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titanium alloys strong and ductileChong, Y.*; Gholizadeh, R.*; Guo, B.*; Tsuru, Tomohito; Zhao, G.*; Yoshida, Shuhei*; Mitsuhara, Masatoshi*; Godfrey, A.*; Tsuji, Nobuhiro*
Acta Materialia, 257, p.119165_1 - 119165_14, 2023/09
Times Cited Count：5 Percentile：87.83(Materials Science, Multidisciplinary)Metastable titanium alloys possess excellent strain-hardening capability, but suffer from a low yield strength. As a result, numerous attempts have been made to strengthen this important structural material in the last decade. Here, we explore the contributions of grain refinement and interstitial additions in raising the yield strength of a Ti-12Mo (wt.%) metastable titanium alloy. Surprisingly, rather than strengthening the material, grain refinement actually lowers the ultimate tensile strength in this alloy. This unexpected and anomalous behavior is attributed to a significant enhancement in strain-induced 
martensite phase transformation, where in-situ synchrotron X-ray diffraction analysis reveals, for the first time, that this phase is much softer than the parent phase. Instead, a combination of both oxygen addition and grain refinement is found to realize an unprecedented strength-ductility synergy in a Ti-12Mo-0.3O (wt.%) alloy. The advantageous effect of oxygen solutes in this ternary alloy is twofold. Firstly, solute oxygen largely suppresses strain-induced transformation to the martensite phase, even in a fine-grained microstructure, thus avoiding the softening effect of excessive amounts of martensite. Secondly, oxygen solutes readily segregate to twin boundaries, as revealed by atom probe tomography. This restricts the growth of 
deformation twins, thereby promoting more extensive twin nucleation, leading to enhanced microstructural refinement. The insights from our work provide a cost-effective rationale for the design of strong yet tough metastable titanium alloys, with significant implications for more widespread use of this high strength-to-weight structural material.
Yoshida, Shuhei*; Fu, R.*; Gong, W.; Ikeuchi, Takuto*; Bai, Y.*; Feng, Z.*; Wu, G.*; Shibata, Akinobu*; Hansen, N.*; Huang, X.*; et al.
IOP Conference Series; Materials Science and Engineering, 1249, p.012027_1 - 012027_6, 2022/08
Times Cited Count：0 Percentile：0.83(Metallurgy & Metallurgical Engineering)
(001) surface using supersonic seeded oxygen molecular beamKatsube, Daiki*; Ono, Shinya*; Takayanagi, Shuhei*; Ojima, Shoki*; Maeda, Motoyasu*; Origuchi, Naoki*; Ogawa, Arata*; Ikeda, Natsuki*; Aoyagi, Yoshihide*; Kabutoya, Yuito*; et al.
Langmuir, 37(42), p.12313 - 12317, 2021/10
Times Cited Count：1 Percentile：6.39(Chemistry, Multidisciplinary)We investigated the oxidation of oxygen vacancies at the surface of anatase TiO(001) using supersonic seeded molecular beam (SSMB) of oxygen. The oxygen vacancies at the top-surface and sub-surface could be eliminated by the supply of oxygen using an SSMB. These results indicate that the interstitial vacancies can be mostly assigned to oxygen vacancies, which can be effectively eliminated by using an oxygen SSMB. Oxygen vacancies are present on the surface of anatase TiO(001) when it is untreated before transfer to a vacuum chamber. These vacancies, which are stable in the as-grown condition, could also be effectively eliminated using the oxygen SSMB.
Kim, S. H.*; Ichikawa, Yudai; Sako, Hiroyuki; Hasegawa, Shoichi; Hayakawa, Shuhei*; Nanamura, Takuya*; Sato, Susumu; Tanida, Kiyoshi; Yoshida, Junya; 11 of others*
Nuclear Instruments and Methods in Physics Research A, 940, p.359 - 370, 2019/10
Times Cited Count：5 Percentile：48.18(Instruments & Instrumentation)Ekawa, Hiroyuki; Ashikaga, Sakiko; Hasegawa, Shoichi; Hashimoto, Tadashi; Hayakawa, Shuhei; Hosomi, Kenji; Ichikawa, Yudai; Imai, Kenichi; Kimbara, Shinji*; Nanamura, Takuya; et al.
Progress of Theoretical and Experimental Physics (Internet), 2019(2), p.021D02_1 - 021D02_11, 2019/02
Times Cited Count：25 Percentile：83.41(Physics, Multidisciplinary)Kimbara, Shinji*; Ekawa, Hiroyuki; Hayakawa, Shuhei; Yoshida, Junya; 12 of others*
Progress of Theoretical and Experimental Physics (Internet), 2019(1), p.011H01_1 - 011H01_9, 2019/01
Times Cited Count：4 Percentile：36.25(Physics, Multidisciplinary)A development has been achieved in the identification method of the charges 1 to 5 of nuclides from the decay of double hypernuclei to be uniquely recognized by their nuclear species. The method is basically the measurement of track volume by the widths, depths, and angles of tracks of exposed nuclei of 
H, 
He, 
Li, 
Be, and 
B in nuclear emulsion at Riken Projectile-fragment Separator of RIKEN Radioactive Isotope Beam Factory. After their calibration by 
particles, we obtained a quadric function to present a unified recognition of tracks with volume ratios of five nuclei to the particles. The function in the emulsion has been applied to a candidate event of a 
hypernucleus for identification of the production and decay processes. We succeeded in recognizing a daughter nuclear fragment of a single-
hypernucleus as 
He with a likelihood ratio of 0.9; the process was then uniquely identified as 
+ 
N 
Be + 
He + 
.
Wakai, Eiichi; Kim, B. J.; Nozawa, Takashi; Kikuchi, Takayuki; Hirano, Michiko*; Kimura, Akihiko*; Kasada, Ryuta*; Yokomine, Takehiko*; Yoshida, Takahide*; Nogami, Shuhei*; et al.
Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 6 Pages, 2013/03
Usuki, Toshiyuki; Yoshida, Katsumi*; Yano, Toyohiko*; Miwa, Shuhei; Osaka, Masahiko
Progress in Nuclear Energy, 53(7), p.1078 - 1081, 2011/09
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)The effects of sintering additives of magnesium silicates, i.e. enstatite (MgSiO
), steatite (MgSiO) and forsterite (MgSiO
), on the fabrication properties and characteristics of the silicon nitride ceramics based inert matrix fuels were experimentally investigated. CeO was selected as simulating element of AmO. Sintered pellets were characterized in term of their densities, thermal conductivities and solubility to nitric acid. The densifications of sintered bodies were enhanced by using additives of magnesium silicates at relative low sintering temperature. The relative density of silicon nitride ceramics based inert matrix fuels with forsterite were achieved above 90% at 1723 K. The thermal conductivities of silicon nitride ceramics based inert matrix fuels varied according to sintering temperature, and those sintered at 1923 K were above 34 W/m K. The grain boundary phases in Silicon nitride ceramics based inert matrix fuels found to be dissolved into HNO.
Yoshida, Yoichi*; Yang, J.*; Kondo, Takafumi*; Seki, Shuhei*; Kozawa, Takahiro*; Tagawa, Seiichi*; Shibata, Hiromi*; Taguchi, Mitsumasa; Kojima, Takuji; Namba, Hideki
JAEA-Review 2005-001, TIARA Annual Report 2004, p.183 - 185, 2006/01
A heavy-ion-pulse radiolysis technology was developed using a single-photon-counting system. In the system, the ion beam was injected a thin scintillator before irradiating the sample. The light emitted from the scintillator by the ion irradiation was used as analyzing source to detect the absorption of primary species in water. Measurement of time-dependent absorption of hydrated electrons in water was achieved using the system, which demonstrates the usefulness of this technique.
Yoshida, Yoichi*; Yang, J.*; Seki, Shuhei*; Saeki, Akinori*; Tagawa, Seiichi*; Shibata, Hiromi*; Taguchi, Mitsumasa; Kojima, Takuji; Namba, Hideki
JAERI-Review 2003-033, TIARA Annual Report 2002, p.145 - 146, 2003/11
no abstracts in English
Seki, Shuhei*; *; *; *; Yoshida, Yoichi*; Kudo, Hisaaki; Sugimoto, Masaki; Morita, Yosuke; Seguchi, Tadao; *; et al.
Journal of Physical Chemistry B, 103(15), p.3043 - 3048, 1999/00
Times Cited Count：47 Percentile：77.87(Chemistry, Physical)no abstracts in English
N-based fuelsYano, Toyohiko*; Yoshida, Katsumi*; Imai, Masamitsu*; Miwa, Shuhei; Osaka, Masahiko
no journal, ,
no abstracts in English
Usuki, Toshiyuki*; Yoshida, Katsumi*; Imai, Masamitsu*; Yano, Toyohiko*; Miwa, Shuhei; Osaka, Masahiko
no journal, ,
no abstracts in English
Usuki, Toshiyuki; Yoshida, Katsumi*; Yano, Toyohiko*; Miwa, Shuhei; Osaka, Masahiko
no journal, ,
Minor actinides (MA) have lasting radio-toxicity. One of the possible ways to reduce radio-toxicity is transmutation of MA using nuclear reactors. Inert matrix (IM) is applied to host material for MA in transmutation. Silicon nitride (SiN) ceramics considered to be a candidate material of IM since it has a high thermal conductivity and shows good resistance to neutron irradiation. In this study, We proposed fabrication of silicon nitride ceramics based IMFs with Ce as simulating element and with magnesium silicates, i.e. enstatite (MgSiO), steatite (MgSiO) and forsterite (MgSiO), as additives. The sintered densities of SiN-based IMFs with forsterite was above 96 % theoretical 1723 K. Furthermore, The thermal conductivities of IMFs sintered at 1923 K were above 34 W/mK.
Kiriyama, Hiromitsu; Ochi, Yoshihiro; Mori, Michiaki; Tanaka, Momoko; Okada, Hajime; Kosuge, Atsushi; Yoshida, Fumiko; Shimomura, Takuya; Sasao, Hajime; Nakai, Yoshiki*; et al.
no journal, ,
We describe two specific high intensity laser systems that are being developed in our laboratory for many applications such as high field science and nonlinear optics. We report on an ultra-high intensity petawatt-class Ti:sapphire chirped-pulse amplification laser system that can produce a pulse energy of 
18 J with 30 fs pulse duration for studying extremely high intensity laser matter interaction process and a small-scaled Yb:YAG chirped-pulse amplification laser system that can generate a pulse energy of 100 m J of 500 fs pulse duration for compact, high efficiency, high repetition system. We discuss the basic design aspects and present the results from our experimental investigations of these laser systems.
Yoshida, Junya; Ekawa, Hiroyuki; Hayakawa, Shuhei; Kasagi, Ayumi*; Nishimura, Shin*; Nyaw, A. N. L.*; Yoshimoto, Masahiro*; Nakazawa, Kazuma*
no journal, ,
J-PARC E07, an experiment with emulsion technique, is carrying out to detect 10 times higher statistics of double hypernuclei compared to the past experiments. This experiment aims to obtain quantitative data on baryon-baryon interaction, such as - and -nucleon interaction, by the mass measurement of various double hypernuclei. We completed beam exposure and photographic processing of the all emulsion modules as scheduled in 2018. In this presentation, the current status of the experiment, progress of analysis, the detection efficiency, and the schedule are introduced. As of Jan. 2019, we have scanned about 53% of 1300 emulsion sheets at least once. We have detected 22 candidate events of double hypernuclei.
scattering events in the J-PARC E40 experimentNanamura, Takuya; Ichikawa, Yudai; Hayakawa, Shuhei; Yoshida, Junya; Miwa, Koji*; Honda, Ryotaro*; Akazawa, Yuya*; Yamamoto, Takeshi
no journal, ,
Hyperon-nucleon scattering experiment is one of the powerful methods for studying YN interaction. However, it is difficult due to short lifetime of hyperon. 
scattering experiments were performed as KEK E251 and KEK E289 in order to measure the differential cross sections. In these experiments, statistics were limited to less than 100 events and differential cross section had too large statistical errors to restrict baryon-baryon interaction models. J-PARC E40 experiment aims for measuring cross sections of 
scatterings with high statistics (
10000 events) by overcoming difficulties of hyperon-nucleon scattering experiment. By using high rate ( 19M /spill) 
beam and large acceptance spectrometer, we can produce and tag large amount of 
beam. LH
target and surrounding detector system CATCH enable us to reconstruct reactions from two body kinematics. Our experimental group completed 
data taking and about half of 
data taking by 2019 Apr. Left data taking will be performed in the end of this fiscal year.
Yoshida, Junya; Hayakawa, Shuhei; Ekawa, Hiroyuki*; Yoshimoto, Masahiro*; Kasagi, Ayumi*; Lin, P. M.*; Nyaw, A. N. L.*; Nakazawa, Kazuma*
no journal, ,
J-PARC E07 is an experiment with the photographic emulsion technique to detect 10 times higher statistics of double hypernuclei compared to the past experiments. This experiment aims to obtain quantitative data on - and -nucleon interaction, by the mass measurement of various double hypernuclei. As of July 2019, we have scanned about 53% of 1300 emulsion sheets at least once and detected about 30 candidate events of double hypernuclei. We start a study of the branching ratio of the decay mode with the accumulating data. However, the detection efficiency is about half of the designed value. It is due to the rugged surface position of emulsion module. We are developing the correction method to reconstruct its original geometry by using proton tracks which punch through SSD and emulsion sheets.
Katsube, Daiki*; Ono, Shinya*; Takayanagi, Shuhei*; Ojima, Shoki*; Maeda, Motoyasu*; Yoshida, Hikaru*; Nishi, Shizuka*; Yoshigoe, Akitaka; Abe, Masayuki*
no journal, ,
TiO has been extensively studied because of high photocatalytic activity. However, the basic reaction process of photocatalysis has not been understood yet. In this study, the difference in water adsorption reaction between rutile and anatase was clarified using synchrotron radiation soft X-ray photoelectron spectroscopy (XPS). The OH component observed at the higher binding energy side was clearly confirmed in the rutile type TiOTiO, suggesting that the rutile type is more reactive to water adsorption.
-N interaction by measurement of twin hypernuclei with hybrid emulsion method at J-PARCHayakawa, Shuhei; Yoshida, Junya
no journal, ,
The studies of hyperon-nucleon and hyperon-hyperon interactions are necessary for the understanding of general baryon-baryon interaction. Even in the 
= -1 sector such as 
and 
, the available data is limited. As for the = -2 sector such as 
and 
, there are few experimental data. The J-PARC E07 experiment was performed to investigate = -2 hypernuclei at J-PARC K1.8 beam line. Using a K- meson beam with the momentum of 1.81 GeV/c, - hyperons are produced in the quasi-free 
, K
- reaction at a diamond target. A method using combined information between two spectrometers and nuclear emulsion, called hybrid emulsion method, was conducted by using silicon-strip detectors and one hundred eighteen emulsion modules. A twin hypernuclear event, named IBUKI event, was observed with a newly developed scanning system. At the - capture point, two hypernuclei of 
Be and He were the most likely to be produced by the conservation laws of energy and momentum. The reaction process of the IBUKI event was identified as - + N Be + He. The binding energy of - + N system was determined to be 1.27 
0.21 MeV. From the consideration of an excited state, the energy level for Be was interpreted to be the ground state (2-) or the other state of the spin doublet (1-). The IBUKI event was the first event whose binding energy was determined with a little ambiguity. The binding energy indicates a bound state of the -N system by an attractive interaction. In this talk, we would like to report the above result of the IBUKI event.
