Merge pull request cms-sw#31983 from ghugo83/fix_preshower_minusZ

Mini-PR: Fix Z side in Preshower

Author: cmsbuild

Geometry/EcalCommonData/src/EcalPreshowerNumberingScheme.cc

@@ -90,10 +90,15 @@ EcalPreshowerNumberingScheme::~EcalPreshowerNumberingScheme() {
   edm::LogVerbatim("EcalGeom") << "Deleting EcalPreshowerNumberingScheme";
 }
 
+/*
+ * Compute the Ecal Preshower DetId.
+ * General NB: if possible, it would be way better to just access the DetID from a hash map from G4 Volume, 
+ * rather than recomputing it for each SimHit - see Tracker.
+ */
 uint32_t EcalPreshowerNumberingScheme::getUnitID(const EcalBaseNumber& baseNumber) const {
-  int level = baseNumber.getLevels();
+  const int numberOfHierarchyLevels = baseNumber.getLevels();
   uint32_t intIndex = 0;
-  if (level > 0) {
+  if (numberOfHierarchyLevels > 0) {
     // depth index - silicon layer 1-st or 2-nd
     int layer = 0;
     if (baseNumber.getLevelName(0).find("SFSX") != std::string::npos) {
@@ -105,18 +110,25 @@ uint32_t EcalPreshowerNumberingScheme::getUnitID(const EcalBaseNumber& baseNumbe
                                   << " of Presh. Si. Strip : " << baseNumber.getLevelName(0);
     }
 
+    // Access different hierarchy levels
+    static constexpr int stripHierachyLevel = 0;
+    static constexpr int boxHierachyLevel = 2;
+    static constexpr int ladderHierachyLevel = 3;
+    static constexpr int regionHierachyLevel = 5;
+
     // Z index +Z = 1 ; -Z = 2
-    int zs = baseNumber.getCopyNumber("EREG");
+
+    int zs = baseNumber.getCopyNumber(regionHierachyLevel);
     int zside = 2 * (1 - zs) + 1;
 
     // box number
-    int box = baseNumber.getCopyNumber(2);
+    int box = baseNumber.getCopyNumber(boxHierachyLevel);
 
     int x = 0, y = 0, ix, iy, id;
     int mapX[10] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
     int mapY[10] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
     const std::string& ladd = baseNumber.getLevelName(3).substr(0, 6);
-    int ladd_copy = baseNumber.getCopyNumber(3);
+    int ladd_copy = baseNumber.getCopyNumber(ladderHierachyLevel);
 
     if (ladd == "SFLX0a" || ladd == "SFLY0a") {
       mapX[5] = mapX[6] = mapX[7] = mapX[8] = mapX[9] = 1;
@@ -397,7 +409,7 @@ uint32_t EcalPreshowerNumberingScheme::getUnitID(const EcalBaseNumber& baseNumbe
     }
 
     // strip number inside wafer
-    int strip = baseNumber.getCopyNumber(0);
+    int strip = baseNumber.getCopyNumber(stripHierachyLevel);
 
     if (layer == 1) {
       if (zside > 0 && y <= 20)
@@ -419,7 +431,7 @@ uint32_t EcalPreshowerNumberingScheme::getUnitID(const EcalBaseNumber& baseNumbe
                                  << " layer " << layer << " strip " << strip << " UnitID 0x" << std::hex << intIndex
                                  << std::dec;
 
-    for (int ich = 0; ich < level; ich++)
+    for (int ich = 0; ich < numberOfHierarchyLevels; ich++)
       edm::LogVerbatim("EcalGeom") << "Name = " << baseNumber.getLevelName(ich)
                                    << " copy = " << baseNumber.getCopyNumber(ich);
 #endif