+
+ AliESDEvent* esd = new AliESDEvent();
+ TTree* tree = (TTree*) esdFile->Get("esdTree");
+ if (!tree) {
+ Error("MUONefficiency", "no ESD tree found");
+ return kFALSE;
+ }
+ esd->ReadFromTree(tree);
+
+ // get run number
+ if (tree->GetEvent(0) <= 0) {
+ Error("MUONefficiency", "no ESD object found for event 0");
+ return kFALSE;
+ }
+ Int_t runNumber = esd->GetRunNumber();
+
+ // load necessary data from OCDB
+ AliCDBManager::Instance()->SetDefaultStorage(ocdbPath);
+ AliCDBManager::Instance()->SetRun(runNumber);
+ if (!AliMUONCDB::LoadField()) return kFALSE;
+