Agenda for 22 Nov 2006 SWMD Telephone Meeting

Brief reports on:

1. T-480 Data analysis et al.
   • Step-by-step instuctions for running Yuri's ESA analysis code on Manchester cluster - Adriana
     Adrina has finished setting up the Manchester cluster with the analysis code needed for processing new calibrations when they are available. The description is complete and allows any of us with an account to carry out the procedure. Jonny will copy across his scripts from SLAC which perform the root-to-mat conversion stage so we are prepared for future calibrations and new data.
   • Bunch length variation
     Steve noted that bunch length variation was not expected to be large within a single run, at least at the level which could account for large shifts in the measured kicks between adjacent collimator y values.
     Suggested that Luis tries to correlate measured kicks with a bunch length - as we do not have such direct information at present, relate to ceramic diode signals instead. This would allow to exclude sigma_z variation as underlying cause of instability in measured deflections.
   • Limiting effects on kick factor resolution? Should also relate large deviations from expected deflections to variation in energy BPMs - Luis to confirm list of variable names in the .mat files corresponding to the energy BPM measurements.
     Are the poor quality of overall (cubic) wakefield fits a consequence of having used long runs? Although we believe BPM calibrations are stable over the duration of a run, possible that beam conditions themselves are not. Would we be better using shorter runs in future?

2. Wire Tests - Carl
   Memory limitations on old Tektronix 7584 scope do not allow trace from complete spectrum corresponding to 25ps pulse to be aquired offline via GPID card - options are take spectrum at highest resolution available (but in several sections), or to use lower resolution and obtain entire trace at once. Plan to try both.
   Jonny will also start to look into using 60GHz VNA as alternative, familiarise himself with method and equipment, but need to finish GdfidL simulations for 2007 run first.
   Other news, in medium term, Steve Jamieson et al. continue with ultra fast laser pulse R&D and there is possibility that this can now be applied to emulate 1ps pulse on wire.
   

3. Wakefield Simulations
   • Low-Dispersion Wakefield Calculation Tools - Mikko Karkkainen, talk at ICAP 2006, Chamonix
     Mikko leaves TEMF end of 2006, future of the ECHO-like code he has been working on needs to be clarified.
   • Status of new collimator modelling - Jonny
     Reviewed simulations with moving mesh GdfidL for 2007 candidate profiles, showing physical boundaries as modelled and kick factors predicted under various conditions, in .csv file.

4. Merlin Simulations
   • link - Adriana
     Updated results from last meeting with 300um sigma_z, using circular aperture with radius equal to x aperture from ILC BDS (c/o Frank) in all cases.
     She plans to look at increase in emittance due to each collimator in the BDS in turn
     To obtain indication of impact of not using rectangular aperture, she will try as alternative using circular apertures with radius equal to y aperture. Also suggested that she repeats but using effective aperture for wakefields equal to the smaller of either x or y apertures for each collimator in turn.

5. Collimator designs and manufacturing
   • Decision on candidate designs for run 3
     1. Summary of ideas & proposal - Nigel
     
     Discussion on what we learn from each design. Definite proposal made, as shown in run 3 collimator designs. Changed original ideas to polish all collimators except one which itself would be intentionally roughened using e.g. sand blasting, to R_a~10um, i.e. 0.1sigma_y at ESA. Unpolished collimator would be in copper to minimise resistive wake contribution. Also, would use collimator with flat section for this. NKW to summarise revised designs agreed at meeting in .ppt file, send to George/Justin/Joe who would make drawings for manufacture. Non-linear taper in one profile to be decided by Jonny, who would send parametrisation of the profile directly to George. Drawings to be available for checking/ sign-off by 4 Dec., and then sent to outside manufacture. Some concern about time available to polish six collimators in time for 2007 run. We can review polishing of collimators when we receive them from company, if we are short of time, could consider polishing a subset of the new collimators.
6. AOB:
   • Material for Mike W.'s SLAC PAC presentation, 4-5 Dec..
   • Plans for abstracts for PAC'07 (New Mexico, 25-29 Jun 2007). Deadline 13 Dec. 2006.
   • EUROTeV COLSim meeting (Grahame Blair/Daniele Schulte) - 4-5 Dec. 2006 at CERN, Jonny/Adriana to attend from people present today.

7. Next meeting - 06-Dec-2006, 1530 GMT.