Fix TOF v20b position and use in mCBM 2020 and 2021 setups, refs #1721

setup/setup_mcbm_beam_2021_03.C

@@ -60,7 +60,7 @@ void setup_mcbm_beam_2021_03()
 //  TString muchGeoTag      = "v19a_mcbm";    // need 3 layers and RPC here
   TString trdGeoTag       = "v20b_mcbm";    // 2021 // 2 TRD modules
 //  TString trdGeoTag       = "v18q_mcbm";    // 2 TRD modules 
-  TString tofGeoTag       = "v20a_mcbm";    // double / triple stack
+  TString tofGeoTag       = "v20b_mcbm";
   TString richGeoTag      = "v20b_mcbm";    // geometry provided by RICH group
   TString psdGeoTag       = "v18d_mcbm";    // at 25 degree, below the beampipe
   // ------------------------------------------------------------------------