ALICE Trigger and Event Selection QA 1Kevin McDermott By: Kevin McDermott August 9, Michigan REU Student Program – Final Presentations

ALICE Kevin McDermott2 Credit: CERN C SideA Side

Min Bias Trigger Detectors Kevin McDermott3 CINT1 Suite = Min Bias Trigger CINT7 Suite = VZERO AND Trigger CINT8 Suite = T0 AND Trigger Other rare triggers are used, e.g. EMCal and PHOS, but not used for the purpose of this analysis (only muon production for Period LHC12c) Credit: ALICE-TDR-011 VZERO C VZERO A T0C T0A SPD

Physics Selection (PS)  PS validates online trigger conditions and rejects background, used offline before any analysis  ALICE, due to various reasons (defocused beams, the vacuum, and long time integration window of TPC), has significantly worse signal-to-background ratio than the other LHC experiments  Stricter event selection by computing the timing of a signal that passes the triggers to ensure that the event passed occurred at the vertex of ALICE (through the VZERO or T0)  Need a high quality data set to do analysis, therefore need to reject background and save actual collisions with high efficiency  Use Quality Assurance (QA) to trend the PS to spot bad runs, monitor beam conditions, and reject clear outliers in analysis Kevin McDermott4

ALICE Physics Selection Quality Assurance (PSQA)  Old PSQA done primarily by hand, not automatic  Old PSQA needed streamlining and did not meet proper coding conventions  Built a new class to automatically generate text output per run to be used for newly designed online interface  Same class generates ROOT output of trending QA with TGraphErrors  Built a separate class to handle visualization of run by run trending Kevin McDermott5

QA Example: Quick Notes  Plots Naming Convention:  Trigger Class Name [Fast or Regular] Trigger Logic #  Error bars on plots are smaller than the point size due to zoomed out scale.  For ratios that were complete subsets, used binomial errors for error calculation  Otherwise, for uncorrelated ratios, used normal error propagation  The following plot is an example of data taking period LHC12c (May-June 2012) for a given trigger class (in this case, kMUS7) 6Kevin McDermott

kMUS7: Muon trigger; low p T single muon, offline V0 selection, CINT7 suite 7Kevin McDermott Accepted/All hidden by V0A/All Special note: Only runs and use both CINT7 and CINT8. Zoom in for example High BG Run

Kevin McDermott8 As kMUS7 is a CINT7 trigger (V0 AND), V0A sits opposite muon arm, and explains why Acc/All is close to V0A/All. In the same way, V0A/All and Acc/All inversely proportional to V0A BG/All.

kMUS7: Muon trigger; low p T single muon, offline V0 selection, CINT7 suite 9Kevin McDermott V0A/All ≅ Acc/All inversely proportional to V0A BG/All

Online Interface: Workflow Kevin McDermott10 QA Analysis Task Output (runs on The Grid) For Each Run Text File Output from AliPSQA (local node) Automatic Processing MonALISA public webpage PS: “Trigger Class [Regular or Fast] Trigger #”: Name of Plotted Ratio, Value, Error PS: "kMUSH7 [Regular] Trigger 3":Accepted/Trigger_class, ,

Online Interface: Snapshot Kevin McDermott11 Note: This is only a preliminary example. All plots produced by the QA run will be instantly viewable on the web.

Summary 1. New AliPSQA class can produce a ROOT file with TGraphErrors that can then be visualized via the AliPSQAVisualization class. 2. PSQA can be performed automatically by setting just a few input and output parameters. AliPSQA produces text files per run that are automatically processed into trending plots on MonALISA, for immediate access for all ALICE members. 3. Trending plots can easily identify runs that are clear outliers to be rejected for data analysis in a given period. 4. When AliPSQA is used in conjunction with run data, trending details are easily understandable. 5. Results of data taking period LHC12c were presented in ALICE official QA meeting. Kevin McDermott12

Acknowledgements  Advisors: Alexander Kalweit and Michele Floris  Lab partner: John Groh  Costin Grigoras  Zaida Conesa Del Valle  CERN, ALICE Collaboration, University of Michigan Kevin McDermott13

Questions? Kevin McDermott14

BACKUP SLIDES Kevin McDermott15

Examples of V0 Timing Kevin McDermott16 Run: Production: ESD muons Trigger class: kMUS7

Examples of V0 Timing Kevin McDermott17 Run: Production: ESD muons Trigger class: kMUS7

Parameters for QA Runs Analyzed: , , , , , , , , , , , , , , , , , , , , , , , , , , Period: LHC12c 18Kevin McDermott

Parameters for QA Explanation of QA Data: Trigger class: Number of events in selected trigger class* Accepted: Accepted events V0A and V0C: Events with signal V0A/V0C in collision time window, recomputed offline over all slabs V0A BG and V0C BG: Events flagged as background from V0 T0: Events with T0 signal in collision time window, computed offline T0BG: Events flagged as background from T0 FO >= 1: Number of events with more than 1 chip hit in pixels, computed offline FO >= 2: Number of events with more than 2 chips hit in pixels, computed offline FO (L1) >= 2: Number of events with more than 2 chip hits in the outer layer of the SPD, computed offline 19Kevin McDermott *For the sake of this presentation, all plots with “Trigger class” are renamed in the legend with “All.” Reference:

QA Results kMUSH7: Muon trigger; high p T single muon, offline V0 selection, CINT7 suite 20Kevin McDermott

QA Results kMUL7: Muon trigger; like sign dimoun, offline V0 selection, CINT7 suite 21Kevin McDermott

QA Results kMUU7: Muon trigger; unlike sign dimuon, offline V0 selection, CINT7 suite 22Kevin McDermott

QA Results kMuonSingleLowPt8: Muon trigger; low p T single muon, offline T0 selection, CINT8 suite 23Kevin McDermott Bad run: already flagged in RCT

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kMuonSingleHighPt8: Muon trigger; high p T single muon, offline T0 selection, CINT8 suite 25Kevin McDermott Bad run

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kMuonLikeLowPt8: Muon trigger; low p T like sign dimuon, offline T0 selection, CINT8 suite 27Kevin McDermott Bad run

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kMuonUnikeLowPt8: Muon trigger; low p T unlike sign dimuon, offline T0 selection, CINT8 suite 29Kevin McDermott Bad run

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Online Interface: Parameters Kevin McDermott31 Run on AliEn or locally If AliEn, cache input files locally? If cache, specify directory Runs to be analyzed (list file) Triggers to be analyzed (list file) Trigger Partitions (list file) Input directory + input ROOT file Output ROOT directory + output ROOT file name Output file text directory + output file text name

Online Interface: Notes Kevin McDermott32  Class AliPSQA with PSQA.C produce output ROOT file with TGraphErrors and text files for MonALISA  TGraphErrors can be visualized with PSQAV.C and AliPSQAVisualization class  All cache/output directories made automatically if they do not exist  List of trigger classes and partitions can be hardcoded, would require TString manipulation.  Current limitations: Size of various data members must be changed by hand if number of trigger classes and/or trigger logic increases