Add mPSD v20a located 40 cm upstream of v18d, refs #1599

psd/psd_v20a_mcbm.geo.info

+PSD geometry v20a_mcbm created with create_psdgeo.C
+
+Number of modules: 1 x 1
+Module size: 20 cm x 20 cm
+PSD translation in cave: (0, -22, 120) cm
+PSD rotation around y axis: 25 degrees
+
+Parameters of module module2060: 
+Size: 20 cm x 20 cm
+Number of layers: 60
+Thickness of lead layers: 1.6 cm
+Thickness of scintillators: 0.4 cm
+Thickness of Tyvek wrap: 0.02 cm
+Thickness of iron box: (0.15 / 0.05 / 2) cm
+Height of fibre channel: 0.2 cm
+Distance of channel from edges: left 0.5 cm, right 2 cm
+
+PSD size is 20 cm x 20 cm x 124.8 cm
+PSD contains 1 modules.

setup/setup_mcbm_beam_2021_03.C

@@ -63,7 +63,7 @@ void setup_mcbm_beam_2021_03()
 //  TString trdGeoTag       = "v18q_mcbm";    // 2 TRD modules 
   TString tofGeoTag       = "v20b_mcbm";
   TString richGeoTag      = "v20d_mcbm";    // geometry provided by RICH group
-  TString psdGeoTag       = "v18d_mcbm";    // at 25 degree, below the beampipe
+  TString psdGeoTag       = "v20a_mcbm";    // at 25 degree, below the beampipe
   // ------------------------------------------------------------------------