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Journal Articles

Simultaneous generation of a proton beam and terahertz radiation in high-intensity laser and thin-foil interaction

Sagisaka, Akito; Daido, Hiroyuki; Nashima, Shigeki*; Orimo, Satoshi; Ogura, Koichi; Mori, Michiaki; Yogo, Akifumi; Ma, J.-L.; Daito, Izuru; Pirozhkov, A. S.; et al.

Applied Physics B, 90(3-4), p.373 - 377, 2008/03

 Times Cited Count:52 Percentile:6.92(Optics)

High-intensity laser and thin-foil interactions produce high energy ions, electrons, hard X-ray, and terahertz radiation. The simultaneous generation of the protons and terahertz radiation will provide us unique applications. In this study we use a Ti:sapphire laser system (JLITE-X) at JAEA for simultaneous generation of the protons and terahertz radiation. The laser beam is focused by an off-axis parabolic mirror at the Ti target surface. The estimated peak intensity is $$sim$$2$$times$$10$$^{17}$$W/cm$$^{2}$$. The simultaneous generation of the protons and terahertz radiation are observed by reducing the ASE duration.

Journal Articles

Depositional records of plutonium and $$^{137}$$Cs released from Nagasaki atomic bomb in sediment of Nishiyama reservoir at Nagasaki

Kokubu, Yoko; Yasuda, Kenichiro; Magara, Masaaki; Miyamoto, Yutaka; Sakurai, Satoshi; Usuda, Shigekazu; Yamazaki, Hideo*; Yoshikawa, Shusaku*; Nagaoka, Shinji*; Mitamura, Muneki*; et al.

Journal of Environmental Radioactivity, 99(1), p.211 - 217, 2008/01

 Times Cited Count:13 Percentile:66.09(Environmental Sciences)

In a sediment core of Nishiyama reservoir at Nagasaki, depth profiles of $$^{240}$$Pu/$$^{239}$$Pu ratio, $$^{239+240}$$Pu and $$^{137}$$Cs concentrations were determined. Sediments containing plutonium and $$^{137}$$Cs, which were fallout deposited immediately after a detonation of Nagasaki atomic bomb, were identified in the core. Observed below the sediments were macroscopic charcoals, providing evidence for initial deposit of the fallout. This is the first entire depositional records of plutonium and $$^{137}$$Cs released from the Nagasaki atomic bomb together with those from atmospheric nuclear tests.

Journal Articles

Geographical distribution of plutonium derived from the atomic bomb in the eastern area of Nagasaki

Kokubu, Yoko; Yasuda, Kenichiro; Magara, Masaaki; Miyamoto, Yutaka; Sakurai, Satoshi; Usuda, Shigekazu; Yamazaki, Hideo*; Yoshikawa, Shusaku*

Journal of Radioanalytical and Nuclear Chemistry, 273(1), p.183 - 186, 2007/07

 Times Cited Count:5 Percentile:57.04(Chemistry, Analytical)

no abstracts in English

Journal Articles

Distribution of plutonium isotopes and $$^{137}$$Cs found in the surface soils of Nagasaki, Japan

Kokubu, Yoko; Yasuda, Kenichiro; Magara, Masaaki; Miyamoto, Yutaka; Sakurai, Satoshi; Usuda, Shigekazu; Yamazaki, Hideo*; Mitamura, Muneki*; Yoshikawa, Shusaku*

Journal of Geosciences, Osaka City University, 50, p.7 - 13, 2007/03

no abstracts in English

Journal Articles

Geological distribution of plutonium isotopes of Nagasaki atomic bomb spread over Nagasaki and Kumamoto area

Kokubu, Yoko; Yasuda, Kenichiro; Magara, Masaaki; Miyamoto, Yutaka; Sakurai, Satoshi; Usuda, Shigekazu; Yamazaki, Hideo*; Yoshikawa, Shusaku*

KEK Proceedings 2006-5, p.36 - 40, 2006/11

no abstracts in English

Oral presentation

Geographical distribution of plutonium derived from the Nagasaki atomic bomb

Kokubu, Yoko; Yasuda, Kenichiro; Magara, Masaaki; Miyamoto, Yutaka; Sakurai, Satoshi; Usuda, Shigekazu; Yoshikawa, Shusaku*; Yamazaki, Hideo*

no journal, , 

no abstracts in English

Oral presentation

Trace of "Black rain" originated from the Nagasaki atomic bomb in sediment of the Nishiyama reservoir at Nagasaki City

Kokubu, Yoko; Yasuda, Kenichiro; Magara, Masaaki; Miyamoto, Yutaka; Sakurai, Satoshi; Usuda, Shigekazu; Murakami, Akiko*; Inoue, Jun*; Yoshikawa, Shusaku*; Yamazaki, Hideo*; et al.

no journal, , 

no abstracts in English

Oral presentation

Origin of plutonium in sediments of the Nishiyama reservoir at Nagasaki city

Kokubu, Yoko; Yasuda, Kenichiro; Magara, Masaaki; Miyamoto, Yutaka; Sakurai, Satoshi; Usuda, Shigekazu; Yoshikawa, Shusaku*; Yamazaki, Hideo*; Nagaoka, Shinji*

no journal, , 

no abstracts in English

Oral presentation

Plutonium in the Nishiyama area of Nagasaki city

Kokubu, Yoko; Yasuda, Kenichiro; Magara, Masaaki; Miyamoto, Yutaka; Sakurai, Satoshi; Usuda, Shigekazu; Yoshikawa, Shusaku*; Yamazaki, Hideo*; Nagaoka, Shinji*

no journal, , 

no abstracts in English

Oral presentation

Simultaneous generation of proton beam and terahertz radiation under intense ultrashort pulse-laser irradiation

Sagisaka, Akito; Daido, Hiroyuki; Pirozhkov, A. S.; Ogura, Koichi; Orimo, Satoshi; Mori, Michiaki; Yogo, Akifumi; Nakamura, Shu*; Iwashita, Yoshihisa*; Shirai, Toshiyuki*; et al.

no journal, , 

no abstracts in English

Oral presentation

Identification of plutonium released from Nagasaki atomic bomb; Approach of measurement of $$^{240}$$Pu/$$^{239}$$Pu isotope ratio by ICP-MS

Kokubu, Yoko

no journal, , 

This presentation is one of the invited talks at a special session of "Advances and future prospect of A-bomb researches" in the 2008 Annual Meeting of the Japan Society of Nuclear and Radiochemical Sciences. Alpha-ray spectrometry of Pu was mainly used to assess plutonium from Nagasaki atomic bomb in the previous studies. However it was difficult to discriminate the plutonium due to atomic explosion in Nagasaki from global fallout by analysis of the $$alpha$$-ray spectrum. In this study, $$^{240}$$Pu/$$^{239}$$Pu ratio measured by ICP-MS was used to identify the source of Pu and distributions of the Pu in sediment and soils were reported. Depth profile of the Pu in a sediment core collected at Nishiyama reservoir, Nagasaki city was determined to obtain depositional record of the Pu from the atomic bomb for 60 years. The Pu was measured in surface soils collected around the hypocenter of the atomic bomb to identify geological distribution of the Pu from the atomic bomb.

Oral presentation

The Evaluation of the environmental effect of the trace of the Nagasaki atomic bomb recorded in the sediments of Nagasaki bay and Nishiyama reservoir at Nagasaki

Yamazaki, Hideo*; Kawashima, Asami*; Kokubu, Yoko; Nagaoka, Shinji*; Tsujimoto, Akira*; Murakami, Akiko*; Yoshikawa, Shusaku*

no journal, , 

no abstracts in English

Oral presentation

Plutonium of Nagasaki atomic bomb deposited around Nagasaki, Japan

Kokubu, Yoko; Magara, Masaaki; Sakurai, Satoshi; Usuda, Shigekazu*; Kimura, Takaumi; Yamazaki, Hideo*; Yoshikawa, Shusaku*; Nagaoka, Shinji*

no journal, , 

Plutonium isotopes were released from Nagasaki atomic bomb which exploded on August 9, 1945. The isotopes are interesting in research on environmental radioactivity, because evident information of the plutonium release provide opportunities to simplify understanding of environmental behavior of Pu. The Nagasaki area is one of the oldest areas that were contaminated with the artificial Pu in the world. As the isotopic composition of Pu depends on its origin, $$^{240}$$Pu/$$^{239}$$Pu ratio is a useful tool for the identification of the source of Pu. This paper is intended to report the $$^{240}$$Pu/$$^{239}$$Pu ratios in sediments and surface soils and distribution of the Pu from the atomic bomb.

Oral presentation

Observation of long-wavelength electromagnetic radiation generated via intense laser matter interaction

Kando, Masaki; Nashima, Shigeki*; Pirozhkov, A. S.; Hayashi, Yukio; Kotaki, Hideyuki; Bulanov, S. V.

no journal, , 

We irradiated laser pulses with energy of 400 mJ - 1J and the pulse duration of 30 fs onto a helium gas-jet target with the irradiance of 10$$^{19}$$ W/cm$$^2$$ and measured the long wavelength ($$sim$$ THz) electromagnetic radiation with a DTGS detector. Among the known mechanism of THz generation via laser-matter interaction, we focus on the soliton mechanism that the laser pulse depletes its energy and its energy is converted to lower frequency light. With a probe light, we observed soliton-like structures. With the DTGS, many noises were obtained when the laser intensity and laser contrast increases.

14 (Records 1-14 displayed on this page)
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