Summary notes of the LCU meeting on 01/07/2008

Present: IA, HB, RC, SF, MG, WH, JJ, PL, AM, JN, TP, TR, FR, RT, TW, SW

Report from meetings

• ICC -> MG
  All sectors are cold or in cool-down.
  Issues observed in sectors 5-6 and 7-8 (main dipoles) have been studied. They do not require warming up and are compatible with the beams planned for this year. The QPS system is upgraded in few places to better match the properties of some of the early production dipoles.
  Sector 5-6 hardware commissioning is finished and the sector was handed over to operation which started detailed tests. This includes ramping and squeeze tests and checking and minimisation of ramp and squeeze times. SF is closely involved in the optimisation of the squeeze for IR1/5. As far as the squeeze for IR8 is concerned, it will be tested as as the sectors 7-8 or 8-1 will be available for powering group of converters.
• SLM -> MG
  Due to the EPAC last week, there was no SLM meeting.

Status of optics database for LHC commissioning (V6.503 optics) -> TR

The commissioning group would like to use as much as possible up-to-date files for the actual machine and decided to use optics V6.503, even if some details are still evolving. The sequence is considered to be debugged and S. Chemly should have launched a request of feedback before formally approve it.
In parallel, there has been work at the level of the layout database to provide the information concerning the aperture of vacuum elements. The information will be stored in a file with the marked definition, mechanical tolerances, and the installation of the markers. There are still discussions on-going to specify generic tolerances to be included in this file.
The use of this information highlighted a number of aperture bottlenecks, which were not known before. In particular, it was found that the aperture at the flange between Q1 and Q2, is below n1=7 at injection. The following approach is followed:
IR1/5: the crossing angle is 190 murad. By reducing it to 170 murad (which is the nominal value for IR2/8 and hence is considered acceptable) the aperture bottlenecks disappear.
IR2/8: three options are possible, namely: reduction of the parallel separation (it is considered acceptable); reducing the budget for closed orbit; increase the value of beta*. The latter should be carefully evaluated in terms of impact on the phase advance constraints between injection/protection devices.
These activities are in progress (contributions by Thys, Werner and Stephane)...

AOB

None

Last update: 03-July-08

MG & HB

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