114 research outputs found
Status of the GINGER project
Large frame Ring laser gyroscopes, based on the Sagnac effect, are top
sensitivity instrumentation to measure angular velocity with respect to the
fixed stars. GINGER (Gyroscopes IN GEneral Relativity) project foresees the
construction of an array of three large dimension ring laser gyroscopes,
rigidly connected to the Earth. GINGER has the potentiality to measure general
relativity effects and Lorentz Violation in the gravity sector, once a
sensitivity of , or better, of the Earth rotation rate is obtained.
Being attached to the Earth crust, the array will also provide useful data for
geophysical investigation. For this purpose, it is at present under
construction as part of the multi-components observatory called Underground
Geophysics at Gran Sasso (UGSS). Sensitivity is the key point to determine the
relevance of this instrument for fundamental science. The most recent progress
in the sensitivity measurement, obtained on a ring laser prototype called
GINGERINO, indicates that GINGER should reach the level of 1 part in
of the Earth rotation rate.Comment: 6 pages, 5 figure
Analysis of ring laser gyroscopes including laser dynamics
Inertial sensors stimulate very large interest, not only for their
application but also for fundamental physics tests. Ring laser gyros, which
measure angular rotation rate, are certainly among the most sensitive inertial
sensors, with excellent dynamic range and bandwidth. Large area ring laser
gyros are routinely able to measure fractions of prad/s, with high duty cycle
and bandwidth, providing fast, direct and local measurement of relevant
geodetic and geophysical signals. Improvements of a factor would open
the windows for general relativity tests, as the GINGER project, an Earth based
experiment aiming at the Lense-Thirring test at level. However, it is
well known that the dynamics of the laser induces non-linearities, and those
effects are more evident in small scale instruments. Sensitivity and accuracy
improvements are always worthwhile, and in general there is demand for high
sensitivity environmental study and development of inertial platforms, where
small scale transportable instruments should be used. We discuss a novel
technique to analyse the data, aiming at studying and removing those
non-linearity. The analysis is applied to the two ring laser prototypes GP2 and
GINGERINO, and angular rotation rate evaluated with the new and standard
methods are compared. The improvement is evident, it shows that the
back-scatter problem of the ring laser gyros is negligible with a proper
analysis of the data, improving the performances of large scale ring laser
gyros, but also indicating that small scale instruments with sensitivity of
nrad/s are feasible.Comment: 9 pages and 7 figure
Hands on GINGER: Seismic Wave measurement
GINGER (Gyroscopes IN GEneral Relativity) will be a 3-D array of mutually orthogonal ring lasers able to measure the general relativistic effects due to the rotation of the Earth (LenseThirring effect). The development of highly sensitive ring laser gyroscopes gives as well the possibility to accurately monitor the rotational ground motions on Earth. The GP2 ring laser, a prototype developed to study how to keep constant at the level of 1 part in 1010 the scale factor of the ring lasers in the GINGER array, has been recently designed and realized and some of its data have been analyzed for geophysical studies. The signal has been extracted from the interferogram raw data and the seismic wave contribution has been obtained by subtracting the contribution due to the Earth rotation
Sagnac Gyroscopes and the GINGER Project
Large-frame optical Sagnac gyroscopes, more commonly called ring laser gyroscopes, are considered the only device able to provide fast and very high sensitivity measurement of the length of the day (LOD) and of the Earth rotation axis variations. Several large-frame Sagnac gyros are presently operative with a high duty cycle and a sensitivity well below fractions of nrad/s in 1 s measurement. At present, other inertial angular rotation sensors are not competitive with ring laser gyroscopes. The feasibility depends on the so-called hetero-lithic ring lasers. The present state of the art is reported and the feasibility of the main goals for geodesy discussed
Observational and Experimental Gravity
We indicate the progress of experimental gravity, present an outlook in this
field, and summarise the Observational/Experimental Parallel Session together
with a related plenary talk on gravitational waves of the 2nd LeCosPA
Symposium.Comment: 1 figure, Second LeCosPa Simposium, December 2015, Taipei Taiwa
Prospects for Stochastic Background Searches Using Virgo and LSC Interferometers
We consider the question of cross-correlation measurements using Virgo and
the LSC Interferometers (LIGO Livingston, LIGO Hanford, and GEO600) to search
for a stochastic gravitational-wave background. We find that inclusion of Virgo
into the network will substantially improve the sensitivity to correlations
above 200 Hz if all detectors are operating at their design sensitivity. This
is illustrated using a simulated isotropic stochastic background signal,
generated with an astrophysically-motivated spectrum, injected into 24 hours of
simulated noise for the LIGO and Virgo interferometers.Comment: 11 pages, uses IOP style files, submitted to CQG for GWDAW11
proceedings; revised in response to referee comment
First deep underground observation of rotational signals from an earthquake at teleseismic distance using a large ring laser gyroscope
Recent advances in large ring laser gyroscopes (RLG) technologies opened the
possibility to observe rotations of the ground with sensitivities up to
over the frequency band of seismological interest
(0.01-1Hz), thus opening the way to a new geophysical discipline, i.e.
rotational seismology. A measure of rotations in seismology is of fundamental
interest for (a) the determination of all the six degrees of freedom that
characterize a rigid body motion, and (b) the quantitative estimate of the
rotational motions contaminating ground translation measurements obtained from
standard seismometers. Within this framework, this paper presents and describes
GINGERino, a new large observatory-class RLG located in Gran Sasso underground
laboratory (LNGS), one national laboratories of the INFN (Istituto Nazionale di
Fisica Nucleare). We also report unprecedented observations and analyses of the
roto-translational signals from a tele-seismic event observed in such a deep
underground environment
Testing general relativity by means of ring lasers
The paper discusses the optimal conguration of one or more ring lasers to be used for measuring
the general relativistic effects of the rotation of the Earth, as manifested on the surface of the planet. The
analysis is focused on devices having their normal vector lying in the meridian plane. The crucial role
of the evaluation of the angles is evidenced. Special attention is paid to the orientation at the maximum
signal, minimizing the sensitivity to the orientation uncertainty. The use of rings at different latitudes is
mentioned and the problem of the non-sphericity of the Earth is commented
Testing general relativity by means of ring lasers
The paper discusses the optimal conguration of one or more ring lasers to be used for measuring
the general relativistic effects of the rotation of the Earth, as manifested on the surface of the planet. The
analysis is focused on devices having their normal vector lying in the meridian plane. The crucial role
of the evaluation of the angles is evidenced. Special attention is paid to the orientation at the maximum
signal, minimizing the sensitivity to the orientation uncertainty. The use of rings at different latitudes is
mentioned and the problem of the non-sphericity of the Earth is commented
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