degrading in divergence and spacial homogeneity within the boundary conditions required from actual spectrometer construction. The optimum focal point was examined. An ideal elliptical shape was modified to reduce its height without serious loss of transmission. The final result was adapted to the construction requirements of AMATERAS. Although the ideas studied in this paper are considered for the AMATERAS case, they can be useful also to other spectrometers in similar situations.
Otsuka, Noriaki; Takeuchi, Tomoaki; Yamamoto, Keiichi; Shibata, Akira; Kimura, Nobuaki; Takemoto, Noriyuki; Tanimoto, Masataka; Tsuchiya, Kunihiko; Sano, Tadafumi*; Unesaki, Hironobu*; et al.
KURRI Progress Report 2013, P. 215, 2014/10
Investigation of a relation between reactor power and brightness of Cherenkov light at Kyoto University Research reactor (KUR) by a CCD camera was performed due to a development of a real-time in-core measurement technique using Cherenkov light. Analyzing the brightness value of individual RGB color component at each pixel, some of the G and B brightness values reached the maximum value of 8-bit binary number, i.e. 255, above about 2-3 MW. Therefore, we corrected the G and B brightness values by the R signals whose brightness value did not saturate even at 5 MW, the maximum reactor power of KUR. Then, the total brightness value was in proportion to the reactor power after the correction. These results indicate the reactor power can be estimated by the observation of Cherenkov light.
Takahashi, Nobuaki*; Murata, Hirohiko*; Mitsubori, Hitoshi*; Sakuraba, Junji*; Soga, Tomohiro*; Aoki, Yasushi*; Kato, Takanori*; Saito, Yuichi; Yamada, Keisuke; Ikenaga, Noriaki*; et al.
Review of Scientific Instruments, 85(2), p.02C306_1 - 02C306_3, 2014/02
Times Cited Count：2 Percentile：11.15(Instruments & Instrumentation)Arai, Masatoshi; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Nakajima, Kenji; Shibata, Kaoru; Takahashi, Nobuaki; Suzuki, Junichi*; Takata, Shinichi; Yamada, Takeshi*; et al.
Journal of the Physical Society of Japan, 82(Suppl.A), p.SA024_1 - SA024_14, 2013/01
Times Cited Count：7 Percentile：47.36(Physics, Multidisciplinary)The paper describes developments of neutron scattering instruments in J-PARC neutron facility, which is a short pulse spallation source operated at a repetition rate 25 Hz and has a proton power 1 MW. New concept has been adopted to utilize high intensity coupled moderator even for a high resolution inelastic scattering instruments by taking a pulse shaping chopper system. Advanced technique has been also realized by taking an ability of event-recording system altogether with an improvement of a chopper system, realizing multi-Ei method. The paper also touches upon a general design concept for diffractometers in accordance with the source characteristics.
Kanaya, Toshiji*; Takahashi, Nobuaki; Takeshita, Hiroki*; Okura, Masatoshi*; Nishida, Koji*; Kaji, Keisuke*
Polymer Journal, 44(1), p.83 - 94, 2012/01
Times Cited Count：28 Percentile：68(Polymer Science)
at the MLF, J-PARCTakahashi, Nobuaki; Shibata, Kaoru; Kawakita, Yukinobu; Nakajima, Kenji; Inamura, Yasuhiro; Nakatani, Takeshi; Nakagawa, Hiroshi; Fujiwara, Satoru; Sato, Taku*; Tsukushi, Itaru*; et al.
Journal of the Physical Society of Japan, 80(Suppl.B), p.SB007_1 - SB007_4, 2011/12
Times Cited Count：6 Percentile：43.3(Physics, Multidisciplinary)Nakajima, Kenji; Kawamura, Seiko; Kikuchi, Tatsuya; Nakamura, Mitsutaka; Kajimoto, Ryoichi; Inamura, Yasuhiro; Takahashi, Nobuaki; Aizawa, Kazuya; Suzuya, Kentaro; Shibata, Kaoru; et al.
Journal of the Physical Society of Japan, 80(Suppl.B), p.SB028_1 - SB028_6, 2011/05
Times Cited Count：125 Percentile：95.68(Physics, Multidisciplinary)AMATERAS is a cold-neutron disk-chopper spectrometer in MLF, J-PARC. The construction of main part of the spectrometer has been completed in spring of 2009. Soon after that, we have started the commissioning work on AMATERAS. The performance of AMATERAS has been examined by test experiments in the course of commissioning. In parallel to these works, we have started the user program on AMATERAS from December 2009 and we are getting scientific results from our spectrometer. In this presentation, we will report the current status of AMATERAS including the results of performance tests and some of examples of scientific outputs.
Arai, Masatoshi; Aizawa, Kazuya; Nakajima, Kenji; Shibata, Kaoru; Takahashi, Nobuaki
JAEA-Review 2009-014, 84 Pages, 2009/07
JAEA-Review-2009-014.pdf:25.2MB
The 2nd International Advisory Committee on "Biomolecular Dynamics Backscattering Spectrometer DNA" was held on November 12th - 13th, 2008 at J-PARC Center, Japan Atomic Energy Agency. This IAC has been organized for aiming to realize an innovative neutron backscattering instrument in the Materials and Life Science Facility (MLF) at the J-PARC and therefore four leading scientists in the field of neutron backscattering instruments has been selected as the member (Dr. Dan Neumann (Chair), Prof. Ferenc Mezei, Dr. Hannu Mutka, Dr. Philip Tregenna-Piggott), and the 1st IAC had been held on February 27th - 29th, 2008. This report includes the executive summary and materials of the presentations in the 2nd IAC.
Kubo, Junichi*; Rahman, N.*; Takahashi, Nobuaki; Kawai, Takahiko*; Matsuba, Go*; Nishida, Koji*; Kanaya, Toshiji*; Yamamoto, Masahide*
Journal of Applied Polymer Science, 112(3), p.1647 - 1652, 2009/05
Times Cited Count：25 Percentile：62.42(Polymer Science)Aiming at improvement of mechanical and dielectric properties of poly(vinyl alcohol) (PVA) we prepared composites of PVA and magnesium nitrate. It was found that the composites were very soft and rubber-like, and the glass transition temperature decreased with increasing the salt concentration. Wide-angle X-ray diffraction and small-angle X-ray scattering revealed that the crystallites of PVA were destroyed by the additive and it was a cause of the softening.
Takahashi, Nobuaki; Shibata, Kaoru; Sato, Taku*; Kawakita, Yukinobu*; Tsukushi, Itaru*; Metoki, Naoto; Nakajima, Kenji; Arai, Masatoshi
Nuclear Instruments and Methods in Physics Research A, 600(1), p.91 - 93, 2009/02
Times Cited Count：8 Percentile：50.49(Instruments & Instrumentation)A time-of-flight crystal-analyzer neutron inelastic scattering spectrometer DNA has been proposed to construct in the MLF of J-PARC. DNA has been designed to have three crystal analyzers, PG(002), Ge(311) and Si(111) at near-backscattering configurations to study dynamics of biomolecules and proteins in wide energy and momentum transfer ranges. In order to develop the Ge(311) analyzer-crystals we have performed neutron beam experiments to check rocking curves on two candidates, i.e., (a) thick hot-pressed wafers and (b) stacked number of thin as-cut wafers, at the MUSASI port, which is a triple-axis instrument, located on the T2 beam line at the JRR-3M guide hall, Tokai, Japan.
Takahashi, Nobuaki
Hamon, 19(1), p.14 - 17, 2009/01
Arai, Masatoshi; Aizawa, Kazuya; Nakajima, Kenji; Shibata, Kaoru; Takahashi, Nobuaki
JAEA-Review 2008-036, 162 Pages, 2008/08
JAEA-Review-2008-036.pdf:38.32MB
A workshop entitled "Biomolecular Dynamics Backscattering Spectrometers" was held on February 27th - 29th, 2008 at J-PARC Center, Japan Atomic Energy Agency. This workshop was planned to be held for aiming to realize an innovative neutron backscattering instrument, namely DNA, in the MLF and thus four leading scientists in the field of neutron backscattering instruments were invited as the International Advisory Committee (IAC member: Dr. Dan Neumann (Chair); Prof. Ferenc Mezei, Dr. Hannu Mutka; Dr. Philip Tregenna-Piggott) for DNA from institutes in the United States, France and Switzerland, where backscattering instruments are in-service. It was therefore held in the form of lecture anterior and then in the form of the committee posterior. This report includes the executive summary of the IAC and materials of the presentations in the IAC and the workshop.
Takahashi, Nobuaki; Shibata, Kaoru; Sato, Taku*; Arai, Masatoshi; Mezei, F.*
Nuclear Instruments and Methods in Physics Research A, 587(2-3), p.350 - 362, 2008/03
Times Cited Count：2 Percentile：22.25(Instruments & Instrumentation)We have developed a novel configuration concept of crystal-chips for a time-of-flight (TOF) crystal-analyzer neutron inelastic scattering spectrometer, which simultaneously achieves time-focusing, spatial-focusing and momentum-correcting abilities. This concept will be adopted to a coming TOF near-backscattering spectrometer, DIANA which has been proposed to construct at Japan Proton Accelerator Research Complex (J-PARC). At first, layout method satisfying both of the time- and spatial-focusing concepts and momentum-correction concept have been introduced briefly, and then, the focusing performances have been evaluated by Monte-Carlo simulations. Simulations have been performed on a generally-used energy-focusing analyzer as a comparison.
Shibata, Kaoru; Takahashi, Nobuaki; Nakagawa, Hiroshi; Fujiwara, Satoru; Kataoka, Mikio; Sato, Taku*; Kawakita, Yukinobu*; Tsukushi, Itaru*
Nihon Kessho Gakkai-Shi, 50(1), p.46 - 50, 2008/02
The instrumental design of an indirect geometry crystal analyzer spectrometer: DNA which is scheduled to be constructed in the Material and Life Science experimental Facility (MLF) at J-PARC, is reported in this article. This spectrometer is mainly aimed at searching for the high quality inelastic scattering spectra with only several mg order biomolecular sample in the plenty of wide range of energy and momentum transfers.
Takahashi, Nobuaki; Shibata, Kaoru; Sato, Taku*; Tamura, Itaru; Kajimoto, Ryoichi; Harjo, S.; Oikawa, Kenichi; Arai, Masatoshi; Mezei, F.*
Journal of Physics and Chemistry of Solids, 68(11), p.2199 - 2203, 2007/11
Times Cited Count：7 Percentile：35.22(Chemistry, Multidisciplinary)A near-backscattering crystal-analyzer neutron inelastic spectrometer, DIANA has been proposed to construct at Materials and Life Science Facility (MLF) of Japan Proton Accelerator Research Complex (J-PARC). It has firstly been designed to see a decoupled non-poisoned moderator in order to obtain higher intensity and better energy resolution. In deed, the decoupled moderator has a narrower pulse width than a coupled moderator, and so it will give us a better energy resolution. However, the peak neutron flux of the decoupled moderator has only a half of the coupled moderator. In order to decide the best choice of this type of near-backscattering instruments, we have reconsidered instrumental parameters including the type of moderators. We have performed Monte-Carlo neutron ray-tracing simulations, using McStas and have compared these results in various viewpoints such as intensities, resolutions, shape of resolution functions, scan ranges and so on.
Takahashi, Nobuaki; Kanaya, Toshiji; Nishida, Koji*; Kaji, Keisuke*
Macromolecules, 40(24), p.8750 - 8755, 2007/11
Times Cited Count：17 Percentile：47.77(Polymer Science)Time-resolved light scattering measurements have been performed on poly(vinyl alcohol) (PVA) in mixed solvents of dimethyl sulfoxide (DMSO) and water with various mixing ratios after quenching from 100
C to 25C to examine physical gelation process. A broad scattering peak characteristic to phase separation appeared in the light scattering profiles after a certain incubation time (
) and the peak position 
moved to higher with annealing time. The results contradict the theoretical predictions and experimental observations for usual phase separation systems, suggesting effects of gelation (or network formation) on the phase separation. The growth kinetics significantly depend on the mixing ratio of DMSO and water, showing that the solvent quality is also a factor to affect the phase separation kinetics during the physical gelation process. The unusual phase separation kinetics is discussed in terms of gelation-induced phase separation.
Kanaya, Toshiji; Matsuba, Go*; Ogino, Yoshiko*; Takahashi, Nobuaki; Nishida, Koji*
Polymer Journal, 39(11), p.1085 - 1097, 2007/11
Times Cited Count：0 Percentile：0.01(Polymer Science)One of the longstanding issues in polymer science is crystallization of polymers under flow, especially formation of the so-called shish-kebab. Recent progress in quantum beam technology shed light on the substantial nature in the shish-kebab formation. In this paper we review our recent experiments on polymer crystallization under flow using time-resolved depolarized light scattering, small-angle and wide-angle X-ray scattering and small-angle neutron scattering in a wide spatial scale from 0.1 nm to several tens m. These studies revealed that the shish-kebab formation is governed by a competition between the crystallization rate and the chain relaxation rate.
Takahashi, Nobuaki; Nishida, Koji*; Inoue, Rintaro*; Ogawa, Hiroki*; Kanaya, Toshiji*; Nagao, Michihiro*
NSL News Letter, 2007-4, p.155 - 157, 2007/04
We have studied dynamics of poly(vinyl alcohol) (PVA) gel in a mixture of deuterated dimethyl sulfoxide (DMSO-d
) and D
O (60/40 by volume) during heating process from 25C to 80C using neutron spin-echo (NSE) techniques.
Takahashi, Nobuaki; Shibata, Kaoru; Sato, Taku*; Arai, Masatoshi
Journal of Neutron Research, 15(1), p.61 - 67, 2007/03
The DIANA spectrometer is an indirect-geometry crystal-analyzer instrument which will be installed at the Materials and Life science experimental Facility (MLF) of Japan Proton Accelerator Research Complex (J-PARC). The available momentum transfer and energy ranges are from about 0.1 A
to 3.9 A and from about 2 
eV to 35 meV, respectively. Three analyzer-crystals, PG(002), Ge(311) and Si(111) are planed to put into place. The energy resolutions of each the former two analyzer-crystal setting are sufficiently high, which are about 15 eV and 40 eV, respectively. We are especially aiming very high energy resolution of about 2.5 eV by using the Si(111) analyzer-crystal together with another pulse-shaping mechanism, an optional setting for the DIANA spectrometer. This option can only be attained by using highly sophisticated silicone crystal, i.e. obtaining low mosaicness, and very sharp pulse-shaped incident neutron beam, which is obtained from counter-rotating 2-disk choppers with each rotation frequency of 300 Hz. Although one can attain such a high energy resolution, it is considerably inefficient to chop one very narrow incident neutron energy band from one frame (one pulse from a moderator). If several incident beam having different energy band from each other are available by chopping within one frame several times, the obtainable energy range substantially enlarge. We discuss the advantage and disadvantage of this multiplication, which is named Repetition Rate Multiplication (RRM), of the optional setting for DIANA spectrometer.
Takahashi, Nobuaki; Shibata, Kaoru; Sato, Taku*; Nakajima, Kenji; Kajimoto, Ryoichi; Oikawa, Kenichi; Arai, Masatoshi; Schanzer, C.*
Proceedings of 18th Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-18) (CD-ROM), p.373 - 381, 2007/00
A time-of-flight near-backscattering neutron inelastic spectrometer, DIANA has been proposed for the Materials and Life science experimental Facility (MLF) at Japan Proton Accelerator Research Complex (J-PARC). It has been designed to achieve a high neutron flux at a range of low energies, whose wavelength band is between about 1.4 
and 6.4 . We have recently decided to attach the instrument to the coupled moderator source beam-line instead of the decoupled source beam-line, in order to achieve highest intensity at the desired wavelength band. On the other hand, a novel focusing analyzer has been theoretically developed and also designed for the instrument. As a result of this work, it is found that a large beam divergence at the sample is acceptable. Therefore, we have reconsidered the guide system in order to maximize the intensity, according to the report about advanced geometries for neutron guides.
