Emittance blow-up and loss maps in the LHC using the transverse damper as exciter

The transverse damper in LHC can be used to excite transverse oscillations in both planes for various purposes. A dedicated firmware has been developed that permits to injects a band limited noise signal into the damper feedback loop that can also be gated synchronously with the revolution frequency in order to act only on a short portion of the beam, for example a single batch. The method has been developed with the aim of blowingup transversely the beam principally for the purpose of efficiently generating in a well controlled way so called ”loss maps” which are an integral part of the verification of the collimation system. The method can also be used to shape the transverse emittance for other purposes and, at low intensity, to probe the machine mechanical aperture or for producing fast and high losses to probe the loss level at which magnets quench. The present MD report summarizes the results of a test on August 26, 2011, demonstrating the method and its selectivity to batches, showing the equivalence of the loss maps with loss maps obtained using the ”classical” method of crossing the 1/3 order resonance and testing a blow-up up to the transverse aperture limit.