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Journal Articles

Experimental evidence for the significance of optical phonons in thermal transport of tin monosulfide

Wu, P.*; Murai, Naoki; Li, T.*; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Kofu, Maiko; Nakajima, Kenji; Xia, K.*; Peng, K.*; Zhang, Y.*; et al.

New Journal of Physics (Internet), 25(1), p.013032_1 - 013032_11, 2023/01

 Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)

Journal Articles

Strong lattice anharmonicity exhibited by the high-energy optical phonons in thermoelectric material

Wu, P.*; Fan, F.-R.*; Hagihara, Masato*; Kofu, Maiko; Peng, K.*; Ishikawa, Yoshihisa*; Lee, S.*; Honda, Takashi*; Yonemura, Masao*; Ikeda, Kazutaka*; et al.

New Journal of Physics (Internet), 22(8), p.083083_1 - 083083_9, 2020/08

 Times Cited Count:6 Percentile:55.6(Physics, Multidisciplinary)

Thermoelectric material SnSe has aroused world-wide interests in the past years, and its inherent strong lattice anharmonicity is regarded as a crucial factor for its outstanding thermoelectric performance. However, the understanding of lattice anharmonicity in SnSe system remains inadequate, especially regarding how phonon dynamics are affected by this behavior. In this work, we present a comprehensive study of lattice dynamics on Na$$_{0.003}$$Sn$$_{0.997}$$Se$$_{0.9}$$S$$_{0.1}$$ by means of neutron total scattering, inelastic neutron scattering, Raman spectroscopy as well as frozen-phonon calculations. Lattice anharmonicity is evidenced by pair distribution function, inelastic neutron scattering and Raman measurements. By separating the effects of thermal expansion and multi-phonon scattering, we found that the latter is very significant in high-energy optical phonon modes. The strong temperature-dependence of these phonon modes indicate the anharmonicity in this system. Moreover, our data reveals that the linewidths of high-energy optical phonons become broadened with mild doping of sulfur. Our studies suggest that the thermoelectric performance of SnSe could be further enhanced by reducing the contributions of high-energy optical phonon modes to the lattice thermal conductivity via phonon engineering.

Journal Articles

Emergence of a complete heavy-quark spin symmetry multiplet; Seven molecular pentaquarks in light of the latest LHCb analysis

Liu, M.-Z.*; Pan, Y.-W.*; Peng, F.-Z.*; S$'a$nchez-S$'a$nchez, M.*; Geng, L.-S.*; Hosaka, Atsushi; Valderrama, M. P.*

Physical Review Letters, 122(24), p.242001_1 - 242001_5, 2019/06

 Times Cited Count:162 Percentile:99.31(Physics, Multidisciplinary)

Journal Articles

Investigation of the electronic structure and lattice dynamics of the thermoelectric material Na-doped SnSe

Wu, P.*; Zhang, B.*; Peng, K. L.*; Hagiwara, Masayuki*; Ishikawa, Yoshihisa*; Kofu, Maiko; Lee, S. H.*; Kumigashira, Hiroshi*; Hu, C. S.*; Qi, Z. M.*; et al.

Physical Review B, 98(9), p.094305_1 - 094305_7, 2018/09

 Times Cited Count:9 Percentile:46.45(Materials Science, Multidisciplinary)

Using angle-resolved photoemission spectroscopy and inelastic neutron scattering, we have studied how electronic structures and lattice dynamics evolve with temperature in Na-doped SnSe.

Journal Articles

A New evaluation of the neutron data standards

Carlson, A. D.*; Pronyaev, V.*; Hale, G. M.*; Zhenpeng, C.*; Capote, R.*; Dur$'a$n, I.*; Hambsch, F.-J.*; Kawano, Toshihiko*; Kunieda, Satoshi; 13 of others*

EPJ Web of Conferences, 146, p.02025_1 - 02025_4, 2017/09

 Times Cited Count:4 Percentile:90.94

Evaluations are being done for the $$^1$$H(n,n), $$^6$$Li(n,t), $$^{10}$$B(n,$$alphagamma$$), $$^{10}$$B(n,$$alpha$$), C(n,n), $$^{197}$$Au(n,$$gamma$$), $$^{235}$$U(n,f) and $$^{238}$$U(n,f) standard cross sections. Evaluations are also being done for data that are not traditional standards including: the Au(n,$$gamma$$) cross section at energies below where it is considered a standard; reference cross sections for prompt $$gamma$$-ray production in fast neutron-induced reactions; reference cross sections for very high energy fission cross sections; the $$^{235}$$U thermal neutron fission spectrum and the $$^{252}$$Cf spontaneous fission neutron spectrum and the thermal constants.

Journal Articles

Hydroxyl radical, sulfate radical and nitrate radical reactivity towards crown ethers in aqueous solutions

Wan, L. K.*; Peng, J.*; Lin, M.; Muroya, Yusa*; Katsumura, Yosuke*; Fu, H. Y.*

Radiation Physics and Chemistry, 81(5), p.524 - 530, 2012/05

 Times Cited Count:16 Percentile:75.65(Chemistry, Physical)

Rate constants of common crown ethers ((C$$_{2}$$H$$_{4}$$O)$$_{n}$$, n=4, 5, 6) and their model compound, 1,4-dioxane(6C2) with some important oxidative radicals, $$^{cdot}$$OH, SO$$_{4}^{cdot-}$$, and NO$$_{3}^{cdot}$$ were determined in various aqueous solutions using pulse radiolysis and laser photolysis techniques. The rate constants for 6C2 and crown ethers with $$^{cdot}$$OH and SO$$_{4}^{cdot-}$$ increase with the number of H-atom in the ethers, indicating that H-abstraction is dominant reaction between crown ethers and these two radicals. The presence of cations in solution has negligible effect on the rate constants for $$^{cdot}$$OH and SO$$_{4}^{cdot-}$$. However, for NO$$_{3}^{cdot}$$, the rate constants is not in proportional to H-atom number in crown ethers, and the 12-crown-4 is most reactive compared with the others. For the studied crown ethers, the rate constants of these oxidative radicals have the order: $$^{cdot}$$OH $$>$$ SO$$_{4}^{cdot-}$$ $$>$$ NO$$_{3}^{cdot}$$. This is the first report on the kinetic behavior of crown ethers with NO$$_{3}^{cdot}$$, and it would be helpful for the understanding of stability of crown ethers in the nuclear fuel reprocessing.

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:28 Percentile:72.42(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:176 Percentile:99.41(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:7 Percentile:49.81(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

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:169 Percentile:98.47(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

Radiation effects on hydroxypropyl methylcellulose phthalate in aqueous system

Xu, L.*; Yue, Z.*; Wang, M.*; Zhai, M.*; Yoshii, Fumio; Seko, Noriaki; Peng, J.*; Wei, G.*; Li, J.*

Nuclear Instruments and Methods in Physics Research B, 265(1), p.394 - 398, 2007/12

 Times Cited Count:5 Percentile:40.99(Instruments & Instrumentation)

A water insoluble cellulose derivative, hydroxypropyl methylcellulose phthalate (HPMCP) hydrogels, was converted to Na type to form hydrogel in paste-like status by radiation crosslinking. Mechanism for radiation crosslinking of cellulose-derivatives in paste-like status was discussed. Crosslinkers, i.e., methyl $$N,N$$-bis-acrylamide (MBA) or ethyleneglycol dimethacrylate (EGDMA) has been used to decrease gelation dose (Dg) of synthesis HPMCP hydrogels and improve its mechanical properties. MBA was found to be more effective for accelerating the crosslinking of HPMCP than EGDMA. Swelling degree of HPMCP hydrogel in many kinds ofsalt solutions followed Hofmeister series, which is ubiquitous in polyelectrolyte hydrogel. Specific reswelling was observed in concentrated KF solution, implying a very strong F$$^{-}$$ binding ability of benzyl group. The comprehensive results obtained in this study will be utilized on the design of HPMCP-based controlled release system.

Journal Articles

Elongation of plasma channel for electron acceleration

Chen, L.-M.; Nakajima, Kazuhisa; Hong, W.*; Hua, J. F.*; Kameshima, Takashi; Kotaki, Hideyuki; Sugiyama, Kiyohiro*; Wen, X.*; Wu, Y.*; Tang, C.*; et al.

Chinese Optics Letters, 5(S1), p.S133 - S135, 2007/05

Journal Articles

Self-guiding of 100 TW femtosecond laser pulses in centimeter-scale underdense plasma

Chen, L.-M.; Kotaki, Hideyuki; Nakajima, Kazuhisa*; Koga, J. K.; Bulanov, S. V.; Tajima, Toshiki; Gu, Y. Q.*; Peng, H. S.*; Wang, X. X.*; Wen, T. S.*; et al.

Physics of Plasmas, 14(4), p.040703_1 - 040703_4, 2007/04

 Times Cited Count:36 Percentile:75.67(Physics, Fluids & Plasmas)

An experiment for the laser self-guiding studies has been carried out with 100 TW laser pulse interaction with the long underdense plasma. Formation of extremely long plasma channel with its length, about 10 mm, 20 times above the Rayleigh length is observed. The self-focusing channel features such as the laser pulse significant bending and the electron cavity formation are demonstrated experimentally for the first time.

Journal Articles

Key quantities for ITB formation and sustainment

Fujita, Takaaki; Aniel, T.*; Barbato, E.*; Behn, R.*; Bell, R. E.*; Field, A. R.*; Fukuda, Takeshi*; Gohil, P.*; Ida, Katsumi*; Imbeaux, F.*; et al.

Europhysics Conference Abstracts, 27A, 4 Pages, 2003/00

no abstracts in English

Journal Articles

Conductometric study of the radial track etch rate; Free shape analysis

Peng, L.; Apel, P.*; Maekawa, Yasunari; Yoshida, Masaru

Nuclear Instruments and Methods in Physics Research B, 168(4), p.527 - 532, 2000/08

 Times Cited Count:12 Percentile:62.25(Instruments & Instrumentation)

no abstracts in English

Oral presentation

Guiding of 100 TW Relativistic Laser Pulses by 10 mm Plasma Channels

Koga, J. K.; Chen, L.-M.; Kotaki, Hideyuki; Nakajima, Kazuhisa; Bulanov, S. V.; Tajima, Toshiki; Gu, Y. Q.*; Peng, H. S.*; Hua, J. F.*; An, W. M.*; et al.

no journal, , 

First experiments for electron acceleration with the laser-gas plasma interaction have been carried out with 30 fs, 100 TW relativistic Ti:Sapphier laser pulse into a long slit (1.2 $$times$$ 10 mm$$^2$$) gas plasma. The 10 mm length plasma channel formed that was longer than 20 times the Rayleigh length. Plasma density was the key factor for this long channel stimulation under 100 TW laser pulse irradiation that was much higher than critical power for relativistic self-focusing. For the first time, channel characteristics such as laser bending, hosing and cavity formation were demonstrated experimentally. In case of long channel guiding, accelerated electron bunch was tightly collimated with low emmitance $$< 0.8 pi$$ mm mrad and quasi-monoenergetic electron bunch ($$sim$$ 70 MeV) was obtained as well. Accelerated electron charge current with electron energy $$>$$ 1 MeV was $$sim$$ 10 nC/shot which was highest value in laser accelerator, to our knowledge, and ascribed to the contribution of long plasma channel. These well controlled laser-driven acceleration is an important cornerstone of relativistic engineering.

Oral presentation

Laser electron acceleration in cm-scale capillary-discharge plasma channel

Kameshima, Takashi; Kotaki, Hideyuki; Kando, Masaki; Daito, Izuru; Kawase, Keigo; Fukuda, Yuji; Chen, L. M.*; Homma, Takayuki; Kondo, Shuji; Esirkepov, T. Z.; et al.

no journal, , 

The acceleration method of laser plasma electron acceleration has very strong electric field, however, the acceleration length is veryshort. Hence, the energy gain of electron beams were confined to be approximately 100 MeV. Recently, this problem was solved by using discharge capillary. The feature of plasma was used that high dense plasma has low refractive index. Distributing plasma inside capillary as low dense plasma is in the center of capillary and high dense plasma is in the external side of capillary can make a laser pulse propaget inside capillary with initial focal spot size. Experiments with capillary were performed in China Academy of Engineering Physics (CAEP) and Japan Atomic Energy Agency (JAEA). We obtained the results of 4.4 J laser pulse optical guiding in 4 cm capillary and 0.56 GeV electron production in CAEP in 2006, and 1 J laser pulse optical guiding in 4 cm capillary and electron beams productions.

Oral presentation

Radiation-induced degradation of cellulose in the 1-butyl-3-methylimidazolium chloride ionic liquid

Peng, J.; Cai, D.*; Hao, Y.*; Zhai, M.*; Lin, M.; Katsumura, Yosuke

no journal, , 

1-butyl-3-methylimidazolium chloride ([Bmim]Cl) ionic liquid has demonstrated good solubility for cellulose without derivation. In this work, the radiation effects on microcrystalline cellulose (MCC) in [Bmim]Cl has been investigated by measuring the molecular weight of MCC after $$gamma$$-ray irradiation. The radiation-induced degradation kinetics of MCC was studied and Gd value of MCC was calculated.

Oral presentation

Pulse radiolysis study of liquid hydrocarbons; Observation and determination of alkyl radicals

Peng, J.; Wan, L. K.*; Lin, M.; Yan, Y.*; Muroya, Yusa*; Katsumura, Yosuke

no journal, , 

Oral presentation

Thermal stability and radiation stability of 1-allyl-3-methylimidazolium chloride ionic liquid used as cellulose solvent

Peng, J.; Hao, Y.*; Hu, S.*; Lin, M.; Katsumura, Yosuke

no journal, , 

The thermal stability of 1-allyl-3-methylimidazolium chloride ionic liquid ([Amim]Cl) was studied by using isothermal thermogravimetric analysis and TG/MS. In addition, the radiation stability of [Amim]Cl was investigated by using UV and NMR. During the heating process, the allyl side chain of [Amim]Cl appears to associate with anion Cl and dissociate from imidazole ring with equal probability as the methyl group does. During the $$gamma$$ irradiation, although the darkening of color in irradiated [Amim]Cl was observed, the chemical structure of [Amim]Cl is stable at dose of 500 kGy under nitrogen atmosphere.

22 (Records 1-20 displayed on this page)