1. Framework for the acceptance and efficiency corrections
S.Arcelli, I.Kraus, A.Mastroserio, R.Vernet
Outline
Description
Status
Ongoing work
14/11/ III Convegno Nazionale sulla Fisica di ALICE A. Mastroserio

2. General Description
Purpose: provide general utilities to assist the user in deriving the corrections and to monitor the quality of his/her selections by histograms
Requirements:
- Container to handle N dim variables Container class
- A common (easy) way to handle cuts Cut class
(event level, acceptance, kinematics, quality, being primary)
Priority list:
- single particle analysis
- V0’s (proceeding in parallel with single particles)
- resonances, decays,…
31/12/2018
A. Mastroserio

3. Correction Framework: Container Classes
AliCFFrame: public TNamed
Defines the grid “frame” and methods
for addressing the grid elements
AliCFGrid: public AliCFFrame
The equivalent of an N-dim histogram
AliCFContainer: public AliCFFrame
Accumulate information at different selection stages via an array of AliCFGrid, while looping on data/MC
AliCFEffGrid: public AliCFGrid
Calculate efficiency maps from info
accumulated on a AliCFContainer, display
projections (integration over other variables)
AliCFDataGrid : public AliCFGrid Handle observed data accumulated in an AliCFContainer, to correct them for efficiency/contamination
AliCFGrid ---> THnSparse: ( )
For more details see:
31/12/2018
A. Mastroserio

4. Correction Framework: Cut Classes
- Event level (Event class, Trigger -> preliminary, the Birmingham group is working on this)
MC (Particle, acceptance > cooperation with other people involved in acceptance studies )
Reconstruction (Track) following the existing code in PWG0
Selection (PID)
Provide Setters for the selections (at the track level default values will be given), then the user will add new ones according to his/her analysis
Provide the QA histos to monitor the cuts.
Have a common “IsSelected” function that returns a boolean (kTRUE, if the object has passed all the setted cuts)
All the cuts are passed as TObjArray pointers to an AliCFmanager which will check the cuts and allow the container filling during the event loop
31/12/2018
A. Mastroserio

5. Correction Framework status TODAY
We have prepared:
Container Classes
Selection Classes
Template macro for single particle spectrum
- A Task inherited from AliAnalysis Task
- Usage of AliMCEventHandler
Tests on Alien (ok), tests on CAF (ongoing)
(---> the code is currently being rearranged for an improved integration in the analysis framework, following the feedback we received during the last offline week.)
31/12/2018
A. Mastroserio

6. General Analysis Diagram
User AnalysisTask
Loop on:
Monte Carlo
Data
xxx.root
CFoutput.root filled with
AliCFContainer
histos (QA+…)
CF AnalysisTask
Calculate Efficiency Maps
Calculate Corrections
-> Corrected Data
CFmacro.C: CF cut list that initializes the CF manager
Post event loop
For more details see:
31/12/2018
A. Mastroserio

7. Correction Framework in local mode
Data Sample: Pythia 20k pp MB using AliRoot: v4-06-Rev-03
Two variables: Pt [0, 4] GeV/c and y [-1, 1]
Selections at different steps:
Step 0 = Generated particles: pions, primary, negative charge
Step 1 = Reconstructible particles: #TrackRefs in ITS =3 , in TPC = 2
Step 2 = Reconstructed tracks: negative charge, #clusters in TPC = 50, no
KinkDaughter, MaxNSigmaToVertex=1, ITSrefit.
Step 3 = identified tracks: pions, id by TPC only without probability cut with
a priori concentrations = {0.,0.,0.85,0.10,0.05}
31/12/2018
A. Mastroserio

8. Selection Steps: Pt and y spectra
Step Step Step Step3
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A. Mastroserio

9. Correction Framework : functionalities
Projection 1D
(integration in y)
Projection 2D
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A. Mastroserio

10. Correction Framework : functionalities
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A. Mastroserio

11. Correction Framework : functionalities
31/12/2018
A. Mastroserio

12. Correction Framework ongoing work (1/2)
Rearrangement of the preliminary structure ongoing…
Container classes:
- Further optimization through replacement of AliCFGrid with THnSparse
Correct error handling in projections, operations (Add, Multiply, Divide...)
done and available in the next Root release.
rebinning and interpolation.
Cut classes:
- Inheritance from AliAnalysisCuts
- Group current elementary cut classes as cuts bundles
(Kinematic, Quality, being Primary,...)
- Usage of AliVParticle interface wherever possible
- QA histograms embedded in selection classes
31/12/2018
A. Mastroserio

13. Correction Framework ongoing work (1/2)
Integration in the Analysis Framework
Tests on Alien done, tests on CAF ongoing
Integration of more refined acceptance selections in the CF framework cut classes
The revisited code will be committed in CVS in the first week of December
After that….every user comment will be appreciated to improve the framework functionalities!
31/12/2018
A. Mastroserio

15. Step 1 / Step 0
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A. Mastroserio

16. Step 2 / Step 1
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A. Mastroserio

17. Step 3 / Step 2
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A. Mastroserio

18. Random bin size
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A. Mastroserio