Observation results by the TAMA300 detector on gravitational wave bursts from stellar-core collapses

We present data-analysis schemes and results of observations with the TAMA300 gravitational-wave detector, targeting burst signals from stellar-core collapse events. In analyses for burst gravitational waves, the detection and fake-reduction schemes are different from well-investigated ones for a chirp-wave analysis, because precise waveform templates are not available. We used an excess-power filter for the extraction of gravitational-wave candidates, and developed two methods for the reduction of fake events caused by non-stationary noises of the detector. These analysis schemes were applied to real data from the TAMA300 interferometric gravitational wave detector. As a result, fake events were reduced by a factor of about 1000 in the best cases. The resultant event candidates were interpreted from an astronomical viewpoint. We set an upper limit of 2.2x10^3 events/sec on the burst gravitational-wave event rate in our Galaxy with a confidence level of 90%. This work sets a milestone and prospects on the search for burst gravitational waves, by establishing an analysis scheme for the observation data from an interferometric gravitational wave detector

大型ヘリカル装置のIC聾アンテナと加熱特性

Ion－cyclotron heating was applied to the Large Helical Device by using single, trap loop antennas located at the outward side of the toroid. Good experimental results were obtaine with adequate plasma　confining configurations and antenna conditionings．Loading resistance of the antenna was2－8Ohm and　this was a sufficiently large value. Various heating characteristics were investigated by changing the　heating modes, ion species and magneticfield configurations．The minoriy-ion heating mode resulted in the best heating performances，and the heatin gcharacteristics largely depended on the cyclotron resonance positions．There were some unique features due to the heliotron configuration．These results showed the　effectiveness of the ICRF heating in a helical device and the appropriateness of the ICRF antenna design　in the LHD