Gravitational Wave Group
Mechanical Quality Factor Enhancement of
Cryogenic Sapphire test Mass
Motivation
Thermal noise will limit the part of the sensitivity of the laser interferometric
gravitational wave detectors. To suppress the thermal noise which is proportional
to square root of T/Q, where T is temperature and Q is the mechanical factor of a
test mass and a suspension wire, cooling and Q enhancement are promising
approaches. Fortunately, sapphire has the multiplier effect because the cooler
sapphire test mass has higher Q factor! In this experiment, we investigated
the Q factor enhancement of several internal modes of one cooled sapphire test mass.
Experimental setup
Result
We could obtain the Q factor of 2.5*10^8 at 4 [K] for the longitudinal mode,
which was 40 times as much as that at room temperature.