NMR line shape of rotating super(3)He-B at large counterflow velocity

We have investigated the NMR line shapes of superfluid super(3)He-B in a rotating cylinder. In the vortex-free state at sufficiently large angular velocity of rotation, Omega greater than or approximate to 1 rad/s, the main feature of the absorption spectrum is a large frequency-shifted peak above the Larmor frequency. The shape of this counterflow peak is both measured and calculated as a function of external magnetic field strength, angular velocity, temperature, and number of vortex lines. The NMR spectrum is derived from the calculated order-parameter texture. Reasonable agreement with the measured line shape is obtained by including line-broadening effects due to the external field inhomogeneity and Leggett-Takagi relaxation.