Search

Your search keyword '"Kan, Koichi"' showing total 6 results
Start Over Author "Kan, Koichi" Search Limiters Full Text
6 results on '"Kan, Koichi"'

1. Commissioning of a compact multibend achromat lattice: A new 3 GeV synchrotron radiation facility

Author

Obara, Shuhei, Ueshima, Kota, Asaka, Takao, Hosaka, Yuji, Kan, Koichi, Nishimori, Nobuyuki, Aoki, Toshitaka, Asano, Hiroyuki, Haga, Koichi, Iba, Yuto, Ihara, Akira, Ito, Katsumasa, Iwashita, Taiki, Kadowaki, Masaya, Kanahama, Rento, Kobayashi, Hajime, Kobayashi, Hideki, Nishihara, Hideo, Nishikawa, Masaaki, Oikawa, Haruhiko, Saida, Ryota, Sakuraba, Keisuke, Sugimoto, Kento, Suzuki, Masahiro, Takahashi, Kouki, Takahashi, Shunya, Tanaka, Tatsuki, Tsuchiyama, Tsubasa, Yoshioka, Risa, Aoki, Tsuyoshi, Dewa, Hideki, Fujita, Takahiro, Kawase, Morihiro, Kiyomich, Akio, Hamano, Takashi, Masaki, Mitsuhiro, Masuda, Takemasa, Matsubara, Shinichi, Okada, Kensuke, Saji, Choji, Taniuchi, Tsutomu, Taniuchi, Yukiko, Ueda, Yosuke, Yamaguchi, Hiroshi, Yanagida, Kenichi, Fukami, Kenji, Hosoda, Naoyasu, Ishii, Miho, Itoga, Toshiro, Iwai, Eito, Magome, Tamotsu, Oishi, Masaya, Ohshima, Takashi, Kondo, Chikara, Sakurai, Tatsuyuki, Shoji, Masazumi, Sugimoto, Takashi, Takano, Shiro, Tamura, Kazuhiro, Watanabe, Takahiro, Tomai, Takato, Azumi, Noriyoshi, Inagaki, Takahiro, Maesaka, Hirokazu, Takahashi, Sunao, Tanaka, Takashi, Inoue, Shinobu, Kumazawa, Hirosuke, Moriya, Kazuki, Sakai, Kohei, Seno, Toshio, Sumitomo, Hiroshi, Takesako, Ryoichi, Tanaka, Shinichiro, Yamamoto, Ryo, Yokomachi, Kazutoshi, Yoshioka, Masamichi, Hara, Toru, Matsui, Sakuo, Hiraiwa, Toshihiko, Tanaka, Hitoshi, and Ego, Hiroyasu

Subjects
Physics - Accelerator Physics, High Energy Physics - Experiment
Abstract

NanoTerasu, a new 3 GeV synchrotron light source in Japan, began user operation in April 2024. It provides high-brilliance soft to tender X-rays and covers a wide spectral range from ultraviolet to tender X-rays. Its compact storage ring with a circumference of 349 m is based on a four-bend achromat lattice to provide two straight sections in each cell for insertion devices with a natural horizontal emittance of 1.14 nm rad, which is small enough for soft X-rays users. The NanoTerasu accelerator incorporates several innovative technologies, including a full-energy injector C-band linear accelerator with a length of 110 m, an in-vacuum off-axis injection system, a four-bend achromat with B-Q combined bending magnets, and a TM020 mode accelerating cavity with built-in higher-order-mode dampers in the storage ring. This paper presents the accelerator machine commissioning over a half-year period and our model-consistent ring optics correction. The first user operation with a stored beam current of 160 mA is also reported. We summarize the storage ring parameters obtained from the commissioning. This is helpful for estimating the effective optical properties of synchrotron radiation at NanoTerasu., Comment: 30 pages, 24 figures, submitted to the journal

Published
2024

3. Direct ionization-driven observational approaches for radical cation formation in solution for pulse radiolysis

Author

1000060705094, Gohdo, Masao, 1000080011203, Tagawa, Seiichi, 1000060553302, Kan, Koichi, 1000090362631, Yang, Jinfeng, 1000050210729, Yoshida, Yoichi, 1000060705094, Gohdo, Masao, 1000080011203, Tagawa, Seiichi, 1000060553302, Kan, Koichi, 1000090362631, Yang, Jinfeng, 1000050210729, and Yoshida, Yoichi

Abstract

Radical cations’ dynamics in early stage reactions in the ionizing radiation induced reaction is essential to understanding the whole reaction scheme. The observation of radical cations in tetrahydrofuran (THF) solutions was demonstrated for time-resolved measurements using pulse radiolysis. The designedly concentrated solutions enabled the observation of the direct ionization-driven radical cations. In THF, the transient absorption spectra of the biphenyl radical cations, which were generated through direct ionization of biphenyl under electron beam irradiation, were found to be associated with the biphenyl radical anions generated by the attachment of an excess electron to the biphenyl. Furthermore, when polystyrene (PS) was used as the solute in THF solutions, transient absorption spectra of the dimer radical cations containing solvated electrons of PS were observed. The findings, therefore, indicate that the time-resolution-based limitation on the radical cation-forming process observation, which was imposed by the diffusion-limited reactions of the solvent radical cations with the solute, could be overcome by employing direct ionization in THF. This method can be employed to study the reactivity of radical cations with solvents and the stability of radical cations in fluid media.

Published
2022

4. Direct ionization-driven observational approaches for radical cation formation in solution for pulse radiolysis

Author

Gohdo, Masao, Tagawa, Seiichi, Kan, Koichi, Yang, Jinfeng, Yoshida, Yoichi, Gohdo, Masao, Tagawa, Seiichi, Kan, Koichi, Yang, Jinfeng, and Yoshida, Yoichi

Abstract

Radical cations’ dynamics in early stage reactions in the ionizing radiation induced reaction is essential to understanding the whole reaction scheme. The observation of radical cations in tetrahydrofuran (THF) solutions was demonstrated for time-resolved measurements using pulse radiolysis. The designedly concentrated solutions enabled the observation of the direct ionization-driven radical cations. In THF, the transient absorption spectra of the biphenyl radical cations, which were generated through direct ionization of biphenyl under electron beam irradiation, were found to be associated with the biphenyl radical anions generated by the attachment of an excess electron to the biphenyl. Furthermore, when polystyrene (PS) was used as the solute in THF solutions, transient absorption spectra of the dimer radical cations containing solvated electrons of PS were observed. The findings, therefore, indicate that the time-resolution-based limitation on the radical cation-forming process observation, which was imposed by the diffusion-limited reactions of the solvent radical cations with the solute, could be overcome by employing direct ionization in THF. This method can be employed to study the reactivity of radical cations with solvents and the stability of radical cations in fluid media.

5. Direct ionization-driven observational approaches for radical cation formation in solution for pulse radiolysis

Author

Gohdo, Masao, Tagawa, Seiichi, Kan, Koichi, Yang, Jinfeng, Yoshida, Yoichi, Gohdo, Masao, Tagawa, Seiichi, Kan, Koichi, Yang, Jinfeng, and Yoshida, Yoichi

Abstract

Radical cations’ dynamics in early stage reactions in the ionizing radiation induced reaction is essential to understanding the whole reaction scheme. The observation of radical cations in tetrahydrofuran (THF) solutions was demonstrated for time-resolved measurements using pulse radiolysis. The designedly concentrated solutions enabled the observation of the direct ionization-driven radical cations. In THF, the transient absorption spectra of the biphenyl radical cations, which were generated through direct ionization of biphenyl under electron beam irradiation, were found to be associated with the biphenyl radical anions generated by the attachment of an excess electron to the biphenyl. Furthermore, when polystyrene (PS) was used as the solute in THF solutions, transient absorption spectra of the dimer radical cations containing solvated electrons of PS were observed. The findings, therefore, indicate that the time-resolution-based limitation on the radical cation-forming process observation, which was imposed by the diffusion-limited reactions of the solvent radical cations with the solute, could be overcome by employing direct ionization in THF. This method can be employed to study the reactivity of radical cations with solvents and the stability of radical cations in fluid media.

6. Femtosecond Pulse Radiolysis

Author

Yang, Jinfeng, Kan, Koichi, Gohdo, Masao, and Yoshida, Yoichi

Subjects
Science / Physics
Abstract

Ultrafast pulse radiolysis with a short-pulsed electron beam and a short-pulsed analyzing light is a powerful time-resolved spectroscopic technique to study the kinetics and reactions of short-lived intermediate species or precursors in radiation chemistry and biology. In this chapter, first, we give an overview of historical developments of ultrafast pulse radiolysis. Then, we describe a femtosecond pulse radiolysis instrument, including the generation of femtosecond electron pulses by a photocathode radio frequency (rf) gun-based linear electron accelerator, the synchronization of femtosecond analyzing laser with the electron pulses, the transient absorption measurement with double-pulse technique, and the observations of the formation processes and ultrafast reactions of hydrated electrons in water. Finally, two innovative techniques, which enable to improve the time resolution in next pulse radiolysis development, are presented.

Published
2018

Catalog

Books, media, physical & digital resources
See catalog results