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Journal Articles

Applicability and limitations of $$G(r,E)$$ analysis transformed from the inelastic neutron scattering data

Nakamura, Mitsutaka; Kikuchi, Tatsuya*; Kawakita, Yukinobu

Physica B; Condensed Matter, 567, p.61 - 64, 2019/08

 Times Cited Count:0 Percentile:100(Physics, Condensed Matter)

Recently, we reported the phonon dynamical study of a polycrystalline NaI by using the dynamical structure factor in real-space $$G(r,E)$$ transformed from the inelastic neutron scattering (INS) data. Our study has shown that the INS experiments under the conventional condition Q$$_{max}$$ $$sim$$ 5$AA$^{-1}$$ can provide us a meaningful information on the phonon dynamics at around the first nearest neighbor distance on accepting the worse real-space resolution. These results suggest the possibility that a large amount of $$S(Q,E)$$ data which were previously obtained can be effectively reused. In this study, we will examine both the applicability and limitations of $$G(r,E)$$ analysis for various types of materials whose INS data were obtained at the Fermi chopper spectrometer 4SEASONS in J-PARC.

Journal Articles

Background issues encountered by cold-neutron chopper spectrometer AMATERAS

Kikuchi, Tatsuya*; Nakajima, Kenji; Kawamura, Seiko; Inamura, Yasuhiro; Nakamura, Mitsutaka; Wakai, Daisuke*; Aoyama, Kazuhiro*; Iwahashi, Takaaki*; Kambara, Wataru*

Physica B; Condensed Matter, 564, p.45 - 53, 2019/07

 Times Cited Count:0 Percentile:100(Physics, Condensed Matter)

Details of the background, that is, unwanted signals accumulated by the data acquisition system of neutron instruments, observed by the cold-neutron chopper spectrometer AMATERAS installed at the Materials and Life Science Experimental Facility at J-PARC are reported. In the design phase of AMATERAS, we carefully considered the achievement of high signal-to-noise ratio, and possible countermeasures were implemented. Actually, recent scientific outputs from AMATERAS indicates that the spectrometer is one of excellent neutron instruments with low background. In spite of that, in nine years of AMATERAS operation, we have encountered unwanted signals due to various reasons, including gamma-rays emitted at materials on or near the beam line including the sample itself, scattered neutrons from the beam line devices, air scattering, electronic noise in data acquisition system, cosmic rays, T0 burst, and other unknown sources. In this report, we discuss the background observed by AMATERAS, especially in the conditions of without samples, comprehensively. The possible sources of these signals and the countermeasures considered against the above sources are discussed, which may be helpful to those who are engaged in other existing or planned neutron-scattering instruments.

Journal Articles

Status of neutron spectrometers at J-PARC

Kajimoto, Ryoichi; Yokoo, Tetsuya*; Nakamura, Mitsutaka; Kawakita, Yukinobu; Matsuura, Masato*; Endo, Hitoshi*; Seto, Hideki*; Ito, Shinichi*; Nakajima, Kenji; Kawamura, Seiko

Physica B; Condensed Matter, 562, p.148 - 154, 2019/06

 Times Cited Count:1 Percentile:59.85(Physics, Condensed Matter)

Journal Articles

Study on use of superconducting magnet and first inelastic neutron scattering experiment under magnetic field at 4SEASONS spectrometer

Kajimoto, Ryoichi; Ishikado, Motoyuki*; Kira, Hiroshi*; Kaneko, Koji; Nakamura, Mitsutaka; Kamazawa, Kazuya*; Inamura, Yasuhiro; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Murai, Naoki; et al.

Physica B; Condensed Matter, 556, p.26 - 30, 2019/03

 Times Cited Count:2 Percentile:39.2(Physics, Condensed Matter)

Journal Articles

Recent progress on practical materials study by Bragg edge imaging at J-PARC

Oikawa, Kenichi; Su, Y.; Kiyanagi, Ryoji; Kawasaki, Takuro; Shinohara, Takenao; Kai, Tetsuya; Hiroi, Kosuke; Harjo, S.; Parker, J. D.*; Matsumoto, Yoshihiro*; et al.

Physica B; Condensed Matter, 551, p.436 - 442, 2018/12

 Times Cited Count:1 Percentile:83.58(Physics, Condensed Matter)

Journal Articles

High-energy magnetic excitations in lightly oxygen-doped lanthanum nickel oxides

Nakajima, Kenji; Kajimoto, Ryoichi

Physica B; Condensed Matter, 551, p.142 - 145, 2018/12

 Times Cited Count:0 Percentile:100(Physics, Condensed Matter)

Journal Articles

Study of the magnetization distribution in a grain-oriented magnetic steel using pulsed polarized neutron imaging

Hiroi, Kosuke; Shinohara, Takenao; Hayashida, Hirotoshi*; Parker, J. D.*; Su, Y.; Oikawa, Kenichi; Kai, Tetsuya; Kiyanagi, Yoshiaki*

Physica B; Condensed Matter, 551, p.146 - 151, 2018/12

 Times Cited Count:2 Percentile:69.15(Physics, Condensed Matter)

Journal Articles

Performances of oscillating radial collimator for the Fermi chopper spectrometer 4SEASONS at J-PARC

Nakamura, Mitsutaka; Kambara, Wataru*; Iida, Kazuki*; Kajimoto, Ryoichi; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Ishikado, Motoyuki*; Aoyama, Kazuhiro*

Physica B; Condensed Matter, 551, p.480 - 483, 2018/12

 Times Cited Count:1 Percentile:83.58(Physics, Condensed Matter)

Recently there has been an increasing need for inelastic neutron scattering experiments under some special environments such as magnetic fields, pressure and high temperatures. In order to obtain high quality data, the unnecessary scattering caused by sample environmental apparatus should be suppressed as much as possible. We have developed an oscillating radial collimator with a view to satisfying users' needs, which is specialized for the Fermi chopper spectrometer 4SEASONS at J-PARC.4SEASONS provides relatively high incident energies, and thus we chose hydrogen free metal sheets as the collimator blades. The control system of this oscillating radial collimator enables us to flexibly tune the oscillating pattern, such as the oscillating speed and oscillating angle. In this presentation, we report the performances and remaining issues of the newly developed oscillating radial collimator for 4SEASONS.

Journal Articles

Phonon dynamics of NaI investigated by G($$r,E$$) analysis

Nakamura, Mitsutaka; Kikuchi, Tatsuya*; Kamazawa, Kazuya*; Kawakita, Yukinobu

Physica B; Condensed Matter, 551, p.351 - 354, 2018/12

 Times Cited Count:2 Percentile:69.15(Physics, Condensed Matter)

The dynamic structure function in real space G($$r,E$$) is deduced from the dynamical structure factor S($$Q,E$$) which can be obtained from inelastic neutron scattering measurement. In this study, we applied the G($$r,E$$) analysis to NaI which is a typical alkali halide crystal. The optic and acoustic phonons of NaI are widely separated in energy because the difference in mass between the constituent atoms is large. These characteristic properties certainly help us to evaluate the G($$r,E$$) features associated with the phonon modes. We measured the S($$Q,E$$) for NaI powder using the Fermi chopper spectrometer 4SEASONS at J-PARC, and converted S($$Q,E$$) into G($$r,E$$) by newly developed software which utilizes the maximum entropy method. Our analysis clearly demonstrated the G($$r,E$$) of TO mode oscillates out of phase with that of LA mode, which is physically reasonable. Further analyses will be given in the presentation.

Journal Articles

Testing of time-of-flight neutron diffraction imaging using a high-resolution scintillator detector with wavelength-shifting fibers

Kawasaki, Takuro; Nakamura, Tatsuya; Gong, W.*; Oikawa, Kenichi

Physica B; Condensed Matter, 551, p.460 - 463, 2018/12

 Times Cited Count:0 Percentile:100(Physics, Condensed Matter)

Journal Articles

Characteristics of the 2012 model lithium-6 time-analyzer neutron detector (LiTA12) system as a high efficiency detector for resonance absorption imaging

Kai, Tetsuya; Sato, Setsuo*; Hiroi, Kosuke; Su, Y.; Segawa, Mariko; Parker, J. D.*; Matsumoto, Yoshihiro*; Hayashida, Hirotoshi*; Shinohara, Takenao; Oikawa, Kenichi; et al.

Physica B; Condensed Matter, 551, p.496 - 500, 2018/12

 Times Cited Count:1 Percentile:83.58(Physics, Condensed Matter)

Journal Articles

Effect of upstream beam collimation on neutron phase imaging with a Talbot-Lau interferometer at the RADEN beam line in J-PARC

Seki, Yoshichika; Shinohara, Takenao; Ueno, Wakana; Parker, J. D.*; Matsumoto, Yoshihiro*

Physica B; Condensed Matter, 551, p.512 - 516, 2018/12

 Times Cited Count:2 Percentile:69.15(Physics, Condensed Matter)

no abstracts in English

Journal Articles

Anomaly of structural relaxation in complex liquid metal of bismuth; Dynamic correlation function of coherent quasi-elastic neutron scattering

Kawakita, Yukinobu; Kikuchi, Tatsuya*; Inamura, Yasuhiro; Tahara, Shuta*; Maruyama, Kenji*; Hanashima, Takayasu*; Nakamura, Mitsutaka; Kiyanagi, Ryoji; Yamauchi, Yasuhiro*; Chiba, Kaori*; et al.

Physica B; Condensed Matter, 551, p.291 - 296, 2018/12

 Times Cited Count:6 Percentile:41.49(Physics, Condensed Matter)

There are elemental liquid metals with complex structures far from the hard sphere (HS) packing model. Liquid Bi has an asymmetric first peak in the structure factors S(Q). The pair distribution function g(r) exhibits strange distance ratio of 1:2 between the first and the second peaks. Since a HS model with two kinds of radius produces asymmetry of the main peak in S(Q), existence of short-lived covalent bonds was discussed. Contrarily, modulation of the atomic distribution by the Friedel oscillations of shielding electrons around metallic ions was discussed. To examine its bonding nature from viewpoints of dynamic correlation functions, we have measured neutron quasielastic scattering of liquid Bi by using cold disk chopper spectrometer installed at MLF of J-PARC. The van Hove function revealed that the shoulder structure located at a longer side of the first peak in g(r) exhibits a longer relaxation time than the main structures such as the first and second peaks.

Journal Articles

Effect of gauge volume on strain measurement in rock materials using time-of-flight neutron diffraction

Abe, Jun*; Sekine, Kotaro*; Harjo, S.; Kawasaki, Takuro; Aizawa, Kazuya

Physica B; Condensed Matter, 551, p.283 - 286, 2018/12

 Times Cited Count:0 Percentile:100(Physics, Condensed Matter)

Journal Articles

Dynamical quadrupole structure factor of frustrated ferromagnetic chain

Onishi, Hiroaki

Physica B; Condensed Matter, 536, p.346 - 349, 2018/05

 Times Cited Count:1 Percentile:83.58(Physics, Condensed Matter)

Journal Articles

Magnetic excitations in the orbital disordered phase of MnV$$_2$$O$$_4$$

Matsuura, Keisuke*; Sagayama, Hajime*; Uehara, Amane*; Nii, Yoichi*; Kajimoto, Ryoichi; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Ji, S.*; Abe, Nobuyuki*; Arima, Takahisa*

Physica B; Condensed Matter, 536, p.372 - 376, 2018/05

 Times Cited Count:1 Percentile:83.58(Physics, Condensed Matter)

Journal Articles

Inelastic X-ray scattering of $$RT$$Al$$_3$$ ($$R$$ = La, Ce, $$T$$ = Cu, Au)

Tsutsui, Satoshi*; Kaneko, Koji; Pospisil, J.; Haga, Yoshinori

Physica B; Condensed Matter, 536, p.24 - 27, 2018/05

 Times Cited Count:0 Percentile:100(Physics, Condensed Matter)

Journal Articles

Detailed study of the structure of the low-energy magnetic excitations in overdoped La$$_{1.75}$$Sr$$_{0.25}$$CuO$$_{4}$$

Ikeuchi, Kazuhiko*; Kikuchi, Tatsuya*; Nakajima, Kenji; Kajimoto, Ryoichi; Wakimoto, Shuichi; Fujita, Masaki*

Physica B; Condensed Matter, 536, p.717 - 719, 2018/05

 Times Cited Count:1 Percentile:83.58(Physics, Condensed Matter)

To examine the detailed structure of low-energy magnetic excitations in a high-transition-temperature superconducting cuprate with heavily hole-doping, we performed inelastic neutron scattering experiments on La$$_{1.75}$$Sr$$_{0.25}$$CuO$$_{4}$$. We observed clear dispersion relations of the previously reported incommensurate (IC) magnetic correlations at $$Q_{rm tet}$$ = (0.5 $$pm$$ $$delta$$, 0.5)/(0.5, 0.5 $$pm$$ $$delta$$). In addition, we show the emergence of continuum magnetic excitations with a ring shape centered at $$Gamma$$ point $$Q_{rm tet}=(0.5, 0.5)$$ in a constant energy spectrum at $$T$$ = 50 K. The radius of the ring ($$r$$ = 0.109) is smaller than the incommensurability ($$delta$$ = 0.118). This suggests that the origin of the ring-like excitations is different from that of the IC magnetic correlations, and the low-energy magnetic excitations of the La$$_{2-x}$$Sr$$_{x}$$CuO$$_{4}$$ system are inherently composed of these two kinds of excitations.

Journal Articles

Element specific electronic states and spin-flip-like behavior of Ce in (Ce$$_{0.2}$$Gd$$_{0.8}$$)Ni composed of heavy fermion CeNi and ferri-magnet GdNi through XMCD method

Yano, Kazuo*; Okane, Tetsuo; Takeda, Yukiharu; Yamagami, Hiroshi; Fujimori, Atsushi; Nishimura, Katsuhiko*; Sato, Kiyoo*

Physica B; Condensed Matter, 515, p.118 - 125, 2017/06

 Times Cited Count:1 Percentile:87.66(Physics, Condensed Matter)

The electronic states of the three constituent elements in the crystal mixed system between CeNi and GdNi, Ce$$_{0.2}$$Gd$$_{0.8}$$Ni, were investigated by soft X-ray magnetic circular dichroism (XMCD). Not only Gd 4f but also Ni 3d and Ce 4f electrons were magnetic and both magnetic moments of Ni and Ce were coupled anti-parallel to the direction of the Gd magnetic moment. After saturation, Ce magnetic moment decreased over 2 T and this behavior was explained by a spin-flip behavior of the Ce magnetic moment. In addition, sum rule analysis has revealed that the magnetic moments of Gd 4 f and Ni 3d electrons could retain small values of orbital magnetic moments.

Journal Articles

Emergent phenomena in perovskite-type manganites

Taguchi, Yasujiro*; Sakai, Hideaki*; Okuyama, Daisuke*; Ishiwata, Shintaro*; Fujioka, Jun*; Fukuda, Tatsuo; Hashizume, Daisuke*; Kagawa, Fumitaka*; Takahashi, Yoichiro*; Shimano, Ryo*; et al.

Physica B; Condensed Matter, 407(11), p.1685 - 1688, 2012/06

 Times Cited Count:3 Percentile:81.83(Physics, Condensed Matter)

274 (Records 1-20 displayed on this page)