Speaker
Description
This presentation provides an overview on the feasibility analysis of a novel suspension for the cryogenic test-mass mirrors of the low-frequency detector of the Einstein Telescope. To overcome the severe limitation imposed on traditional suspensions by the tensile stress for simultaneously achieving low thermal noise, safer mechanical margins and high thermal conductance, this configuration takes advantage of the higher compressive strength of silicon with respect to its tensile strength. We propose the use of vertical rigid beams with large cross sections working in tension, combined with short flexures working in compression. 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, they provide high thermal conductance for cryogenic cooling. The beams have negligible vertical elastic compliance and are therefore unable to compensate for unavoidable machining tolerances. This compensation is achieved instead with vertical blade springs.
The presentation reports on the mechanical and thermal behaviour, the feasibility of using optical anti-springs to reduce the pendulum resonant frequency, the suspension thermal noise, and the requirements of an active anti-spring acting on the blade springs to filter enough vertical thermal noise coming from the room-temperature vibration isolation system.
