-induced total reaction cross sections based on the intranuclear cascade model

Nakano, Masahiro*; Yamaguchi, Yuji; Furuta, Toshimasa*; Uozumi, Yusuke*

Physical Review C, 110(6), p.064620_1 - 064620_5, 2024/12

https://doi.org/10.1103/PhysRevC.110.064620

Alpha-induced total reaction cross sections in the low-energy region below 400 MeV are investigated using an intranuclear cascade model based on the extended framework for nucleon- and deuteron-induced reactions. Experimental data for C, Si, Ca, and Pb targets are reproduced well by calculations performed with reasonable parameters close to those determined in other studies. It is shown that two effects, namely, discrete level constraint (DLC) and the Coulomb effect, provide important contributions that depend on the incident- energy and target. The DLC effect is limited to a narrow region of low-energy and is very important in light targets. The Coulomb effect is decisive on cross sections in Pb, while the DLC contribution for the heavy target is small. It is concluded that this trend in the contribution of both effects is consistent with proton- and deuteron-induced total reaction cross sections.

Estimation method for residual sodium amount on unloaded dummy fuel assembly

Kawaguchi, Munemichi; Hirakawa, Yasushi; Sugita, Yusuke; Yamaguchi, Yutaka

Nuclear Technology, 210(1), p.55 - 71, 2024/01

https://doi.org/10.1080/00295450.2023.2214261

This study has developed an estimation method for residual sodium film and sodium lumps on dummy fuel pins in Monju and demonstrated sodium draining behavior through gaps among the pins, experimentally. The amounts of the residual sodium on the surface of the pins were measured using the three-type test specimens: (a) single pin, (b) 7-pin assembly, and (c) 169-pin assembly. The experiments revealed that the withdrawal speed of the pins and improvement of the sodium wetting increased drastically the amounts of the residual sodium. Furthermore, the experiments using the 169-pin assembly measured the practical amounts of the residual sodium in the dummy fuel assembly of short length and demonstrated sodium draining behavior through the dummy fuel assembly. The estimation method includes four models: a viscosity flow model, Landau-Levich-Derjaguin (LLD) model, an empirical equation related to the Bretherton model, and a capillary force model in a tube. The calculation predicted comparable amounts of the residual sodium with the experiments. An uncertain of the sodium wetting effects were close to 1.8 times the estimation values of the LLD model. With this estimation method, the amounts of the residual sodium on the unloaded Monju dummy fuel assembly can be evaluated.

The Translational, rotational, and phonon dynamics of water in ZrO/water nanofluid

Yoshida, Koji*; Sanada, Yusuke*; Yamaguchi, Toshio*; Matsuura, Masato*; Tamatsukuri, Hiromu; Uchiyama, Hiroshi*

Journal of Molecular Liquids, 366, p.120218_1 - 120218_9, 2022/11

https://doi.org/10.1016/j.molliq.2022.120218

Thermally altered subsurface material of asteroid (162173) Ryugu

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.

Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03

https://doi.org/10.1038/s41550-020-01271-2

Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.

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

https://doi.org/10.1126/science.aav7432

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.

Molecular gyrotops with a five-membered heteroaromatic ring; Synthesis, temperature-dependent orientation of dipolar rotors inside the crystal, and its birefringence change

Masuda, Toshiyuki*; Arase, Junko*; Inagaki, Yusuke*; Kawahara, Masatoshi*; Yamaguchi, Kentaro*; Ohara, Takashi; Nakao, Akiko*; Momma, Hiroyuki*; Kwon, E.*; Setaka, Wataru*

Crystal Growth & Design, 16(8), p.4392 - 4401, 2016/08

https://doi.org/10.1021/acs.cgd.6b00508

Development of multi-purpose MW gyrotrons for fusion devices

Minami, Ryutaro*; Kariya, Tsuyoshi*; Imai, Tsuyoshi*; Numakura, Tomoharu*; Endo, Yoichi*; Nakabayashi, Hidetaka*; Eguchi, Taku*; Shimozuma, Takashi*; Kubo, Shin*; Yoshimura, Yasuo*; et al.

Nuclear Fusion, 53(6), p.063003_1 - 063003_7, 2013/06

https://doi.org/10.1088/0029-5515/53/6/063003

A Study to control chemical reactions using Si:2p core ionization; Site-specific fragmentation

Nagaoka, Shinichi*; Fukuzawa, Hironobu*; Prmper, G.*; Takemoto, Mai*; Takahashi, Osamu*; Yamaguchi, Takuhiro*; Kakiuchi, Takuhiro*; Tabayashi, Kiyohiko*; Suzuki, Isao*; Harries, J.; et al.

Journal of Physical Chemistry A, 115(32), p.8822 - 8831, 2011/07

https://doi.org/10.1021/jp203664r

Azimuthal correlations of electrons from heavy-flavor decay with hadrons in and Au+Au collisions at = 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

https://doi.org/10.1103/PhysRevC.83.044912

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.

Observation of spontaneously excited waves in the ion cyclotron frequency range on JT-60U

Ichimura, Makoto*; Higaki, Hiroyuki*; Kakimoto, Shingo*; Yamaguchi, Yusuke*; Nemoto, Tatsuki*; Katano, Makoto*; Ishikawa, Masao; Moriyama, Shinichi; Suzuki, Takahiro

Nuclear Fusion, 48(3), p.035012_1 - 035012_7, 2008/03

https://doi.org/10.1088/0029-5515/48/3/035012

In this paper, experimental observations of spontaneously excited waves in the ion cyclotron range of frequency (ICRF) on JT-60U are described. The fluctuations in ICRF are driven by the presence of non-thermal ion distribution in magnetic confinement plasmas. Two types of magnetic fluctuations are detected: one is due to high energy D ions from neutral beam injections and the other is due to fusion products (FPs) of He and T ions. These fluctuations have been reported as ion cyclotron emissions (ICEs) in the burning plasma experiments on large tokamaks. This paper describes the first measurement of the spatial structures of the excited modes in the poloidal and toroidal directions. It is confirmed by using ICRF antennas as magnetic probes that all modes excited spontaneously have magnetic components and couple to the antenna straps. The modes due to D ions have small toroidal wave number and will behave as electrostatic waves. On the while, the measurement of finite in the modes due to FP ions supports the excitation of the Alfvn waves is the possible origin of FP-ICEs. It is also confirmed that the excited modes due to FP ions have different wave structures and are suggested to be in the different branch of the Alfvn waves, that is, the fast Alfvn wave and the slow Alfvn wave. Frequency peaks due to FP ions are sometimes split into doublet shape as observed in JET experiments. The phase differences of both peaks are measured and indicate that two waves are traveling in both toroidal directions. Both beam-driven ICEs and FP-ICEs are observed and those spatial structures are obtained on JT-60U.