Enrico Maccioni

Measuring Gravito-magnetic Effects by Multi Ring-Laser Gyroscope

SUMMARY We propose an under-ground experiment to detect the general relativistic effects due to the curvature of space-time around the Earth (de Sitter effect) and to rotation of the planet (dragging of the inertial frames or Lense-Thirring effect). It is based on the comparison between the IERS value of the Earth rotation vector and corresponding measurements obtained by a tri-axial laser detector of rotation. The proposed detector consists of six large ring-lasers arranged along three orthogonal axes. In about two years of data taking, the 1% sensitivity required for the measurement of the Lense-Thirring drag can be reached with square rings of 6

MEASUREMENT OF THE CALCIUM 1P1-1D2 TRANSITION RATE IN A LASER-COOLED ATOMIC-BEAM

m

Fiber laser strain sensor device

side, assuming a shot noise limited sensitivity (

Interferometric length metrology for the dimensional control of ultra-stable ring laser gyroscopes

20 prad/s/\sqrt{Hz}

NEMO: A PROJECT FOR A KM3 UNDERWATER DETECTOR FOR ASTROPHYSICAL NEUTRINOS IN THE MEDITERRANEAN SEA

). The multi-gyros system, composed of rings whose planes are perpendicular to one or the other of three orthogonal axes, can be built in several ways. Here, we consider cubic and octahedron structures. The symmetries of the proposed configurations provide mathematical relations that can be used to study the stability of the scale factors, the relative orientations or the ring-laser planes, very important to get rid of systematics in long-term measurements, which are required in order to determine the relativistic effects.

Status and first results of the NEMO Phase-2 tower

The efficiency of laser cooling in a thermal beam of calcium has been investigated under different cooling schemes. Special attention has been paid to analysis of the loss factor represented by the decay of atoms excited by the cooling laser to the 1P1 state into the metastable 1D2 level. The cooling scheme at a fixed laser frequency makes possible a good estimation of the branching ratio R between the decay probability from the 1P1 level to the ground 1S0 state and to the metastable 1D2 state. The measured value of (1.0 ± 0.15) × 105 seems high enough to produce only a small reduction in the cooling efficiency.

The optical modules of the phase-2 of the NEMO project

We present a fiber laser strain sensor (FLSS) with noise-equivalent sensitivity equal to or better than 80?p?rms?(Hz)?1/2 at very low frequencies, from 100?mHz to several hundreds of hertz. The strain affects the fiber laser emission wavelength, and an imbalanced Mach?Zender interferometer (MZI) converts wavelength variations into phase-amplitude variations. The sensor has been also tested in the time domain by applying sinusoidal strain bursts: the device also shows a good signal-to-noise ratio at the lowest burst frequencies.

A W–InSb point contact diode for harmonic generation and mixing in the visible

We present the experimental test of a method for controlling the absolute length of the diagonals of square ring laser gyroscopes. The purpose is to actively stabilize the ring cavity geometry and to enhance the rotation sensor stability in order to reach the requirements for the detection of the relativistic Lense-Thirring effect with a ground-based array of optical gyroscopes. The test apparatus consists of two optical cavities 1.32 m in length, reproducing the features of the ring cavity diagonal resonators of large frame He-Ne ring laser gyroscopes. The proposed measurement technique is based on the use of a single diode laser, injection locked to a frequency stabilized He-Ne/Iodine frequency standard, and a single electro-optic modulator. The laser is modulated with a combination of three frequencies allowing to lock the two cavities to the same resonance frequency and, at the same time, to determine the cavity Free Spectral Range (FSR). We obtain a stable lock of the two cavities to the same optical frequency reference, providing a length stabilization at the level of 1 part in

Deep underground rotation measurements: GINGERino ring laser gyroscope in Gran Sasso

10^{11}

Measuring general relativity effects in a terrestrial lab by means of laser gyroscopes

, and the determination of the two FSRs with a relative precision of 0.2 ppm. This is equivalent to an error of 500 nm on the absolute length difference between the two cavities.