arXiv subjects

Giorgio Carelli

Publications and source records attributed to Giorgio Carelli.

17 recordsLinked to original sources

arXiv2025

Fast frequency reconstruction using Deep Learning for event recognition in ring laser data

The reconstruction of a frequency with minimal delay from a sinusoidal signal is a common task in several fields; for example Ring Laser Gyroscopes, since their output signal is a beat frequency. While conventional methods require several seconds of data, we present a neural network approach capable of reconstructing frequencies of several hundred Hertz within approximately 10 milliseconds. This enables rapid trigger generation. The method outperforms standard Fourier-based techniques, improving frequency estimation precision by a factor of 2 in the operational range of GINGERINO, our Ring Laser Gyroscope.\\ In addition to fast frequency estimation, we introduce an automated classification framework to identify physical disturbances in the signal, such as laser instabilities and seismic events, achieving accuracy rates between 99\% and 100\% on independent test datasets for the seismic class. These results mark a step forward in integrating artificial intelligence into signal analysis for geophysical applications.

cs.LG↗

arXiv2024

Fringe Contrast characterization and optimization for Ring Laser Gyroscopes

Top sensitivity Ring Laser Gyroscopes based on a simple mechanical scheme, so called heterolithic, have shown to operate on a continuous basis; since the mirror positions are not fixed, unwanted signals can occur, and data selection is necessary. For this purpose, Fringe Contrast is very useful. It depends on output beams intensity, alignment, and polarization; the model of the alignment and polarization contributions to Contrast has been implemented, and tested on the GP2 prototype. Polarization changes are corrected by acting on the output beams with plates, in order to recombine linearly polarized light. Using such model, the GP2 prototype was characterized as for polarization of the beams, inside the cavity and at their interference, and for non-planarity; as a result, the interfering beams off-axis has also been measured.

physics.optics↗

arXiv2024

Noise level of a ring laser gyroscope in the femto-rad/s range

Absolute angular rotation rate measurements with sensitivity better than prad/s would be beneficial for fundamental science investigations. On this regard, large frame Earth based ring laser gyroscopes are top instrumentation as far as bandwidth, long--term operation, and sensitivity are concerned. Here, we demonstrate that the GINGERINO active--ring laser upper limiting noise is close to $2 \times 10^{-15}$ rad/s for $\sim 2 \times 10^5$ s of integration time, as estimated by the Allan deviation evaluated in a differential measurement scheme. This is more than a factor 10 better than the theoretical prediction so far accounted for ideal ring lasers shot--noise with the two beams counter--propagating inside the cavity considered as two independent propagating modes. This feature is related to the peculiarity of real ring laser system dynamics that causes phase cross--talking among the two counter--propagating modes. In this context, the independent beam model is, then, not applicable and the measured noise limit falls below the expected one.

quant-ph↗

arXiv2023

Comparative analysis of local angular rotation between the Ring Laser Gyroscope GINGERINO and GNSS stations

The study of local deformations is a hot topic in geodesy. Local rotations of the crust around the vertical axis can be caused by deformations. In the Gran Sasso area the ring laser gyroscope GINGERINO and the GNSS array are operative. One year of data of GINGERINO is compared with the ones from the GNSS stations, homogeneously selected around the position of GINGERINO, aiming at looking for rotational signals with period of days common to both systems. At that purpose the rotational component of the area circumscribed by the GNSS stations has been evaluated and compared with the GINGERINO data. The coherences between the signals show structures that even exceed 60$\%$ coherence over the 6-60 days period; this unprecedented analysis is validated by two different methods that evaluate the local rotation using the GNSS stations. The analysis reveals that the shared rotational signal's amplitude in both instruments is approximately $10^{-13} rad/s$, an order of magnitude lower than the amplitudes of the signals examined using the coherence method. The comparison of the ring laser data with GNSS antennas provides evidence of the validity of the ring laser data for very low frequency investigation, essential for fundamental physics test.

physics.app-ph↗

arXiv2023

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 $10^{-9}$, 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 $10^{11}$ of the Earth rotation rate.

gr-qc↗

arXiv2022

GINGER

In this paper, we outline the scientific objectives, the experimental layout, and the collaborations envisaged for the GINGER (Gyroscopes IN GEneral Relativity) project. The GINGER project brings together different scientific disciplines aiming at building an array of Ring Laser Gyroscopes (RLGs), exploiting the Sagnac effect, to measure continuously, with sensitivity better than picorad/ s, large bandwidth (ca. 1 kHz), and high dynamic range, the absolute angular rotation rate of the Earth. In the paper, we address the feasibility of the apparatus with respect to the ambitious specifications above, as well as prove how such an apparatus, which will be able to detect strong Earthquakes, very weak geodetic signals, as well as general relativity effects like Lense-Thirring and De Sitter, will help scientific advancements in Theoretical Physics, Geophysics, and Geodesy, among other scientific fields.

gr-qc↗

arXiv2021

Constraining Theories of Gravity by GINGER experiment

The debate on gravity theories to extend or modify General Relativity is very active today because of the issues related to ultra-violet and infra-red behavior of Einstein's theory. In the first case, we have to address the Quantum Gravity problem. In the latter, dark matter and dark energy, governing the large scale structure and the cosmological evolution, seem to escape from any final fundamental theory and detection. The state of art is that, up to now, no final theory, capable of explaining gravitational interaction at any scale, has been formulated. In this perspective, many research efforts are devoted to test theories of gravity by space-based experiments. Here we propose straightforward tests by the GINGER experiment, which, being Earth based, requires little modeling of external perturbation, allowing a thorough analysis of the systematics, crucial for experiments where sensitivity breakthrough is required. Specifically, we want to show that it is possible to constrain parameters of gravity theories, like scalar-tensor or Horava-Lifshitz gravity, by considering their post-Newtonian limits matched with experimental data. In particular, we use the Lense-Thirring measurements provided by GINGER to find out relations among the parameters of theories and finally compare the results with those provided by LARES and Gravity Probe-B satellites.

gr-qc↗

arXiv2021

Effects of temperature variations in high sensitivity Sagnac gyroscope

GINGERINO is one of the most sensitive Sagnac laser-gyroscope based on an heterolithic mechanical structure. It is a prototype for GINGER, the laser gyroscopes array proposed to reconstruct the Earth rotation vector and in this way to measure General Relativity effects. Many factors affect the final sensitivity of laser gyroscopes, in particular, when they are used in long term measurements, slow varying environmental parameters come into play. To understand the role of different terms allows to design more effective mechanical as well as optical layouts, while a proper model of the dynamics affecting long term (low frequency) signals would increase the effectiveness of the data analysis for improving the overall sensitivity. In this contribution we focus our concerns on the effects of room temperature and pressure aiming at further improving mechanical design and long term stability of the apparatus. Our data are compatible with a local orientation changes of the Gran Sasso site below $μ$rad as predicted by geodetic models. This value is, consistent with the requirements for GINGER and the installation of an high sensitivity Sagnac gyroscope oriented at the maximum signal, \textit{i.e.} along the Earth rotation axes.

gr-qc↗

arXiv2021

Reaching the sensitivity limit of a Sagnac gyroscope through linear regression analysis

The sensitivity to angular rotation of the top class Sagnac gyroscope GINGERINO is carefully investigated with standard statistical means, using 103 days of continuous operation and the available geodesic measurements of the Earth angular rotation rate. All features of the Earth rotation rate are correctly reproduced. The sensitivity of fractions of frad/s is attained for long term runs. This excellent sensitivity and stability put Sagnac gyroscopes at the forefront for fundamental physics, in particular for tests of general relativity and Lorentz violation, where the sensitivity plays the key role to provide reliable data for deeper theoretical investigations. The achieved sensitivity overcomes the conventionally expected one for Sagnac ring laser gyroscopes.

gr-qc↗

arXiv2020

An underground Sagnac gyroscope with sub-prad/s rotation rate sensitivity: toward General Relativity tests on Earth

Measuring in a single location on Earth its angular rotation rate with respect to the celestial frame, with a sensitivity enabling access to the tiny Lense-Thirring effect is an extremely challenging task. GINGERINO is a large frame ring laser gyroscope, operating free running and unattended inside the underground laboratory of the Gran Sasso, Italy. The main geodetic signals, i.e., Annual and Chandler wobbles, daily polar motion and Length of the Day, are recovered from GINGERINO data using standard linear regression methods, demonstrating a sensitivity better than 1 prad/s, therefore close to the requirements for an Earth-based Lense-Thirring test.

astro-ph.IM↗

arXiv2019

Identification and correction of Sagnac frequency variations: an implementation for the GINGERINO data analysis

Ring laser gyroscopes are top sensitivity inertial sensors used in the measurement of angular rotation rates. It is well known that the response of such remarkable instruments can in principle access the very low frequency band, but the occurrence of nonlinear effects in the laser dynamics imposes severe limitations in terms of sensitivity and stability. We report here general relationships aimed at evaluating corrections able to effectively account for nonlinear laser dynamics. The so-derived corrections are applied to analyse thirty days of continuous operation of the large area ring laser gyroscope GINGERINO leading to duly reconstruct the Sagnac frequency $ω_S$. The analysis shows that, on the average, the evaluated corrections affect the measurement of the Earth rotation rate $Ω_E$ at the level of 1 part in $1.5\times10^{3}$. Among the identified corrections, the null shift term $ω_{NS}$ is the dominant one. It turns out proportional to the optical losses $μ$ of the ring cavity, which are changing in time at the level of $10\%$ within the considered period of thirty days. The time behaviour is reconstructed based on available signals (interferogram and mono-beam intensities), and the Allan deviation of the estimated $Ω_E$ shows a remarkable long term stability, leading to a sensitivity better than $10^{-10}$rad/s with more than $10$s of integration time, and approaching $(8.5\pm 0.5)\times 10^{-12}$rad/s with $4.5\times10^{5}$s of integration time.

physics.ins-det↗

arXiv2019

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 $10-100$ would open the windows for general relativity tests, as the GINGER project, an Earth based experiment aiming at the Lense-Thirring test at $1\%$ 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.

gr-qc↗

arXiv2016

First Results of GINGERino, a deep underground ringlaser

Large ring-laser gyroscopes are capable of measuring angular rotations with a precision well below fractions of $prad/s$, not far from $10^{-14}$ $rad/s$, the accuracy required for General Relativity tests, this is what the GINGER (Gyroscope-IN-GEneral-Relativity) experiment is aiming for. These features do not guarantee the possibility of measuring the General Relativity Lense--Thirring effect, that manifests itself as a tiny ($\approx 10^{-9} \times Ω_E$) perturbation of the Earth rotation rate. An underground location being in principle less affected by external local disturbances represents a good candidate for housing such a challenging experiment. GINGERino is a test apparatus to investigate the residual local disturbances in the most inner part of the underground international laboratory of the GranSasso (LNGS). It consists of a square ring laser with a $3.6$ m side. The instrument has been tailored to be the larger allowed by the particular location inside the laboratory. Its main objective is to measure the very low frequency rotational motions, in order to prove that LNGS is a suitable location for very low noise measurements and, possibly, General Relativity tests. Aside this main goal, GINGERino will provide unique data for geodesy and geophysics. Its installation has been completed during 2015. Since then, several long set of data have been collected, and the apparatus has been continuously running unattended for more than one week. The typical power spectrum sensitivity was a few $ 10^{-10} rad/s/\sqrt(Hz)$, with integration time not longer than tens of seconds. Improvements of the apparatus are ongoing in order to improve the integration time.

physics.ins-det↗

arXiv2016

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 $10^{-11}$ $\frac{rad}{s}$ 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.

physics.geo-ph↗

arXiv2011

Measuring the Virgo area tilt noise with a laser gyroscope

We report on the measurements of tilt noise performed at the Virgo site with a ring laser gyroscope. The apparatus is a He-Ne laser operating in a square cavity mounted on a vertical plane perpendicular to the north-south arm of the inteferometer. We discuss the possibility of using the ring laser signal to improve the performances of the control system of the Virgo seismic suspensions. The comparison between the ring laser signal and the control signals for the longitudinal translations of the inverted pendulum (IP) shows remarkable coherence in the frequency range 20-200 mHz.

physics.ins-det↗

arXiv2011

A 1.82 m^2 ring laser gyroscope for nano-rotational motion sensing

We present a fully active-controlled He-Ne ring laser gyroscope, operating in square cavity 1.35 m in side. The apparatus is designed to provide a very low mechanical and thermal drift of the ring cavity geometry and is conceived to be operative in two different orientations of the laser plane, in order to detect rotations around the vertical or the horizontal direction. Since June 2010 the system is active inside the Virgo interferometer central area with the aim of performing high sensitivity measurements of environmental rotational noise. So far, continuous not attempted operation of the gyroscope has been longer than 30 days. The main characteristics of the laser, the active remote-controlled stabilization systems and the data acquisition techniques are presented. An off-line data processing, supported by a simple model of the sensor, is shown to improve the effective long term stability. A rotational sensitivity at the level of ten nanoradiants per squareroot of Hz below 1 Hz, very close to the required specification for the improvement of the Virgo suspension control system, is demonstrated for the configuration where the laser plane is horizontal.

physics.ins-det↗

arXiv2010

Rotational sensitivity of the "G-Pisa" gyrolaser

G-Pisa is an experiment investigating the possibility to operate a high sensitivity laser gyroscope with area less than $1 \rm m^2$ for improving the performances of the mirrors suspensions of the gravitational wave antenna Virgo. The experimental set-up consists in a He-Ne ring laser with a 4 mirrors square cavity. The laser is pumped by an RF discharge where the RF oscillator includes the laser plasma in order to reach a better stability. The contrast of the Sagnac fringes is typically above 50% and a stable regime has been reached with the laser operating both single mode or multimode. The effect of hydrogen contamination on the laser was also checked. A low-frequency sensitivity, below $1 \rm Hz$, in the range of $10^{-8} \rm {(rad / s)/ \sqrt{Hz}}$ has been measured.

physics.optics↗