| Co-Investigator(Kenkyū-buntansha) |
YAMAZAKI Toshitaka Astrometry and Celestial Mechanics Division, Research Associate, 位置天文・天体力学研究系, 助手 (90182485)
ARAI Koji Astrometry and Celestial Mechanics Division, Research Associate, 位置天文・天体力学研究系, 助手 (50321584)
TAKAHASI Ryutaro Astrometry and Celestial Mechanics Division, Research Associate, 位置天文・天体力学研究系, 助手 (60270451)
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| Budget Amount *help |
¥12,800,000 (Direct Cost: ¥12,800,000)
Fiscal Year 2002: ¥6,400,000 (Direct Cost: ¥6,400,000)
Fiscal Year 2001: ¥6,400,000 (Direct Cost: ¥6,400,000)
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| Research Abstract |
There are several projects going on, which aim at gravitational wave detection using laser interferometers : the Japanese TAMA project, the American LIGO project, the French-Italian VIRGO project, and the German-British GEO project. It is quite possible that gravitational waves could be detected in several years. However, it is necessary to improve the sensitivity of the antennas further in order to establish the gravitational wave astronomy.
The resonant sideband extraction (RSE), which is a variable bandwidth interferometer, is one of the advanced technologies that could improve the sensitivity of the interferometer in a limited frequency band.
There has been several basic experiments on the RSE interferometer so far, but they were all performed as table-top experiments in the air, as well as they were all using multi-modulation schemes for signal extraction. Since the RSE interferometer requires an extremely high finesse of the arm cavity, thus, extremely high reflectivity of the mirr
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ors, it is not preferable to operate the interferometer in the air because of possible degradation of the mirrors in the air. Also the table-top experiment uses mirrors fixed to the table, which are very different from the suspended mirrors in a real gravitational wave lantenna. Moreover, the multi-modulation scheme makes the interferometer control even more complicated.
Therefore in this research, we performed the experiment in the vacuum system using a small suspension system, which made it possible to have a better and more realistic environment. Also we invented a single modulation method for signal extraction, which ensures the simplicity of the control system. We have succeeded in operating the RSE interferometer using the single modulation with the third harmonic demodulation in a vacuum system using suspended mirrors for the first time in the world. We also successfully developed an induced current damping method for the small suspension system. Other than the above-mentioned success, we have been investigating the possibility of using a polarization method in a table-top experiment. In the theoretical aspect of the RSE interferometer, we have been analizing the quantum noise of the interferometer.
With all the efforts and success altogether we believe that we will be ready to finalize the design of the RSE interferometer for the future large antenna just by optimizing the design parameters by further experiment. Less
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