Speaker
Description
TOrsion-Bar Antenna (TOBA) is a ground-based gravitational wave detector using torsion pendulums. The resonant frequency of torsional motion is ∼ 1 mHz, therefore TOBA has good sensitivity in low frequency. TOBA can detect IMBH binary mergers, NN, and even contribute to earthquake early warning systems. A prototype Phase-III TOBA is under development to demonstrate noise reduction and precise measurement. The target sensitivity for Phase-Ⅲ TOBA is $10^{-15}$ /√Hz. To achieve this sensitivity, we need to reduce the noise of the optical system, thermal noise, and seismic noise. In previous research, a suspension system with optical readout was constructed. However, cavity lock was not achieved in that study.
In this work, we demonstrated and established torsion pendulums control method for TOBA and improved sensitivity.
We have developed a method to lock the cavity between the TMs and control their motion. This approach utilizes high-speed frequency actuators and stepwise control each degree of freedom in rotation and translation. Using this method, we successfully achieved the first cavity lock in TOBA. This achievement improved the sensitivity by approximately 1 to 4 orders compared to the optical lever measurements in the previous study.
In our presentation, we present the current status and future prospects toward Phase- III TOBA completion.