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Description
Accomodating stable recycling cavities in Advanced Virgo+ would fundamentally change the behavior of the interferometer in a variety of ways, introducing many advantages in terms of residual noise in the sensitivity curve, but also necessarily forcing to re-design the control scheme to account for the four new mirrors in the folded cavities.
The Virgo Interferometer Sensing & Control team has carried out the simulation groundwork to explore the consequences of this upgrade, especially from the point of view of the controllability of the detector, to evaluate performances and robustness of the new design and look for criticalities in its commissioning.
This work aims to illustrate the process of this work by detailing the criteria used to choose the control sidebands, to construct of the whole sensing scheme, to estimate the coupling with the sensitivity curve and the accuracy requirements for each control loop.
This process culminates with the computation of the decoupling angle, that gives a quantitative estimation of the overall controllability of the design.
This set of results provides the first, fundamental indication of whether a particular design is controllable and how robust it is, a necessary condition for its success.