  Landau damping is an essential mechanism for ensuring collective beam
stability in particle accelerators. Precise knowledge of how strong Landau
damping is, is key to making accurate predictions on beam stability for
state-of-the-art high energy colliders. In this paper we demonstrate an
experimental procedure that would allow quantifying the strength of Landau
damping and the limits of beam stability using an active transverse feedback as
a controllable source of beam coupling impedance. In a proof-of-principle test
performed at the Large Hadron Collider stability diagrams for a range of Landau
Octupole strengths have been measured. In the future, the procedure could
become an accurate way of measuring stability diagrams throughout the machine
cycle.
