Temperature dependence of damping and frequency shifts of the scissors mode of a trapped Bose-Einstein condensate

We have studied the properties of the scissors mode of a trapped Bose-Einst ein condensate of Rb-87 atoms at finite temperature. We measured a signific ant shift in the frequency of the mode below the hydrodynamic limit and a s trong dependence of the damping rate as the temperature increased. We compa red our damping rate results to recent theoretical calculations for other o bserved collective modes, finding a fair agreement. From the frequency meas urements we deduce the moment of inertia of the gas and show that it is que nched below the transition point, because of the superfluid nature of the c ondensed gas.