BBLR meeting, 07.02.2008 ------------------------ RC, UD, JPK, GS, FZ Steve Peggs informed JPK that "LHC Production Project" will not finance wires. Production Project will have much more money available than US-LARP. Lyn's advice is that we do it at CERN. We should have a proposal and discussion with Lyn. First we should have a discussion with Roland Garoby to see whether BI will continue. Rama mentions that the money of the Production Project is already allocated. MD requests should be sent a.s.a.p. for SPS (to Elias) and RHIC (to Wolfram) [RHIC proton tun until end of February]. Ulrich: suggestion of different filling pattern - e.g. bunches with LR collision only, and other bunches with LR and BBLR. Ulrich's presentation LRBB separation scans at injection, LRBNB at 100 GeV, BBLR at injection, BBLR at top energy. LRBB at injection: 1.5e11 p/bunch. Jean-Pierre: is 2.5e11 possible? Rama: 2e11 may be possible (AGS limitation) Also limits from polarization. (?) Conclusion: 7 sigma threshold. Chromaticity normal. No information on octupoles. Beam loss over 300k turns in simulations. 5 sigma in simulations. 7 sigma in experiment. Rama: could put 30% more emittance in simulation to make it fit. Jean-Pierre: what does it mean for the LHC? Ulrich: doubts about scaling law, details later no loss of Gaussian shape (could be due to chromatic effects) Jean-Pierre: worried if single interaction introduces dynamic aperture at 7 sigma LRBB scan at 100 GeV protons several experiments, some show losses, others not simulations do not predict any beam loss => Frank: why is the simulation result so emormously for the two energies, and does not scale at all? Is this due to the different tunes, oor due to a different modeling of sextupoles & chromaticity? Rama: LRBB at injection was done at IP and shifted, for top energy shifted Rama: why don't put errors in the machine, especially at top energy the triplet errors would dominate. Ulrich: at LHC the errors do not matter Frank: chromaticity as rotation or via sextupoles? Guido: are losses compatible with change of closed orbit? Rama: no effect, maybe some aperture effect at top energy? Ulrich: another (experimental) violation of scaling at top energy: sensitivity depends on the location of the long-range collision (IP or shifted by 10 m), while in simulations there is no change (no losses in either case); at injection the results are the same for both collisions points. 3 of 4 experiments showed no losses at top energy, neither at the nominal IP nor shifted. One experiment showed large losses at 3 sigma separation (collision point at the IP). Rama: another possibility is a bigger beta* at top energy Rama: showed one experiment at top energy which revealed losses (5%), collision point shifted by 10 m. Ulrich: BBLR at top energy, 12.5 sigma at 7 sigma (consistent); BBLR 6 sigma at injection. All consistent. But the BBLR has much higher losses (50% vs 5%; could be partly difference of protons and gold beams). 2nd MD also ~7 sigma profiles are bunch no 301 is excited whenever the tune is measured - this bunch loses current continually bunch profiles Jean-Pierre: We are at the limit of the instrumentation for the profile measurements bunch #1 looks fine some bunches are very different from others Rama: this is representative of future LHC situation Jean-Pierre: losses of a few percent will not be visible in the distribution Ulrich: MD3 results must be dropped Answers to JPK's emails. Rama: how different are the bunches? Jean-Pierre: maybe the tails were lost, but in the LHC we have collimators which will cut the tails Ulrich: many conclusions and replies Wolfram's suggestion: difference "no HO" and "with HO" Wolfram & Natalia's conclusion: it is possible to have a # collisions at 5 sigma separation, but they don't know how many (??) Rama: start with long-distance LR collisions at all IPs. Two schools are merged. Start with BBLR and then bring beams into collision and repeat the current scan. Could one intentionally have different emittances for all the bunches?