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

南極ドームふじ基地における第2期氷床深層コア掘削

南極ドームふじ基地において，第2 期氷床深層コア掘削が行われた．2001 年のパイロット孔掘削に引き続き2003/2004 シーズンから4 か年にわたり本格的な深層コア掘削を実施し，2007 年1 月に3035.22 m 深に達した．夏期間のみの掘削としたので，効率よく掘削できるように第1 期深層コア掘削システムの問題点を解決しながら多くの改良を施した．特に1 回の掘削で採取可能なコア長を2.3 m から3.84 m にしたことと切削チップ収納効率を高めたことが大きい．本報告では，現地で使用した掘削システムの概要とともに，掘削の方法，掘削の経過を述べるとともに，掘削中に生じた様々なトラブルについても報告し，併せて今後の課題を示した． The second deep ice coring project was carried out at Dome Fuji, Antarctica. Following the pilot hole drilling in 2001, deep ice core drilling was conducted for four years from the 2003/2004 austral summer season, reaching a depth of 3035.22 m in January 2007. The drilling was performed only in the summer season. Therefore, many improvements were made to the problems of the first deep ice core drilling system to enable efficient drilling. In particular, the core length that can be obtained at one time was increased from 2.3m to 3.84 m, and the chip storage efficiency was enhanced. In this report, the outline of the drilling system, the method of drilling, the progress of drilling operation, and various troubles were reported. Also, future issues are indicated

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