TChain* openMCChain(TString path)
{
  TString basedir = gSystem->Getenv("VMCWORKDIR");
  TChain* chain=new TChain("cbmsim");

  char* dir = gSystem->ExpandPathName(path.Data());
  void* dirp = gSystem->OpenDirectory(dir);

  const char* entry;
  char* ext=".reco.root";
  TString str;

  while((entry = (char*)gSystem->GetDirEntry(dirp))) 
    {
      str = entry;
      if(str.EndsWith(ext))
	chain->AddFile((char*)gSystem->ConcatFileName(dir, entry));
    }
  return chain;
}