Pulsed neutron imaging based crystallographic structure study of a Japanese sword made by Sukemasa in the Muromachi period

Oikawa, Kenichi; Kiyanagi, Yoshiaki*; Sato, Hirotaka*; Omae, Kazuma*; Pham, A.*; Watanabe, Kenichi*; Matsumoto, Yoshihiro*; Shinohara, Takenao; Kai, Tetsuya; Harjo, S.; et al.

Materials Research Proceedings, Vol.15, p.207 - 213, 2020/02

https://doi.org/10.21741/9781644900574-32

Interaction of soft X-ray laser pulse radiation with aluminum surface; Nano-meter size surface modification

Ishino, Masahiko; Faenov, A.*; Tanaka, Momoko; Hasegawa, Noboru; Nishikino, Masaharu; Tamotsu, Satoshi*; Pikuz, S.*; Inogamov, N. A.*; Zhakhovsky, V. V.*; Skobelev, I.*; et al.

AIP Conference Proceedings 1465, p.236 - 240, 2012/07

https://doi.org/10.1063/1.4737565

We irradiated the focusing soft X-ray laser pulses having a wavelength of 13.9 nm and the duration of 7 ps to aluminum surface. After the irradiation process, the irradiated surface was observed with a scanning electron microscope. The surface modifications caused by soft X-ray laser single pulse exposure were clearly seen. In addition, it was found that the conical structures having around 100 nm in diameters were formed in the shallow features. The nano-meter size modified surface structures on aluminum induced by the soft X-ray laser pulse is interesting as the newly surface structure. Hence, the soft X-ray laser beam would be a candidate for a tool of micromachining. We also provide a thermomechanical modeling of the soft X-ray laser interaction with aluminum briefly to explain the surface modification.

Surface modifications of metals induced by soft X-ray laser pulse irradiations

Ishino, Masahiko; Faenov, A. Y.*; Tanaka, Momoko; Hasegawa, Noboru; Nishikino, Masaharu; Tamotsu, Satoshi*; Pikuz, T.; Oba, Toshiyuki*; Kaihori, Takeshi; Kawachi, Tetsuya

Journal of Laser Micro/Nanoengineering, 7(2), p.147 - 151, 2012/05

https://doi.org/10.2961/jlmn.2012.02.0004

We irradiated the soft X-ray laser (SXRL) pulses having a wavelength of 13.9 nm, the duration time of 7 ps to aluminum (Al), copper (Cu) and gold (Au) surfaces. After the irradiation processes of SXRL beam with laser flux of 14 mJ/cm for Al case and of 21 mJ/cm for Cu and Au cases, the modified surfaces were observed with the visible microscope, the scanning electron microscope, and the atomic force microscope. The surface modifications caused by the SXRL irradiations were clearly seen on the surfaces, and it was found that the conical structures having around 100 nm in diameters were formed on the Al surface under a single pulse shot. The conical structures were formed in the features with the average depth of about 40 nm, and this value was in accordance with the attenuation length of the SXRL beam for Al. The modified structure on Al surface induced by SXRL pulse irradiations is different from those of Cu and Au surfaces. The modified structure formed on Al surface induced by the SXRL pulse exposure is interesting as the newly structure. Hence, the SXRL beam would be a candidate for a tool of micromachining, which enable to fabricate of three dimensional structures with nano-meter size on Al surface.

Development of silver tape target system for high repetition X-ray laser

Nishikino, Masaharu; Ochi, Yoshihiro; Hasegawa, Noboru; Kawachi, Tetsuya; Oba, Toshiyuki; Kaihori, Takeshi; Nagashima, Keisuke

X-Ray Lasers 2010; Springer Proceedings in Physics, Vol.136, p.93 - 98, 2011/12

http://ci.nii.ac.jp/ncid/BB05543208

The improvement of X-ray laser generation so as to have a high repetition rate will open up the possibility of new applications. In the last decade, progress in reducing the required pump energy for the X-ray lasing and raising the repetition rate has been achieved by new technologies, such as the Transient Collisional Excitation (TCE) scheme and Grazing Incidence Pumping (GRIP). Under this circumstance, the development of continuous pumping to the target system is an important issue for realizing an XRL with the high repetition rate. We have developed a 13.9 nm XRL using a silver tape target4 and demonstrated a highly coherent XRL with an oscillator-amplifier configuration5 using two tape target systems and the TOPAZ laser system6 with a 10-J and a 0.1-Hz repetition rate. The output energy is comparable to the X-ray laser generated with a silver-deposited slab target, and the pointing stability using the new tape target system is better than conventional slab target.

Development of the X-ray interferometer and the method of spatial and temporal synchronization of XRL and optical pulse

Hasegawa, Noboru; Ochi, Yoshihiro; Kawachi, Tetsuya; Terakawa, Kota*; Tomita, Takuro*; Yamamoto, Minoru; Nishikino, Masaharu; Oba, Toshiyuki; Kaihori, Takeshi; Imazono, Takashi; et al.

X-Ray Lasers 2010; Springer Proceedings in Physics, Vol.136, p.353 - 358, 2011/12

http://ci.nii.ac.jp/ncid/BB05543208

The understanding of the dynamics of the initial process is important for the micro processing and welding by the ultra-short laser pulse. The X-ray laser is suitable for probing this initial process because it has short wavelength (Ni-like Ag, 13.9 nm) and short duration (7 ps). For this investigation, the origin of time of the pumping pulse is quite important. In this study, we used the scintillation plate and the plasma gate technique to realize the spatial and temporal synchronization of the pump and probe pulses. For the spatial alignment, a CsI scintillation plate that was set at the sample position was illuminated by both the X-ray laser pulse, and the fluorescence light were detected by the CCD camera. For the temporal synchronization, we set a thin foil at the sample position. We measured the transmission of the X-ray laser while changing a temporal delay of the pumping laser with respect to the time of X-ray laser pulse to obtain the origin of the irradiation time.

Evaluation of ZnO fast scintillator spatial resolution using the FZP-focused X-ray laser

Tanaka, Momoko; Nakazato, Tomoharu*; Shimizu, Toshihiko*; Yamanoi, Kohei*; Sakai, Kohei*; Sarukura, Nobuhiko*; Nishikino, Masaharu; Oba, Toshiyuki; Kaihori, Takeshi; Ochi, Yoshihiro; et al.

JAEA-Conf 2011-001, p.126 - 128, 2011/03

https://jopss.jaea.go.jp/pdfdata/JAEA-Conf-2011-001.pdf

The spatial resolution of hydrothermal method grown zinc oxide (ZnO) scintillator was evaluated using X-ray laser focused with Fresnel zone plate. The fluorescence image of the ZnO scintillator was measured to be less than 10um using CCD camera coupled with a Schbartzchild expander mirror. The availability of large size ZnO crystal up to 3-inch is quite attractive for future lithography and imaging applications.

Observations of the intense soft X-ray emissions from ultra thin Au films irradiated with high contrast laser pulses

Ishino, Masahiko; Kado, Masataka; Nishikino, Masaharu; Shinohara, Kunio*; Tamotsu, Satoshi*; Yasuda, Keiko*; Hasegawa, Noboru; Kishimoto, Maki; Oba, Toshiyuki; Kawachi, Tetsuya

Proceedings of SPIE, Vol.7589, p.75891B_1 - 75891B_8, 2010/02

https://doi.org/10.1117/12.839945

Soft X-ray microscopes operating in the water window are capable of imaging living hydrated biological specimens. Laser produced plasmas are attractive soft X-ray sources, because of their short duration time. Based on the minimum dose calculation, soft X-ray photons more than 10 photons/m at the sample surface are needed to acquire an image of the biological specimens with spatial resolution up to 100 nm. The observations of soft X-ray emissions from laser produced plasmas using ultra thin film targets have been carried out. Au thin films were irradiated by a high contrast Nd:glass laser pulses. The spectral properties of emitted soft X-rays were monitored by an X-ray spectrograph from the rear side with respect to the surface of laser irradiation. The observed emission intensities had an obvious dependence on the film thickness, and the most intense emissions were obtained at the thickness of 28 nm. The experimental results have suggested that the most of the laser energy irradiated is absorbed by the film target, and it is resulted an efficient energy deposition from laser to X-rays.

Demonstration of a highly coherent 13.9 nm X-ray laser from a silver tape target

Nishikino, Masaharu; Ochi, Yoshihiro; Hasegawa, Noboru; Kawachi, Tetsuya; Yamatani, Hiroshi*; Oba, Toshiyuki; Kaihori, Takeshi; Nagashima, Keisuke

Review of Scientific Instruments, 80(1), p.116102_1 - 116102_3, 2009/11

https://doi.org/10.1063/1.3262634

A highly coherent 13.9 nm X-ray laser is generated under an oscillator-amplifier configuration using a new tape target system and a driver laser system with a 0.1 Hz repetition rate. The output energy is comparable to the X-ray laser generated with a silver-deposited slab target, and the pointing stability using the new tape target system is better than conventional slab targets.

New driver laser system for double target X-ray lasers at JAEA

Ochi, Yoshihiro; Hasegawa, Noboru; Kawachi, Tetsuya; Nishikino, Masaharu; Tanaka, Momoko; Kishimoto, Maki; Oba, Toshiyuki

X-Ray Lasers 2008; Springer Proceedings in Physics, Vol.130, p.161 - 166, 2009/00

Functional analysis of root elongation zone in hydrotropism in using heavy-ion microbeam

Miyazawa, Yutaka*; Sakashita, Tetsuya; Negishi, Hiroshi*; Kobayashi, Akie*; Kaneyasu, Tomoko*; Oba, Atsushi*; Morohashi, Keita*; Kakizaki, Takehiko*; Funayama, Tomoo; Hamada, Nobuyuki*; et al.

JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 116, 2008/03

https://jopss.jaea.go.jp/pdfdata/JAEA-Review-2007-060.pdf

We examined the role of root cap and elongation zone cells in root hydrotropism of using heavy ion and laser microbeam. Heavy ion microbeam irradiation of the elongation zone, but not that of the columella cells, significantly and temporarily suppressed the development of hydrotropic curvature. However, laser ablation confirmed that columella cells are indispensable for hydrotropism. Systemic heavy ion broad beam irradiation suppressed de novo expression of INDOLE ACETIC ACID 5 gene. Our results indicate that both the root cap and elongation zone have indispensable and functionally distinct roles in root hydrotropism, and that de novo gene expression might be required for hydrotropism in the elongation zone, but not in columella cells.