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Sasaki, Akira; Nishihara, Katsunobu*; Sunahara, Atsushi*; Nishikawa, Takeshi*; Koike, Fumihiro*; Tanuma, Hajime*
no journal, ,
no abstracts in English
-ray spectrum mixed in the 565 keV mono-energetic neutron calibration fieldTanimura, Yoshihiko; Tsutsumi, Masahiro
no journal, ,
no abstracts in English
Sato, Tatsuhiko; Niita, Koji*
no journal, ,
The review of simulation codes applicable to neutron dosimetry will be presented at the meeting.
Tsuji, Toshiyuki*; Kobayashi, Akira*; Yoshida, Eiji*; Ichihara, Chikara*; Adachi, Shigeto*; Ishii, Yasuyuki; Haga, Junji
no journal, ,
no abstracts in English
Yamauchi, Toshihiko; Nakagaki, Keita; Kanno, Yoshinori*; Kobayashi, Seiji*; Takemoto, Ryo*
no journal, ,
no abstracts in English
Kamiura, Yoshitomo*; Umezawa, Kenji*; Teraoka, Yuden; Yoshigoe, Akitaka
no journal, ,
Nitrogen ion beams (N
, N
) with kinetic energy of 2.5 keV were irradiated to poly W surfaces with thin oxide films at room temperature. The element ratio and depth profile of chemical bonding states for the modified-W surface were analyzed by photoemission spectroscopy with the surface reaction analysis apparatus at the BL23SU in the SPring-8. W4f photoemission spectra were observed using synchrotron radiation of 592 eV for the W surfaces which were irradiated by nitrogen ion beams with the dose of 2
10
ions/cm
. Nitridized W in addition to metal W4f
, W4f
and their oxidized components were observed. N1s photoemission spectra, which were simultaneously measured, showed a chemical shift in the high energy side. This implies that nitrogen atoms were in the dpper positions.
Yamamoto, Yoshihisa*; Togashi, Hideaki*; Kato, Atsushi*; Suemitsu, Maki*; Narita, Yuzuru*; Teraoka, Yuden; Yoshigoe, Akitaka
no journal, ,
Formation processes of one atomic oxide layer and time evolution of chemical bonding states at the interface were investigated by using real-time photoemission spectroscopy with synchrotron radiation. Time evolutions for oxide components (Si
:n=1-4) of Si2p photoemission spectra, observed in the conditions of 813K substrate temperature and 1.110
Pa O pressure, were analyzed. Rapid increase of Si
component until oxygen dose of 10 L indicates existance of a reaction path through the Si state. On the other hand, contrary to the Si(001) oxidation, the Si
component was larger than the Si
component during oxidation. Reaction mechanisms was considered from these facts. Oxygen insertion into chain-like Si-Si bonds densely existing on the (110) surface (A bond) and Si-Si bonds on the (-110) surface is an origin of the first layer oxidation at Si(110) surface. The A bonds may be oxidized partially due to storage of oxidation strains.
Togashi, Hideaki*; Yamamoto, Yoshihisa*; Goto, Seiichi*; Takahashi, Yuya*; Nakano, Takuya*; Konno, Atsushi*; Suemitsu, Maki*; Asaoka, Hidehito; Yoshigoe, Akitaka; Teraoka, Yuden
no journal, ,
Oxygen-adsorbed Si(110)-162 surfaces at room temperature and their thermally-treated surfaces were analyzed by real-time photoemission spectroscopy with synchrotron radiation (SR-PES) and scanning tunneling microscopy (STM). Thermal stability of the oxygen-adsorbed Si(110) surfaces was clearified. By thermal annealing of Si(110) surface exposed to 10L oxygen gas at room temperature, photoemission peak positions of Si and Si components were shifted to higher energy side by 0.20eV and 0.12eV,respectively, and reached nearly to those of thermal oxide films. This behaviour is due to change of Si-O-Si bond angle and Si-O bond length. The STM observation for Si(110) surfaces revealed that the oxygen-adsorbed surface structure changed to the condensed oxide structure by thermal annealing. These SR-PES and STM results showed that the oxygen-adsorbed Si(110)-162 structure was metastable and changed to more stable condensed oxide structure by thermal annealing.
Otobe, Tomohito
no journal, ,
The optical breakdown is the most important process to control and manipulate the dielectrics by the intense laser field. However, the first-principle simulation for this process has not been studied. In this study, we employ the time-dependent density functional theory (TD-DFT) to describe the electron dynamics of many electron system. Our computational results shows that the electron excitation occurs around the electric bond and the above threshold photo-absorption process which is similar to the atom or molecular case.
oxidation of H-terminated Si(110) surfaceNakano, Takuya*; Togashi, Hideaki*; Matsumoto, Mitsutaka*; Yamamoto, Yoshihisa*; Suzuki, Yasushi*; Teraoka, Yuden; Yoshigoe, Akitaka; Suemitsu, Maki*
no journal, ,
Time evolution of oxide layers in the H-terminated Si(110) surface by the UV/O treatment at room temperature was observed by photoemission spectroscopy with synchrotron radiation. Special oxidation mechanisms for the H-terminated Si(110) surface were found. Si(110) surfaces were hydrogenated by HF treatments. The surface was irradiated and oxidized by UV light (253.7, 184.9 nm) of a low pressure Hg lamp in the air. The UV/O irradiation time dependence of oxide thickness showed a step-wise profile. The step width was about 0.2 nm. The value is close to one oxide layer thickness (0.19 nm) for the Si(110) surface. Si atoms at the Si(110) surface are categolized to A bonds which are chain-like dense bonds, and B bonds which connect up and down A bond chains. The step-wise oxidation behaviour is reasonable if oxidation at the B bonds, in which oxidation strain is smaller than that of A bonds, has larger reaction rate than at the A bonds.
molecular beamOkada, Michio*; Vattuone, L.*; Moritani, Kosuke*; Gerbi, A.*; Savio, L.*; Yoshigoe, Akitaka; Teraoka, Yuden; Rocca, M.*; Kasai, Toshio*
no journal, ,
Initial oxidation processes at Cu(100) and Cu(410) surfaces by hyperthermal oxygen molecular beams (HOMB) have been investigated. In order to make clear effects of surface temperature, oxidation behaviour of steps at the Cu(410) surface, which had a moderate oxidation rate, was studied by high energy-resolution X-ray photoemission spectroscopy at the BL23SU in the SPring-8. Consequently, formation of CuO was observed at room temperature by using HOMB of about 2 eV. And metastable CuO was formed at 100 K. These facts indicate that interest surface layers can be formed by controlling incident energy of oxygen molecular beams and surface temperature.
-ray irradiation effects on 6H-SiC MOSFET fabricated using dry oxidationIwamoto, Naoya; Oshima, Takeshi; Onoda, Shinobu; Kojima, Kazutoshi*; Kawano, Katsuyasu*
no journal, ,
no abstracts in English
To, Kentaro; Yamagishi, Hideshi; Soyama, Kazuhiko; Ochi, Atsuhiko*; Tanimori, Toru*
no journal, ,
Neutron scattering experiment using high intensity pulsed neutrons will be carried out in Materials and Life Science Facility at J-PARC. Several features are desired for neutron detectors in the experiments. The detectors require features such as a good spatial resolution, high detection efficiency, and fast response. In view of these requirements, we have developed a 2D position sensitive neutron detector system consist of micro-pattern detector array as detection device. In this presentation, characteristics of the 2D micro-pixel gas chamber (MPGC) under Cf-252 neutron irradiation are reported. The irradiation experiments were carried out using a mixture gas of helium and carbon tetrafluoride with total pressures of 4 and 5 atm. Signal pulse peak of neutrons can be identified and be discriminated easily from background noise generated in lower channels. Here, degradation of gas gain arisen from a charge up effect was not observed in our MPGC system.
Akahane, Yutaka; Aoyama, Makoto; Sugiyama, Akira; Kubo, Ryoichi; Ogawa, Kanade; Tsuji, Koichi; Yamakawa, Koichi
no journal, ,
A diode-pumped, cryogenically-cooled Yb:LuLiF
regenerative amplifier has been developed for the first time to our knowledge, which generated 6-mJ, 13-ps pulses at 999 nm wavelength without a pulse compressor.
Sagisaka, Akito; Daido, Hiroyuki; Ma, J.-L.; Pirozhkov, A. S.; Mori, Michiaki; Yogo, Akifumi; Ogura, Koichi; Orimo, Satoshi; Nishiuchi, Mamiko; Kiriyama, Hiromitsu; et al.
no journal, ,
no abstracts in English
-FeSi/Si(100) interface using ion irradiated Si substrateSasase, Masato*; Yamamoto, Hiroyuki; Yamaguchi, Kenji; Shamoto, Shinichi
no journal, ,
Beta iron disilicide thin film has been fabricated on Si substrate by means of ion beam sputter deposition method. By 1 keV irradiation at the fluence of 310
ions/m, epitaxially grown -FeSi film has been obtained on Si(100) subatrate with atomically smooth interface.
Maekawa, Masaki; Kawasuso, Atsuo; Hirade, Tetsuya; Miwa, Yukio
no journal, ,
We developed the scanning positron microscope. By scanning the positron microbeam which diameter is several micrometers, spatial distributions of annihilation rays can be obtained. It becomes possible to acquire the two-dimensional distributions of vacancy-type defects, or to perform the defect observation in the selected area. A small sealed sodium-22 source (effective diameter of 2 mm, 55 MBq) developed by us is used as positron source. Using a objective lens, a positron microbeam of 1.9 micrometer is formed. When the stainless steel which has stress corrosion cracking is observed, we found defective areas far from the tip of crack. Those cannot be detected by conventional optical and electron microscope.
Yamazaki, Tatsuya; Asaoka, Hidehito; Taguchi, Tomitsugu; Shamoto, Shinichi; Toyoshima, Yasutake*
no journal, ,
no abstracts in English
Koike, Masato; Kawazoe, Tadashi*; Imazono, Takashi; Miyauchi, Shinji*; Sano, Kazuo*; Otsu, Motoichi*
no journal, ,
Multilayer gratings having a groove density of 7600 lines/mm have been fabricated by depositing Mo/SiO multilayer coating on the surface of laminar-type master gratings fabricated by use of a new lithography machine based on optical near field technologies. The diffraction efficiency was measured by reflectometers in the wavelength range of 0.7-2.0 nm at a synchrotron radiation facility. The multilayer grating having a groove depth of 3nm and multilayer period length of 5.33 nm showed diffraction efficiencies of 0.028 at 0.70 nm and 0.005 at 2.0 nm were observed for the incidence angles of 88.020 deg and 80.764 deg, respectively. We also discuss the analysis of the roughness in terms of Debye-Waller factor comparing the experimental and theoretical diffraction efficiencies as well as the groove depth using experimental efficiency minima of the zero-th order light.
7 by OYoshigoe, Akitaka; Teraoka, Yuden
no journal, ,
In order to clarify the O adsorption on Si(111)-77, we investigated surface temperature dependence of initial sticking probability (S0) by synchrotron radiation real-time O1s XPS. All experiments were performed at SUREAC2000 of BL23SU in SPring-8. Translational energy (En) is controlled up to 2.3eV. The variable leak valve was used to perform the 0.03eV exposure condition. The S0 is evaluated to be the differential value at the zero dosage in the oxygen uptake curve. In the condition observed for negligibly small variation of S0 depending on En (0.15eV, 2.23eV), the Ts dependence is not observed within the margin of error. This result implys that the direct adsorption mechanism is dominant in this energy region. On the other hand, we found that the S0 decreases with increasing Ts and thus the trapping mediated adsorption mechanism is dominant in the energy condition of 0.03eV and 0.06eV. These results are consistent with the reaction dynamics observed in En dependence of S0.