Results of the search for inspiraling compact star binaries from TAMA300's observation in 2000-2004

We analyze the data of TAMA300 detector to search for gravitational waves from inspiraling compact star binaries with masses of the component stars in the range 1-3Msolar. In this analysis, 2705 hours of data, taken during the years 2000-2004, are used for the event search. We combine the results of different observation runs, and obtained a single upper limit on the rate of the coalescence of compact binaries in our Galaxy of 20 per year at a 90% confidence level. In this upper limit, the effect of various systematic errors such like the uncertainty of the background estimation and the calibration of the detector's sensitivity are included.Comment: 8 pages, 4 Postscript figures, uses revtex4.sty The author list was correcte

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

Tentative Utilization of a Raindrop Size Distribution Meter Specially Designed for the Observation of Tropical Precipitation in the TOGA/COARE Project

金沢大学理工研究域電子情報学系降雨のレーダ・データを定量的に解析する上で雨滴の粒径分布が得られると有効である。そのためTOGA/COAREプロジェクトで実施された2台のドップラーレーダによるデュアル観測においても、このために特別に開発された雨滴の粒径分布の測定装置がパプア・ニューギニャのマヌス島で使用された。本装置は1つの光源と2台のビデオ・カメラの光学系から成っており、その間を、上部のスリットを通って落下する雨滴のイメージを擦りガラスで一様にした面光源を背景とする影の像として捉え、それをデジタル処理するものである。2台のカメラは異なるシャッタ-速度に固定され、一方は雨滴の粒径を他方は落下速度を同じ雨滴について同時に計測する。この場合、落下速度は粒径の検定のために間欠的に参照されるので、小さい雨滴に関しても信頼度が高いのが、特徴である。ここでは、得られた結果から2つの典型例として、ガンマー関数型分布と2山型分布のものを挙げ、これらが弱い対流と強い対流の雲からの降雨にそれぞれ対応していること示した。2山型の事例は得られたレーダの解析図と比較して議論され、熱帯特有の「暖かい雨」の形成機構として考えられる併合成長の証拠として、また雨滴の蒸発過程の可能性等が考察された。 To offer precise data for a more quantitative analysis of the data obtained by the dual Doppler radar system, a specially designed raindrop size distribution meter was utilized at Manus Island, Papua New Guinea, in the TOGA/COARE project. The measuring device consists of an optical system with a light source and two video cameras. The raindrops that fall through a slit are illuminated against a uniform surface light source by means of a frosted glass plate immediately next to them and their shadow images are photographed by two video cameras with different shutter speeds for simultaneously measuring size and velocity of fall of the same raindrop. Fall velocity is used to examine the size measured and provides a highly reliable measurement of size for even the smaller raindrops. In this paper, two different types of size distribution of raindrops are shown by a single modal Gamma function and a bimodal distribution corresponding to relatively weak and relatively strong convective clouds, respectively. The bimodal case is discussed in comparison with the radar data analyzed in a few instances of a series of rainfall periods and some of the results provide possible evidence for the warm-rain mechanism and evaporation processes