------------------------------------------------------------ Minutes of the ABP-RLC section meeting of 28.11.2006 present: OB, EM, WH, FR, GR, BS, FZ excused: FR web site: http://ab-abp-rlc.web.cern.ch/ab-abp-rlc/ ------------------------------------------------------------ Report from Meetings -------------------- APC (GR) A longer-time flat-top SPS cycle was set up for the COMPASS experiment. G. Arduini described the motivation and the SPS accelerator view. No problems were encountered, except for some saturated profile monitors and BLMs. The experiment side was satisfied as well. WH asked for the SPS cycle to be used for next year. This was not known and it is likely to depend on the CNGS progress. Also at the APC, J. Borburgh reported that the extraction septa are sparking more frequently than in the past. No difference in the sparking rate could be observed between long-flat top run and a normal run. Next, J. Borburgh also discussed the overheating of the yoke. M. Widorski reported on radiation monitoring. He described a new safety code, and he presented 6 November results on radiation monitors. Radiation limits are exceeded in various points (e.g., on the PS bridge and at many PS places). The measured radiation at the PS extraction septum is a factor ~100 lower than that predicted simulations. The next APC meeting will take place in the coming week. Topics to be addressed include extraction losses and longitudinal blow-up studies in the PS. SLM (OB) Simon reported from the SPC. OPERA announced that they need a total of 220,000 lead bricks, and so far only 1200 bricks (0.5%) have been produced. It was commented that they are always "1 month away" from mass production. The original estimate of a nominal production rate of 1000 per day, has been lowered to 500 per day. Jos Engelen said we will not send any CNGS beam unless the detector has acquired a critical mass of 75% of the lead bricks. Even with a production 500 / day, it will take 1 year to reach this point. The emulsion is already bought, and it has a 5 years lifetime. For us, this means that next year we will have no high-intensity beam from the SPS, and multi-turn extraction in the PS is less urgent. PAF (OB) The outcome of the last meeting on 12.5 ns was discussed. PAF decided not to write officially that 12.5-ns is not interesting, and that PAF is not publishing any recommendation before the SPC received the white paper. OB recalled that even without e-cloud the cooling margin is fully used up for image-current and SR heating. JW will be replaced in the PAF by Malika. Malika will become PAF secretary and follow up neutrino factory scenarios. LTC (OB) The Y chamber was discussed. LHCCWG progress and FQWG status were also presented. The next meeting will treat a follow up on open actions, PS instrumentation, and impedance. Y chamber (EM) -------------- 8 Y or recombination chambers in total. NIM paper showed that a trapped mode may exist, but its impact is negligible. EM received MAFIA results from B. Spataro for the Y chamber in IR2L and IR8R (2 in total). Approximate and real geometries (from Derun Li) were considered. The previous Z/n value for the Y chamber was about 100 microOhm per chamber. In the design report, we have a total contribution of Z/n~1 mOhm, which roughly equals 8 x 0.1 mOhm. MAFIA simulations for the two modified chambers indicate a 30-40% increase in Z/n. The total impedance does not change appreciably. Therefore, the impedance estimate of the LHC design report can be kept. Higher order modes have frequencies outside the bunch spectrum (above 4 GHz). OB asked for the MAFIA boundary conditions, which could introduce spurious trapped modes. FZ commented that the increase of the broadband impedance was opposite to what he had naively expected for an enlarged aperture. WH asked whether we can get the MAFIA input files. EM responded that these questions will be discussed during Bruno's visit at CERN. ACTION => boundary conditions and MAFIA files (EM) Kicker Impedance with Rainer Hasse (EM) --------------------------------------- EM reported that benchmarking with GSI is now progressing on the kicker impedance. First GSI results are available. The shape of the GSI and CERN impedance curves is not the same at the moment. This benchmarking effort will continue. AOB --- OB reminded the team of the ABP Christmas party, due to which there will be no RLC meeting in two weeks. GR announced that incoherent e-cloud effects will be discussed in a separate meeting on Thursday morning. Posted on the web: Slides by JJ & EM Web site: http://ab-abp-rlc.web.cern.ch/ab-abp-rlc/