[u/mrichter/AliRoot.git] / PWG4 / UserTasks / PHOS_embedding / Readme

These are tasks to perform PHOS embedding. Steps are following:
1. Steering macro Embeding.C reads list of data ESDs to embed and calculates number of events
2. Performs simulation of the same number of events, using enclosed Config.C 
   (single pi0 per event with flat or Hagedorn spectrum)
   then simulated signals are reconstructed clusters and converted to AOD
3. Then class AliPHOSEmbedding is called
   - read data ESDs, extract PHOS calocells, convert them to PHOSDigits
   - run default reconstruction to avoid possible problems with different 
     OCDBs used now and in official reconstruction. Apply final calibration if necessary
   - merge digits with (re-calibrated if necessary) signal digits
   - reconstruct digits with embedding signal (with final calibration if necessary)
4. As a result of all these procedures AOD is produced with
   - MC information about embedded pi0s
   - standard CaloClosters, CaloCells with final calibration
   - Embedded CaloClusters, embedded CaloCells with final calibration
5. Run analysis with
   - AliAnalysisTaskPi0Efficiency: Signal (nominator in efficiency calculation) is any cluster with 
     contribution from simulated pi0s. Only for cross-check, this appoach is not quite correct at high accupancy.
   - AliAnalysisTaskPi0DiffEfficiency: correct approach, Signal (nominator in efficiency calculation) is
     difference between Real inv. mass distribution after and before embedding.

Note that to perform MC simulation one needs either access to official OCDB (Why do I need TPC drift velocity to simulate PHOS????)
or local copy of OCDB. Also histograms with new/old calibrations should be provided if necessary.
Commit	Line	Data
02f0b8e7	1	These are tasks to perform PHOS embedding. Steps are following:
	2	1. Steering macro Embeding.C reads list of data ESDs to embed and calculates number of events
	3	2. Performs simulation of the same number of events, using enclosed Config.C
	4	(single pi0 per event with flat or Hagedorn spectrum)
	5	then simulated signals are reconstructed clusters and converted to AOD
	6	3. Then class AliPHOSEmbedding is called
	7	- read data ESDs, extract PHOS calocells, convert them to PHOSDigits
	8	- run default reconstruction to avoid possible problems with different
	9	OCDBs used now and in official reconstruction. Apply final calibration if necessary
	10	- merge digits with (re-calibrated if necessary) signal digits
	11	- reconstruct digits with embedding signal (with final calibration if necessary)
	12	4. As a result of all these procedures AOD is produced with
	13	- MC information about embedded pi0s
	14	- standard CaloClosters, CaloCells with final calibration
	15	- Embedded CaloClusters, embedded CaloCells with final calibration
	16	5. Run analysis with
	17	- AliAnalysisTaskPi0Efficiency: Signal (nominator in efficiency calculation) is any cluster with
	18	contribution from simulated pi0s. Only for cross-check, this appoach is not quite correct at high accupancy.
	19	- AliAnalysisTaskPi0DiffEfficiency: correct approach, Signal (nominator in efficiency calculation) is
	20	difference between Real inv. mass distribution after and before embedding.
	21
	22	Note that to perform MC simulation one needs either access to official OCDB (Why do I need TPC drift velocity to simulate PHOS????)
	23	or local copy of OCDB. Also histograms with new/old calibrations should be provided if necessary.
	24