Interferometer design of the KAGRA gravitational wave detector

TL;DR

This paper details the optimized design of the KAGRA gravitational wave detector's interferometer, focusing on achieving high sensitivity and stability within practical constraints at an underground site.

Contribution

It presents a comprehensive optimization and detailed design of KAGRA's interferometer, including sensing schemes and control strategies, under real-world constraints.

Findings

Optimized interferometer parameters for KAGRA.

Developed robust length and alignment sensing schemes.

Achieved design choices balancing sensitivity and stability.

Abstract

KAGRA is a cryogenic interferometric gravitational wave detector being constructed at the underground site of Kamioka mine in Gifu prefecture, Japan. We performed an optimization of the interferomter design, to achieve the best sensitivity and a stable operation, with boundary conditions of classical noises and under various practical constraints, such as the size of the tunnel or the mirror cooling capacity. Length and alignment sensing schemes for the robust control of the interferometer are developed. In this paper, we describe the detailed design of the KAGRA interferometer as well as the reasoning behind design choices.