TPC: add UseGeant4Edep ionisation-fluctuation flag for Kr-83m calibration simulations by Ankyyadav · Pull Request #15615 · AliceO2Group/AliceO2

Ankyyadav · 2026-07-21T09:24:30Z

Adds TPCDetParam.UseGeant4Edep, an opt-in flag (default off) that uses Geant4's energy deposit directly for ionisation in Detector::ProcessHits, with Fano-limited charge fluctuation via a Gamma-distributed smear (mean/variance tuned for GEANT4). Used for 83mKr TPC calibration simulations.
- SetSpecialPhysicsCuts() calls matmgr.SpecialCut() for the TPC drift-gas media before the base class reads simcuts.dat (which sets a 10 keV default for these media). This is now exposed as TPCDetParam.SpecialCutsGeV (default 1e-6 GeV = 1 keV), so the actual effective cut
  can be set via configKeyValues.

Please consider the following formatting changes to AliceO2Group#15615

wiechula · 2026-07-24T07:36:51Z

+namespace KrGenConfig
+{
+inline double rInner = 83.5;
+inline double rOuter = 246.5; // TPC outermost pad row outer edge ~247 cm; stay inside
+inline double halfZ = 249.7;
+inline int nPerEvent = 1000; // override at runtime via KR_N_PER_EVENT env var
+} // namespace KrGenConfig


Is this namespace needed? I guess the variables could also go to the class.
If you would like to keep it follow the naming convention for the namespaces: lower case with underscore
namespace kr_gen_config

Part of the variable can then be const or constexpr.

Thanks for the comments. I have made the changes

wiechula · 2026-07-24T07:37:43Z

+struct KrProduct {
+  int pdg;
+  double eKin;
+};


Seems to be only used in KrDecayTable, so it could also go there.

wiechula · 2026-07-24T07:47:38Z

+      std::cout << "[KrDecayTable] Loaded from " << path << "\n"
+                << "  T1: E=" << fE1 << " keV  ICC=" << ICC_T1
+                << "  K_frac=" << Kfrac_T1 << "\n"
+                << "  T2: E=" << fE2 << " keV  ICC=" << ICC_T2 << "\n";


Use LOG(info) and remove last \n. Also in other places. Or the appropriate log level.

wiechula · 2026-07-24T07:49:37Z

+      o2::tpc::KrGenConfig::nPerEvent = n;
+    }
+  }
+  std::cout << "[GeneratorKrDecay] Init:"


wiechula · 2026-07-24T07:49:52Z

+                << "  K_frac=" << Kfrac_T1 << "\n"
+                << "  T2: E=" << fE2 << " keV  ICC=" << ICC_T2 << "\n";
+    } else {
+      std::cout << "[KrDecayTable] WARNING: could not parse " << path


wiechula · 2026-07-24T07:50:00Z

+                << " — using hardcoded fallback values\n";
+    }
+  } else {
+    std::cout << "[KrDecayTable] WARNING: G4LEVELGAMMADATA not set"


wiechula · 2026-07-24T07:51:32Z

+  Bool_t importParticles() override;
+
+ private:
+  o2::tpc::KrDecayTable* mTable;


Use std::unique_ptr

wiechula · 2026-08-13T08:31:39Z

+namespace o2
+{
+namespace tpc
+{


Suggested change

namespace o2

{

namespace tpc

{

namespace o2::tpc

{

Thanks for the comments. I have included the suggested changes

wiechula · 2026-08-13T08:33:14Z

+} // namespace tpc
+} // namespace o2


Suggested change

} // namespace tpc

} // namespace o2

} // namespace o2::tpc

wiechula · 2026-08-13T08:33:32Z

+namespace o2
+{
+namespace eventgen
+{


Suggested change

namespace o2

{

namespace eventgen

{

namespace o2::eventgen

{

wiechula · 2026-08-13T08:33:48Z

+// O2 status encoding from MCGenProperties.h
+// bits 0-8: hepmc(9), bits 9-18: gen(10), bits 19-28: reserved(10), bits 29-31: sentinel=5
+inline int krO2EncodedStatus(int hepmc, int gen = 0)
+{
+  return (5 << 29) | ((gen & 0x3FF) << 9) | (hepmc & 0x1FF);
+}


Can be part of GeneratorKrDecay

wiechula · 2026-08-13T08:35:19Z

+} // namespace eventgen
+} // namespace o2


Suggested change

} // namespace eventgen

} // namespace o2

} // namespace o2::eventgen

wiechula · 2026-08-13T08:37:22Z

+static bool parseG4PhotonEvap(const char* path,
+                              double& E_T1,     // T1 gamma energy [keV]
+                              double& ICC_T1,   // T1 ICC_total
+                              double& Kfrac_T1, // T1 K-shell fraction of ICC
+                              double& E_T2,     // T2 gamma energy [keV]
+                              double& ICC_T2)   // T2 ICC_total


Can't this be part of KrDecayTable?

wiechula · 2026-09-14T08:57:47Z

+namespace o2
+{


wiechula · 2026-09-14T08:59:28Z

+
+// ── GeneratorKrDecay ─────────────────────────────────────────────────────
+
+namespace o2


also here collapse the namespace

…on support - TPCDetParam.UseGeant4Edep: use Geant4's own energy deposit for ionisation instead of Bethe-Bloch/NA49, with a configurable SpecialCutsGeV threshold - Adds the Kr-83m decay generator (GeneratorKrDecay) as a compiled Generator subclass in Detectors/TPC/simulation, with a thin krGenerator.C macro for use as an o2-sim external generator - Adds plotCluster.C for viewing the resulting calibration spectrum

Ankyyadav requested review from davidrohr, shahor02 and wiechula as code owners July 21, 2026 09:24

alibuild mentioned this pull request Jul 21, 2026

Please consider the following formatting changes to #15615 Ankyyadav/AliceO2#1

Merged

Ankyyadav marked this pull request as draft July 21, 2026 09:25

Ankyyadav added a commit to Ankyyadav/AliceO2 that referenced this pull request Jul 21, 2026

Merge pull request #1 from alibuild/alibot-cleanup-15615

833f9a1

Please consider the following formatting changes to AliceO2Group#15615

Ankyyadav force-pushed the feature/tpc-kr-calibration-generator branch from 833f9a1 to dfc712d Compare July 23, 2026 13:54

alibuild mentioned this pull request Jul 23, 2026

Please consider the following formatting changes to #15615 Ankyyadav/AliceO2#2

Closed

Ankyyadav force-pushed the feature/tpc-kr-calibration-generator branch from dfc712d to cc9dea4 Compare July 23, 2026 14:01

Ankyyadav marked this pull request as ready for review July 23, 2026 14:04

wiechula requested changes Jul 24, 2026

View reviewed changes

Ankyyadav force-pushed the feature/tpc-kr-calibration-generator branch from cc9dea4 to d6a0c54 Compare July 24, 2026 09:01

Ankyyadav requested a review from wiechula July 27, 2026 19:27

Ankyyadav force-pushed the feature/tpc-kr-calibration-generator branch from d6a0c54 to 7f4271e Compare August 16, 2026 13:31

Ankyyadav force-pushed the feature/tpc-kr-calibration-generator branch from 7f4271e to 38af72c Compare September 2, 2026 08:10

wiechula requested changes Sep 14, 2026

View reviewed changes

Ankyyadav force-pushed the feature/tpc-kr-calibration-generator branch from 38af72c to 89cf669 Compare September 14, 2026 19:03

alibuild mentioned this pull request Sep 14, 2026

Please consider the following formatting changes to #15615 Ankyyadav/AliceO2#3

Open

	} // namespace eventgen
	} // namespace o2
	} // namespace o2::eventgen


		// ── GeneratorKrDecay ─────────────────────────────────────────────────────

		namespace o2

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Ankyyadav commented Jul 21, 2026

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