Speaker
Description
Beam tube baffles are a significant noise source in large gravitational-wave interferometers. This issue was studied for the initial LIGO and Virgo detectors, but the design must be revisited for next-generation observatories such as Cosmic Explorer and Einstein Telescope. The original baffle design relied on the hardware knowledge and materials available at the time, and the analysis used analytic approximations constrained by the computing capabilities of that era. Because the arm tube is one of the most expensive components of an interferometer, a more reliable and optimized design that minimizes both cost and noise is essential.
In this work, baffle-induced noise is evaluated using numerical simulations with minimal approximations. The presentation focuses on a simulation tool developed for the Cosmic Explorer baffle design, based on the FFT-based field calculation package SIS (Stationary Interferometer Simulation), originally developed for Advanced LIGO. The framework enables flexible studies of beam tube configurations and accurately models successive clipping by baffles, including serration effects and independent offsets and motions of individual baffles. We also discuss near-field scattering using BRDF data and modeling of mirror surface aberrations based on measurements of existing coated mirrors.