Transverse Damper

The LHC ADT system [1] provides a maximum kick strength of 2 $\mu$rad at 450 GeV in the 3 kHz - 1 MHz BW (at 10 MHz only 10% strength is left). It can be operated in "extended BW" with a BW up to ~20 MHz.

It has 4 pick-ups per planes per beams ($\beta$-function between 100-180 m depending on the PU/plane/beams) [1].

From [2], the typical noise RMS is 1-2 $\mu m$ at (8-14 $\mu$m$_{\rm pk-pk}$) The SNR is expected to be improved by more than a factor 3 after LS2.

From [3], with an operational gain of 0.04, corresponding to a damping time of 50 turns, the contribution of the noise to the emittance growth rate in LHC is estimated around 2%/h.

The details of the gain along the cycle are reported in [4].

Publications

• Progress In Transverse Feedbacks and Related Diagnostics for Hadron Machines, W. Hofle, IPAC2013, Shanghai, China (2013)

• LHC transverse feedback system: First results of commissioning, E.V. Gorbachev et al., RuPAC 2008, (2008)

• Beam dynamics in synchrotrons with digital wideband transverse feedback systems, V. M. Zhabitsky, Physics of Particles and Nuclei, 45 (2014)

• [3]: Impact of the ADT on the beam quality with high brightness beams in collision (MD2155), X. Buffat et al., CERN, 2018

• Modeling of the emittance growth due to decoherence in collision at the Large Hadron Collider, X. Buffat et al., Phys. Rev. Accel. Beams 23, 021002

HL-WP2 Meetings

• 118^th, Review of ADT impact on emittance growth, X. Buffat

• [2]: 118^th, Plans for improved ADT pick up resolution, D. Valuch

• [1]: 75^th, Expected performance of the HL-LHC transverse feedback, W. Hofle

• 75^th, Do we need a Wide-Band Transverse feedback in the LHC/HL-LHC?, K. Shing Bruce Li

Other meetings

• [4]: ADT upgrades for HL-LHC, D. Valuch et al., 8^th HL-LHC Collaboration Meeting, 16^th October 2018

• ADT re-commissioning, D. Valuch, 116^th LBOC, 10^th March 2020