Feature/ubt segmented

src/SHiPMaterials.cpp

@@ -179,6 +179,32 @@ void SHiPMaterials::createMaterials() {
     scintillator->add(m_elements["Hydrogen"], 0.085);
     scintillator->lock();
     m_materials["Scintillator"] = scintillator;
+
+    // Mylar / PET (density 1.39 g/cm³): C10H8O4 → C 62.50%, H 4.20%, O 33.30%
+    GeoMaterial* mylar =
+        new GeoMaterial("Mylar", 1.39 * GeoModelKernelUnits::g / GeoModelKernelUnits::cm3);
+    mylar->add(m_elements["Carbon"], 0.6250);
+    mylar->add(m_elements["Hydrogen"], 0.0420);
+    mylar->add(m_elements["Oxygen"], 0.3330);
+    mylar->lock();
+    m_materials["Mylar"] = mylar;
+
+    // ArCO2 70/30 drift gas (density 1.842e-3 g/cm³): Ar 67.93%, C 8.75%, O 23.32%
+    GeoMaterial* arco2 =
+        new GeoMaterial("ArCO2", 1.842e-3 * GeoModelKernelUnits::g / GeoModelKernelUnits::cm3);
+    arco2->add(m_elements["Argon"], 0.6793);
+    arco2->add(m_elements["Carbon"], 0.0875);
+    arco2->add(m_elements["Oxygen"], 0.2332);
+    arco2->lock();
+    m_materials["ArCO2"] = arco2;
+
+    // Polystyrene (density 1.06 g/cm³): C8H8 → C 92.26%, H 7.74%
+    GeoMaterial* polystyrene =
+        new GeoMaterial("Polystyrene", 1.06 * GeoModelKernelUnits::g / GeoModelKernelUnits::cm3);
+    polystyrene->add(m_elements["Carbon"], 0.9226);
+    polystyrene->add(m_elements["Hydrogen"], 0.0774);
+    polystyrene->lock();
+    m_materials["Polystyrene"] = polystyrene;
 }
 
 }  // namespace SHiPGeometry

subsystems/UpstreamTagger/README.md

@@ -1,36 +1,124 @@
 # UpstreamTagger
 
-Upstream veto tagger.
+Upstream Background Tagger (UBT) — segmented drift tube and scintillator tile detector.
 
 ## Description
 
-The UpstreamTagger subsystem implements a scintillator slab upstream of the decay vessel, used to veto charged particles entering from the target region. Currently modelled as a single monolithic scintillator box. The full implementation requires bar segmentation with SiPM readout.
+The UpstreamTagger implements the UBT as a segmented 2×3 m² tracking plane placed at
+z = 32720 mm, upstream of the decay vessel. It consists of:
 
-The volume is created as a `GeoFullPhysVol` (rather than `GeoPhysVol`) to allow sensitive detector registration via `SHiPUBTManager`.
+- **Drift tubes** — mylar straw tubes (5 mm diameter, 15 µm wall, ArCO2 70/30 fill, 1.2 m long)
+  arranged in double-staggered layers
+- **Scintillator tiles** — 1×1×1 cm³ polystyrene tiles in two 40×40 blocks
 
 ## Geometry Tree
 
 ```
-Upstream_Tagger (Scintillator, 4400×6400×160 mm)
+UBT_Envelope_LV  (Air, 2000×3000×16 mm)
+├── UBT_Top_Left_LOG       (Air, outer top band, left half-plane)
+│   ├── UBT_Top_Left_S0_T*_Wall  (Mylar, hollow tube annulus)
+│   └── UBT_Top_Left_S0_T*_Gas   (ArCO2, solid cylinder) [sensitive]
+│   ├── UBT_Top_Left_S1_T*_Wall
+│   └── UBT_Top_Left_S1_T*_Gas   [sensitive]
+├── UBT_Top_Right_LOG      (Air, outer top band, right half-plane)
+│   └── ...
+├── UBT_Bottom_Left_LOG    (Air, outer bottom band, left half-plane)
+│   └── ...
+├── UBT_Bottom_Right_LOG   (Air, outer bottom band, right half-plane)
+│   └── ...
+├── UBT_Central_LOG        (Air, central tube strip x=[-600,+600])
+│   ├── UBT_Central_S*_T*_Wall
+│   └── UBT_Central_S*_T*_Gas    [sensitive]
+├── UBT_TileLeft_LOG       (Air, left tile block x=[-1000,-600])
+│   └── UBT_TileLeft_T*_*        [sensitive]
+└── UBT_TileRight_LOG      (Air, right tile block x=[+600,+1000])
+    └── UBT_TileRight_T*_*       [sensitive]
 ```
 
-Position in world: z = 32720 mm.
+## Detector Layout
+
+```
+  Y
+  +1500 ┌──────────────────────────────────────────┐
+        │  Top_Left tubes  +  Top_Right tubes       │  y = [+200, +1500] mm
+  +200  ├───────────┬──────────────────┬────────────┤
+        │ PS tiles  │  Central tubes   │  PS tiles  │  y = [-200, +200] mm
+        │ (left)    │  x=[-600,+600]   │  (right)   │
+  -200  ├───────────┴──────────────────┴────────────┤
+        │  Bottom_Left tubes + Bottom_Right tubes   │  y = [-1500, -200] mm
+  -1500 └──────────────────────────────────────────┘
+        -1000 -600                  +600 +1000     → X (mm)
+```
+
+### Drift tubes
+
+| Region | X extent (mm) | Y extent (mm) | Z centre (mm) |
+|--------|--------------|---------------|---------------|
+| Top_Left | [-1000, +200] | [+200, +1500] | -5 |
+| Top_Right | [-200, +1000] | [+200, +1500] | +5 |
+| Bottom_Left | [-1000, +200] | [-1500, -200] | -5 |
+| Bottom_Right | [-200, +1000] | [-1500, -200] | +5 |
+| Central | [-600, +600] | [-200, +200] | 0 |
+
+Each region uses a double-staggered layer: two sub-layers separated by one tube
+radius in Z and half a pitch in Y, giving full azimuthal coverage.
+
+Tube gas and wall volumes are placed as **siblings** in the envelope (not nested)
+to avoid Geo2G4 copy-number corruption with shared logical volumes.
+
+### Scintillator tiles
+
+Two 40×40 blocks of 1×1×1 cm³ polystyrene tiles, flush with the tube layer in Z.
+
+## Sensitive Volumes
+
+All sensitive volumes are `GeoFullPhysVol` and are registered with `SHiPUBTManager`:
+
+| Collection | LV name pattern | Count |
+|---|---|---|
+| Tube gas | `UBT_*_TubeGas_LV` | ~1000+ |
+| Tiles | `UBT_Tile_LV` | 3200 |
 
 ## Materials
 
-| Material     | Density    | Usage           |
-|--------------|------------|-----------------|
-| Scintillator | 1.023 g/cm³ | Detector slab  |
 
-## Status
+| Material | Density | Usage |
+|---|---|---|
+| Mylar | 1.39 g/cm³ | Tube wall (15 µm) |
+| ArCO2 | 1.842×10⁻³ g/cm³ | Drift gas (70% Ar, 30% CO2) |
+| Polystyrene | 1.06 g/cm³ | Scintillator tiles |
+| Air | 1.29×10⁻³ g/cm³ | Envelopes |
+
+
+## Position in World
+
+z = 32720 mm (centre of 32520–32920 mm range, from subsystem_envelopes.csv).
 
-- [x] C++ implementation (monolithic slab)
-- [ ] Implement bar segmentation with SiPM readout
-- [ ] Verification against GDML
+## Geant4 Integration
 
-## TODO
+To register sensitive detectors in a Geant4 application:
+
+```cpp
+SHiPUBTManager ubtManager;
+UpstreamTaggerFactory factory(materials);
+factory.build(&ubtManager);
+
+// After Geo2G4 conversion, iterate the G4LogicalVolumeStore and register
+// your SD on volumes whose name contains "TubeGas_LV" or "Tile_LV":
+auto* sd = new MyUBTSD("UBTSD");
+for (auto* lv : *G4LogicalVolumeStore::GetInstance()) {
+    const auto& name = lv->GetName();
+    if (name.find("TubeGas_LV") != std::string::npos ||
+        name.find("Tile_LV")    != std::string::npos)
+        lv->SetSensitiveDetector(sd);
+}
+```
+
+## Status
 
-- Implement individual scintillator bar segmentation
-- Add SiPM readout geometry
-- Register individual bars as sensitive volumes (currently the whole slab is one volume)
-- Verify slab dimensions against GDML reference
+- [x] Full segmented geometry (drift tubes + tiles)
+- [x] Double-staggered tube layers per region
+- [x] GeoFullPhysVol sensitive volume registration via SHiPUBTManager
+- [x] New materials (Mylar, ArCO2, Polystyrene) added to SHiPMaterials
+- [ ] Verification of tube count against GDML reference
+- [ ] SiPM readout geometry

subsystems/UpstreamTagger/include/UpstreamTagger/SHiPUBTManager.h

@@ -7,28 +7,65 @@
 #include <GeoModelKernel/GeoVDetectorManager.h>
 #include <GeoModelKernel/GeoVPhysVol.h>
 
+#include <vector>
+
 namespace SHiPGeometry {
 
 /**
  * @brief Detector manager for the Upstream Background Tagger (UBT).
  *
- * Stores the single GeoFullPhysVol sensitive slab and satisfies the
- * GeoVDetectorManager interface for downstream Geant4 integration.
+ * Stores the sensitive volumes of the UBT: drift tube gas volumes and
+ * scintillator tile volumes, all registered as GeoFullPhysVol.
+ *
+ * Two sets of sensitive volumes:
+ *  - Drift tube gas cylinders (ArCO2 70/30)
+ *  - Polystyrene scintillator tiles (1×1×1 cm³)
+ *
+ * The legacy single-slab interface (setSlabVolume / getFullPV) is kept
+ * for backwards compatibility with the monolithic placeholder.
  */
 class SHiPUBTManager : public GeoVDetectorManager {
    public:
     SHiPUBTManager() = default;
     ~SHiPUBTManager() override = default;
 
+    // ---- Legacy slab interface (monolithic placeholder) --------------------
     void setSlabVolume(GeoFullPhysVol* fpv) { m_slab = fpv; }
     GeoFullPhysVol* getFullPV() const { return m_slab; }
 
-    unsigned int getNumTreeTops() const override { return m_slab ? 1u : 0u; }
+    // ---- Segmented detector interface --------------------------------------
+    void addTubeGasVolume(GeoFullPhysVol* fpv) { m_tubeGasVolumes.push_back(fpv); }
+    void addTileVolume(GeoFullPhysVol* fpv) { m_tileVolumes.push_back(fpv); }
+
+    const std::vector<GeoFullPhysVol*>& getTubeGasVolumes() const { return m_tubeGasVolumes; }
+    const std::vector<GeoFullPhysVol*>& getTileVolumes() const { return m_tileVolumes; }
+
+    std::size_t numTubeGasVolumes() const { return m_tubeGasVolumes.size(); }
+    std::size_t numTileVolumes() const { return m_tileVolumes.size(); }
+
+    // ---- GeoVDetectorManager interface ------------------------------------
+    unsigned int getNumTreeTops() const override {
+        // If segmented volumes exist use them, otherwise fall back to slab
+        const auto n = m_tubeGasVolumes.size() + m_tileVolumes.size();
+        return n > 0 ? static_cast<unsigned int>(n) : (m_slab ? 1u : 0u);
+    }
 
-    PVConstLink getTreeTop(unsigned int /*i*/) const override { return PVConstLink(m_slab); }
+    PVConstLink getTreeTop(unsigned int i) const override {
+        const auto nTubes = m_tubeGasVolumes.size();
+        const auto nTiles = m_tileVolumes.size();
+        if (nTubes + nTiles > 0) {
+            if (i < nTubes)
+                return PVConstLink(m_tubeGasVolumes[i]);
+            if (i < nTubes + nTiles)
+                return PVConstLink(m_tileVolumes[i - nTubes]);
+        }
+        return PVConstLink(m_slab);
+    }
 
    private:
     GeoFullPhysVol* m_slab{nullptr};
+    std::vector<GeoFullPhysVol*> m_tubeGasVolumes;
+    std::vector<GeoFullPhysVol*> m_tileVolumes;
 };
 
 }  // namespace SHiPGeometry

subsystems/UpstreamTagger/include/UpstreamTagger/UpstreamTaggerFactory.h

@@ -11,32 +11,61 @@ class SHiPMaterials;
 class SHiPUBTManager;
 
 /**
- * @brief Factory for the UpstreamTagger (upstream veto tagger) geometry
+ * @brief Factory for the Upstream Background Tagger (UBT) geometry.
  *
- * Creates a scintillator slab as a GeoFullPhysVol (sensitive volume).
- * Based on GDML reference: Box 440×640×16 cm (full dimensions).
- * Z: 32.52 to 32.92 m → centre: 32.72 m, half-length: 0.20 m
- * Half-width: 2.20 m, half-height: 3.20 m
+ * Builds a segmented 2×3 m² tracker plane of drift tubes and scintillator tiles.
+ *
+ * ## Detector layout
+ *
+ * ```
+ *   Y
+ *   +1500 ┌──────────────────────────────────────────┐
+ *         │  Top_Left tubes  +  Top_Right tubes       │  y = [+200, +1500]
+ *   +200  ├───────────┬──────────────────┬────────────┤
+ *         │ PS tiles  │  Central tubes   │  PS tiles  │  y = [-200, +200]
+ *         │ (left)    │  x=[-600,+600]   │  (right)   │
+ *   -200  ├───────────┴──────────────────┴────────────┤
+ *         │  Bottom_Left tubes + Bottom_Right tubes   │  y = [-1500, -200]
+ *   -1500 └──────────────────────────────────────────┘
+ *         -1000 -600                  +600 +1000     → X (mm)
+ * ```
+ *
+ * ## Sensitive volumes
+ * All tube gas volumes (GeoFullPhysVol, LV name contains "TubeGas_LV") and
+ * tile volumes (GeoFullPhysVol, LV name "UBT_Tile_LV") are registered with
+ * the supplied SHiPUBTManager for downstream Geant4 SD registration.
+ *
+ * ## Envelope dimensions (half-extents, mm)
+ *   halfX = 1000,  halfY = 1500,  halfZ = 8
+ *
+ * ## Position in world
+ *   z = 32720 mm (centre of the 32520–32920 mm z range)
  */
 class UpstreamTaggerFactory {
    public:
     explicit UpstreamTaggerFactory(SHiPMaterials& materials);
     ~UpstreamTaggerFactory() = default;
 
     /**
-     * @brief Build the UpstreamTagger geometry.
-     * @param manager Optional manager to register the sensitive slab; may be null.
-     * @return Pointer to the GeoFullPhysVol scintillator slab.
+     * @brief Build the full segmented UBT plane.
+     * @param manager Optional manager to register sensitive volumes; may be null.
+     * @return Pointer to the envelope GeoPhysVol.
      */
     GeoVPhysVol* build(SHiPUBTManager* manager = nullptr);
 
+    // Envelope half-dimensions (mm) — used by the test to check against CSV limits
+    // Envelope half-dimensions match CSV: half_width=750mm, half_height=1600mm
+    static constexpr double s_halfX = 750.0;
+    static constexpr double s_halfY = 1600.0;
+    static constexpr double s_halfZ = 8.0;
+
    private:
     SHiPMaterials& m_materials;
 
-    // Dimensions from GDML: Box 440×640×16 cm → half: 220×320×8 cm (mm)
-    static constexpr double s_halfX = 2200.0;
-    static constexpr double s_halfY = 3200.0;
-    static constexpr double s_halfZ = 80.0;
+    static constexpr double s_tubeROuter_mm = 2.5;
+    static constexpr double s_tubeWall_mm = 0.015;
+    static constexpr double s_tubeHalfLen_mm = 600.0;
+    static constexpr double s_tileSide_mm = 10.0;
 };
 
 }  // namespace SHiPGeometry