Kimio Tsubono
University of Tokyo
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Publication
Featured researches published by Kimio Tsubono.
Classical and Quantum Gravity | 2008
Ryutaro Takahashi; Koji Arai; Daisuke Tatsumi; Mitsuhiro Fukushima; Toshitaka Yamazaki; M. K. Fujimoto; K. Agatsuma; Y. Arase; Noriyasu Nakagawa; A. Takamori; Kimio Tsubono; R. DeSalvo; A. Bertolini; S. Márka; V. Sannibale
TAMA300 has been upgraded to improve the sensitivity at low frequencies after the last observation run in 2004. To avoid the noise caused by seismic activities, we installed a new seismic isolation system —- the TAMA seismic attenuation system (SAS). Four SAS towers for the test-mass mirrors were sequentially installed from 2005 to 2006. The recycled Fabry–Perot Michelson interferometer was successfully locked with the SAS. We confirmed the reduction of both length and angular fluctuations at frequencies higher than 1 Hz owing to the SAS.
Physical Review Letters | 2011
K. Ishidoshiro; Masaki Ando; A. Takamori; H. Takahashi; K. Okada; Nobuyuki Matsumoto; Wataru Kokuyama; Nobuyuki Kanda; Yoichi Aso; Kimio Tsubono
We present the first upper limit on gravitational wave (GW) backgrounds at an unexplored frequency of 0.2 Hz using a torsion-bar antenna (TOBA). A TOBA was proposed to search for low-frequency GWs. We have developed a small-scaled TOBA and successfully found Ω(gw)(f)<4.3×10(17) at 0.2 Hz as demonstration of the TOBAs capabilities, where Ω(gw)(f) is the GW energy density per logarithmic frequency interval in units of the closure density. Our result is the first nonintegrated limit to bridge the gap between the LIGO band (around 100 Hz) and the Cassini band (10(-6)-10(-4)u2009u2009Hz).
Journal of Physics: Conference Series | 2008
Kakeru Takahashi; Masaki Ando; Kimio Tsubono
We developed a laser stabilization system composed of optical fibers. In this system all optical devices used for stabilization are connected with optical fibers. This system has advantages for space use and for low-frequency (< 10 Hz) stabilization. We suppressed the intensity noise to 6 × 10-7/√Hz at 1 Hz, and to 4 × 10-8/√Hz at 1 kHz. We also suppressed the frequency noise to 20 Hz/√Hz at 1 Hz, and to 2 Hz/√Hz at 80 Hz. This system is one of the candidates for the laser stabilization system of DECIGO.
Classical and Quantum Gravity | 2007
Daisuke Tatsumi; Ryutaro Takahashi; Koji Arai; Noriyasu Nakagawa; K. Agatsuma; Toshitaka Yamazaki; Mitsuhiro Fukushima; Masa Katsu Fujimoto; A. Takamori; A. Bertolini; V. Sannibale; R. DeSalvo; S. Márka; Masaki Ando; Kimio Tsubono; Tomomi Akutsu; Kazuhiro Yamamoto; Hideki Ishitsuka; Takashi Uchiyama; Shinji Miyoki; Masatake Ohashi; Kazuaki Kuroda; Norichika Awaya; Nobuyuki Kanda; Akito Araya; Souichi Telada; Takayuki Tomaru; T. Haruyama; Akira Yamamoto; Nobuaki Sato
The current status of the TAMA and CLIO detectors in Japan is reported in this paper. These two interferometric gravitational wave detectors are being developed for the large cryogenic gravitational wave telescope (LCGT) which is a future plan for detecting gravitational wave signals at least once per year. TAMA300 is being upgraded to improve the sensitivity in a low-frequency region after the last observational experiment in 2004. To reduce the seismic noises, we are installing a new seismic isolation system, called the TAMA seismic attenuation system, for the four test masses. We confirmed stable mass locks of a cavity and improvements of length and angular fluctuations by using two SASs. We are currently optimizing the performance of the third and fourth SASs. We continue TAMA300 operation and R&D studies for the LCGT. The next data taking is planned for the summer of 2007. CLIO is a 100 m baseline length prototype detector for LCGT to investigate interferometer performance in cryogenic condition. The key features of CLIO are that it locates the Kamioka underground site for a low-seismic noise level, and adopts cryogenic Sapphire mirrors for low-thermal noise level. The first operation of the cryogenic interferometer was successfully demonstrated in February 2006. Current sensitivity at room temperature is close to the target sensitivity within a factor of 4. Several observational experiments at room temperature have been done. Once the displacement noise reaches the thermal noise level of room temperature, its improvement by cooling test mass mirrors should be demonstrated.
Journal of Physics: Conference Series | 2008
K. Agatsuma; Ryutaro Takahashi; Koji Arai; Daisuke Tatsumi; Mitsuhiro Fukushima; Toshitaka Yamazaki; M. K. Fujimoto; Y. Arase; Noriyasu Nakagawa; A. Takamori; Kimio Tsubono; Kazuaki Kuroda; Masatake Ohashi; R. DeSalvo; A. Bertolini; S. Márka; V. Sannibale
A new seismic isolation system, TAMA Seismic Attenuation System (TAMA-SAS), was installed to TAMA300 in order to improve the sensitivity at low frequencies. Inertial damping is one of the hierarchical control systems of the TAMA-SAS which are employed to give full play to its ability. We have established two servo loops to control the Inverted Pendulum (IP) which composes the SAS. One is the servo loop using LVDT position sensors to keep the position of the IP. The other is the inertial damping which uses accelerometers to control the inertial motion of the IP for the horizontal direction. The fluctuation of the IP was reduced using our servo system. In addition, reduction of angular and longitudinal fluctuation of the mirror was also confirmed. These results indicate that the control for the IP properly works and the isolation performance of the TAMA-SAS was improved.
Physical Review Letters | 2010
Masaki Ando; K. Ishidoshiro; Kazuhiro Yamamoto; Kent Yagi; Wataru Kokuyama; Kimio Tsubono; A. Takamori
Physica C-superconductivity and Its Applications | 2010
Koji Ishidoshiro; Masaki Ando; A. Takamori; K. Okada; Kimio Tsubono
Physical Review D | 2007
Kazuhiro Yamamoto; Masaki Ando; Keita Kawabe; Kimio Tsubono