  We have studied experimentally the escape dynamics in underdamped
capacitively shunted and unshunted Josephson junctions with submicroampere
critical currents below 0.5 K temperatures. In the shunted junctions, thermal
activation process was preserved up to the highest temperature where the escape
in the unshunted junctions exhibits the phase diffusion. Our observations in
the shunted junctions are in good agreement with the standard thermal
activation escape, unlike the results in the unshunted junctions.
