News and hot topics Impedance meeting 14/04/2014

EDMS documents TDI: problems with NEG coating  will reinstall the boron nitride blocks as they were before LS1  we will have to monitor closely the heating and transverse impedance of the jaws at restart in 2015  Additional studies to assess power loss during the scrubbing run 2012 under way (Juan) UA9: EDMS document launched without checks on our side  Already existing tank, but significant longitudinal modes at 900 MHz (~100 kOhm)  EDMS could not be approved (despite our quick reaction) and will likely be postponed after LS1 New wire scanner: misunderstanding at IEFC  EDMS document should go through, see proposed procedure in the next slide

Proposed procedure for EDMS approval status from impedance team Reminder: all EDMS documents information at SEEN: – the request is not relevant for impedance (installation not seen at all by the beam wakefields  new cables, racks, etc.) – we don’t have enough information to conclude from simulations (either not enough input data or resolution of simulations not satisfying)  We add a comment specifying that we wait for something before confirmation. REJECT – If simulations/measurements/predictions show that the impedance of the new installation is predicted to be unacceptable ACCEPT: – If simulations/measurements/predictions indicate that the impedance would be acceptable (even if the required bench measurements before installation are not available)  We then add provisions in comments: - Impedance bench Measurements should be consistent with simulation results - for instance: the installation can only be temporary (before LS2 for many SPS devices) The idea here is that we would prefer to have bench measurements already at the ECR approval stage, but in most cases it is not possible as the device is not built yet.

Bench measurements Measurements performed on: – LHC UA9 goniometer – SPS wire scanners (looking for a solution to wire breaking) – New TOTEM pot (to validate the new pot design) – Rotatable collimators (for HL-LHC) – TCTP collimators (to check the impact of the transverse modes) Upcoming measurements: – BGV tank (very tight schedule, but not clear yet when it is possible as the tank is not ready)  proposal today: May 5 to May 9 – New wire scanner (tank ready, measurements next week with Emiliano and BI equipment) – TOTEM pots (next week with Nicola Minafra) – Vacuum diagnostics (on two prototypes) Many thanks to the very efficient measurement team (Joseph, Olav, Fritz, Nicolo, Nicola, Emiliano)

Requests Come back of the CMS/TOTEM hamburg pipe Vacuum diagnostics New RF fingers next to collimators Collimation team: “Can the rotatable collimators be installed as is?” EN-MME: how do we reduce the impedance of the taper of collimators with BPMs? Should we install the wire scanner with the new plate? Ferrite heating for TCTP (this afternoon) Crab cavity impedance update, HL-LHC WP2.4 meeting on Wed, and crab cavity review on May 5-6. Deadline for HL-LHC impedance and beam dynamics report in May Stripline impedance for HL-LHC?