[u/mrichter/AliRoot.git] / RICH / api.txt

How to open session:
	use static method  AliRunLoader::Open("galice.root","AlicE","update")
How to get total number of events in galice.root:
	use AliRun::GetEventsPerRun()        
How to avoid using gAlice:
	detector->GetLoader()->GetRunLoader()->GetAliRun() returns gAlice global pointer.
How to retrieve pointer to alice run loader:
        use pRICH->GetLoader()->GetRunLoader() (all detector classes inherit from AliDetector which has GetLoader())
	use method AliRun::GetRunLoader for gAlice (deprecated)
How to get pointers to different root trees:
	TreeE belongs to AliRunLoader, available after AliRunLoader::LoadHeader()
	TreeK belongs to AliRunLoader, available after AliRunLoader::LoadKinematics()
	TreeH belongs to AliLoader   , available after AliLoader::LoadHits()
	TreeS belongs to AliLoader   , available after AliLoader::LoadSDigits()
	TreeD belongs to AliLoader   , available after AliLoader::LoadDigits()
	TreeR belongs to AliLoader   , available after AliLoader::LoadRecPoints()
        all methods return 0 on success. 
How to get event of interest:
	AliRunLoader::GetEvent(event_number) returns 0 on success
How to deal with the stack of particles?
        - first of all, the stack includes primary as well as secondary particles
	- pointer to the stack is taken:
         	AliRun::Stack() (global gAlice of type AliRun - deprecated way to do)
          	AliRunLoader::Stack() but before one needs to load event header by AliRunLoader::LoadHeader() otherwise both methods return 0.
          	Moreover loading header gives the information about number of particles only. 
          	To retrieve the list of particle one also needs to load kinematics by AliRunLoader::LoadKinematics()        
	- total amount of particles in stack for a given event:        
         	AliStack::GetNtrack() 
                AliRun::GetEvent() (after LoadHeader())
	- total amount of primary particles in stack for a given event (after LoadHeader()): 
        	AliStack::GetNprimary() 
How to retrieve hits:
	Hits are stored on primary by primary basis. Hits for the given primary is TClonesArray.
   	To retrieve all hits one needs to do:
     	-initialize the root tree and containers:   pRich->GetLoader()->LoadHits();  (AliLoader::LoadHits() returns 0 on success)
     	-read number of entries in TreeH:           pRich->GetLoader()->TreeH()->GetEntries()
     	-then for each entry:                       pRich->GetLoader()->TreeH()->GetEntry(i)
How to retrieve sdigits? 
	Sdigits stored in tree S with the branch of TClonesArray, all sdigits in a single TClonesArray
	So the tree has only one entry.
	One needs to say:
	-pRich->GetLoader()->LoadSDigits(); this one open file, get the tree and invoke AliRICH::SetTreeAddress()    
How to retrieve digits? 
	Digits stored in tree D with the 7 branches of TClonesArray, one per chamber, all digits of a given chamber in a single TClonesArray
	So the tree has only one entry.
	-One needs to say:
	  pRich->GetLoader()->LoadDigits(); this one opens file, gets the tree and invoke AliRICH::SetTreeAddress() which in turn corresponds 
          branches of the tree to the digits containers in memory. There are 7 containers, one per chamber, all of them belong to AliRICH.
	-Then one needs to take the tree entry (only one) to the memory:
          pRich->GetLoader()->TreeD()->GetEntry(0) 
	-Finally pRich->Digits(chamber_number) returns the pointer to TClonesArray of AliRICHdigit          
What are the debug methods avail:
        AliLog::SetGlobalDebugLevel(AliLog::kDebug)
How to get info for a given particle number:
	Header and Kinematics trees must be loaded, then possible to retrieve pointer to Stack of particles
	Int_t AliRunLoader::LoadHeader(); Int_t AliRunLoader::LoadKinematics()
	AliStack *AliRunLoader::Stack()
	TParticle *AliStack::Particle(tid)
	TParticle::Print()
How to deal with AliRunDigitizer:
	AliRunDigitizer::Exec() just call AliRunDigitizer::Digitize()	
What are the meanings of different VMC flags:         
	gMC->IsTrackAlive()
	gMC->IsTrackStop()
	gMC->IsTrackDisappeared()
How to get pad number for a local position:
	use static TVector AliRICHParam::Loc2Pad(TVector2 position);
Why list of chambers belongs to AliRICHParam:

How to check if a given stack particle is primary:
	Stack is TClonesArray of TParticle. TParticle::GetMother(0) returns -1 if it's primary (no mother)         
How to loop over all possible object:         
  for(Int_t iEventN=0;iEventN < GetLoader()->GetRunLoader()->GetAliRun()->GetEventsPerRun();iEventN++){//events loop
    for(Int_t iEntryN=0;iEntryN < GetLoader()->TreeH()->GetEntries();iEntryN++){//TreeH loop
      GetLoader()->TreeH()->GetEntry(iEntryN);//get current entry (prim)  
      for(Int_t iHitN=0;iHitN<Hits()->GetEntries();iHitN++){//hits loop
        AliVHMPIDHit *pHit=(AliVHMPIDHit*)Hits()->At(iHitN);//get current hit 
        
      }//hits loop
    }//TreeH loop
  }//events loop


RICH full simulation-reconstruction sequence

hits->sdigit:
	Responsible method is AliRICH::Hits2SDigits
	One hit may affect one or more pads.
        Hit position is taken on the anode wires plane as the most of avalanche is developed there.
        This position is not directly available, track intersections with entrance and exit of amplification gap are only stored.
        So the position in the middle of the gap is calculated as average out of pHit->In() and pHit->Out() positions.
        Then, total charge collected for this hit is calculated by AliRICHParam::Hit2Qdc.    
        Area of disintegration is a list of pads affected by current hit. This is a parameter of Mathienson    
sdigits->digits:
	The necessety of sdigits is dictated by the fact that trasport engine transports track by track. It means that it may happen that the same
        pad is affected by few tracks. But this might be known after the trasport of full event only. 

Generalized structure of AliReconstruction:

Run()
{
  if(there is galice.root)                                          |
    AliRunLoader::Open(....)                                        | this is done in InitRunLoader()
  else                                                              |
    if(raw data process requested)                                  |
      create galice.root on the base of AliRawReader::NextEvent     |   
  
  for(all detectors){                                               |
   if(detector not selected to run) skip this detector              |
   reconstructor=get detector's reconstructor                       | this is done in RunLocalReconstruction()
   if(detector HasLocalReconstruction) skip this detector           | IMPORTANT! if HasLocalReconstruction() returns YES use RunLocalEventReconstruction instead
   if(run upon raw data)                                            |  
     reconstructor->Reconstruct(fRunLoader, fRawReader);            |   
   else                                                             |
     reconstructor->Reconstruct(fRunLoader);                        |
  }

  for(all events){                                                      
  
    for(all detectors){                                                 |            
      if(detector not selected to run) skip this detector               |
      reconstructor=get detector's reconstructor                        | 
      loader=get detector's loader                                      | this is done in RunLocalEventReconstruction()
      if(raw data process requested and detector HasDigitConversion){   | 
        loader->LoadDigits("update");                                   | open file and invoke  detector->SetTreeAddress();
        loader->CleanDigits();                                          |   
        loader->MakeDigitsContainer();                                  | create tree
        reconstructor->Reconstruct(fRawReader,loader->TreeD());         | expected to fill TreeD out of raw reader
        loader->WriteDigits("overwrite");                               | 
        loader->UnloadDigits();                                         |  
      }                                                                 |
      if(detector do not HasLocalReconstruction) skip this detector     | IMPORTANT! assumed that this detector is already processed in RunLocalReconstruction()
      loader->LoadRecPoints("update");                                  |
      loader->CleanRecPoints();                                         |
      loader->MakeRecPointsContainer();                                 | 
      if(fRawReader && reconstructor do not HasDigitConversion()){      | 
        reconstructor->Reconstruct(fRawReader, loader->TreeR());        | expected to fill TreeR out of raw reader
      }else{                                                            |
        loader->LoadDigits("read");                                     |
        reconstructor->Reconstruct(loader->TreeD(),loader->TreeR());    | the only operations inside are pDigTree->GetEntry(0) and pCluTree->Fill();
        loader->UnloadDigits();                                         | 
      }                                                                 |
      loader->WriteRecPoints("OVERWRITE");                              |
      loader->UnloadRecPoints();                                        |
    }//detectors loop                                                   |
    
  }//events loop 
}
Commit	Line	Data
5b919694	1	How to open session:
d3eb6079	2	use static method AliRunLoader::Open("galice.root","AlicE","update")
8493d0aa	3	How to get total number of events in galice.root:
	4	use AliRun::GetEventsPerRun()
	5	How to avoid using gAlice:
	6	detector->GetLoader()->GetRunLoader()->GetAliRun() returns gAlice global pointer.
d3eb6079	7	How to retrieve pointer to alice run loader:
	8	use pRICH->GetLoader()->GetRunLoader() (all detector classes inherit from AliDetector which has GetLoader())
	9	use method AliRun::GetRunLoader for gAlice (deprecated)
998b831f	10	How to get pointers to different root trees:
ab6b554e	11	TreeE belongs to AliRunLoader, available after AliRunLoader::LoadHeader()
	12	TreeK belongs to AliRunLoader, available after AliRunLoader::LoadKinematics()
	13	TreeH belongs to AliLoader , available after AliLoader::LoadHits()
	14	TreeS belongs to AliLoader , available after AliLoader::LoadSDigits()
	15	TreeD belongs to AliLoader , available after AliLoader::LoadDigits()
	16	TreeR belongs to AliLoader , available after AliLoader::LoadRecPoints()
d3eb6079	17	all methods return 0 on success.
	18	How to get event of interest:
	19	AliRunLoader::GetEvent(event_number) returns 0 on success
5b919694	20	How to deal with the stack of particles?
998b831f	21	- first of all, the stack includes primary as well as secondary particles
5b919694	22	- pointer to the stack is taken:
d3eb6079	23	AliRun::Stack() (global gAlice of type AliRun - deprecated way to do)
5b919694	24	AliRunLoader::Stack() but before one needs to load event header by AliRunLoader::LoadHeader() otherwise both methods return 0.
5b919694	25	Moreover loading header gives the information about number of particles only.
d3eb6079	26	To retrieve the list of particle one also needs to load kinematics by AliRunLoader::LoadKinematics()
5b919694	27	- total amount of particles in stack for a given event:
	28	AliStack::GetNtrack()
	29	AliRun::GetEvent() (after LoadHeader())
	30	- total amount of primary particles in stack for a given event (after LoadHeader()):
	31	AliStack::GetNprimary()
d3eb6079	32	How to retrieve hits:
	33	Hits are stored on primary by primary basis. Hits for the given primary is TClonesArray.
	34	To retrieve all hits one needs to do:
	35	-initialize the root tree and containers: pRich->GetLoader()->LoadHits(); (AliLoader::LoadHits() returns 0 on success)
	36	-read number of entries in TreeH: pRich->GetLoader()->TreeH()->GetEntries()
	37	-then for each entry: pRich->GetLoader()->TreeH()->GetEntry(i)
	38	How to retrieve sdigits?
09c52ebc	39	Sdigits stored in tree S with the branch of TClonesArray, all sdigits in a single TClonesArray
	40	So the tree has only one entry.
	41	One needs to say:
8493d0aa	42	-pRich->GetLoader()->LoadSDigits(); this one open file, get the tree and invoke AliRICH::SetTreeAddress()
d3eb6079	43	How to retrieve digits?
	44	Digits stored in tree D with the 7 branches of TClonesArray, one per chamber, all digits of a given chamber in a single TClonesArray
	45	So the tree has only one entry.
	46	-One needs to say:
	47	pRich->GetLoader()->LoadDigits(); this one opens file, gets the tree and invoke AliRICH::SetTreeAddress() which in turn corresponds
	48	branches of the tree to the digits containers in memory. There are 7 containers, one per chamber, all of them belong to AliRICH.
	49	-Then one needs to take the tree entry (only one) to the memory:
	50	pRich->GetLoader()->TreeD()->GetEntry(0)
	51	-Finally pRich->Digits(chamber_number) returns the pointer to TClonesArray of AliRICHdigit
	52	What are the debug methods avail:
8493d0aa	53	AliLog::SetGlobalDebugLevel(AliLog::kDebug)
5b919694	54	How to get info for a given particle number:
d3eb6079	55	Header and Kinematics trees must be loaded, then possible to retrieve pointer to Stack of particles
09c52ebc	56	Int_t AliRunLoader::LoadHeader(); Int_t AliRunLoader::LoadKinematics()
	57	AliStack *AliRunLoader::Stack()
	58	TParticle *AliStack::Particle(tid)
	59	TParticle::Print()
5b919694	60	How to deal with AliRunDigitizer:
09c52ebc	61	AliRunDigitizer::Exec() just call AliRunDigitizer::Digitize()
8493d0aa	62	What are the meanings of different VMC flags:
5b919694	63	gMC->IsTrackAlive()
	64	gMC->IsTrackStop()
	65	gMC->IsTrackDisappeared()
5b919694	66	How to get pad number for a local position:
d3eb6079	67	use static TVector AliRICHParam::Loc2Pad(TVector2 position);
5b919694	68	Why list of chambers belongs to AliRICHParam:
8493d0aa	69
	70	How to check if a given stack particle is primary:
	71	Stack is TClonesArray of TParticle. TParticle::GetMother(0) returns -1 if it's primary (no mother)
	72	How to loop over all possible object:
	73	for(Int_t iEventN=0;iEventN < GetLoader()->GetRunLoader()->GetAliRun()->GetEventsPerRun();iEventN++){//events loop
	74	for(Int_t iEntryN=0;iEntryN < GetLoader()->TreeH()->GetEntries();iEntryN++){//TreeH loop
	75	GetLoader()->TreeH()->GetEntry(iEntryN);//get current entry (prim)
	76	for(Int_t iHitN=0;iHitN<Hits()->GetEntries();iHitN++){//hits loop
	77	AliVHMPIDHit pHit=(AliVHMPIDHit)Hits()->At(iHitN);//get current hit
5b919694	78
8493d0aa	79	}//hits loop
	80	}//TreeH loop
	81	}//events loop
0422a446	82
	83
	84	RICH full simulation-reconstruction sequence
	85
	86	hits->sdigit:
	87	Responsible method is AliRICH::Hits2SDigits
	88	One hit may affect one or more pads.
	89	Hit position is taken on the anode wires plane as the most of avalanche is developed there.
	90	This position is not directly available, track intersections with entrance and exit of amplification gap are only stored.
	91	So the position in the middle of the gap is calculated as average out of pHit->In() and pHit->Out() positions.
	92	Then, total charge collected for this hit is calculated by AliRICHParam::Hit2Qdc.
	93	Area of disintegration is a list of pads affected by current hit. This is a parameter of Mathienson
	94	sdigits->digits:
	95	The necessety of sdigits is dictated by the fact that trasport engine transports track by track. It means that it may happen that the same
	96	pad is affected by few tracks. But this might be known after the trasport of full event only.
	97
	98	Generalized structure of AliReconstruction:
	99
	100	Run()
	101	{
	102	if(there is galice.root) \|
	103	AliRunLoader::Open(....) \| this is done in InitRunLoader()
	104	else \|
	105	if(raw data process requested) \|
	106	create galice.root on the base of AliRawReader::NextEvent \|
	107
	108	for(all detectors){ \|
	109	if(detector not selected to run) skip this detector \|
	110	reconstructor=get detector's reconstructor \| this is done in RunLocalReconstruction()
	111	if(detector HasLocalReconstruction) skip this detector \| IMPORTANT! if HasLocalReconstruction() returns YES use RunLocalEventReconstruction instead
	112	if(run upon raw data) \|
	113	reconstructor->Reconstruct(fRunLoader, fRawReader); \|
	114	else \|
	115	reconstructor->Reconstruct(fRunLoader); \|
	116	}
	117
	118	for(all events){
	119
	120	for(all detectors){ \|
	121	if(detector not selected to run) skip this detector \|
	122	reconstructor=get detector's reconstructor \|
	123	loader=get detector's loader \| this is done in RunLocalEventReconstruction()
	124	if(raw data process requested and detector HasDigitConversion){ \|
	125	loader->LoadDigits("update"); \| open file and invoke detector->SetTreeAddress();
	126	loader->CleanDigits(); \|
	127	loader->MakeDigitsContainer(); \| create tree
	128	reconstructor->Reconstruct(fRawReader,loader->TreeD()); \| expected to fill TreeD out of raw reader
	129	loader->WriteDigits("overwrite"); \|
	130	loader->UnloadDigits(); \|
	131	} \|
	132	if(detector do not HasLocalReconstruction) skip this detector \| IMPORTANT! assumed that this detector is already processed in RunLocalReconstruction()
	133	loader->LoadRecPoints("update"); \|
	134	loader->CleanRecPoints(); \|
	135	loader->MakeRecPointsContainer(); \|
	136	if(fRawReader && reconstructor do not HasDigitConversion()){ \|
	137	reconstructor->Reconstruct(fRawReader, loader->TreeR()); \| expected to fill TreeR out of raw reader
	138	}else{ \|
	139	loader->LoadDigits("read"); \|
	140	reconstructor->Reconstruct(loader->TreeD(),loader->TreeR()); \| the only operations inside are pDigTree->GetEntry(0) and pCluTree->Fill();
	141	loader->UnloadDigits(); \|
	142	} \|
	143	loader->WriteRecPoints("OVERWRITE"); \|
	144	loader->UnloadRecPoints(); \|
	145	}//detectors loop \|
146
147	}//events loop
148	}