Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 58

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Coherent eddies transporting passive scalars through the plant canopy revealed by Large-Eddy simulations using the lattice Boltzmann method

Watanabe, Tsutomu*; Takagi, Marie*; Shimoyama, Ko*; Kawashima, Masayuki*; Onodera, Naoyuki; Inagaki, Atsushi*

Boundary-Layer Meteorology, 181(1), p.39 - 71, 2021/10

A double-distribution-function lattice Boltzmann model for large-eddy simulations of a passive scalar field is described within and above a plant canopy. For a top-down scalar, for which the plant canopy serves as a distributed sink, the flux of the scalar near the canopy top are predominantly determined by sweep motions originating far above the canopy. By contrast, scalar ejection events are induced by coherent eddies generated near the canopy top. In this paper, the generation of such eddies is triggered by the downward approach of massive sweep motions to existing wide regions of weak ejective motions from inside to above the canopy.

Journal Articles

Highly sensitive detection of sodium in aqueous solutions using laser-induced breakdown spectroscopy with liquid sheet jets

Nakanishi, Ryuzo; Oba, Hironori; Saeki, Morihisa; Wakaida, Ikuo; Tanabe, Rie*; Ito, Yoshiro*

Optics Express (Internet), 29(4), p.5205 - 5212, 2021/02

 Times Cited Count:0 Percentile:0(Optics)

Laser-induced breakdown spectroscopy (LIBS) combined with liquid jets was applied to the detection of trace sodium (Na) in aqueous solutions. The sensitivities of two types of liquid jets were compared: a liquid cylindrical jet with a diameter of 500 $$mu$$m and a liquid sheet jet with a thickness of 20 $$mu$$m. Compared with the cylindrical jet, the liquid sheet jet effectively reduced the splash from the laser-irradiated surface and produced long-lived luminous plasma. The limit of detection (LOD) of Na was determined to be 0.57 $$mu$$g/L for the sheet jet and 10.5 $$mu$$g/L for the cylindrical jet. The LOD obtained for the sheet jet was comparable to those obtained for commercially available inductively coupled plasma emission spectrometers.

Journal Articles

The Surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.

Science, 364(6437), p.272 - 275, 2019/04

 Times Cited Count:140 Percentile:99.81(Multidisciplinary Sciences)

The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.

Journal Articles

Coupled bunch instability and its cure at J-PARC RCS

Shobuda, Yoshihiro; Saha, P. K.; Hotchi, Hideaki; Harada, Hiroyuki; Takayanagi, Tomohiro; Tamura, Fumihiko; Tani, Norio; Togashi, Tomohito; Toyama, Takeshi*; Watanabe, Yasuhiro; et al.

Proceedings of 8th International Particle Accelerator Conference (IPAC '17) (Internet), p.2946 - 2949, 2017/05

no abstracts in English

Journal Articles

Theoretical elucidation of space charge effects on the coupled-bunch instability at the 3 GeV Rapid Cycling Synchrotron at the Japan Proton Accelerator Research Complex

Shobuda, Yoshihiro; Chin, Y. H.*; Saha, P. K.; Hotchi, Hideaki; Harada, Hiroyuki; Irie, Yoshiro*; Tamura, Fumihiko; Tani, Norio; Toyama, Takeshi*; Watanabe, Yasuhiro; et al.

Progress of Theoretical and Experimental Physics (Internet), 2017(1), p.013G01_1 - 013G01_39, 2017/01

AA2016-0375.pdf:3.07MB

 Times Cited Count:10 Percentile:69(Physics, Multidisciplinary)

The Rapid Cycling Synchrotron (RCS), whose beam energy ranges from 400 MeV to 3 GeV and which is located in the Japan Proton Accelerator Research Complex, is a kicker-impedance dominant machine, which violates the impedance budget from a classical viewpoint. Contrary to conventional understanding, we have succeeded to accelerate a 1-MW equivalent beam. The machine has some interesting features: for instance, the beam tends to be unstable for the smaller transverse beam size, the beam is stabilized by increasing the peak current ${it etc}$. Space charge effects play an important role in the beam instability at the RCS. In this study, a new theory has been developed to calculate the beam growth rate with the head-tail and coupled-bunch modes ($$m,mu$$) while taking space charge effects into account. The theory sufficiently explains the distinctive features of the beam instabilities at the RCS.

Journal Articles

Effect of liquid-sheet thickness on detection sensitivity for laser-induced breakdown spectroscopy of aqueous solution

Oba, Hironori; Saeki, Morihisa; Wakaida, Ikuo; Tanabe, Rie*; Ito, Yoshiro*

Optics Express (Internet), 22(20), p.24478 - 24490, 2014/10

 Times Cited Count:14 Percentile:66.41(Optics)

For aqueous-solution-based elemental analysis, we used a thin liquid sheet ($$mu$$m-scale thickness) in laser-induced breakdown spectroscopy with nanosecond laser pulses. Laser-induced plasma is emitted by focusing a pulsed Nd:YAG laser (1064 nm) on a 5- to 80-$$mu$$m-thick liquid sheet in air. To optimize the conditions for detecting elements, we studied how the signal-to-background ratio (SBR) for H$$alpha$$ Balmer and Na-neutral emission lines depends on the liquid-sheet thickness. The SBR of the H$$alpha$$ Balmer and Na-neutral lines was maximized for a sheet thickness of $$sim$$20 $$mu$$m at the laser energy of 100 mJ. The hydrodynamics of liquid flow induced by the laser pulse was analyzed by laser flash shadowgraph imaging. Time-resolved observation of the hydrodynamics and plasma emission suggests that the dependence of the SBR on the liquid-sheet thickness is correlated with the volume of flowing liquid that interacts with the laser pulses.

Journal Articles

Progress of injection energy upgrade project for J-PARC RCS

Hayashi, Naoki; Harada, Hiroyuki; Horino, Koki; Hotchi, Hideaki; Kamiya, Junichiro; Kinsho, Michikazu; Saha, P. K.; Shobuda, Yoshihiro; Takayanagi, Tomohiro; Tani, Norio; et al.

Proceedings of 4th International Particle Accelerator Conference (IPAC '13) (Internet), p.3833 - 3835, 2014/07

no abstracts in English

Journal Articles

Power supply of the pulse steering magnet for changing the painting area between the MLF and the MR at J-PARC 3 GeV RCS

Takayanagi, Tomohiro; Hayashi, Naoki; Ueno, Tomoaki; Horino, Koki; Togashi, Tomohito; Kinsho, Michikazu; Watanabe, Yasuhiro; Irie, Yoshiro*

Proceedings of 4th International Particle Accelerator Conference (IPAC '13) (Internet), p.681 - 683, 2014/07

The power supply of the pulse steering magnet has been produced. The power supply has the equipment used to excite the pulse current and the direct-current (DC) to correspond to two modes that the painting injection for beam users and the central injection for beam commissioning. The pulse current has been performed with good accuracy whose deviation to a setting current becomes to be less than 0.2%. In case of the central injection, the power supply excites the current in DC mode, which has been realized the ripple current below 0.01%. This paper describes the design parameters and the experimental results of the power supply.

Journal Articles

Measurement scheme of kicker impedances via beam-induced voltages of coaxial cables

Shobuda, Yoshihiro; Irie, Yoshiro*; Toyama, Takeshi*; Kamiya, Junichiro; Watanabe, Masao

Nuclear Instruments and Methods in Physics Research A, 713, p.52 - 70, 2013/06

 Times Cited Count:6 Percentile:49.64(Instruments & Instrumentation)

Journal Articles

High precision tracking control for rapid cycling magnets

Watanabe, Yasuhiro; Tani, Norio; Adachi, Toshikazu*; Someya, Hirohiko*; Irie, Yoshiro*

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.538 - 540, 2012/08

Rapid cycling magnets are excited using a resonant circuit and the current waveform is a DC-biased sinusoidal pattern. However, non-linear characteristic of the magnet produces harmonic components in the magnetic field. The harmonic components are different for each type of magnet depending upon the degree of saturation, and it causes a tracking error. This paper proposes harmonic current control in the resonant circuit to reduce harmonic components in the magnetic field.

Journal Articles

Event structure and double helicity asymmetry in jet production from polarized $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Y.*; Al-Bataineh, H.*; Alexander, J.*; Aoki, K.*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review D, 84(1), p.012006_1 - 012006_18, 2011/07

 Times Cited Count:25 Percentile:72.31(Astronomy & Astrophysics)

We report on the event structure and double helicity asymmetry ($$A_{LL}$$) of jet production in longitudinally polarized $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV. Photons and charged particles were measured by the PHENIX experiment. Event structure was compared with the results from PYTHIA event generator. The production rate of reconstructed jets is satisfactorily reproduced with the next-to-leading-order perturbative QCD calculation. We measured $$A_{LL}$$ = -0.0014 $$pm$$ 0.0037 at the lowest $$P_T$$ bin and -0.0181 $$pm$$ 0.0282 at the highest $$P_T$$ bin. The measured $$A_{LL}$$ is compared with the predictions that assume various $$Delta G(x)$$ distributions.

Journal Articles

Identified charged hadron production in $$p + p$$ collisions at $$sqrt{s}$$ = 200 and 62.4 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review C, 83(6), p.064903_1 - 064903_29, 2011/06

 Times Cited Count:156 Percentile:99.42(Physics, Nuclear)

Transverse momentum distributions and yields for $$pi^{pm}, K^{pm}, p$$, and $$bar{p}$$ in $$p + p$$ collisions at $$sqrt{s}$$ = 200 and 62.4 GeV at midrapidity are measured by the PHENIX experiment at the RHIC. We present the inverse slope parameter, mean transverse momentum, and yield per unit rapidity at each energy, and compare them to other measurements at different $$sqrt{s}$$ collisions. We also present the scaling properties such as $$m_T$$ and $$x_T$$ scaling and discuss the mechanism of the particle production in $$p + p$$ collisions. The measured spectra are compared to next-to-leading order perturbative QCD calculations.

Journal Articles

Azimuthal correlations of electrons from heavy-flavor decay with hadrons in $$p+p$$ and Au+Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.

Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04

 Times Cited Count:8 Percentile:52.71(Physics, Nuclear)

Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled $$p+p$$ collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to $$p+p$$ collisions.

Journal Articles

Energy band structure of SiO$$_{2}$$/4H-SiC interfaces and its modulation induced by intrinsic and extrinsic interface charge transfer

Watanabe, Heiji*; Kirino, Takashi*; Kagei, Yusuke*; Harries, J.; Yoshigoe, Akitaka; Teraoka, Yuden; Mitani, Shuhei*; Nakano, Yuki*; Nakamura, Takashi*; Hosoi, Takuji*; et al.

Materials Science Forum, 679-680, p.386 - 389, 2011/03

 Times Cited Count:19 Percentile:99.43

Journal Articles

Measurement of neutral mesons in $$p$$ + $$p$$ collisions at $$sqrt{s}$$ = 200 GeV and scaling properties of hadron production

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Y.*; Al-Bataineh, H.*; Alexander, J.*; Aoki, K.*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review D, 83(5), p.052004_1 - 052004_26, 2011/03

 Times Cited Count:149 Percentile:98.49(Astronomy & Astrophysics)

The PHENIX experiment at RHIC has measured the invariant differential cross section for production of $$K^0_s$$, $$omega$$, $$eta'$$ and $$phi$$ mesons in $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV. The spectral shapes of all hadron transverse momentum distributions are well described by a Tsallis distribution functional form with only two parameters, $$n$$ and $$T$$, determining the high $$p_T$$ and characterizing the low $$p_T$$ regions for the spectra, respectively. The integrated invariant cross sections calculated from the fitted distributions are found to be consistent with existing measurements and with statistical model predictions.

Journal Articles

Extreme ultraviolet free electron laser seeded with high-order harmonic of Ti:sapphore laser

Togashi, Tadashi*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Okino, Tomoya*; Yamanouchi, Kaoru*; et al.

Optics Express (Internet), 19(1), p.317 - 324, 2011/01

 Times Cited Count:88 Percentile:96.89(Optics)

The 13th harmonic of a Ti:sapphire (Ti:S) laser in the plateau region was injected as a seeding source to a 250-MeV free-electron-laser (FEL) amplifier. When the amplification conditions were fulfilled, strong enhancement of the radiation intensity by a factor of 650 was observed. The random and uncontrollable spikes, which appeared in the spectra of the Self-Amplified Spontaneous Emission (SASE) based FEL radiation without the seeding source, were found to be suppressed drastically to form to a narrow-band, single peak profile at 61.2 nm. The properties of the seeded FEL radiation were well reproduced by numerical simulations. We discuss the future precept of the seeded FEL scheme to the shorter wavelength region.

Journal Articles

Design of the pulse bending magnet for switching the painting area between the MLF and MR in J-PARC 3-GeV RCS

Takayanagi, Tomohiro; Yoshimoto, Masahiro; Watanabe, Masao; Saha, P. K.; Ueno, Tomoaki; Togashi, Tomohito; Yamazaki, Yoshio; Kinsho, Michikazu; Fujimori, Hiroshi*; Irie, Yoshiro*

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.3293 - 3295, 2010/05

It has been designed the pulse bending magnet for switching the painting area to the MLF and MR, which is located in injection line area in J-PARC 3-GeV RCS. After upgrading the linac energy to 400 MeV, the two pulse magnets switch the injection beam orbit to change the each painting area by each shot of 25 Hz. The magnetic field strength switching by 25 Hz are required for the painting injection. Furthermore, in the case of the beam commissioning of the 3-GeV RCS, the center injection is performed. Therefore, the wide range of the beam bending angle from 3 mrad to 38 mrad is required for the pulse magnets.

Journal Articles

Interface engineering of Ge MOS devices with Zr0$$_{2}$$ gate dielectrics

Hosoi, Takuji*; Okamoto, Gaku*; Kutsuki, Katsuhiro*; Kagei, Yusuke*; Harries, J.; Yoshigoe, Akitaka; Teraoka, Yuden; Shimura, Takayoshi*; Watanabe, Heiji*

Oyo Butsuri Gakkai Hakumaku, Hyomen Butsuri Bunkakai, Shirikon Tekunoroji Bunkakai Kyosai Tokubetsu Kenkyukai Kenkyu Hokoku, p.145 - 148, 2010/01

We developed high quality high-$$k$$/Ge gate stacks with reduced leakage current and superior interface quality, which was fabricated by direct deposition of ZrO$$_{2}$$ on Ge substrate and thermal oxidation. Synchrotron radiation photoelectron spectroscopy revealed that thermal oxidation at 823 K caused not only an intermixing between ZrO$$_{2}$$ and Ge but also the formation of GeO$$_{2}$$ at the interlayer. We obtained an equivalent oxide thickness (EOT) of 1.9 nm, and an interface state density of 10$$^{11}$$ cm$$^{-2}$$eV$$^{-1}$$ for Au/ZrO$$_{2}$$/Ge capacitors. Furthermore, we found that the A1$$_{2}$$0$$_{3}$$ capping on the Zr0$$_{2}$$ 1ayer is effective for decreasing EOT. The interface state density as low as 5.3$$times$$10$$^{10}$$ cm$$^{-2}$$eV$$^{-1}$$ was obtained for the Al$$_{2}$$O$$_{3}$$/ZrO$$_{2}$$/Ge stack with 30 min oxidation. The EOT could be reduced to l.6 nm by 10 min oxidation. The leakage current was two orders of magnitude lower than the conventional poly-Si/SiO$$_{2}$$/Si stack.

Journal Articles

Deuterium depth profiling in graphite tiles not exposed to hydrogen discharges before air ventilation of JT-60U

Hayashi, Takao; Sugiyama, Kazuyoshi*; Mayer, M.*; Krieger, K.*; Masaki, Kei; Tanabe, Tetsuo*; Sato, Masayasu

Journal of Nuclear Materials, 390-391, p.667 - 670, 2009/05

 Times Cited Count:1 Percentile:10.95(Materials Science, Multidisciplinary)

Absolute concentrations and the depth profiles of D in plasma-facing graphite tiles used in JT-60U were determined by means of the D($$^{3}$$He, p)$$^{4}$$He resonant nuclear reaction. The analyzed samples were not exposed to H discharges before air ventilation. The maximum depth of analysis is about 1.4 $$times$$ 10$$^{24}$$ carbon (C) atoms/m$$^{2}$$, corresponding to a linear depth of 16 $$mu$$m for the density of 1.7 $$times$$ 10$$^{3}$$ kg/m$$^{3}$$. The highest D concentration was found at the inboard mid-plane of first wall area. The maximum D concentration is D/C=0.13, and the concentration decrease with the depth. The D retention within 16 $$mu$$m is 1.9 $$times$$ 10$$^{22}$$ D atoms/m$$^{2}$$. The D retentions in this paper were about 2$$sim$$9 times larger than previous samples, which were located on the same area and exposed to the hydrogen discharges. This indicates the H plasma discharges were effective to remove the D (and T) from graphite tiles in the first wall area.

Journal Articles

Performance of the bump system for the painting injection at J-PARC

Takayanagi, Tomohiro; Ueno, Tomoaki; Togashi, Tomohito; Harada, Hiroyuki*; Saha, P. K.; Hotchi, Hideaki; Kinsho, Michikazu; Kamiya, Junichiro; Watanabe, Masao; Yoshimoto, Masahiro; et al.

Proceedings of 2009 Particle Accelerator Conference (PAC '09) (DVD-ROM), p.1507 - 1509, 2009/05

The shift bump-magnets, which give a constant bump field in a horizontal plane during injection, comprise four magnets connected in series. However, the total integrated magnetic field over the four magnets is not zero because of the magnetic field interferences with the neighboring quadrupole magnets. So the gap of each magnet was adjusted by inserting thin insulators into the splitting plane of the side yoke so that the field integration becomes zero. The closed orbit distortion due to the field imbalances was then confirmed to be less than 1 mm. Another four paint bump-magnets are connected to their own power supplies, separately. The excitation of each magnet is calibrated by using the beam so that the created bump orbit satisfies the position and inclination at the injection point, and there are no orbit distortions outside the injection area.

58 (Records 1-20 displayed on this page)