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Journal Articles

Dependence of charge-exchange efficiency on cooling water temperature of a beam transport line

Yamamoto, Kazami; Hatakeyama, Shuichiro; Saha, P. K.; Moriya, Katsuhiro; Okabe, Kota; Yoshimoto, Masahiro; Nakanoya, Takamitsu; Fujirai, Kosuke; Yamazaki, Yoshio; Suganuma, Kazuaki

EPJ Techniques and Instrumentation (Internet), 8(1), p.9_1 - 9_9, 2021/07

The 3 GeV Rapid Cycling Synchrotron at the Japan Proton Accelerator Research Complex supplies a high-intensity proton beam for neutron experiments. Various parameters are monitored to achieve a stable operation, and it was found that the oscillations of the charge-exchange efficiency and cooling water temperature were synchronized. We evaluated the orbit fluctuations at the injection point using a beam current of the injection dump, which is proportional to the number of particles that miss the foil and fail in the charge exchange, and profile of the injection beam. The total width of the fluctuations was approximately 0.072 mm. This value is negligible from the user operation viewpoint as our existing beam position monitors cannot detect such a small signal deviation. This displacement corresponds to a 1.63$$times$$10$$^{-5}$$ variation in the dipole magnetic field. Conversely, the magnetic field variation in the L3BT dipole magnet, which was estimated by the temperature change directly, is 4.08$$times$$10$$^{-5}$$. This result suggested that the change in the cooling water temperature is one of the major causes of the efficiency fluctuation.

Journal Articles

Spin-orbit-induced Ising ferromagnetism at a van der Waals interface

Matsuoka, Hideki*; Barnes, S. E.*; Ieda, Junichi; Maekawa, Sadamichi; Bahramy, M. S.*; Saika, B. K.*; Takeda, Yukiharu; Wadachi, Hiroki*; Wang, Y.*; Yoshida, Satoshi*; et al.

Nano Letters, 21(4), p.1807 - 1814, 2021/02

 Times Cited Count:1 Percentile:72.02(Chemistry, Multidisciplinary)

Journal Articles

Atomic-scale visualization of surface-assisted orbital order

Kim, H.*; Yoshida, Yasuo*; Lee, C.-C.*; Chang, T.-R.*; Jeng, H.-T.*; Lin, H.*; Haga, Yoshinori; Fisk, Z.*; Hasegawa, Yukio*

Science Advances (Internet), 3(9), p.eeao0362_1 - eeao0362_5, 2017/09

 Times Cited Count:8 Percentile:63.32(Multidisciplinary Sciences)

Journal Articles

Split Fermi surface properties in Ulmannite NiSbS and PdBiSe with the cubic chiral crystal structure

Kakihana, Masashi*; Teruya, Atsushi*; Nishimura, Kengo*; Nakamura, Ai*; Takeuchi, Tetsuya*; Haga, Yoshinori; Harima, Hisatomo*; Hedo, Masato*; Nakama, Takao*; Onuki, Yoshichika

Journal of the Physical Society of Japan, 84(9), p.094711_1 - 094711_8, 2015/09

 Times Cited Count:13 Percentile:70.14(Physics, Multidisciplinary)

Journal Articles

Magnetic susceptibility of multiorbital systems

Kubo, Katsunori; Hotta, Takashi

Journal of the Physical Society of Japan, 75(1), p.013702_1 - 013702_4, 2006/01

 Times Cited Count:11 Percentile:57.78(Physics, Multidisciplinary)

Effects of orbital degeneracy on magnetic susceptibility in paramagnetic phases are investigated within a mean-field theory. Under certain crystalline electric fields, the magnetic moment consists of two independent moments, e.g., spin and orbital moments. In such a case, the magnetic susceptibility is given by the sum of two different Curie-Weiss relations, leading to the deviation from the Curie-Weiss law. Such behavior may be observed in $$d$$- and $$f$$-electron systems with $$t_{2g}$$ and $$Gamma_8$$ ground states, respectively. As a potential application of our theory, we attempt to explain the difference in the temperature dependence of magnetic susceptibilities of UO$$_2$$ and NpO$$_2$$. Then, we find that the difference in the temperature dependence can be naturally explained by considering the effects of the octupole moments in NpO$$_2$$.

Journal Articles

Structural properties and phase transition of hole-orbital-ordered (C$$_{2}$$H$$_{5}$$NH$$_{3}$$)$$_{2}$$CuCl$$_{4}$$ studied by resonant and non-resonant X-ray scatterings under high pressure

Owada, Kenji; Ishii, Kenji; Inami, Toshiya; Murakami, Yoichi; Shobu, Takahisa*; Osumi, Hiroyuki*; Ikeda, Naoshi*; Oishi, Yasuo*

Physical Review B, 72(1), p.014123_1 - 014123_10, 2005/07

 Times Cited Count:23 Percentile:67.58(Materials Science, Multidisciplinary)

The effects of hydrostatic pressure on a structure and the corresponding resonant X-ray scattering (RXS) spectrum have been investigated for the hole-orbital-ordered compound (C$$_{2}$$H$$_{5}$$NH$$_{3}$$)$$_{2}$$CuCl$$_{4}$$. We have found a structural phase transition at Pc=4 GPa. The reduction of the Jahn-Teller distortion (JTD) toward Pc is also ascertained by structural analyses. The gradual change in the color of the crystal is also observed in connection with the structural change near Pc. We experimentally confirmed that the RXS intensity comes from the polarization of the density of states of px and py symmetries, which is mainly dominated not by the on-site 3d-4p Coulomb interaction but by the JTD of the CuCl$$_{6}$$ octahedron. The RXS study under a high pressure shows no striking change as JTD is suppressed by the application of pressure. On the other hand, the RXS intensity becomes zero above Pc. The results indicate that the local environment of the Cu$$^{2+}$$ ion markedly changes. Two possible structures above Pc are proposed.

JAEA Reports

Study of beam fluctuation of high speed variably-polarizing undulator APPLE-2 in 2001 Dec.-2002 Nov.

Nakatani, Takeshi; Agui, Akane; Yoshigoe, Akitaka; Tanaka, Hitoshi*; Takao, Masaru*; Takeuchi, Masao*; Matsushita, Tomohiro*; Aoyagi, Hideki*

JAERI-Tech 2005-027, 29 Pages, 2005/05

JAERI-Tech-2005-027.pdf:5.14MB

We measured the orbit fluctuation caused by APPLE-2 type undulator (ID23) installed in the SPring-8 storage ring by using the developed real time measurement system of electron and photon beam position monitors. We quantitatively found two characteristic fluctuations correlating with the ID23 motion by wavelet transform which is a kind of frequency analysis. One originates from the variation of error field during the ID drive. The other originates from the stray magnetic field leaked from the servomotors for the phase drive. Using these results, we tried to get rid of the effect of error fields on the beam orbit by the precise feed-forward correction table and the stray field shield. Consequently we succeeded in suppressing the orbit fluctuation down to sub-micron during the gap drive, which is observed by photon beam position monitors installed in downstream 20m from each light source point.

Journal Articles

Spin wave and orbital ordering in the C-type antiferromagnetic phase of Nd$$_{1-x}$$Sr$$_{x}$$MnO$$_{3}$$

Kajimoto, Ryoichi; Yoshizawa, Hideki*; Kawasaki, Ryuichi*; Noda, Kohei*; Kuwahara, Hideki*

Journal of the Physical Society of Japan, 74(1), p.502 - 503, 2005/01

 Times Cited Count:1 Percentile:12.06(Physics, Multidisciplinary)

The spin wave dispersion relation of the C-type antiferromagnetic structure in Nd$$_{0.25}$$Sr$$_{0.75}$$MnO$$_{3}$$ was determined by neutron scattering. The spin exchange interactions show a large anisotropy, which evidences the d$$_{3z^2-r^2}$$ orbital ordering along the $$c$$ axis. The exchange interaction along the $$c$$ direction is fairly large and similar to the value in the ferromagnetic metallic phase, suggesting there is finite hopping of charges along the orbital chains.

Journal Articles

MCD measurement at the Tb $$M$$$$_{4,5}$$-edges of Tb$$_{17}$$Fe$$_{x}$$Co$$_{(83-x)}$$ perpendicular magnetization films

Agui, Akane; Mizumaki, Masaichiro*; Asahi, Toru*; Sayama, Junichi*; Matsumoto, Koji*; Morikawa, Tsuyoshi*; Nakatani, Takeshi; Matsushita, Tomohiro*; Osaka, Tetsuya*; Miura, Yoshimasa*

Transactions of the Magnetics Society of Japan, 4(4-2), p.326 - 329, 2004/11

The electronic and spin state of the perpendicular magnetization film Tb$$_{17}$$Fe$$_{x}$$Co$$_{(83-x)}$$ was investigated by means of magnetic circular dichroism spectroscopy for each element. The samples are Tb$$_{17}$$Fe$$_{x}$$Co$$_{(83-x)}$$ while the ratio of a rare-earth metal Tb to transition metals Fe and Co is constant, the composition ratio of Fe and Co is changed. Changing the ratio, we estimated the expected orbital moments $$<$$$$L$$$$_{z}$$$$>$$ of Tb 4f electrons. The macroscopic magnetic property is studied from the microscopic point of view.

Journal Articles

EPR studies of 5-bromouracil crystal after irradiation with X rays in the bromine K-edge region

Yokoya, Akinari; Takakura, Kaoru*; Watanabe, Ritsuko; Akamatsu, Ken*; Ito, Takashi*

Radiation Research, 162(4), p.469 - 473, 2004/10

 Times Cited Count:2 Percentile:7.41(Biology)

X-ray absorption spectra from single crystals of 5-Bromouracil were measured with the transmission mode in the energy range from 13.41 to 13.50 keV using the linearly polarized synchrotron radiation (SR). A characteristic resonance structure, consisting of four peaks, was recognized in the spectra in the Br K-edge region. The intensities of these peaks were strongly dependent on the crystal rotation about the normal of the crystal b-c plane, which was set perpendicular to the X-ray beam direction. (SR X-rays are polarized in the horizontal plane.) Molecular orbital calculations indicate that these resonance peaks are associated with the transitions from the 1s electron of Br to the Br-C molecular antibonding orbitals and to a shape resonance. The observed anisotropy of each photoabsorption peak might originate from the angular dependences of these molecular orbitals.

Journal Articles

Global ${it ab initio}$ potential energy surfaces for the lowest three doublet states (1$$^{2}$$A', 2$$^{2}$$A', and 1$$^{2}$$A") of the BrH$$_{2}$$ system

Kurosaki, Yuzuru; Takayanagi, Toshiyuki

Journal of Chemical Physics, 119(15), p.7838 - 7856, 2003/10

 Times Cited Count:26 Percentile:65.54(Chemistry, Physical)

Adiabatic potential energy surfaces of the lowest three doublet states (1$$^{2}$$A', 2$$^{2}$$A', and 1$$^{2}$$A") for the BrH$$_{2}$$ system have been calculated globally using the MRCI+Q method with the aug-cc-pVTZ basis set. Spin-orbit effects were considered on the basis of Breit-Pauli Hamiltonian. The calculated adiabatic energies were fitted to the analytical functional form of many-body expansion. The barrier heights of the abstraction and exchange reactions on the ground-state PES were calculated to be 1.28 and 11.71 kcal mol$$^{-1}$$, respectively, at the MRCI+Q/aug-cc-pVTZ level of theory. The fits for the three PESs were successful within the accuracy of 0.1 kcal mol$$^{-1}$$. Thermal rate constants for the abstraction and exchange reactions and their isotopic variants were calculated with the fitted 1$$^{2}$$A' PES using the ICVT/LAG method. The calculated rate constants for the abstarction reactions agree fairly well with experiment but those for the exchange reactions were much smaller than experiment, which suggests that the reliable experimental data are still insufficient.

Journal Articles

Design of beam optics in the proton beam transport line from synchrotron to spallation neutron target

Meigo, Shinichiro; Noda, Fumiaki*; Fujimori, Hiroshi*; Ikeda, Yujiro

Proceedings of ICANS-XVI, Volume 3, p.967 - 976, 2003/07

In J-PARC project, spallation target is irradiated by 3 GeV proton beam of 1 MW. Due to hands on maintenance for the proton beam lines, loss of proton beam is limited less than 1 W/m. Since it is difficult to predict the phase space distribution of the proton beam, we decided that the beam line have to be larger acceptance for 324 $$pi$$ mrad, which is determined by the collimator located in the synchrotron. Distortion of proton beam is caused by the by the instability of angle at the extraction of 3-GeV synchrotron, miss alignment of the magnet, and un-uniformity of the magnet field. In this study, the distortion is calculated. In order to fit the conditions, the stability of extraction angles should be kept smaller than 0.2 mrad. As for the magnetic field, it is found that the uniformity should be kept better 5x10$$^{-4}$$ and 2x10$$^{-3}$$ for bending and quadruple magnets, respectively. It is also found the error of alignments should be limited smaller than 1.0 mm and 1.0 mrad.

Journal Articles

Tritium distribution in the first wall of JT-60U

Masaki, Kei; Sugiyama, Kazuyoshi*; Tanabe, Tetsuo*; Goto, Yoshitaka*; Tobita, Kenji; Miyo, Yasuhiko; Kaminaga, Atsushi; Kodama, Kozo; Arai, Takashi; Miya, Naoyuki

Nihon Genshiryoku Gakkai Wabun Rombunshi, 2(2), p.130 - 139, 2003/06

no abstracts in English

Journal Articles

X-ray magnetic circular dichroism at the ${it K}$ edge of Mn$$_{3}$$GaC

Takahashi, Manabu*; Igarashi, Junichi

Physical Review B, 67(24), p.245104_1 - 245104_5, 2003/06

 Times Cited Count:23 Percentile:72(Materials Science, Multidisciplinary)

We theoretically investigate the origin of the X-ray magnetic circular dichroism (XMCD) spectra at the K edge of Mn and Ga in the ferromagnetic phase of Mn$$_{3}$$GaC on the basis of an ab initio calculation. Taking account of the spin-orbit interaction in the LDA scheme, we obtain the XMCD spectra in excellent agreement with the recent experiment. We have analyzed the origin of each structure, and thus elucidated the mechanism of inducing the orbital polarization in the p symmetric states. We also discuss a simple sum rule connecting the XMCD spectra with the orbital moment in the p symmetric states.

JAEA Reports

Study of closed orbit distortion from high speed phase switching of variably-polarizing undulator APPLE-2 in 2001 March-June

Nakatani, Takeshi; Tanaka, Hitoshi*; Takao, Masaru*; Agui, Akane; Yoshigoe, Akitaka; Takeuchi, Masao*; Aoyagi, Hideki*; Okuma, Haruo*

JAERI-Tech 2003-048, 29 Pages, 2003/05

JAERI-Tech-2003-048.pdf:1.14MB

no abstracts in English

Journal Articles

Resonant X-ray scattering in KCuF$$_{3}$$

Takahashi, Manabu*; Igarashi, Junichi

Physica B; Condensed Matter, 329-333(Part2), p.870 - 871, 2003/05

 Times Cited Count:2 Percentile:15.73(Physics, Condensed Matter)

We study the resonant X-ray scattering (RXS) spectra around the Cu K edge in KCuF$$_{3}$$ on the basis of the band structure calculation combined with the LDA+U approximation. The lattice distortion is introduced as inputs of the calculation. We reproduce well the experimental spectra as a function of photon energy around the main--K--edge (MKE). The spectral structure around the MKE is independent of the magnetic order (MO) and the orbital order (OO) but strongly dependent on the magnitude of the Jahn--Teller distortion (JTD).

Journal Articles

Tritium distribution in JT-60U W-shaped divertor

Masaki, Kei; Sugiyama, Kazuyoshi*; Tanabe, Tetsuo*; Goto, Yoshitaka*; Miyasaka, Kazutaka*; Tobita, Kenji; Miyo, Yasuhiko; Kaminaga, Atsushi; Kodama, Kozo; Arai, Takashi; et al.

Journal of Nuclear Materials, 313-316, p.514 - 518, 2003/03

 Times Cited Count:53 Percentile:95.26(Materials Science, Multidisciplinary)

Detailed tritium profiles on the JT-60U W-shaped divertor and first wall tiles were examined by Tritium Imaging Plate Technique (TIPT) and full combustion method. The tritium deposition image obtained by TIPT was consistent with the distribution measured by combustion method. The highest tritium concentration was 60 kBq/cm$$^{2}$$ at the dome top tile. However, deposition layer was not obviously observed on the dome top tile. The tritium concentration in the inner divertor target tile was lower (2 kBq/cm$$^{2}$$) even with the thick deposition layer of $$sim$$60 $$mu$$m. This tritium distribution can be explained by energetic triton particle loss due to ripple loss. According to the simulation using the OFMC code, 31% of the triton particles produced by D-D nuclear reaction is implanted deeply to the wall without fully losing the initial energy of 1 MeV.

Journal Articles

Magnetic resonant X-ray scattering in KCuF$$_{3}$$

Takahashi, Manabu*; Usuda, Manabu; Igarashi, Junichi

Physical Review B, 67(6), p.064425_1 - 064425_7, 2003/02

 Times Cited Count:21 Percentile:69.61(Materials Science, Multidisciplinary)

We study the magnetic resonant X-ray scattering (RXS) spectra around the K edge of Cu in KCuF$$_{3}$$ on the basis of an ab initio calculation. We use the full-potential linearlized augumented plane wave method in the LDA+U scheme, and introduce the lattice distortion as inputs of the calculation. We obtain finite intensity on magnetic superlattice spots by taking account of the spin-orbit interaction. We also calculate the RXS intensity on orbital superlattice spots. It is found that the intensity increases with increasing Jahn-Teller distortion.

JAEA Reports

Abstracts of the Workshop on Orbital Ordering and Fluctuations in d- and f-electron Systems; March 4-6, 2002, ASRC, JAERI, Tokai, Japan

Ueda, Kazuo; Hotta, Takashi

JAERI-Review 2002-037, 31 Pages, 2002/12

JAERI-Review-2002-037.pdf:2.7MB

Strongly correlated f- and d-electron systems including heavy Fermion systems and transition metal oxides are important source of exciting new phenomena in condensed matter physics. Recently it has been recognized in more profound way that the orbital degeneracy of the f- and d-electrons plays very important role underlying those exotic phenomena. The idea of the present workshop is to bring active researchers in the field together and to exchange ideas in informal atmosphere. In the workshop many interesting results were presented and stimulating discussions were made as clearly seen by the present report.

Journal Articles

Orbital ordering in manganites and ruthenates

Hotta, Takashi; Dagotto, E.*

Physica B; Condensed Matter, 312-313(1-4), p.700 - 702, 2002/03

 Times Cited Count:2 Percentile:15.17(Physics, Condensed Matter)

The crucial role of the orbital degree of freedom is here discussed in order to understand the complex spin and charge structures of transition metal oxides. For manganites, it is shown that diagonal charge stripes in the ferromagnetic phase are induced by the staggered orbital ordered pattern, while for ruthenates, a novel orbital ordering is found to exist in the G-type antiferromagnetic structure, with a hole arrangement as recently observed in X-ray experiments.

37 (Records 1-20 displayed on this page)