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Toyoshima, Hiroaki*; Hiraga, Kenta*; Ono, Shinya*; Tanaka, Masatoshi*; Ozawa, Kenichi*; Mase, Kazuhiko*; Hirao, Norie; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Baba, Yuji
Photon Factory Activity Report 2011, Part B, P. 102, 2012/00
The knowledge of the interaction between organic molecules and semiconductor surfaces plays an important role in adapting organic semiconductors into the semiconductor technology. In the present study, the process of 
-sexithiophene (-6T) thin layer formation on passivated silicon (Si) surfaces has been investigated in-situ by means of PES, angle-depended NEXAFS (near-edge X-ray absorption fine-structure), SDRS, and RDS. For water-adsorbed Si(001), it was found that the majority of -6T molecules are standing on the substrate. Above 3 nm, most of molecules are standing and constitute well ordered islands or films. For ethylene adsorbed Si(001) on the contrary, some of -6T molecules are flat-lying, resulting in less prominent orientation. Thus, the orientation of molecules depends on the method of passivation, which opens the possibility of controlling the molecular orientation by the surface modification.
(10) and H(0.07) measurable electronic pocket dosimeter for 
- and 
-raysTakahashi, Masa; Sekiguchi, Masato; Miyauchi, Hideaki; Tachibana, Haruo; Yoshizawa, Michio; Kato, Toru*; Yamaguchi, Akihito*
Journal of Nuclear Science and Technology, 45(Suppl.5), p.225 - 228, 2008/06
Times Cited Count：6 Percentile：40.09(Nuclear Science & Technology)Sekiguchi, Masato; Takahashi, Masa; Miyauchi, Hideaki; Tachibana, Haruo; Komuro, Yuji*; Nemoto, Kiyoko*; Okawa, Ikuko*; Yoshizawa, Michio
Proceedings of 2nd Asian and Oceanic Congress Radiological Protection (AOCRP-2) (CD-ROM), p.114 - 117, 2006/10
In the Japan Atomic Energy Research Institute (JAERI), which was merged with the Japan Nuclear Cycle Development Institute into the Japan Atomic Energy Agency in 2005, individual monitoring and dose record keeping for radiation workers have been conducted since 1957. This report outlines the statistics of the number of radiation workers and individual doses, such as annual collective doses, annual average doses, the maximum doses and dose distributions, over the past 48 years from 1957 to 2005. Individual doses were increased due to the augment of trouble and maintenance of new experimental facilities in 1960's. The collective doses and annual average doses in 1960's exceeded 1,200 man-mSv and 0.4mSv, respectively, in some years. Then, consecutive dose reduction efforts made the collective dose significantly decrease to less than 400 man-mSv (
1/3 of the highest) and the average dose to 0.04 mSv (1/10 of the highest). The collective doses in recent years keep almost constant even though radiation works increase in some high-contaminated hot laboratories for the decontamination and maintenance of experimental equipments. It was found from the analysis of cumulative distributions that there was a specific work-group exposed to significantly high dose compared with other workers.
Shiraishi, Akemi; Sekiguchi, Masato; Tachibana, Haruo; Yoshizawa, Michio; Komuro, Yuji*; Nemoto, Kiyoko*; Okawa, Ikuko*
JAEA-Data/Code 2006-014, 36 Pages, 2006/06
JAEA-Data-Code-2006-014.pdf:2.46MB
In Japan Atomic Energy Research Institute (JAERI), individual monitoring and dose data recording for radiation workers have been conducted since 1957, the next year of which JAERI was established. This report compiles the statistics of individual doses, such as average doses, collective doses, the number of radiation workers and dose distributions, over the past 48 years from 1957 to 2005, when JAERI merged with Japan Nuclear Cycle Development Institute into Japan Atomic Energy Agency. Transition of the statistics showed the history of radiation works in JAERI and many efforts for dose reduction based on the ALARA principle recommended by ICRP. In addition, it was found from the analysis of cumulative distributions that, in recent years, there was a specific work-group exposed to significantly high dose compared with other workers.
Am in the lungKinase, Sakae; Oi, Yoshihiro; Sekiguchi, Masato
Radioisotopes, 52(8), p.378 - 382, 2003/08
no abstracts in English
Yamamoto, Hisashi*; Sekiguchi, Yoshiyuki*; *; *; Kawashima, Masatoshi*; *; *
PNC TN941 79-112, 156 Pages, 1979/07
This report describes the results of the Nuclear Power Calibration test and the Power Distribution measurements made on the core center axis by micro fission chambers. The nuclear power leve1 was determined from the relationship between the calculated reaction rates and the count rates obtained by the Pu239 micro fission chambers which were inserted in the Joyo core. The Pu239 chambers used in this test were previously calibrated in the known neutron field of a thermal reactor. The principal results of this test are as follows: (1)It was confirmed that the relationship between the SRMS count rates and nuclcar power level is linear in the range of 0.1KW 10 KW. (2)The SRMS and IRMS indicators overlap in the range of 1KW 10 KW. The IRMS indicators show, linearity with the power level a above 1 KW. (3)Five fission reaction rates, Pu239, Pu240, U235, U238 and Th232, were measured along the center axis of the core using micro fission chambers. The axial power peaking factor was 1.19. The measured value of axial peaking factor agreed with the one predicted by design. (4)The SRMS count rates increase about 8% when temperature of primary sodium increases by 100
C. (5)The core fuel assemblies stored in the in-vessel fuel rack affect the count rates of the neutron monitoring system. When one core fuel assembly is loaded in a fuel rack position on a line connecting the core center and SRMS counters, the count rates increase about 25%. The additional nuclear characteristics determined in this teat are: (6)Isothermal temperature coefficient was -3.65 
10
% 
/
/C (190C 250C) (7)The reactivity change due to the replacement of a normal core assembly at the core center with a special subassembly for this test was -0.085% /k.
Shiraishi, Akemi; Sekiguchi, Masato; Tachibana, Haruo; Yoshizawa, Michio; Komuro, Yuji*; Nemoto, Kiyoko*; Okawa, Ikuko*
no journal, ,
no abstracts in English
-beta mixed fieldsTakahashi, Masa; Sekiguchi, Masato; Tachibana, Haruo; Hoshi, Shintaro; Yoshizawa, Michio; Kato, Toru*; Yamaguchi, Akihito*
no journal, ,
no abstracts in English
Miyauchi, Hideaki; Sekiguchi, Masato; Takahashi, Masa; Yasuda, Takayuki; Tachibana, Haruo; Yoshizawa, Michio
no journal, ,
no abstracts in English
-sexithiophene ultra-thin films on passivated Si(001) surfacesHiraga, Kenta*; Toyoshima, Hiroaki*; Ono, Shinya*; Hirao, Norie; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Baba, Yuji; Mukai, Kozo*; Yoshinobu, Jun*; Tanaka, Masatoshi*
no journal, ,
It is important to control orientation structure and electric property at the interface between organic semiconductor molecule and surfaces of semiconductor substrates in order for the development of commercial base organic transistors and solar cells. In the present work, we have investigated the surface reflection spectroscopy (RDS, SRDS), S-1s angle resolved near-edge X-ray absorption fine-structure (NEXAFS), and UPS for -sexithiophene (-6T) ultra-thin films with a variety of thickness from 0.25 to 1.0 nm. The results of RDS and SDRS, and NEXAFS gave the information on orientation structure of the -6T molecules. In contrast, UPS gave the uniformity of the thin films. We report on how orientation structures and condensed structures are changed depending on the method of passivation and the film thickness.
-sexithiophene thin films grown on semiconductor surface studied by near-edge X-ray absorption fine structureHiraga, Kenta*; Toyoshima, Hiroaki*; Nakajima, Junki*; Tanaka, Hiroya*; Ono, Shinya*; Tanaka, Masatoshi*; Sekiguchi, Tetsuhiro; Hirao, Norie; Shimoyama, Iwao; Baba, Yuji
no journal, ,
It is important to investigate structure of organic thin films grown on semiconductor surfaces for fabrication of the organic semiconductors.
Kodama, Hiraku*; Hiraga, Kenta*; Ono, Shinya*; Sekiguchi, Tetsuhiro; Baba, Yuji; Tanaka, Masatoshi*
no journal, ,
The electronic property of organic semiconductor depends strongly on the interfacial structure between organic molecule and the substrate. We have investigated the structure of a-sexithiophene (-6T) molecule thin films grown on semiconductor surfaces including SiO
, GaSe, and WSe, using NEXAFS spectroscopy. Using polarized X-ray, orientation structure of a-6T molecules can be precisely determined. It was found that the orientation structure depend on the substrates. -6T on GaSe is oriented with long molecular axis being flat-lying parallel to the surface. On the hand, -6T on SiO is up-right standing. The tendency of orientation direction change was interpreted in terms of the interfacial interaction between -6T molecule and the substrates.
-sexithiophene thin films grown on layered materialsKodama, Hiraku*; Hiraga, Kenta*; Ono, Shinya*; Sekiguchi, Tetsuhiro; Baba, Yuji; Tanaka, Masatoshi*
no journal, ,
Orientation of organic semiconductor has been important issue because of its strong anisotropy of the electronic property. We have investigated the orientation effect of -sexithiphene (6T) molecule deposited on WSe or GaSe substrate, which is layered semiconductor material. Thickness was controlled by regulating deposition rate and time. Orientation angle was analyzed by angle-resolved NEXAFS spectroscopy. The results show that molecular orientation angle depend not only on the substrate but also the thickness. Tilt angle is thought to be determined by the energy stability due to the commensurate at the interface as well as the molecule-substrate interaction.
Sekiguchi, Kentaro; Jinno, Satoshi*; Tanaka, Hirotaka*; Ichinose, Kosuke*; Kanasaki, Masato*; Sakaki, Hironao; Kondo, Kiminori; Matsui, Ryutaro; Kishimoto, Yasuaki; Fukuda, Yuji
no journal, ,
The size of clusters, produced in an expansion of supercooled, high pressure molecular hydrogen gas into vacuum, has been evaluated by measuring the angular distribution of scattered light. The data are analyzed based on the Mie scattering theory. Here obtaining the size distribution of clusters reduces to solving the inverse problem. Since the scattering coefficient is a matrix, it is necessary to determine the inverse matrix. However, if you solve this equation straightforward, the size distribution often oscillates to the negative values and becomes the discrete distribution by external factors such as noise included in the measurement results. Therefore, we have built an algorithm to determine the size distribution in combination with a non-negative least square method and a Phillips-Twomey method to obtain a smooth solution.
Tanaka, Hirotaka; Jinno, Satoshi*; Kanasaki, Masato*; Sekiguchi, Kentaro; Ichinose, Kosuke*; Sakaki, Hironao; Kondo, Kiminori; Matsui, Ryutaro; Kishimoto, Yasuaki; Fukuda, Yuji
no journal, ,
The size of clusters, produced in an expansion of supercooled, high pressure molecular hydrogen gas into vacuum, has been evaluated by measuring the angular distribution of scattered light. The data are analyzed based on the Mie scattering theory. Here obtaining the size distribution of clusters reduces to solving the inverse problem. Since the scattering coefficient is a matrix, it is necessary to determine the inverse matrix. However, if you solve this equation straightforward, the size distribution often oscillates to the negative values and becomes the discrete distribution by external factors such as noise included in the measurement results. Here, the validity of the method is confirmed by performing a calibration study using the standard micro-particles.
Fukuda, Yuji; Kanasaki, Masato*; Sekiguchi, Kentaro; Sugiyama, Akira; Kondo, Kiminori
no journal, ,
In the characterization of ion beams using CR-39, information on ion energies, incident angles, and ion species can be extracted from the geometrical structure of the etch pits. In this study, the spatial distribution of accelerated ions has been measured by using 55 cm
wide CR-39 detectors. In addition, by measuring the etch pit open mouth radius and the gray scale, the energy distributions of accelerated ions were also evaluated.
