  Spin-echo experiments are reported for 3He-4He solutions under extremely high
B/T conditions, B=14.75 T and T >= 1.73 mK. The 3He concentration x_3 was
adjusted close to the value x_c = 3.8% at which the spin rotation parameter
muM_0 vanishes. In this way the transverse and longitudinal spin diffusion
coefficients D_perp, D_parallel were measured while keeping |muM_0| < 1. It is
found that the temperature dependence of D_perp deviates strongly from 1/T^2,
with anisotropy temperature T_a = 4.26 +/- 0.18 mK. This value is close to the
theoretical prediction for dilute solutions, and suggests that spin current
relaxation remains finite as the temperature tends to zero.
