void geometry()
{
   TString dir = gSystem->UnixPathName(__FILE__);
   dir.ReplaceAll("geometry.C", "");
   dir.ReplaceAll("/./", "/");
   gROOT->Macro(Form("%s/na49.C", dir.Data()));
   gROOT->Macro(Form("%s/na49geomfile.C", dir.Data()));
}