Downgrade rich

Please insert x between square brackets to tick the boxes, add a meaningful description if the title is not enough and check the outcome with the "Preview" tab

In case you committed a new geometry:

• Ran the scripts for materials and radiation length check on my new geometry file? (and read carefully the output of course)

  bash ci_scripts/check_radlen.sh <path>/<file>.geo.root

• Added also the corresponding creation macro?
• Checked that the geometry does not contains unexpected overlaps, e.g. either at end of the creation macro or with the something similar to the mCBM macro
  macro/mcbm/mcbm_check_overlaps.C

In case you committed a new setup file:

• Checked that all geometries listed are present in the repository?
• Ran the CBMROOT macro/geometry/check_media.C on the corresponding .geo.root file? (output by the transport macro)

setup/setup_sis100_electron.C

@@ -7,6 +7,7 @@
  **
  **/
 
+// 2023-04-04 - EC - Downgrade to rich v21a
 // 2023-03-01 - EC - Default FEB23 geometries
 // 2022-09-13 - EC - Replaces rich with v22a
 // 2022-09-11 - EC - Adds v21i beampipe for 10AGeV beampipe
@@ -25,7 +26,7 @@ void setup_sis100_electron()
   TString pipeGeoTag      = "v21d:v21i";
   TString mvdGeoTag       = "v20d_tr";
   TString stsGeoTag       = "v22c";
-  TString richGeoTag      = "v22a";
+  TString richGeoTag      = "v21a";
   TString trdGeoTag       = "v20b_1e";
   TString tofGeoTag       = "v21a_1e";
   TString psdGeoTag       = "v22a";  // Paused or Removed Detector System, placeholder for Forward Wall Detector