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Journal Articles

Conceptual design of an abnormality sign determination system for the general control system of the Materials and Life Science Experimental Facility at J-PARC

Sakai, Kenji; Oi, Motoki; Teshigawara, Makoto; Naoe, Takashi; Haga, Katsuhiro; Watanabe, Akihiko*

Journal of Neutron Research, 22(2-3), p.337 - 343, 2020/10

For operating a spallation neutron source and a muon target safely and efficiently, a general control system (GCS) operates within Materials and Life Science Experimental Facility (MLF). GCS administers operation and interlock processes of many instruments under various operation status. Since the first beam injection in 2008, it has operated stably without any serious troubles for more than ten years. GCS has a data storage server storing operational data on status around target stations. It has functioned well to detect and investigate unusual situations by checking data in this server. For continuing stable operation of MLF in future, however, introduction of abnormality sign determination system (ASDS) will be necessary for picking up potential abnormalities of target stations caused by radiation damages, time-related deterioration and so on. It will judge abnormalities from slight state transitions of target stations based on analysis with various operational data throughout proton beams, target stations, and secondary beams during long-term operations. This report mentions present status of GCS, conceptual design of ASDS, and installation of an integral data storage server which can deal with various data for ASDS integrally.

Journal Articles

Energy resolution and neutron flux of the 4SEASONS spectrometer revisited

Kajimoto, Ryoichi; Nakamura, Mitsutaka; Iida, Kazuki*; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Inamura, Yasuhiro; Ishikado, Motoyuki*

Journal of Neutron Research, 22(2-3), p.99 - 107, 2020/10

Journal Articles

Pulsed magnet system at MLF in J-PARC

Watanabe, Masao; Nojiri, Hiroyuki*

Journal of Neutron Research, 21(1-2), p.39 - 45, 2019/05

Magnetic field acts directly on the spin and the orbital motion of electron in the material and interesting quantum phenomena and phase transition are found in high magnetic field. Recently, experimental equipments using neutron beams in high magnetic field have been rapidly developed. For example, superconducting DC magnet up to 17 T has developed for neutron scattering experiments. Although the sample environment team in the MLF have several DC superconducting magnets up to 7 T as a sample environment apparatus, some users have requested the preparation of higher field magnets. However, another magnet technology is needed to generate higher than 20 T. However, it is difficult to construct such a large system in the MLF from the point of view of construction space. It is practical to employ a pulsed magnetic field as it enables operation of smaller energy as well as downsizing of the instruments. Therefore, we have been developed a compact and movable pulsed magnet system up to 30 T.

Journal Articles

Cryogenic sample environments shared at the MLF, J-PARC

Kawamura, Seiko; Takahashi, Ryuta*; Ishikado, Motoyuki*; Yamauchi, Yasuhiro*; Nakamura, Masatoshi*; Ouchi, Keiichi*; Kira, Hiroshi*; Kambara, Wataru*; Aoyama, Kazuhiro*; Sakaguchi, Yoshifumi*; et al.

Journal of Neutron Research, 21(1-2), p.17 - 22, 2019/05

The Cryogenics and Magnets group in the Sample Environment team is responsible for operation of cryostats and magnets for user's experiments at the MLF in J-PARC. We have introduced a top-loading $$^4$$He cryostat, a bottom-loading $$^3$$He cryostat, a dilution refrigerator insert and a superconducting magnet. The frequency of use of them dramatically becomes higher in these two years, as the beam power and the number of proposal increase. To respond such situation, we have made efforts to enhance performance of these equipment as follows. The $$^3$$He cryostat originally involves an operation software for automatic initial cooling down to the base temperature and automatic re-charge of $$^3$$He. Recently we made an additional program for automatic temperature control with only the sorb heater. Last year, a new outer vacuum chamber of the magnet with an oscillating radial collimator (ORC) was fabricated. The data quality was drastically improved by introducing this ORC so that the magnet can be used even for the inelastic neutron scattering experiments.

Journal Articles

Sample environment at the J-PARC MLF

Kawamura, Seiko; Oku, Takayuki; Watanabe, Masao; Takahashi, Ryuta; Munakata, Koji*; Takata, Shinichi; Sakaguchi, Yoshifumi*; Ishikado, Motoyuki*; Ouchi, Keiichi*; Hattori, Takanori; et al.

Journal of Neutron Research, 19(1-2), p.15 - 22, 2017/11

Sample environment (SE) team at the Materials and Life Science Experimental Facility (MLF) in J-PARC has worked on development and operation of SE equipment and devices. All the members belong to one sub-team at least, such as Cryogenic and magnet, High temperature, High pressure, Soft matter and special environment including Pulse magnet, Hydrogen environment, Light irradiation and $$^3$$He spin filter. Cryostats, a magnet, furnaces, a VX-6-type Paris-Edinburgh press and a prototype of a Spin-Exchange Optical Pumping (SEOP) based $$^3$$He spin filter for polarized neutron beam experiments are in operation. Furthermore, a prototype of compact power supply for a pulsed magnet system is currently developed. In the J-PARC Research Building, several pieces of equipment for softmatter research such as a rheometer and a gas and vapor adsorption measurement instrument have been prepared.

Journal Articles

Curved neutron guide of the cold neutron disk-chopper spectrometer at J-PARC

Kajimoto, Ryoichi; Nakajima, Kenji; Nakamura, Mitsutaka; Osakabe, Toyotaka; Sato, Taku*; Arai, Masatoshi

Journal of Neutron Research, 16(3-4), p.81 - 86, 2008/09

Cold Neutron Double-Chopper Spectrometer (CNDCS) is under construction for the spallation neutron source at Materials and Life Science Facility (MLF), Japan Proton Accelerator Research Complex (J-PARC). It is dedicated for research of inelastic phenomena with low energy transfer utilizing an incident energy of $$E_i le 80$$ meV. It has a 30 m moderator-sample distance ($$L_1$$) and a supermirror-coated neutron guide tube between the moderator and the sample. The guide tube is curved to eliminate unwanted fast neutron and $$gamma$$ ray emitted immediately after a proton hits the target. In the present paper, we present the performance of the curved guide of CNDCS obtained by Monte Carlo simulation using McStas. We will report energy dependence of gain in intensity and beam distributions for several kinds of supermirrors, in comparison to the case utilizing a $$T$$$$_{0}$$ chopper and a straight guide.

Journal Articles

Conceptual design of magic chopper used for 4SEASONS at J-PARC

Nakamura, Mitsutaka; Arai, Masatoshi; Kajimoto, Ryoichi; Yokoo, Tetsuya*; Nakajima, Kenji; Krist, T.*

Journal of Neutron Research, 16(3-4), p.87 - 92, 2008/09

no abstracts in English

Journal Articles

Measurement of residual stress on a unidirectional solidified Al$$_{2}$$O$$_{3}$$/YAG eutectic composite using synchrotron and neutron diffraction

Suzuki, Hiroshi; Waku, Yoshiharu*; Nakagawa, Narihito*; Akita, Koichi*; Moriai, Atsushi; Morii, Yukio

Journal of Neutron Research, 15(2), p.113 - 120, 2007/06

The residual stress in only YAG phase was measured on the surface of the Al$$_{2}$$O$$_{3}$$-Y$$_{3}$$Al$$_{5}$$O$$_{12}$$(YAG) eutectic composite(Al$$_{2}$$O$$_{3}$$/YAG MGC) using the low energy synchrotron X-rays. The residual stresses in plane stress condition were significantly different between top and side surfaces of the specimen. Therefore, an anisotropic triaxial residual stress probably exists within the MGC. The residual stress within the MGC was also measured using a neutron diffraction. The residual stress in the YAG phase rose from compression in the solidification direction to tension in perpendicular direction. The residual stress in the Al$$_{2}$$O$$_{3}$$ phase was anisotropic compression and there was no tension in all directions. This anisotropic residual stress could be explained by the crystallographic anisotropy of thermal expansion in the Al$$_{2}$$O$$_{3}$$ phase. However, both phase stresses were not balanced, so that it is expected that there would be the stress distribution in MGC sample used in this study.

Journal Articles

Utilization of multiple incident energies on cold-neutron disk-chopper spectrometer at J-PARC

Nakamura, Mitsutaka; Nakajima, Kenji; Kajimoto, Ryoichi; Arai, Masatoshi

Journal of Neutron Research, 15(1), p.31 - 37, 2007/03

The efficiency of measurement on a chopper spectrometer will be significantly improved, if we can measure a number of inelastic scattering processes simultaneously. In such measurements we should deliver the multiple incident energy neutrons to the sample within a pulse period of the source. This method was proposed by Mezei and referred to as Repetition Rate Multiplication (RRM) measurement. Since optimizing the chopper spectrometer for monochromatic beam experiment is our first priority, the RRM measurement might be optional operation. However, even without replacing a chopper blade nor accepting very long flight path, a slight modification of the instrument design enables the RRM measurement in considerably excellent performance. In this talk, we will explain the instrument design to realize the RRM measurement on chopper spectrometers at J-PARC, and show its performance.

Journal Articles

High intensity chopper spectrometer 4SEASONS at J-PARC

Kajimoto, Ryoichi; Yokoo, Tetsuya*; Nakajima, Kenji; Nakamura, Mitsutaka; Soyama, Kazuhiko; Ino, Takashi*; Shamoto, Shinichi; Fujita, Masaki*; Oyama, Kenji*; Hiraka, Haruhiro*; et al.

Journal of Neutron Research, 15(1), p.5 - 12, 2007/03

We are developing a new chopper-type neutron inelastic spectrometer 4SEASONS for the spallation neutron source at J-PARC. This spectrometer has middle energy resolution and two orders higher efficiency than the ones at ISIS for a single crystal measurement. With this spectrometer, we try to explore novel quantum phenomena, in particular, the mechanism of the high-$$T_c$$ superconductivity. The high flux at a sample is achieved by incorporating the well designed transport devices in addition to the high flux of the source. The energy resolution is estimated to be 5-6% at $$hbaromega$$ = 0. Furthermore, the most distinguishing feature of 4SEASONS is the availability of the repetition rate multiplication (RRM) method. The RRM method enables us to utilize many $$E_i$$'s at the same time, which will increase the efficiency of the measurement more than five times and make the survey of 4D space of $$mathbf{Q}$$-$$omega$$ much easier.

Journal Articles

Repetition rate multiplication capability for a high energy resolution mode of DIANA at J-PARC

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$$^{-1}$$ to 3.9 A$$^{-1}$$ and from about 2 $$mu$$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 $$mu$$eV and 40 $$mu$$eV, respectively. We are especially aiming very high energy resolution of about 2.5 $$mu$$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.

Journal Articles

Cold-neutron disk-chopper spectrometer at J-PARC

Nakajima, Kenji; Nakamura, Mitsutaka; Kajimoto, Ryoichi; Osakabe, Toyotaka; Kakurai, Kazuhisa; Matsuda, Masaaki; Metoki, Naoto; Wakimoto, Shuichi; Sato, Taku*; Ito, Shinichi*; et al.

Journal of Neutron Research, 15(1), p.13 - 21, 2007/03

no abstracts in English

Journal Articles

Search for orbital excitation in YTiO$$_3$$ by neutron scattering

Shamoto, Shinichi; Tsubota, Masami*; Iga, Fumitoshi*; F${aa}$k, B.*; Kajitani, Tsuyoshi*

Journal of Neutron Research, 13(1-3), p.175 - 178, 2005/03

YTiO$$_3$$ with T$$_c$$~30 K has been studied by the MARI spectrometer with E$$_i$$=130 meV and 500 meV at T=5 K, 40K, and 200 K. We have not found any clear orbital excitation in a wide Q-E range (0.5$$<$$Q$$<$$25$AA $^{-1}$$, 6$$<$$E$$<$$350 meV). The intensity of orbital excitation would be significantly weak in comparison with the phonon.

Journal Articles

The Design of the neutron total scattering spectrometer for hydrogenous materials at J-PARC-JSNS

Suzuya, Kentaro; Kameda, Yasuo*; Otomo, Toshiya*; Yoshida, Koji*; Ito, Keiji*; Fukunaga, Toshiharu*; Misawa, Masakatsu*

Journal of Neutron Research, 13(1-3), p.123 - 128, 2005/03

The design, performance, philosophy, lessons learned and advantages of the neutron total scattering spectrometer for hydrogenous materials, FAST, under consideration for the J-PARC-JSNS, are described. In particular, novel instrumentation concept such as the small fractional scattered neutron flight path, $$gamma$$= L$$_{2}$$/(L$$_{1}$$+L$$_{2}$$), where L$$_{1}$$ is the incident flight path, moderator to sample, L$$_{2}$$ is the scattered neutron flight path from sample to detector, is presented and their expected performance at the JSNS is considered.

Journal Articles

Phonon anomaly on Na$$_x$$HfNCl superconductors with ${it T}$$$_c$$=22 K

Shamoto, Shinichi; Hirai, Atsuo*; Yamanaka, Shoji*; Aso, Naofumi*; Kajitani, Tsuyoshi*

Journal of Neutron Research, 12(4), p.295 - 300, 2004/12

Inelastic neutron scattering measurements have been performed on superconducting Na$$_x$$HfNCl powder samples with x=0.27 and 0.38 (T$$_c$$ =22 K). We have observed several temperature dependent phonon anomalies, e.g., at E=15, 29, 76, and 81 meV for the former sample. A phonon peak with E=14.5 meV at Q=6 $AA $^{-1}$$ increases for both samples with decreasing temperature below T=40 K, which is much higher than T$$_c$$. The phonon peak is assigned to an ab-plane vibrational mode, E$$_u$$, of chlorine and hafnium atoms, which strongly modifies the electronic band structure. The phonon anomaly is discussed in terms of carrier inhomogeneity.

Journal Articles

Inelasticity effect on neutron scattering intensities of the null-H$$_{2}$$O

Kameda, Yasuo*; Sasaki, Motoya*; Usuki, Takeshi*; Otomo, Toshiya*; Ito, Keiji*; Suzuya, Kentaro; Fukunaga, Toshiharu*

Journal of Neutron Research, 11(3), p.153 - 163, 2003/09

We describe results of time-of-flight (TOF) neutron diffraction of the liquid water null-H$$_{2}$$O in order to investigate the effect of both the scattering angle and the neutron flight path ratio to the observed self-scattering intensities. An empirical inelasticity correction procedure is proposed using the self-scattering intensity observed for the null-H$$_{2}$$O.

Journal Articles

Optimization of coupled and decoupled hydrogen moderators for a short-pulse spallation source

Watanabe, Noboru; Harada, Masahide; Kai, Tetsuya; Teshigawara, Makoto; Ikeda, Yujiro

Journal of Neutron Research, 11(1-2), p.13 - 23, 2003/03

no abstracts in English

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