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LBS#12 , 22 March 2010

LBS#12 , 22 March 2010. Comments on Luminosity Scans. S. White. Strategy. Two cases to be distinguished: Calibration Scans: Performed a few times on experiments request. All input parameters (step size, number of steps..) on experiments request.

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LBS#12 , 22 March 2010

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  1. LBS#12, 22 March 2010 Comments on Luminosity Scans S. White

  2. Strategy • Two cases to be distinguished: • Calibration Scans: Performed a few times on experiments request. All input parameters • (step size, number of steps..) on experiments request. • Optimization Scans: Performed when needed. Fully automated as part of routine operation. • Need to optimize duration. Allow for full online analysis by the LHC operator. • Experience from last year: • Some experiments had integration times larger than the ramping time of the magnets: data • points overlapping between steps. • Integration time not specified: Online analysis from the CCC not possible. • Implementation: • The overall duration of a scan depends on: • Magnet Ramp: Machine property • (~few seconds). • Acquisition: User input. Depends on rates. • Determines the statistical accuracy of the step. • Integration time: Set by the experiment. • Wait ramping time + integration time • before starting acquisition: all data points valid. • Reduced integration time would optimize • the duration of a scan.

  3. In Practice • The integration time has to be specified in DIP in the field “intTime” (in seconds). • Experiments (CMS, ATLAS) distinguish ‘normal running” (long integration times) from • “scan running” (reduced integration times). • Optimization Scans: • Long integration times are not compatible with luminosity optimization which will be • performed during “normal running”. • The integration time for the scans should ALWAYS be of the order of a few seconds. If not • the data cannot be used for optimization and will be ignored. • The LumiScan# publications are used only for luminosity optimization and calibration: Can • the data published over DIP always come from the “scan running” acquisition mode? • Calibration Scans: • Dedicated beam time. • Other measurements (beam spot…) can be interesting. • Expert from the experiment should be present. • Integration time can be increased if necessary. No specific requirements.

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