Developing heavy (100kg-400kg) fused silica suspensions for next generation gravitational wave detectors

"The Institute for Gravitational Research is a leader in the development of suspension hardware for current and future gravitational wave detectors. The group provides fused silica suspension technology which underpins the aLIGO detectors/A+ upgrade, and Next Generation detectors (A# and Cosmic Explorer/ Einstein Telescope). The development of monolithic fused silica suspensions was an essential step to lower the thermal noise floor of the aLIGO instruments to enable them to detect the first gravitational waves in 2015.

This project will develop suspension technology for the next generation of gravitational wave telescope operating with mirror masses in the 100kg (A#) to 400kg (Cosmic Explorer/Einstein Telescope) range. The studentship will work to build a prototype lower stage suspension comprising the "mirror", and upper 2 mass stages of the 4-stage quadruple pendulum. The total length of the final stage will be increased up to 2m to further improve the thermal noise performance. In addition, the student will undertake bespoke Finite Element modelling to assess the modal properties of the suspension and determine the thermal noise due to intrinsic fused silica loss and weld loss. We will utilise new modelling techniques to integrate the energy stored within the fibre bending region to assess the fraction of pendulum energy stored in elasticity and gravitation.

The methodology will focus on developing a fully engineered suspension for a third-generation detector and undertaking the necessary risk reduction for next generation instruments. We will focus on the most efficient way to pull fused silica fibres, their strength properties when operated at stresses up to 2GPa, techniques to weld them onto the sides of the test mass attachment ears with a smaller format CO2 laser welding system, and how to optimally align masses up to 400kg."