Advanced Virgo Plus for O5 -- Design Report Overview

Understand

This document presents an overview of the design, implementation, and expected performance of the Advanced Virgo Plus (AdV+) upgrades in view of the O5 observing run.

• Following the experience gained during the O4 commissioning and operations, the Virgo Collaboration has revised the upgrade strategy to address limitations associated with marginally stable recycling cavities.
• The O5 upgrade program combines elements from the original AdV+ Phase II project with new design solutions, including the implementation of stable recycling cavities, a major modification to the central interferometer layout, and a comprehensive renewal of critical subsystems.
• The planned upgrades are organized in two steps, targeting progressive improvements in operational stability, noise reduction, and detector sensitivity.