Abstract
Growing expectations for integrated luminosity during upcoming LHC runs introduce new challenges for LHC beam operation in the scope of online luminosity control. Because some LHC experiments are limited in the maximum event rates, their luminosity is leveled to a constant value. Various techniques may be used for luminosity leveling, changing the betatron function at the interaction point is one of them. This paper explains the main operational requirements of a betatron function leveling scheme for the upcoming LHC run. Issues concerning the beam optics, orbits and collimator settings are discussed. The proposed architecture for control system integration will be discussed. A few operational scenarios with different beam configurations foreseen for the next LHC run will be presented. LUMINOSITY An important parameter that affects the quality of the recordedluminosityattheLHCistheeventpile–up, thenumber of simultaneous particle interactions during one bunch crossing. A high event pile–up complicates the physics analysis and degrades the data quality for certain types of physics channels. The event pile–up µ is directly proportional to the luminosity per bunch crossing Lbb, µ= Lbb× �P, where �P is the total cross section for pp interactions at the LHC, �P= 70− 85 mbarn. The total luminosity Lp is given by Lp= k Lbb where k is the number of bunch crossings per turn. The bunch pair luminosity for round beams at an interaction point can be written as
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