pointer to the stack:
AliRunLoader::Stack()

total amount of particles in stack for a given event:
AliStack::GetNtrack() or AliRun::GetEvent()


total amount of primiry particles in stack for a given event:
AliStack::GetNprimary() or TreeH()::GetEntries()

to open session 
AliRunLoader::Open(


Hits a stored on primiry by primiry basis. To retrieve all hits one needs to do:

initialise the root tree and containers:    AliLoader::LoadHits() 
read number of primiries in current event:
loop on the list of primiries:



How to retrive 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()    



gAlice->GetMCApp()->GetCurrentTrackNumber()


Debug staff:

AliModule::GetDebug() 
AliModule::SetDebug()
AliRun::GetDebug()
AliRun::SetDebug()






pointer to gAlice