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Yamamura, Sota*; Fujiwara, Kota*; Honda, Kota*; Yoshida, Hiroyuki; Horiguchi, Naoki; Kaneko, Akiko*; Abe, Yutaka*
Physics of Fluids, 34(8), p.082110_1 - 082110_13, 2022/08
Times Cited Count:2 Percentile:44.26(Mechanics)Liquid spreading and atomization due to jet impingement in liquid-liquid systems are considered to be crucial for understanding the cooling behavior of high-temperature molten material in a shallow water pool. This phenomenon takes place when a liquid jet enters a pool filled with other immiscible liquid. The jet spreads radially after impinging on the floor while forming a thin liquid film and atomizing droplets. In this paper, we explain the result to quantify the unsteady three-dimensional behavior of the spreading jet by the employment of 3D-LIF measurements and 3-dimensional reconstruction. Under high flow velocity conditions, the phenomena of hydraulic jump and atomization of the liquid film occurred along with the spreading. To evaluate the spreading behavior, a comparison of the jump radius position of the liquid-liquid system as the representative value was made with the one calculated by the existing theory of a gas-liquid system. As the result, the spreading of the liquid film in the liquid-liquid system was suppressed compared with that in the gas-liquid system. Furthermore, the PTV method was successfully used to measure the velocity boundary layer and velocity profile in the liquid film, which are important factors that affect the spreading mechanism of the liquid film. These results revealed that in liquid-liquid systems, shear stress at the liquid-liquid interface causes a decrease in the flow velocity and suppressed the development of the velocity boundary layer. Also, to evaluate the atomization behavior, the number and diameter distribution of the droplets were measured from the acquired 3-dimensional shape data of the jet. As the result, the number of droplets increased with the flow velocity. Based on these results, we concluded that the spreading of the liquid film is affected by such atomization behavior.
Kubo, Kotaro; Fujiwara, Keita*; Tanaka, Yoichi; Hakuta, Yuto*; Arake, Daisuke*; Uchiyama, Tomoaki*; Muramatsu, Ken*
Proceedings of 29th International Conference on Nuclear Engineering (ICONE 29) (Internet), 8 Pages, 2022/08
After the Fukushima Daiichi Nuclear Power Plant accident, the importance of conducting probabilistic risk assessments (PRAs) of external events, especially seismic activities and tsunamis, was recognized. The Japan Atomic Energy Agency has been developing a computational methodology for seismic PRA, called the direct quantification of fault tree using Monte Carlo simulation (DQFM). When appropriate correlation matrices are available for seismic responses and capacities of components, the DQFM makes it possible to consider the effect of correlated failures of components connected through AND and/or OR gates in fault trees, which is practically difficult when methods using analytical solutions or multidimensional numerical integrations are used to obtain minimal cut set probabilities. The usefulness of DQFM has already been demonstrated. Nevertheless, a reduction of the computational time of DQFM would allow the large number of analyses required in PRAs conducted by regulators and/or operators. We; therefore, performed scoping calculations using three different approaches, namely quasi-Monte Carlo sampling, importance sampling, and parallel computing, to improve calculation efficiency. Quasi-Monte Carlo sampling, importance sampling, and parallel computing were applied when calculating the conditional core damage probability of a simplified PRA model of a pressurized water reactor, using the DQFM method. The results indicated that the quasi-Monte Carlo sampling works well at assumed medium and high ground motion levels, importance sampling is suitable for assumed low ground motion level, and that parallel computing enables practical uncertainty and importance analysis. The combined implementation of these improvements in a PRA code is expected to provide a significant acceleration of computation and offers the prospect of practical use of DQFM in risk-informed decision-making.
Kimura, Fumihito*; Yamamura, Sota*; Fujiwara, Kota*; Yoshida, Hiroyuki; Saito, Shimpei*; Kaneko, Akiko*; Abe, Yutaka*
Nuclear Engineering and Design, 389, p.111660_1 - 111660_11, 2022/04
Times Cited Count:3 Percentile:71.05(Nuclear Science & Technology)Horiguchi, Naoki; Yoshida, Hiroyuki; Yamamura, Sota*; Fujiwara, Kota*; Kaneko, Akiko*; Abe, Yutaka*
Proceedings of 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19) (Internet), 14 Pages, 2022/03
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 () of jet production in longitudinally polarized collisions at = 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 = -0.0014 0.0037 at the lowest bin and -0.0181 0.0282 at the highest bin. The measured is compared with the predictions that assume various distributions.
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 , and in collisions at = 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 collisions. We also present the scaling properties such as and scaling and discuss the mechanism of the particle production in collisions. The measured spectra are compared to next-to-leading order perturbative QCD calculations.
Kawase, Keigo; Kando, Masaki; Hayakawa, Takehito; Daito, Izuru; Kondo, Shuji; Homma, Takayuki; Kameshima, Takashi*; Kotaki, Hideyuki; Chen, L. M.*; Fukuda, Yuji; et al.
Nuclear Instruments and Methods in Physics Research A, 637(1, Suppl.), p.S141 - S144, 2011/05
Times Cited Count:7 Percentile:49.05(Instruments & Instrumentation)We report the present status of the sub-MeV X-ray generation via Compton backscattering by using 150-MeV electron beam and the Nd:YAG laser. In particular, we show the result of the X-ray generation experiment and of the laser pulse compression for increasing the X-ray flux.
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 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 collisions.
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 , , and mesons in collisions at = 200 GeV. The spectral shapes of all hadron transverse momentum distributions are well described by a Tsallis distribution functional form with only two parameters, and , determining the high and characterizing the low 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.
Ogino, Haruyuki*; Kono, Takahiko; Yamasoto, Kotaro; Fujiwara, Keiko*; Suzuki, Chihiro*
Nihon Genshiryoku Gakkai-Shi ATOMO, 52(8), p.458 - 461, 2010/08
no abstracts in English
Kawase, Keigo; Kando, Masaki; Hayakawa, Takehito; Daito, Izuru; Kondo, Shuji; Homma, Takayuki; Kameshima, Takashi*; Kotaki, Hideyuki; Chen, L. M.*; Fukuda, Yuji; et al.
JAEA-Conf 2010-002, p.95 - 98, 2010/06
At the previous symposium in Advanced Photon Research, we proposed and demonstrated the laser pulse compression via stimulated Brillouin scattering (SBS) for increasing the flux of the Compton backscattered X rays. After that, we improved the SBS pulse compression system by introducing the image relay in the laser transport line. As a result, we achieve the stably compressed laser pulse with a duration of 2.1 ns and with an energy of 0.84 J. By installing this system into the Compton backscattered X-ray source, the X-ray flux will be increased 3.2 times for the present system at the KPSI-JAEA.
Kawase, Keigo; Kando, Masaki; Hayakawa, Takehito; Daito, Izuru; Kondo, Shuji; Homma, Takayuki; Kameshima, Takashi; Kotaki, Hideyuki; Chen, L.*; Fukuda, Yuji; et al.
Nuclear Physics Review, 26(Suppl.), p.94 - 99, 2009/07
We constructed MeV- and sub-MeV-photon sources by means of Compton backscattering with a laser light and an electron beam at SPring-8 and KPSI-JAEA. MeV-photon source consists of a continuous-wave optically-pumped far infrared laser and an 8-GeV stored electron beam. Sub-MeV-photon source consists of a Nd:YAG pulse-laser and an 150-MeV electron beam accelerated by a microtron. Both source have been succeeded backscattered photon generation. In this talk, I will present characteristics and future prospects of these photon sources.
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki; Shimomura, Takuya*; Tanoue, Manabu*; Akutsu, Atsushi; Okada, Hajime; Motomura, Tomohiro*; Kondo, Shuji; Kanazawa, Shuhei; et al.
JAEA-Conf 2008-007, p.13 - 16, 2008/08
One of the main bottlenecks for the applications of ultrashort and ultrahigh-peak power lasers in high-field physics is a temporal contrast of the pulses. In ultrahigh-peak power lasers, a nanosecond background of the amplified spontaneous emission (ASE) is generated at the same time as the femtosecond pulse. This background is mostly generated in the preamplifier (regenerative, multipass amplifier). Even though the contrast level is usually in the range from 10 to 10, this level is not sufficiently low at relativistic intensities greater than 10W/cm to avoid unwanted pre-plasmas generation. We demonstrated a high-contrast, high-peak power laser with optical parametric chirped-pulse amplification (OPCPA). With the use of OPCPA, contrast is enhanced to better than 710 in a few picoseconds before the main pulse, which corresponds to an improvement of three to four orders in magnitude compared with conventional systems.
Kawase, Keigo; Kando, Masaki; Hayakawa, Takehito; Daito, Izuru; Kondo, Shuji; Homma, Takayuki; Kameshima, Takashi; Kotaki, Hideyuki; Chen, L.-M.; Fukuda, Yuji; et al.
Review of Scientific Instruments, 79(5), p.053302_1 - 053302_8, 2008/05
Times Cited Count:19 Percentile:62.52(Instruments & Instrumentation)Reported in this article is the generation of unique polarized X-rays in the sub-MeV region by means of the Thomson backscattering of the Nd:YAG laser photon with a wavelength of 1064 nm on the 150 MeV electron from the microtron accelerator. The maximum energy of the X-ray photons is estimated to about 400 keV. The total energy of the backscattered X-ray pulse is measured with an imaging plate and a LYSO scintillator. The angular divergence of the X-rays is also measured by using the imaging plate. We confirm that the X-ray beam is polarized according to the laser polarization direction with the Compton scattering method. In addition, we demonstrate the imaging of the object shielded by lead with the generated X-rays.
Kawase, Keigo; Kando, Masaki; Hayakawa, Takehito; Daito, Izuru; Kondo, Shuji; Homma, Takayuki; Kameshima, Takashi; Kotaki, Hideyuki; Chen, L. M.; Fukuda, Yuji; et al.
no journal, ,
We obtained polarized X-rays in the sub-MeV region generated in the Compton backscattering of the Nd:YAG laser photons and the 150 MeV electron beam at KPSI-JAEA. The maximum X-ray energy is 400 keV. There is no light source with tunable polarization in the sub-MeV region at this moment in the world. We present the result of the X-ray generation experiments and the characteristics of the generated X-rays in the meeting.
Kawase, Keigo; Kando, Masaki; Hayakawa, Takehito; Daito, Izuru; Kondo, Shuji; Homma, Takayuki; Kameshima, Takashi; Kotaki, Hideyuki; Chen, L. M.; Fukuda, Yuji; et al.
no journal, ,
We start a study of the Compton backscattered X-ray generation with the Nd:YAG laser photons and the 150 MeV electron beam from the microtron accelerator at KPSI-JAEA. The maximum energy of the generated X-ray is estimated to 400 keV. We report the present status and the future prospects of this study at the meeting.
Kawase, Keigo; Kando, Masaki; Hayakawa, Takehito; Daito, Izuru; Kondo, Shuji; Homma, Takayuki; Kameshima, Takashi; Kotaki, Hideyuki; Chen, L. M.; Fukuda, Yuji; et al.
no journal, ,
We start a study of the Compton backscattered X-ray generation with the Nd:YAG laser photons and the 150 MeV electron beam from the microtron accelerator at KPSI-JAEA. The maximum energy of the generated X-ray is estimated to 400 keV. We report the present status the sub-MeV X-ray source and the future prospects at this workshop.
Kawase, Keigo; Kando, Masaki; Hayakawa, Takehito; Daito, Izuru; Kondo, Shuji; Homma, Takayuki; Kameshima, Takashi; Kotaki, Hideyuki; Chen, L.*; Fukuda, Yuji; et al.
no journal, ,
We succeed the sub-MeV X-ray generation via the Compton backscattering by using the 150-MeV electron beam with the microtron accelerator and the Nd:YAG laser at KPSI-JAEA. The maximum energy of the generated X-rays is 400 keV, and the flux is estimated to be 20 photon/pulse. In this symposium, we present the experimental results and the future prospects for the sub-MeV X-ray generation.
Kawase, Keigo; Kando, Masaki; Hayakawa, Takehito; Daito, Izuru; Kondo, Shuji; Homma, Takayuki; Kameshima, Takashi; Kotaki, Hideyuki; Chen, L. M.*; Fukuda, Yuji; et al.
no journal, ,
After the confirmation of the generation of the Compton backscattered X-rays with Nd:YAG laser and 150 MeV electron beam pulses at last fiscal year, we make some improvements for increase the generated X-ray flux. As one of them, we are developing the laser pulse compression with the stimulated Brillouin scattering (SBS) to obtain a high peak intensity of the Nd:YAG laser. As the SBS medium, we adopt a liquid fluorocarbon which has well achievements for the pulse compression at ILE at Osaka University. We aim the compressed pulse duration to be less than 1 ns. On this meeting we show the present status of the SBS pulse compression system for the Compton backscattering. In addition, we present the recent result of the Compton backscattering experiment without the laser compression technique.
Kawase, Keigo; Kando, Masaki; Hayakawa, Takehito; Daito, Izuru; Kondo, Shuji; Homma, Takayuki; Kameshima, Takashi; Kotaki, Hideyuki; Chen, L. M.*; Fukuda, Yuji; et al.
no journal, ,
After the confirmation of the generation of the Compton backscattered X-rays with Nd:YAG laser and 150 MeV electron beam pulses at last fiscal year, we make some improvements for increase the generated X-ray flux. As one of them, we are developing the laser pulse compression with the stimulated Brillouin scattering(SBS) to obtain a high peak intensity of the Nd:YAG laser. On this meeting we show the present status of the SBS pulse compression system for the Compton backscattering. In addition, we present the recent result of the Compton backscattering experiment without the laser compression technique.