Impedance Working Group Update ICE meeting June 12 th 2013

General: – Andrea Mostacci visiting from La Sapienza for 4 weeks (works on beam screens, TCTP, advice for bench measurements and mode damping in general) – Upgrade of ZBASE from Matlab to Python (Nicolas) – Ongoing: Impedance simulations and calculations at low beta (Carlo and Tatiana) – Ongoing: CST simulations with very short bunches (Eirini) – Ongoing: transverse impedance of insert with mode matching (Nicolo) – Ongoing: mode matching of elliptical steps (Serena) – Ongoing: material measurements (Eirini and Carlo) – Will start soon: set up of new design for bench measurement (V. Vaccaro and INFN) – CST2013 now available (need to install it from DFS/applications, not CMF): very different GUI! PSB – Talk at PSB-LIU  conclusion: no preference from impedance side between corrugated chamber and ceramic chamber (Carlo). – Starting construction of impedance model (Carlo). – Computation of indirect space charge (Carlo with the help of Olav). PS – Long list of elements to be simulated for PS-LIU provided by Simone (started by Mauro) – Design report for PS-LIU: articles on (1) longitudinal impedance by Mauro and (2) transverse impedance by Mauro and Benoit (deadline for mid-August). – PS septum studies by Serena completed

SPS – Problem with the new design of wire scanners – New investigations on the origin and impact of the 1.4GHz mode of the enamel flanges (Jose Varela Campo and LIU-SPS) – Request for computations for new Y chamber for the crab cavity tests in SPS LHC – Studies on impedance of TCP collimators with GdFidL (M. Zobov) – Collimation review (talk by Nicolas): review of post-LS1 impedance collimators – Measurements of new design of ATLAS-ALFA roman pot filler prototype on-going (Olav and Joseph). Request for max 5 micron copper coating. – AFP week with results from Antonello (AFP) and Nicola (TOTEM). – HPS (Hamburg pipe for CMS) review this week, and request for assistance. – On-going investigations for new transverse emittance diagnostics (BGV). – BSRT: new measurements performed but are they sensitive enough? – No specific news for MKI and TDI. – Coating on TCDQ/TCDS evaluated by Nicolas. – Ongoing: action on heating with various types of ferrites for TCTP (Benoit). – UA9: design for goniometer for LHC has been modified several times. EN-STI initiated a collaboration with LAL Orsay for the Cherenkov detector.

HL-LHC – 800 MHz cavities: preliminary impedance evaluation by M. Zobov. – Update on actions and deadlines mentioned by Elias at the beginning of the meeting Other machines/projects – ELENA (Tatiana): First studies for the resistive Wall Ongoing studies for the BPMs Plans: injection and extraction kickers + RF cavities – T-LEP: preliminary impedance model by Nicolas (RF cavities+ RW) – CLIC: ongoing work on damping ring striplines (Eirini) and plans for a profile monitor for the drive beam (Adam Jeff from BI)

What is working well – Very fruitful assistance of the many visitors from other labs. Many thanks! – In order to follow and assist the design of all these items in all machines with the available manpower, we help several equipment groups and experiments perform their own simulations (in particular in BE-BI, EN-STI, TOTEM, ATLAS-AFP). – We are now finally moving to the impedance of PS and PSB! – Gaining a lot of experience in most types of accelerator devices – Still theoretical work ongoing despite all the applied simulations, but it is important to keep a reasonable ratio What is working less well: – Procedures to fully analyze a device are not yet standard, working on it – CST licenses are limited (recently increased from 15 to 20) – Problems to simulate the impact of very short bunches with available codes – Some structures are currently impossible to simulate (too large volumes with too small gaps) – For heating, bench measurements are often not sensitive enough to ensure that there will be no problem in the LHC – Lacking conceptual and practical experience in damping modes with waveguides and couplers. – team and tools not well dimensioned to be in the loop of design iterations – Unrealistic deadlines set by designers to analyze a device, and especially to optimize it if its initial impedance is too high. LS1 much more busy for the impedance team than the run