The observed relaxation times of the energy stored in solid-body-like rotating flow (symbols) compared with the model of pumping by the quantum boundary layer characterized by the time t_g^* (solid black line). Here, Omega_0 = 1.6 rad s^-1, Omega_1 = 0.20 rad s^-1, p = 27 s and the fitted energy pumping efficiency is beta^-1 = 0.57. The data include measurements at pressures of 15.0 and 15.7 bar. We plot the difference t_g(Omega_f) - t_g(Omega_0), where t_g(Omega_0) is separately measured with Omega_f = Omega_0, to account for any excess energy (such as near-resonant inertial waves or geostrophic modes) not present in our model. Different colours correspond to different temperatures in the range (0.14-0.19) T_c and thus values of the mutual friction parameter alpha, as marked in the figure. Upwards-pointing triangles correspond to data measured with the upper spectrometer, while downwards-pointing triangles correspond to data from the lower spectrometer.
