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Phos4 Studies and Fit functions for Timing

Phos4 Studies and Fit functions for Timing. Michael Henke, Valerie Lang Kirchhoff-Institute for Physics , University of Heidelberg L1Calo Joint Meeting, 12.01.2010, Heidelberg. Phos4 Scan-Studies. Run 124774: 12.08.2009 2079 Events 20-40 Events per Phos4 block LAr pulsed

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Phos4 Studies and Fit functions for Timing

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  1. Phos4 Studies and Fit functionsfor Timing Michael Henke, Valerie Lang Kirchhoff-Institute forPhysics, University of Heidelberg L1Calo Joint Meeting, 12.01.2010, Heidelberg

  2. Phos4 Scan-Studies • Run 124774: • 12.08.2009 • 2079 Events • 20-40 Eventsper Phos4 block • LArpulsed • TriggerTower0x00100501(emBarrel) Michael Henke, Valerie Lang

  3. Phos4 Scan-Studies • Run 124774  Trigger Tower 0x00100501(similartoTaylor‘swork) Correctedfor a shiftofthepedestalwithrespecttothe Phos4-Step Michael Henke, Valerie Lang

  4. Close lookat pulse top • Deviationsfrom an ideal peak form aroundthemaximum • Thiscomplicatesthedeterminationofthe pulse maximum‘sposition. Whybother? Maximum‘spositionfrom Phos4 histogram = referencevalueforqualitydeterminationof a certainfit functionto Phos4 pulse Calibrationprecision Michael Henke, Valerie Lang

  5. Peak topsforothertriggertowers Trigger tower 0x00100200  fairly ideal pulse Trigger tower 0x00100301 Trigger tower 0x00100901 Trigger tower 0x00100e01 Michael Henke, Valerie Lang

  6. Numberofchannelsaffected • Roughestimate: • Look at 500 channelsfor 3 partitions • Count affectedchannels • Noinformation on TileCalorimeterasthiswasn‘tpulsed • Results: Michael Henke, Valerie Lang

  7. Causesofpeakirregularities? • Data from Phos4-Scan plottedwithoutmeancalculationoverthe individual Phos4-blocks(pedestalshiftcorrectionapplied) • Colourindicatesnumberoftimes a certain ADC countoccured Trigger tower 0x00100501: Michael Henke, Valerie Lang

  8. Causesofpeakirregularities? Trigger tower 0x00100501: => Irregularitiesdon‘tstemfromstronglydeviatingvalues in themeancalculation Michael Henke, Valerie Lang

  9. Considerotherruns • Run 124777: • 5 minuteslaterthanrun 124774 • 2042 events • LArpulsed • Unfortunately: manypulsesaresaturated, i.e. noinformationabout pulse peak form • Compare 2 non-saturatedchannels Trigger tower 0x01100a03 Michael Henke, Valerie Lang

  10. Considerotherruns • Run 124777: • 5 minuteslaterthanrun 124774 • 2042 events • LArpulsed • Unfortunately: manypulsesaresaturated, i.e. noinformationabout pulse peak form • Compare 2 non-saturatedchannels Trigger tower 0x01100a03 Michael Henke, Valerie Lang

  11. Considerotherruns • Run 124777: • 5 minuteslaterthanrun 124774 • 2042 events • LArpulsed Trigger tower 0x00110d03 • Strong similaritiesof pulse formsbetweenruns 124774 and 124777 Michael Henke, Valerie Lang

  12. Preliminaryconclusions • Results: • Pulse peakdeformation non-negligibleeffect • Causesneedtobeunderstoodforreasonabletestingofthe fit functionsandprecisecalibration • Possibleexplanation:Addition ofsinglecalorimetercellsignalsto a triggertoweris not perfectlyaligned in time • Next investigativesteps: • Look atnewerruns  Havetimingupdatesfixedtheproblem? • Take Phos4 runswithonlypartsofthetriggertowercellsactivated  seeifeffectsdisappear • Look at Phos4 runswiththeTileCalorimeterpulsed  Doesthe same effectappear? Michael Henke, Valerie Lang

  13. Fitsto Phos4 pulses: Gauss-Landau fit • Earlierstudies:Simple Gauss-Landau fit worksbestfor: • Tilecalorimeter => pulse doesn‘tdropbelowpedestal • 5 slice readout=> smallfittingrange • Sometimesmissing Phos4 steps • Now: • LArCalorimeter • 15 slice readout • Improvedcontrolof Phos4chip Plot fromPaul‘sdiplomathesis Michael Henke, Valerie Lang

  14. Fitsto Phos4 pulses Gauss-Landau withundershoot Trigger tower 0x01140a02 Gauss-Landau Lorentz-Landau withundershoot Landau-Landau withundershoot Michael Henke, Valerie Lang

  15. Fitsto Phos4 pulses Gauss-Landau withundershoot •  Gauss-Landau fit withundershootseemstoworkbest • Largestapplicablerange • Best agreementwithhistogram, especiallyaroundthepeak (judgedbyeye) Landau-Landau withundershoot  More quantitative approaches in work Michael Henke, Valerie Lang

  16. Fitsto real pulse simulations • Motivation: • Look atfitsfor all possiblemistimings • Procedure: • Read out every 25thvalueofthe Phos4 scan • Plot in a newhistogram Michael Henke, Valerie Lang

  17. Fitsto real pulse simulations Gauss-Landau fit Gauss-Landau fit withundershoot • Motivation: • Look atfitsfor all possiblemistimings • Procedure: • Read out every 25thvalueofthe Phos4 scan • Plot in a newhistogram • Fit withGauss-Landau andGauss-Landau withundershoot • Move thereadoutpointby 1ns in Phos4 histogram (Phos4 scanbackwards) Michael Henke, Valerie Lang

  18. Fitsto real pulse simulations • Motivation: • Look atfitsfor all possiblemistimings • Procedure: • Read out every 25thvalueofthe Phos4 scan • Plot in a newhistogram • Fit withGauss-Landau andGauss-Landau withundershoot • Move thereadoutpointby 1ns in Phos4 histogram (Phos4 scanbackwards) Phos4 maximum‘sposition: DeterminedbyGauss-Landau fit tothehighest 10% ofvalues Michael Henke, Valerie Lang

  19. Fitsto real pulse simulations Gauss-Landau fit Gauss-Landau fit withundershoot Better fit = Gauss-Landau withundershoot  7-10 slice readoutissufficient Michael Henke, Valerie Lang

  20. Correlationplots • Definitions: • mistimings = shiftofdigitalisationagainstperfectdigitalisation • fitdigi–fitphos4 = max. positionfrom fit to real pulse – Phos4 reference • Results: • Simple Gauss-Landau fit showssomeunwantedstructure removed in new fit • Comparabledistributionwidths in y-direction LAremEndCap A Gauss-Landau Gauss-Landau withundershoot Michael Henke, Valerie Lang

  21. Conclusions • Pulse peakdeformations • Not a rare phenomenon • Tobefurtherinvestigated (maybealreadysolved) • Fit functionsforfinetiming • The Gauss-Landau functionincludingtheundershootgivesthecurrentlybest fit for Phos4 and real pulses • 7-10 slice readoutissufficientforstableandprecisefitting • Outlook • Quantificationofagreementof different fit functionswith Phos4 scans • More detailedanalysisofcorrelationsregarding real pulses Michael Henke, Valerie Lang

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