Speaker
Description
Torsion-Bar Antenna (TOBA) is a ground-based gravitational-wave detector using a torsion pendulum. The resonant frequency of torsional motion is $\sim 1\, \mathrm{mHz}$, therefore TOBA has good design sensitivity in low frequency, specifically $10^{-19} \, /\sqrt{\mathrm{Hz}}$ at $0.1\, \mathrm{Hz}$. TOBA can detect intermediate-mass black hole binary mergers, Newtonian noise, and so on. A prototype detector Phase-III TOBA with a 35 cm-scale test mass is under development to demonstrate noise reduction. The target sensitivity is set to $10^{-15} \, /\sqrt{\mathrm{Hz}}$ at $0.1\, \mathrm{Hz}$. To achieve our target sensitivity, we need to measure the pendulum rotation precisely. We propose a wavefront sensor with a coupled cavity (Coupled WFS) as an angular sensor for Phase-III TOBA. In our method, an auxiliary cavity is used to compensate Gouy phase of a main cavity and enhance the first-order TEM modes in the main cavity. The experimental demonstration was successfully performed. Here we show the principle of TOBA and demonstration results of a Coupled WFS.
