1000 hours of data taken on TAMA300

and the first lock of the recycled TAMA300

Seiji Kawamura, National Astronomical Observatory of Japan seiji.kawamura@nao.ac.jp
The TAMA project, the Japanese effort for detecting gravitational waves using the 300m laser interferometer (TAMA300), took an unprecedented 1000 hours of data in the summer of 2001. Just recently the power recycling system was implemented in TAMA300, and the recycled interferometer was successfully locked.

During the observation period, the interferometer was remarkably stable: it held lock continuously for more than 20 hours several times, and the overall duty cycle was 86%. The observational functions of the detector had been drastically improved for this data run: a newly-developed automatic re-locking system of the whole interferometer worked reliably, a newly-established quick look system helped us to find any unusual behavior of the interferometer as well as the data taking system, and a newly-implemented medium-speed data acquisition system (64 channels) supplemented the existing high-speed and low-speed data acquisition system (100 channels) for recording important detector information. As for the sensitivity of the detector, it had been improved around 100 Hz by a factor of 10 compared with the sensitivity obtained in the summer of 2000, resulting in a significant improvement of the sensitivity to chirps from heavier-mass binary coalescence. The best strain sensitivity of $5x10^{-21} {\rm Hz}^{-1/2}$ around 1 kHz remained the same as before.

During the above-mentioned data run, the interferometer was operated without the power recycling system. Since then we have begun implementing recycling in TAMA300. Around the end of 2001 the recycled interferometer was finally locked for a few seconds for the first time in the history of TAMA300! The lock has been made more and more robust by re-activating the alignment control system for the test masses and by adjusting all the servo systems carefully. As of Jan. 23, 2002, TAMA300 with recycling can hold lock for up to 46 minutes continuously. We will continue to stabilize the lock of the interferometer as well as to improve the sensitivity of the detector.

Please have a look at our home page for more details, http://tamago.mtk.nao.ac.jp

Jorge Pullin 2002-02-11