  We report the first experimental observations of the reflection of a dust
acoustic solitary wave from a potential barrier in a dusty plasma medium. The
experiments have been carried out in an inverted $\Pi$-shaped Dusty Plasma
Experimental (DPEx) device in a DC glow discharge plasma environment. The dust
acoustic solitary wave is excited by modulating the plasma with a short
negative Gaussian pulse that is superimposed over the discharge voltage. The
solitary wave structure is seen to move towards a potential barrier, created by
the sheath around a biased wire, and turn back after reflecting off the
barrier. The amplitude, width, and velocity of the soliton are recorded as a
function of time. The experiment is repeated for different strengths of the
potential barrier and for different initial amplitudes of the solitary wave. It
is found that the distance of the closest approach of the solitary wave to the
centre of the barrier increases with the increase of the strength of the
potential barrier and with the decrease of the initial wave amplitude. An
emissive probe is used to measure the sheath potential and its thickness by
measuring the plasma potential profile in the axial direction over a range of
resistances connected to the biased wire. A modified Korteweg de Vries equation
is derived and numerically solved to qualitatively understand the experimental
findings.
