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to extreme environmentsHorikawa, Daiki*; Yamaguchi, Ayami*; Sakashita, Tetsuya; Tanaka, Daisuke*; Hamada, Nobuyuki*; Yukuhiro, Fumiko*; Kuwahara, Hirokazu*; Kunieda, Takekazu*; Watanabe, Masahiko*; Nakahara, Yuichi*; et al.
Astrobiology, 12(4), p.283 - 289, 2012/04
Times Cited Count：23 Percentile：68.76(Astronomy & Astrophysics)We examined the hatchability of hydrated and anhydrobiotic eggs of the tardigrade to hatch after ionizing irradiation (helium ions), extremely low and high temperatures, and high vacuum. Anhydrobiotic eggs (50% lethal dose; 1690 Gy) were substantially more radioresistant than hydrated ones (50% lethal dose; 509 Gy). Anhydrobiotic eggs also have a broader temperature resistance compared with hydrated ones. Over 70% of the anhydrobiotic eggs treated at high and low temperatures, but all of the hydrated eggs failed to hatch. After exposure to high vacuum conditions, the hatchability of the anhydrobiotic eggs was comparable to that of untreated control eggs.
Hasegawa, Noboru; Kawachi, Tetsuya; Sasaki, Akira; Yamatani, Hiroshi; Kishimoto, Maki; Ochi, Yoshihiro; Tanaka, Momoko; Nishikino, Masaharu; Kunieda, Yuichi; Nagashima, Keisuke; et al.
Journal of Physics; Conference Series, 163(1), p.012062_1 - 012062_4, 2009/06
Times Cited Count：2 Percentile：66.96(Physics, Multidisciplinary)The precise knowledge about the wavelength and the spectral width of the lasing line is important for the applications of X-ray lasers, and especially for the spectral width, it is good benchmark of the atomic code because it depends on the electron collisional excitation and de-excitation rate coefficient. Only a few measurements of the spectral width of the laser line have been reported, because the spectral width of the X-ray laser is so narrow that the required spectral resolution is quite high. In this study, we took the nickel-like molybdenum X-ray laser as an example, and measure the spectral width by use of the high resolution spectrometer in order to compare it with a theoretical one.
Hasegawa, Noboru; Sasaki, Akira; Yamatani, Hiroshi; Kishimoto, Maki; Tanaka, Momoko; Ochi, Yoshihiro; Nishikino, Masaharu; Kunieda, Yuichi; Kawachi, Tetsuya; Yoneda, Hitoki*; et al.
Journal of the Optical Society of Korea, 13(1), p.60 - 64, 2009/03
Times Cited Count：5 Percentile：29.51(Optics)The precise knowledge about the spectral width of the X-ray laser line is important to generate the circularly polarized X-ray laser. There are three magnetic sub-levels at lower state of the collisional excitation X-ray laser transition of the nickel-like ion X-ray laser medium. The polarization of each transition is circular or linear. Therefore the circularly polarized X-ray laser could be extracted by the influence of the Zeeman effect if the X-ray laser medium was under the external magnetic field. The strength of the magnetic field required for the circularly polarized X-ray laser is determined by the spectral width of the X-ray laser. Only a few measurements of the spectral width of the laser line have been reported, because the spectral width of the X-ray laser is so narrow that the required spectral resolution is quite high. In this study, we took the nickel-like molybdenum X-ray laser as an example and succeeded the measurement of the spectral width of the X-ray laser.
; A New model animal for astrobiologyHorikawa, Daiki*; Kunieda, Takekazu*; Abe, Wataru*; Watanabe, Masahiko*; Nakahara, Yuichi*; Yukuhiro, Fumiko*; Sakashita, Tetsuya; Hamada, Nobuyuki*; Wada, Seiichi*; Funayama, Tomoo; et al.
Astrobiology, 8(3), p.549 - 556, 2008/06
Times Cited Count：94 Percentile：90.99(Astronomy & Astrophysics)We report the successful rearing of the herbivorous tardigrade, , by supplying the green alga 
as food. The life span was 35 d, deposited eggs required 5.7 d to hatch, and animals began to deposit eggs 9 d after hatching. The reared individuals of this species had an anhydrobiotic capacity throughout their life cycle in egg, juvenile, and adult stages. Furthermore, the reared adults in an anhydrobiotic state were tolerant of temperatures of 90
C and -196C and exposure to 99.8% acetonitrile or irradiation with 4000 Gy 
He ions. Based on their life history traits and tolerance to extreme stresses, 
might be a suitable model for astrobiological studies of multicellular organisms.
Saito, Kimiaki; Saito, Hidetoshi*; Kunieda, Etsuo*; Narita, Yuichiro*; Myojoyama, Atsushi*; Fujisaki, Tatsuya*; Kawase, Takatsugu*; Kaneko, Katsutaro*; Ozaki, Masahiro*; Deloar, H. M.*; et al.
Joho Shori, 48(10), p.1081 - 1088, 2007/10
no abstracts in English
Saito, Kimiaki; Kunieda, Etsuo*; Narita, Yuichiro*; Kimura, Hideo; Hirai, Masaaki*; Deloar, H. M.*; Kaneko, Katsutaro*; Ozaki, Masahiro*; Fujisaki, Tatsuya*; Myojoyama, Atsushi*; et al.
Radiation Protection Dosimetry, 116(1-4), p.190 - 195, 2005/12
Times Cited Count：2 Percentile：17.6(Environmental Sciences)A dose calculation system for providing accurate dose distribution in a patient body is under developing for supporting radiotherapy using photons and electrons. In this system, a sophisticated human model, a precise accelerator head model, and a Monte Carlo calculation will be utilized to perform realistic simulation. The dose distribution is calculated by this system on the ITBL computer at the dose calculation center, and the related data are transferred through a network. This system is intended to support the quality assurance of current treatments carried out in Japan. Further, this system is planned to apply to advanced radiotherapy. The project started on November 2003 and is scheduled to continue for five years. Prototypes of some parts constituting the system have been already developed, and the fundamental features on the radiation fields have been investigated. On the basis of the fundamental investigation, the final system will be designed and constructed.
Ochi, Yoshihiro; Hasegawa, Noboru; Kawachi, Tetsuya; Nagashima, Keisuke; Kishimoto, Maki; Tanaka, Momoko; Nishikino, Masaharu; Sukegawa, Kota; Yamatani, Hiroshi; Kunieda, Yuichi; et al.
no journal, ,
We have developed a chirped pulse amplification laser with flash lamp pumped zigzag slab Nd:glass amplifiers for pumping the TCE X-ray lasers at 0.1-Hz repetition rate at the Japan Atomic Energy Agency. The laser provided 7 J/1.6 ps main pulse and 1/8 intensity pre-pulse at 1.2 ns before the main pulse. An energy fluctuation at 0.1-Hz operation was 20% (RMS), which was comparable with our present laser using rod amplifiers. The line focus on the target surface was 20 
m in the width and 0.8 cm in the length. By using this laser, gain saturated Ni-like silver laser (
= 13.9 nm) with energy output of 
1 J was obtained. The beam divergence of the Ni-like silver laser was 
mrad. Consequently, the peak spectrum brilliance was estimated to be 10
photons/s/mm
/mrad2/0.1%BW. With 0.1-Hz repetition rate, this X-ray laser can be a powerful tool for a variety of applications.
Ochi, Yoshihiro; Kawachi, Tetsuya; Hasegawa, Noboru; Kishimoto, Maki; Nagashima, Keisuke; Tanaka, Momoko; Nishikino, Masaharu; Kunieda, Yuichi; Sukegawa, Kota; Yamatani, Hiroshi
no journal, ,
no abstracts in English
Ochi, Yoshihiro; Kishimoto, Maki; Hasegawa, Noboru; Kawachi, Tetsuya; Nagashima, Keisuke; Tanaka, Momoko; Nishikino, Masaharu; Kunieda, Yuichi; Yamatani, Hiroshi; Sukegawa, Kota
no journal, ,
no abstracts in English
Kawachi, Tetsuya; Nagashima, Keisuke; Kishimoto, Maki; Hasegawa, Noboru; Tanaka, Momoko; Ochi, Yoshihiro; Nishikino, Masaharu; Sukegawa, Kota; Yamatani, Hiroshi; Kunieda, Yuichi
no journal, ,
Laser-driven plasma X-ray laser is a promised compact, high quality X-ray source with high peak brilliance. Now using commercial base pumping laser, gain saturated X-ray laser has been obtained with the wavelength up to 12 nm with high repetition-rate. Furthermore using X-ray seeder and amplifier technique, we have demonstrated fully spatial coherent X-ray laser at a wavelength of 13.9 nm. In a view point of the application of X-ray lasers, using the coherence, high density plasma diagnostics by X-ray laser interferometer, surface investigation by X-ray speckle technique, and electron spectroscopy pumped by X-ray laser have been demonstrated, and the applicable research field is expanding with the increase of the repetition-rate. In this paper, the present status of the X-ray lasers and the future prospect will be presented including the applicable research fields and the possibility of shorter wavelength X-ray laser with KeV energy region.
Saito, Kimiaki; Kunieda, Etsuo*; Narita, Yuichiro*; Myojoyama, Atsushi*; Saito, Hidetoshi*
no journal, ,
Kunieda, Yuichi; Nagashima, Keisuke; Hasegawa, Noboru; Ochi, Yoshihiro
no journal, ,
no abstracts in English
Saito, Kimiaki; Kunieda, Etsuo*; Narita, Yuichiro*; Kaneko, Katsutaro*; Hirai, Masaaki*; Oku, Yohei*; Deloar, H. M.*; Fujisaki, Tatsuya*; Myojoyama, Atsushi*; Saito, Hidetoshi*
no journal, ,
no abstracts in English
Wadachi, Hiroki*; Kunieda, Takekazu*; Abe, Wataru*; Nakahara, Yuichi*; Watanabe, Masahiko*; Sakashita, Tetsuya; Hamada, Nobuyuki*; Kobayashi, Yasuhiko; Higashi, Seigo*; Okuda, Takashi*
no journal, ,
We collected some kinds of tardigrade to develop multi-cellular model oraganism for extremotolerant. Among four kinds of collected tardigrade, we found that a tardigrade at Sapporo-city feeded 
and could breed. The life-time of in an artificial culture condition is about 35 days and 5.7 days for hatching. During the whole life-time, one animal laids 8 eggs. In addition, it was observed that could enter an ametabolic dry state called anhydrobiosis in all stages of life-time. Furthermore, we observed a high surviving-rate even if exposed in various kinds of extreme environments.
Wadachi, Hiroki*; Kunieda, Takekazu*; Sakashita, Tetsuya; Kawai, Kiyoshi*; Iwata, Kenichi*; Nakahara, Yuichi*; Hamada, Nobuyuki*; Koseki, Shigenobu*; Yamamoto, Kazutaka*; Kobayashi, Yasuhiko; et al.
no journal, ,
We studied the effects of the exposure of extreme environments on life-time and breeding ability of tardigrade to reveal the possibility of multi-cellular organism existences in the outerspace. A life time of animals is the shortest in the heavy-ion exposed animals than any other stressors. There were significant decrease in the number of egg-laying and hatching rate between irradiated and non-irradiated animals. However, we found the next generation in all experimental conditions. Our findings suggest that tardigrades exposed to even any extreme environments could have a descendant.
Nishikino, Masaharu; Hasegawa, Noboru; Kawachi, Tetsuya; Ochi, Yoshihiro; Nagashima, Keisuke; Tanaka, Momoko; Kishimoto, Maki; Kunieda, Yuichi; Yamatani, Hiroshi
no journal, ,
We are developing plasma X-ray lasers pumped by ultra-short pulse lasers and have concentrated our efforts on developing a silver X-ray laser (13.9 nm) with spatially full coherence and application research using a highly coherent X-ray laser. Recently, we have developed a new pumping laser system, which is a CPA laser consisting of an OPCPA pre-amplifier and zigzag-slab type glass amplifiers. For the purpose of further application experiments, 0.1-Hz operation of the driver laser and the X-ray laser at a wavelength of 13.9 nm were succeeded.
; A Model for astrobiological studiesHorikawa, Daiki*; Kunieda, Takekazu*; Abe, Wataru*; Koshikawa, Shigeyuki*; Nakahara, Yuichi*; Watanabe, Masahiko*; Iwata, Kenichi*; Sakashita, Tetsuya; Hamada, Nobuyuki*; Higashi, Seigo*; et al.
no journal, ,
We report the first successful rearing of the herbivorous tardigrade, , by supplying a green alga as a food. The reared individuals of this species had an anhydrobiotic capacity throughout their life cycle, from eggs, to juveniles, and to adults. Reared adults, while in an anhydrobiotic state, were tolerant to temperatures -196C and 100C. Furthermore, they were shown to be tolerant to the exposure to 99.8% acetonitrile, 1 GPa of hydrostatic pressure, or 5000 Gy of He ion radiation. We will report the details of these results, along with the description of their life history. Due to the observed tolerance to such extreme environmental conditions, we propose R. varieornatus to be included as a suitable model for astrobiological studies of multicellular organisms.
Kawachi, Tetsuya; Kishimoto, Maki; Kado, Masataka; Tanaka, Momoko; Hasegawa, Noboru; Ochi, Yoshihiro; Nishikino, Masaharu; Ishino, Masahiko; Imazono, Takashi; Kunieda, Yuichi; et al.
no journal, ,
Recent progress in X-ray laser research in Japan Atomic Energy Agency is reviewed. Using the nickel-like silver soft X-ray laser at the wavelength of 13.9 nm, the application experiments have been conducted in the research fields such as material science, high-density plasma diagnostics, XRL ablation, XRL imaging using single-shot holography and atomic physics. The repetition rate of the XRL beam has been improved from each 10-20 minutes to 0.1 Hz by using new driver laser system with Nd: glass zigzag slab amplifier, and we are now constructing new beam line for the pump-probe measurement of the surface phase-transition by the method of X-ray laser interferometer. In the research activity on the extension of the wavelength region of the X-ray lasers, firstly, the demonstration of novel coherent X-ray generation by "flying mirror" technique is reported. The second is theoretical investigation of the resonance photo-pumping scheme toward water-window region.
Kunieda, Yuichi; Kawachi, Tetsuya; Hasegawa, Noboru; Nagashima, Keisuke
no journal, ,
no abstracts in English
Hasegawa, Noboru; Kawachi, Tetsuya; Sasaki, Akira; Kishimoto, Maki; Tanaka, Momoko; Ochi, Yoshihiro; Nishikino, Masaharu; Kunieda, Yuichi; Iwamae, Atsushi*; Yoneda, Hitoki*
no journal, ,
We tried to generate the circularly polarized X-ray laser by use of the high power pulse magnet system. There are three magnetic sub-levels at lower state of the collisional excitation X-ray laser transition. For example, nickel-like X-ray laser transition (4d (m = 0) - 4p (m = -1, 0, +1)), the polarization from each transitions are right-handed circular (
m = -1), left-handed circular (m = +1), and linear (m = 0) along to the quantization axis. If the quantization axis were decided by the magnetic field from the outside of the X-ray laser medium, the circularly polarized X-ray laser can be extracted. In this study, we tried to generate the circularly polarized X-ray laser by using the nickel-like molybdenum X-ray laser medium (18.9 nm) with 20 Tesla magnetic field generated by the pulse power magnet system.
Kunieda, Yuichi; Kawachi, Tetsuya; Hasegawa, Noboru; Nagashima, Keisuke
no journal, ,
We propose a novel ultra-fast X-ray detector by use of the evanescent field assisted by surface plasmon resonance (SPR). Under the SPR condition driven by the short laser pulse, the plasmons in the metal surface are excited followed by emitting free electrons in vacuum, which are accerelated by the gradient of the strength of the evanescent electric field. Under the condition that an additional X-ray pulse is temporally synchronized with the driving pulse of SPR, the kinetic energy of the emitted electrons originated from the evanescent field may be shifted due to the effect of the photoionization with the incident X-ray. This scheme has potential to determine the duration of the X-ray pulse by monitoring the energy shift as a function of the timing of the driving pulse of SPR. In the presentation, we report the preliminary experiment and show the prospect of this scheme as the ultra-fast X-ray detector.
