Silica fibers production and characterization for future gravitational waves detectors

The observation of gravitational waves is highly in uenced by the detectors sensitivity, thatis limited at low frequencies (10 -100 Hz) by the thermal noise. For this reason, the monolithicsuspensions are one of the most important upgrades of the interferometric detectors includingAdvanced Ligo (aLigo) and Advanced Virgo (AdV). Currently the silica bers are built to minimizethe thermal noise in the band of interest and to t the load constraints. Nevertheless, the need tohave larger reference masses for the future updates of Virgo and also for the future 3G detectors atroom temperature, requires redesigning the bers, and all the facilities for their production, testingand characterization, for instance the bers for Advanced Virgo Plus (AdV+) will be 60% thicker todeal with a working load 2.5 times higher. We will describe the manufacturing system, the nominalcharacteristics and the mechanical measurements of AdV's silica bers, as well as the updates toimprove the production and characterization process for the new speci cations of AdV+. Finallyan approach to the study of fatigue for silica bers will be presented; the study of the behaviorof pristine bers is important to achieve a consistent model of lifetime prediction for maintenanceand security reasons.