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High-multiplicity trigger in pp. 2012: Main-satellite collisions ~2000 colliding bcs separated by 25 ns Low pile-up: µ < 0.5% High mult trigger (LHC12h,i): CSHM8 = T0 vertex & >= 120 FO outer chips Factor 10 larger statistics at high multiplicity Search for collective behavior at HM:
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High-multiplicity trigger in pp 2012: • Main-satellite collisions • ~2000 colliding bcs separated by 25 ns • Low pile-up: µ < 0.5% • High mult trigger (LHC12h,i): CSHM8 = T0 vertex & >= 120 FO outer chips • Factor 10 larger statistics at high multiplicity Search for collective behavior at HM: • Mean pT • Particle ratios • Near-side ridge • … Technical issues to be studied: • QA on LHC12h period • Pile-up rejection • Background rejection • Bias due to T0 requirement instead of VBAND • V0-based multiplicity analysis • Possible improvements of HM trigger in run2 (e.g. topological FO trigger) Min. bias LHC10b,c,d,e High mult LHC10e High mult LHC12h