arXiv subjects

Gerardo Iannone

Publications and source records attributed to Gerardo Iannone.

4 recordsLinked to original sources

arXiv2026

Thermal Noise Reduction in Ternary Optical Coatings: From Ti::GeO$_2$-Based Ternary Systems to High Index Materials

Minimizing coating thermal noise is crucial for enhancing gravitational wave detector sensitivity, with a target Amplitude Spectral Density Reduction Factor (ASD RF) of $0.5$ relative to standard coatings. This study investigates the design of low-noise dielectric stacks using the 'Double Stack of Doublet' strategy, explored via ad-hoc optimization heuristics specifically developed for efficient parametric analysis of coating performance. We analyze the performance limits of ternary coatings based on SiO$_2$, Ti::SiO$_2$, and Ti::GeO$_2$, considering material property uncertainties and absorption constraints. Optimization results show that this system, even with relaxed absorbance constraint (1 ppm), falls short of the target, achieving a best ASD RF of $\sim 0.69$. Consequently, we explore alternative ternary 'Double Stack of Doublet' designs incorporating higher-refractive-index materials. Simulations demonstrate that incorporating alternative high-index materials offers a promising pathway, potentially enabling the achievement of the project target. We discuss the optimization strategies, performance trade-offs, design robustness, and implications of using high-index, potentially higher-loss materials for next-generation optical coatings.

physics.optics↗

arXiv2025

Comparative Analysis of Thermal Models for Test Masses in Next-Generation Gravitational Wave Interferometers

Accurate thermal modeling of Terminal Test Masses (TTMs) is crucial for optimizing the sensitivity of gravitational wave interferometers like Virgo. In fact, in such gravitational wave detectors even minimal laser power absorption can induce performance-limiting thermal effects. This paper presents a detailed investigation into the steady-state thermal behavior of TTMs. In particular, future scenarios of increased intracavity laser beam power and optical coating absorption are considered. We develop and compare two numerical models: a comprehensive model incorporating volumetric heat absorption in both the multilayer coating and the bulk substrate, and a simplified reduced model where the coating's thermal impact is represented as an effective surface boundary condition on the substrate. Our simulations were focused on a ternary coating design, which is a candidate for use in next-generation detectors. Results reveal that higher coating absorption localizes peak temperatures near the coating--vacuum interface. Importantly, the comparative analysis demonstrates that temperature predictions from the reduced model differ from the detailed model by only milli-Kelvins, a discrepancy often within the experimental uncertainties of the system's thermo-physical parameters. This finding suggests that computationally efficient reduced models can provide sufficiently accurate results for thermal management and first-order distortion analyses. Moreover, the critical role of accurately characterizing the total power absorbed by the coating is emphasized.

physics.app-ph↗

arXiv2025

A cryogenic test-mass suspension with flexures operating in compression for third-generation gravitational-wave detectors

This paper presents an analysis of the conceptual design of a novel silicon suspension for the cryogenic test-mass mirrors of the low-frequency detector of the Einstein Telescope gravitational-wave observatory. In traditional suspensions, tensional stress is a severe limitation for achieving low thermal noise, safer mechanical margins and high thermal conductance simultaneously. In order to keep the tensional stress sufficiently low, we propose the use of rigid beams with large cross sections, combined with short flexures under compressional load. This configuration takes advantage of the many times higher strength of silicon in compression to respect to its strength in tension. The flexures are mechanically robust and at the same time soft in the working direction, thus producing low suspension thermal noise and, by being short, provide high thermal conductance for cryogenic cooling. The rigid beams, located between the test mass and an intermediate mass, allow the elimination of the recoil mass used conventionally for applying control forces for interferometer lock, and the use of optical anti-springs to reduce the pendulum resonant frequency to further improve the vibration isolation of the test mass. The configuration has the capability to reach a lower mirror operational temperature, which is expected to produce a substantial reduction of the thermal noise in the mirrors of the interferometer.

gr-qc↗

arXiv2011

Second order invariants and holography

Motivated by recent works on the role of the Holographic principle in cosmology, we relate a class of second order Ricci invariants to the IR cutoff characterizing the holographic Dark Energy density. The choice of second order invariants provides an invariant way to account the problem of causality for the correct cosmological cutoff, since the presence of event horizons is not an \emph{a priori} assumption. We find that these models work fairly well, by fitting the observational data, through a combined cosmological test with the use of SNeIa, BAO and CMB. This class of models is also able to overcome the fine-tuning and coincidence problems. Finally, to make a comparison with other recent models, we adopt the statistical tests AIC and BIC.

hep-th↗