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Removed Z0 modes + fixed Z0 decay
1 parent de2da01 commit e625584

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3 files changed

+71
-46
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3 files changed

+71
-46
lines changed

‎MC/config/common/external/generator/perfConf.json‎

Lines changed: 23 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,23 @@
1+
{
2+
"generators": [
3+
{
4+
"cocktail": [
5+
{
6+
"name": "pythia8pp",
7+
"config": ""
8+
},
9+
{
10+
"name": "external",
11+
"config": {
12+
"fileName": "${O2DPG_MC_CONFIG_ROOT}/MC/config/common/external/generator/performanceGenerator.C",
13+
"funcName": "Generator_Performance()",
14+
"iniFile": ""
15+
}
16+
}
17+
]
18+
}
19+
],
20+
"fractions": [
21+
1
22+
]
23+
}

‎MC/config/common/external/generator/performanceGenerator.C‎

Lines changed: 45 additions & 44 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,7 @@
11
// External generator requested in https://its.cern.ch/jira/browse/O2-6235
22
// for multidimensional performance studies
3+
// Example usage:
4+
// o2-sim -j 8 -o test -n 100 --seed 612 -g hybrid --configKeyValues "GeneratorHybrid.configFile=${O2DPG_MC_CONFIG_ROOT}/MC/config/common/external/generator/perfConf.json"
35
namespace o2
46
{
57
namespace eventgen
@@ -8,8 +10,7 @@ namespace o2
810
class GenPerf : public Generator
911
{
1012
public:
11-
GenPerf(float fraction = 0.03f, unsigned short int nsig = 100, unsigned short int tag = 1, bool setDecayZ0 = false)
12-
: mDecayZ0(setDecayZ0)
13+
GenPerf(float fraction = 0.03f, unsigned short int nsig = 100, unsigned short int tag = 1)
1314
{
1415
if (fraction == -1) {
1516
LOG(info) << nsig << " Signal particles will be generated in each event";
@@ -36,15 +37,13 @@ namespace o2
3637
mTag = tag;
3738
LOG(info) << "Generator with tag " << mTag << " is selected";
3839
}
39-
if (mDecayZ0){
40-
LOG(info) << "Z0 decays will be handled with Pythia8";
41-
mPythia = std::make_unique<Pythia8::Pythia>();
42-
// Configure Pythia8 with minimal beam setup for standalone decays
43-
mPythia->readString("WeakSingleBoson:ffbar2gmZ = on");
44-
mPythia->init(); // Initialize
45-
} else {
46-
LOG(info) << "Z0 decays will be created but not transported (incompatible with Geant4 physics list)";
47-
}
40+
LOG(info) << "Z0 decays are handled with Pythia8";
41+
mPythia = std::make_unique<Pythia8::Pythia>();
42+
// Turn off all event generation - we only want to decay our Z0
43+
mPythia->readString("ProcessLevel:all = off");
44+
// Disable standard event checks since we're manually building the event
45+
mPythia->readString("Check:event = off");
46+
mPythia->init(); // Initialize
4847
Generator::setTimeUnit(1.0);
4948
Generator::setPositionUnit(1.0);
5049
}
@@ -74,14 +73,10 @@ namespace o2
7473
for (int k = 0; k < nSig; k++){
7574
auto part = genMap[mTag]();
7675
if(part.GetPdgCode() == 23) {
77-
if(!mDecayZ0) {
78-
mParticles.push_back(part);
79-
} else {
80-
auto daughters = decayZ0(part);
81-
for (auto &dau : daughters)
82-
{
83-
mParticles.push_back(dau);
84-
}
76+
auto daughters = decayZ0(part);
77+
for (auto &dau : daughters)
78+
{
79+
mParticles.push_back(dau);
8580
}
8681
} else {
8782
mParticles.push_back(part);
@@ -95,7 +90,6 @@ namespace o2
9590
unsigned short int mNSig = 0; // Number of particles to generate
9691
unsigned int mNUE = 0; // Number of tracks in the Underlying event
9792
unsigned short int mTag = 1; // Tag to select the generation function
98-
bool mDecayZ0 = false; // Whether to decay Z0 with Pythia8
9993
std::unique_ptr<Pythia8::Pythia> mPythia; // Pythia8 instance for particle decays not present in the physics list of Geant4 (like Z0)
10094
const std::vector<std::shared_ptr<o2::eventgen::Generator>>* mGenList = nullptr; // Cached generators list
10195
std::map<unsigned short int, std::function<TParticle()>> genMap;
@@ -317,10 +311,22 @@ namespace o2
317311
std::vector<TParticle> decayZ0(TParticle &z0)
318312
{
319313
std::vector<TParticle> subparts;
320-
// Start a Pythia8 event with Z0
321-
mPythia->next();
322-
// Find the Z0 and its final products
323314
auto &event = mPythia->event;
315+
// Reset event record for new decay
316+
event.reset();
317+
// Add the Z0 particle to the event record
318+
// Arguments: id, status, mother1, mother2, daughter1, daughter2,
319+
// col, acol, px, py, pz, e, m, scale, pol
320+
// Status code: 91 = incoming particles (needed for proper decay handling)
321+
int iZ0 = event.append(23, 91, 0, 0, 0, 0, 0, 0,
322+
z0.Px(), z0.Py(), z0.Pz(), z0.Energy(), z0.GetMass());
323+
// Set production vertex
324+
event[iZ0].vProd(z0.Vx(), z0.Vy(), z0.Vz(), 0.0);
325+
// Forcing decay by calling hadron level function
326+
if (!mPythia->forceHadronLevel())
327+
{
328+
cout << "Warning: Z0 decay failed!" << endl;
329+
}
324330
for (int j = 0; j < event.size(); ++j)
325331
{
326332
const Pythia8::Particle &p = event[j];
@@ -343,39 +349,34 @@ namespace o2
343349
iZ0 = event[iZ0].daughter1();
344350
}
345351
// Recursively collect all final-state descendants
346-
std::function<void(int)> collectFinalState = [&](int idx)
352+
std::function<void(int)> collectAllDescendants = [&](int idx)
347353
{
348354
const Pythia8::Particle &particle = event[idx];
349-
350-
if (particle.isFinal())
355+
subparts.push_back(TParticle(particle.id(), particle.status(),
356+
-1, -1, -1, -1,
357+
particle.px(), particle.py(),
358+
particle.pz(), particle.e(),
359+
p.xProd(), p.yProd(), p.zProd(), p.tProd()));
360+
subparts.back().SetStatusCode(o2::mcgenstatus::MCGenStatusEncoding(particle.status(), 0).fullEncoding);
361+
subparts.back().SetUniqueID(mGenID + 1);
362+
subparts.back().SetBit(ParticleStatus::kToBeDone,
363+
o2::mcgenstatus::getHepMCStatusCode(subparts.back().GetStatusCode()) == 1);
364+
// Not final-state, recurse through daughters
365+
if (!particle.isFinal())
351366
{
352-
subparts.push_back(TParticle(particle.id(), particle.status(),
353-
-1, -1, -1, -1,
354-
particle.px(), particle.py(),
355-
particle.pz(), particle.e(),
356-
p.xProd() + z0.Vx(), p.yProd() + z0.Vy(), p.zProd() + z0.Vz(), 0.0));
357-
subparts.back().SetStatusCode(o2::mcgenstatus::MCGenStatusEncoding(particle.status(), 0).fullEncoding);
358-
subparts.back().SetUniqueID(mGenID+1);
359-
subparts.back().SetBit(ParticleStatus::kToBeDone,
360-
o2::mcgenstatus::getHepMCStatusCode(subparts.back().GetStatusCode()) == 1);
361-
}
362-
else
363-
{
364-
// Not final-state, recurse through daughters
365367
int d1 = particle.daughter1();
366368
int d2 = particle.daughter2();
367369
if (d1 > 0)
368370
{
369371
for (int k = d1; k <= d2; ++k)
370372
{
371-
collectFinalState(k);
373+
collectAllDescendants(k);
372374
}
373375
}
374376
}
375377
};
376-
377378
// Start collecting from the final Z0
378-
collectFinalState(iZ0);
379+
collectAllDescendants(iZ0);
379380
break; // Found and processed the Z0
380381
}
381382
}
@@ -390,8 +391,8 @@ namespace o2
390391
// fraction == -1 enables the fixed number of signal particles per event (nsig)
391392
// tag selects the generator type to be used
392393
FairGenerator *
393-
Generator_Performance(const float fraction = 0.03f, const unsigned short int nsig = 100, unsigned short int tag = 1, bool setDecayZ0 = false)
394+
Generator_Performance(const float fraction = 0.03f, const unsigned short int nsig = 100, unsigned short int tag = 1)
394395
{
395-
auto generator = new o2::eventgen::GenPerf(fraction, nsig, tag, setDecayZ0);
396+
auto generator = new o2::eventgen::GenPerf(fraction, nsig, tag);
396397
return generator;
397398
}

‎MC/config/common/ini/GeneratorPerformanceFix.ini‎

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,8 @@
11
# Test performance generator for multidimensional studies using fix number of signal particles per event
22
# Parameters are in order: fraction of signal particles, fixed number of signal particles per event, tag to select the generator type
3-
# and flag to decay or not Z0 (Pythia8 instance used - false by default)
4-
# fraction = -1 enables the fixed number of signal particles per event (nsig)
3+
# Setting fraction = -1 enables the fixed number of signal particles per event (nsig).
4+
# An hybrid configuration JSON file is provided in ${O2DPG_MC_CONFIG_ROOT}/MC/config/common/external/generator/perfConf.json to run the generator
5+
# in fraction based mode
56
[GeneratorExternal]
67
fileName = ${O2DPG_MC_CONFIG_ROOT}/MC/config/common/external/generator/performanceGenerator.C
78
funcName = Generator_Performance(-1, 100, 1)

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