261 research outputs found

### Mirror-orientation noise in a Fabry-Perot interferometer gravitational wave detector

The influence of angular mirror-orientation errors on the length of a Fabry-Perot resonator is analyzed geometrically. Under conditions in which dominant errors are static or vary slowly over time, the analysis permits a simple prediction of the spectrum of short-term cavity length fluctuations resulting from mirror-orientation noise. The resulting model is applicable to the design of mirror control systems for the Laser Interferometer Gravitational-Wave Observatory, which will monitor separations between mirrored surfaces of suspended inertial test bodies as a way to measure astrophysical gravitational radiation. The analysis is verified by measuring the response of the Laser Interferometer Gravitational- Wave Observatory's 40-m interferometer test-bed to the rotation of its mirrors

### Possibility of Direct Measurement of the Acceleration of the Universe Using 0.1 Hz Band Laser Interferometer Gravitational Wave Antenna in Space

It may be possible to construct a laser interferometer gravitational wave
antenna in space with $h_{rms}\sim 10^{-27}$ at $f\sim 0.1{\rm Hz}$ in this
century. We show possible specification of this antenna which we call DECIGO.
Using this antenna we show that 1) typically $10^5$ ($10^4\sim 10^6$) chirp
signals of coalescing binary neutron stars per year may be detected with S/N
$\sim 10^4$. 2) We can directly measure the acceleration of the universe by ten
years observation of binary neutron stars. 3) The stochastic gravitational
waves of \Omega_{GW}\gsim 10^{-20} predicted by the inflation may be detected
by correlation analysis for which effects of the recent cosmic acceleration
would become highly important. Our formula for phase shift due to accelerating
motion might be also applied for binary sources of LISA.Comment: 5 pages, 1 figure, revised version, Phys.Rev.Lett in pres

### Quantum Noise in Differential-type Gravitational-wave Interferometer and Signal Recycling

There exists the standard quantum limit (SQL), derived from Heisenberg's
uncertainty relation, in the sensitivity of laser interferometer
gravitational-wave detectors. However, in the context of a full
quantum-mechanical approach, SQL can be overcome using the correlation of shot
noise and radiation-pressure noise. So far, signal recycling, which is one of
the methods to overcome SQL, is considered only in a recombined-type
interferometer such as Advanced-LIGO, LCGT, and GEO600. In this paper, we
investigated quantum noise and the possibility of signal recycling in a
differential-type interferometer. As a result, we found that signal recycling
is possible and creates at most three dips in the sensitivity curve of the
detector. Then, taking advantage of the third additional dip and comparing the
sensitivity of a differential-type interferometer with that of a
next-generation Japanese GW interferometer, LCGT, we found that SNR of inspiral
binary is improved by a factor of 1.43 for neutron star binary, 2.28 for 50
M_sun black hole binary, and 2.94 for 100 M_sun black hole binary. We also
found that power recycling to increase laser power is possible in our
signal-recycling configuration of a detector.Comment: 17 pages, submitted to Phys.Rev.

### Resonant speed meter for gravitational wave detection

Gravitational-wave detectors have been well developed and operated with high
sensitivity. However, they still suffer from mirror displacement noise. In this
paper, we propose a resonant speed meter, as a displacement noise-canceled
configuration based on a ring-shaped synchronous recycling interferometer. The
remarkable feature of this interferometer is that, at certain frequencies,
gravitational-wave signals are amplified, while displacement noises are not.Comment: 4 pages, 4 figure

### 観光資源開発の方向性

土地は資本、労働とならんで生産の三要素の一つである。しかし工業社会における主たる産業が製造業であり、そしてそこでの生産活動が土地の豊度をはじめとする自然条件に大きい影響を受けることなく、付加価値の増大およびそのための労働生産性が追求されるものであるだけに、土地の生産に対する役割はそれほど重視されることはなかった。今日の大衆観光は、そうした工業社会によってもたらされてきたものである。大衆の生存費以上の所得増や余暇時間の増加、交通・宿泊をはじめとする観光産業の発展などは、いずれも工業社会の成果であり、１９６０年代以降それらが互いに結びつくことによって、大衆観光は飛躍的に発展してきた。そうして観光資源の開発は、観光資源をベースにした観光地という土地への考察が十分になされないまま、製造業同様の付加価値の増大を重視したものになった。ただ観光資源開発は、そうした資本・賃労働関係によるところの付加価値の側面ばかりでなく、観光地という土地の特性が観光対象となっているだけに、農業同様に、土地の優劣に大きい影響を受ける側面もある。現実に、土地の優位性を追求しない観光資源開発の多くはこれまで失敗に終わってきた。本稿は、資本・労働・土地という生産の三要素という視点から、持続可能な観光資源開発の方向性を示そうとするものである

### Displacement- and Timing-Noise Free Gravitational-Wave Detection

Motivated by a recently-invented scheme of displacement-noise-free
gravitational-wave detection, we demonstrate the existence of
gravitational-wave detection schemes insusceptible to both displacement and
timing (laser) noises, and are thus realizable by shot-noise-limited laser
interferometry. This is possible due to two reasons: first, gravitational waves
and displacement disturbances contribute to light propagation times in
different manners; second, for an N-detector system, the number of signal
channels is of the order O(N^2), while the total number of timing- and
displacement-noise channels is of the order O(N).Comment: 4 pages, 3 figures; mistake correcte

### Direct Measurement of Thermal Fluctuation of High-Q Pendulum

We achieved for the first time a direct measurement of the thermal
fluctuation of a pendulum in an off-resonant region using a laser
interferometric gravitational wave detector. These measurements have been well
identified for over one decade by an agreement with a theoretical prediction,
which was derived by a fluctuation-dissipation theorem. Thermal fluctuation is
dominated by the contribution of resistances in coil-magnet actuator circuits.
When we tuned these resistances, the noise spectrum also changed according to a
theoretical prediction. The measured thermal noise level corresponds to a high
quality factor on the order of 10^5 of the pendulum.Comment: 10 pages, 4 figure

### Development of a frequency-detuned interferometer as a prototype experiment for next-generation gravitational-wave detectors

We report on our prototype experiment that uses a 4-m detuned resonant sideband extraction interferometer with suspended mirrors, which has almost the same configuration as the next-generation, gravitational-wave detectors. We have developed a new control scheme and have succeeded in the operation of such an interferometer with suspended mirrors for the first time ever as far as we know. We believe that this is the first such instrument that can see the radiation pressure signal enhancement, which can improve the sensitivity of next-generation gravitational-wave detectors

### Interferometers for Displacement-Noise-Free Gravitational-Wave Detection

We propose a class of displacement- and laser-noise free
gravitational-wave-interferometer configurations, which does not sense
non-geodesic mirror motions and laser noises, but provides non-vanishing
gravitational-wave signal. Our interferometer consists of 4 mirrors and 2
beamsplitters, which form 4 Mach-Zehnder interferometers. By contrast to
previous works, no composite mirrors are required. Each mirror in our
configuration is sensed redundantly, by at least two pairs of incident and
reflected beams. Displacement- and laser-noise free detection is achieved when
output signals from these 4 interferometers are combined appropriately. Our
3-dimensional interferometer configuration has a low-frequency response
proportional to f^2, which is better than the f^3 achievable by previous
2-dimensional configurations.Comment: 5 pages, 4 figure

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