Nobuaki Sato

LARGE-SCALE CRYOGENIC GRAVITATIONAL WAVE TELESCOPE

We present here the Large-scale Cryogenic Gravitational wave Telescope (LCGT) project which is aimed to improve the sensitivity of the existing gravitational wave projects by ten times. LCGT is the project constructing the km-scale gravitational wave detector in Japan succeeding the TAMA project, which adopts cryogenic mirrors with a higher power laser. We are planing to build it in an underground site in Kamioka mine. If its target sensitivity is attained, we will be able to catch a few events per month.

Atmospheric Neutrino Background and Pion Nuclear Effect for KAMIOKA Nucleon Decay Experiment

The main source of background for nucleon decay experiments is the interaction of atmospheric neutrinos in the detector. To estimate this background a Monte Carlo program was developed, which simulates the neutrino interactions and the nuclear effects of secondary pions. The program reproduced existing neutrino data as well as global features of the contained events in the KAMIOKA nucleon decay experiment. Neutrino induced background for nucleon decay was then calculated.

CRYOGENIC COOLING OF A SAPPHIRE MIRROR-SUSPENSION FOR INTERFEROMETRIC GRAVITATIONAL WAVE DETECTORS

Abstract The sensitivity of large-scale interferometric gravitational wave detectors currently under construction will be limited by thermal noise in the mirror-suspension system. Cryogenic cooling is made difficult because of the necessarily high laser power (5 kW) incident on the mirrors. An all sapphire system of high conductivity and low loss has been developed. Experiments confirm that mirrors for the TAMA detector could be cooled to as low as 14.5 K. This represents two orders of magnitude reduction in the mirror-suspension thermal noise energy.

Measurement of the mechanical loss of a cooled reflective coating for gravitational wave detection

We have measured the mechanical loss of a dielectric multilayer reflective coating (ion-beam sputtered

Present status of large-scale cryogenic gravitational wave telescope

{\mathrm{SiO}}_{2}

The CLIO project

and

Status of Japanese gravitational wave detectors

{\mathrm{Ta}}_{2}{\mathrm{O}}_{5}

Japanese large-scale interferometers

) in cooled mirrors. The loss was nearly independent of the temperature (

Status of the CLIO project

4\text{ }\text{ }\mathrm{K}\ensuremath{\sim}300\text{ }\text{ }\mathrm{K}

Design and construction status of CLIO

), frequency, optical loss, and stress caused by the coating, and the details of the manufacturing processes. The loss angle was