arXiv subjects

Eugenio Coccia

Publications and source records attributed to Eugenio Coccia.

4 recordsLinked to original sources

arXiv2020

Lunar Gravitational-Wave Antenna

Monitoring of vibrational eigenmodes of an elastic body excited by gravitational waves was one of the first concepts proposed for the detection of gravitational waves. At laboratory scale, these experiments became known as resonant-bar detectors first developed by Joseph Weber in the 1960s. Due to the dimensions of these bars, the targeted signal frequencies were in the kHz range. Weber also pointed out that monitoring of vibrations of Earth or Moon could reveal gravitational waves in the mHz band. His Lunar Surface Gravimeter experiment deployed on the Moon by the Apollo 17 crew had a technical failure rendering the data useless. In this article, we revisit the idea and propose a Lunar Gravitational-Wave Antenna (LGWA). We find that LGWA could become an important partner observatory for joint observations with the space-borne, laser-interferometric detector LISA, and at the same time contribute an independent science case due to LGWA's unique features. Technical challenges need to be overcome for the deployment of the experiment, and development of inertial vibration sensor technology lays out a future path for this exciting detector concept.

gr-qc↗

arXiv2013

Measurement of the thermal expansion coefficient of an Al-Mg alloy at ultra-low temperatures

We describe a result coming from an experiment based on an Al-Mg alloy (~ 5% Mg) suspended bar hit by an electron beam and operated above and below the termperature of transition from superconducting to normal state of the material. The amplitude of the bar first longitudinal mode of oscillation, excited by the beam interacting with the bulk, and the energy deposited by the beam in the bar are the quantities measured by the experiment. These quantities, inserted in the equations describing the mechanism of the mode excitation and complemented by an independent measurement of the specific heat, allow us to determine the linear expansion coefficient of the material.

cond-mat.mtrl-sci↗

arXiv2004

On the possible sources of gravitational wave bursts detectable today

We discuss the possibility that galactic gravitational wave sources might give burst signals at a rate of several events per year, detectable by state-of-the-art detectors. We are stimulated by the results of the data collected by the EXPLORER and NAUTILUS bar detectors in the 2001 run, which suggest an excess of coincidences between the two detectors, when the resonant bars are orthogonal to the galactic plane. Signals due to the coalescence of galactic compact binaries fulfill the energy requirements but are problematic for lack of known candidates with the necessary merging rate. We examine the limits imposed by galactic dynamics on the mass loss of the Galaxy due to GW emission, and we use them to put constraints also on the GW radiation from exotic objects, like binaries made of primordial black holes. We discuss the possibility that the events are due to GW bursts coming repeatedly from a single or a few compact sources. We examine different possible realizations of this idea, such as accreting neutron stars, strange quark stars, and the highly magnetized neutron stars (``magnetars'') introduced to explain Soft Gamma Repeaters. Various possibilities are excluded or appear very unlikely, while others at present cannot be excluded.

gr-qc↗

arXiv2002

Resonance widening in spherical GW detectors: model descriptions of the dissipation processes

Internal friction effects are responsible for line widening of the resonance frequencies in mechanical oscillators and result in damped oscillations of its eigenmodes with a decay time Q/ω. We study the solutions to the equations of motion for the case of spherical oscillators, to be used as next generation of acoustic gravitational wave detectors, based on various different assumptions about the material's constituent equations. Quality factor dependence on mode frequency is determined in each case, and a discussion of its applicability to actual gravitational wave detectors is made on the basis of available experimental evidence.

gr-qc↗