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ALICE3-TRK: several fixes in the digitization code #14733

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Merged
mconcas merged 5 commits into from
Oct 13, 2025
Merged

ALICE3-TRK: several fixes in the digitization code #14733

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ce53c4e
ALICE3-TRK: deal with ML/OT L4 mixed lenght and shape
atriolo Oct 13, 2025
3e9ba85
ALICE3-TRK: adjust ML/OT staves length according to the current geometry
atriolo Oct 13, 2025
350c0c8
ALICE3-TRK: increase number of steps into silicon to 25. Setting temp…
atriolo Oct 13, 2025
8d2d373
ALICE3-TRK: fix digits distribution along columns by removing the res…
atriolo Oct 13, 2025
309a5c9
ALICE3-TRK: considering the OT half-stave as the smallest elemenent f…
atriolo Oct 13, 2025
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70 changes: 46 additions & 24 deletions Detectors/Upgrades/ALICE3/TRK/base/include/TRKBase/SegmentationChip.h
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Original file line number Diff line number Diff line change
Expand Up @@ -35,18 +35,18 @@ class SegmentationChip
// The "detector coordinate system" refers to the hit position in row,col inside the sensor
// This class provides the transformations from the local and detector coordinate systems
// The conversion between global and local coordinate systems is operated by the transformation matrices
// For the curved VD layers there exist three coordinate systems and one is transient.
// For the curved VD layers there exist four coordinate systems.
// 1. The global (curved) coordinate system. The chip's center of coordinate system is
// defined at the the mid-point of the detector.
// 2. The local (flat) coordinate system. This is the tube segment projected onto a flat
// surface. In the projection we implicitly assume that the inner and outer
// stretch does not depend on the radius.
// 3. The detector coordinate system. Defined by the row and column segmentation
// defined at the upper edge in the flat coord.
// 2. The local (curved) coordinate system, centered in 0,0,0.
// 3. The local (flat) coordinate system. This is the tube segment projected onto a flat
// surface, centered in the middle of the chip, with the y axis pointing towards the interaction point.
// In the projection we implicitly assume that the inner and outer stretch does not depend on the radius.
// 4. The detector coordinate system. Defined by the row and column segmentation.
// For the flat ML and OT layers, there exist two coordinate systems:
// 1. The global (flat) coordinate system. The chip's center of coordinate system is
// defined at the the mid-point of the detector.
// 2. The detector coordinate system. Defined by the row and column segmentation
// 2. The detector coordinate system. Defined by the row and column segmentation.
// TODO: add segmentation for VD disks

public:
Expand Down Expand Up @@ -121,15 +121,20 @@ class SegmentationChip
pitchCol = PitchColMLOT;
maxWidth = constants::ML::width;
maxLength = constants::ML::length;
} else if (subDetID == 1 && layer >= 4) { // OT
} else if (subDetID == 1 && layer == 4) { // ML/OT (mixed layer, length = ML but staggered as OT)
pitchRow = PitchRowMLOT;
pitchCol = PitchColMLOT;
maxWidth = constants::OT::width;
maxLength = constants::OT::length;
maxWidth = constants::OT::halfstave::width;
maxLength = constants::ML::length;
} else if (subDetID == 1 && layer > 4) { // OT
pitchRow = PitchRowMLOT;
pitchCol = PitchColMLOT;
maxWidth = constants::OT::halfstave::width;
maxLength = constants::OT::halfstave::length;
}
// convert to row/col
iRow = static_cast<int>(std::floor((maxWidth / 2 - xRow) / pitchRow));
iCol = static_cast<int>(std::floor((zCol + maxLength / 2) / pitchCol));
iRow = static_cast<int>(((maxWidth / 2 - xRow) / pitchRow));
iCol = static_cast<int>(((zCol + maxLength / 2) / pitchCol));
};

// Check local coordinates (cm) validity.
Expand All @@ -143,9 +148,12 @@ class SegmentationChip
} else if (subDetID == 1 && layer <= 3) { // ML
maxWidth = constants::ML::width;
maxLength = constants::ML::length;
} else if (subDetID == 1 && layer >= 4) { // OT
maxWidth = constants::OT::width;
maxLength = constants::OT::length;
} else if (subDetID == 1 && layer == 4) { // ML/OT (mixed layer, length = ML but staggered as OT)
maxWidth = constants::OT::halfstave::width;
maxLength = constants::ML::length;
} else if (subDetID == 1 && layer > 4) { // OT
maxWidth = constants::OT::halfstave::width;
maxLength = constants::OT::halfstave::length;
}
return (-maxWidth / 2 < x && x < maxWidth / 2 && -maxLength / 2 < z && z < maxLength / 2);
}
Expand All @@ -162,9 +170,12 @@ class SegmentationChip
} else if (subDetID == 1 && layer <= 3) { // ML
nRows = constants::ML::nRows;
nCols = constants::ML::nCols;
} else if (subDetID == 1 && layer >= 4) { // OT
nRows = constants::OT::nRows;
nCols = constants::OT::nCols;
} else if (subDetID == 1 && layer == 4) { // ML/OT (mixed layer, length = ML but staggered as OT)
nRows = constants::OT::halfstave::nRows;
nCols = constants::ML::nCols;
} else if (subDetID == 1 && layer > 4) { // OT
nRows = constants::OT::halfstave::nRows;
nCols = constants::OT::halfstave::nCols;
}
return (row >= 0 && row < static_cast<float>(nRows) && col >= 0 && col < static_cast<float>(nCols));
}
Expand Down Expand Up @@ -210,9 +221,12 @@ class SegmentationChip
} else if (subDetID == 1 && layer <= 3) { // ML
xRow = 0.5 * (constants::ML::width - PitchRowMLOT) - (row * PitchRowMLOT);
zCol = col * PitchRowMLOT + 0.5 * (PitchRowMLOT - constants::ML::length);
} else if (subDetID == 1 && layer >= 4) { // OT
xRow = 0.5 * (constants::OT::width - PitchRowMLOT) - (row * PitchRowMLOT);
zCol = col * PitchColMLOT + 0.5 * (PitchColMLOT - constants::OT::length);
} else if (subDetID == 1 && layer == 4) { // ML/OT (mixed layer, length = ML but staggered as OT)
xRow = 0.5 * (constants::OT::halfstave::width - PitchRowMLOT) - (row * PitchRowMLOT);
zCol = col * PitchRowMLOT + 0.5 * (PitchRowMLOT - constants::ML::length);
} else if (subDetID == 1 && layer > 4) { // OT
xRow = 0.5 * (constants::OT::halfstave::width - PitchRowMLOT) - (row * PitchRowMLOT);
zCol = col * PitchColMLOT + 0.5 * (PitchColMLOT - constants::OT::halfstave::length);
}
}

Expand Down Expand Up @@ -263,17 +277,25 @@ class SegmentationChip
}

/// Print segmentation info
static const void Print() noexcept
static void Print() noexcept
{
LOG(info) << "Number of rows:\nVD L0: " << constants::VD::petal::layer::nRows[0]
<< "\nVD L1: " << constants::VD::petal::layer::nRows[1]
<< "\nVD L2: " << constants::VD::petal::layer::nRows[2]
<< "\nML stave: " << constants::ML::nRows
<< "\nOT stave: " << constants::OT::nRows;
<< "\nOT half stave: " << constants::OT::halfstave::nRows;

LOG(info) << "Number of cols:\nVD: " << constants::VD::petal::layer::nCols
<< "\nML stave: " << constants::ML::nCols
<< "\nOT stave: " << constants::OT::nCols;
<< "\nOT half stave: " << constants::OT::halfstave::nCols;

LOG(info) << "Pitch rows [cm]:\nVD: " << PitchRowVD
<< "\nML stave: " << PitchRowMLOT
<< "\nOT stave: " << PitchRowMLOT;

LOG(info) << "Pitch cols [cm]:\nVD: " << PitchColVD
<< "\nML stave: " << PitchColMLOT
<< "\nOT stave: " << PitchColMLOT;
}
};

Expand Down
19 changes: 14 additions & 5 deletions Detectors/Upgrades/ALICE3/TRK/base/include/TRKBase/Specs.h
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Expand Up @@ -102,16 +102,25 @@ constexpr int nCols{static_cast<int>(length / chip::pitchZ)};

namespace ML
{
constexpr double width{constants::moduleMLOT::width * 1}; // width of the stave
constexpr double length{constants::moduleMLOT::length * 10}; // length of the stave
constexpr double width{constants::moduleMLOT::width * 1}; // width of the stave
// constexpr double length{constants::moduleMLOT::length * 10}; // length of the stave
constexpr double length{124 * cm}; // length of the stave, hardcoded to fit the implemented geometry
constexpr int nRows{static_cast<int>(width / constants::moduleMLOT::chip::pitchX)}; // number of rows in the stave
constexpr int nCols{static_cast<int>(length / constants::moduleMLOT::chip::pitchZ)}; // number of columns in the stave
} // namespace ML

namespace OT
{ //// TODO: add shorter lenght of the stave of L4
constexpr double width{moduleMLOT::width * 2}; // width of the stave
constexpr double length{moduleMLOT::length * 20}; // length of the stave
{
namespace halfstave
{
constexpr double width{moduleMLOT::width * 1}; // width of the half stave
// constexpr double length{moduleMLOT::length * 20}; // length of the halfstave
constexpr double length{258 * cm}; // length of the halfstave, hardcoded to fit the implemented geometry
constexpr int nRows{static_cast<int>(width / moduleMLOT::chip::pitchX)}; // number of rows in the halfstave
constexpr int nCols{static_cast<int>(length / moduleMLOT::chip::pitchZ)}; // number of columns in the halfstave
} // namespace halfstave
constexpr double width{halfstave::width * 2}; // width of the stave
constexpr double length{halfstave::length}; // length of the stave
constexpr int nRows{static_cast<int>(width / moduleMLOT::chip::pitchX)}; // number of rows in the stave
constexpr int nCols{static_cast<int>(length / moduleMLOT::chip::pitchZ)}; // number of columns in the stave
} // namespace OT
Expand Down
6 changes: 3 additions & 3 deletions Detectors/Upgrades/ALICE3/TRK/simulation/include/TRKSimulation/DPLDigitizerParam.h
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Expand Up @@ -37,9 +37,9 @@ struct DPLDigitizerParam : public o2::conf::ConfigurableParamHelper<DPLDigitizer
float strobeQRiseTime0 = 450.; ///< q @ which strobe rise time is 0

double timeOffset = 0.; ///< time offset (in seconds!) to calculate ROFrame from hit time
int chargeThreshold = 150; ///< charge threshold in Nelectrons
int minChargeToAccount = 15; ///< minimum charge contribution to account
int nSimSteps = 18; ///< number of steps in response simulation
int chargeThreshold = 1; ///< charge threshold in Nelectrons
int minChargeToAccount = 1; ///< minimum charge contribution to account
int nSimSteps = 25; ///< number of steps in response simulation
float energyToNElectrons = 1. / 3.6e-9; // conversion of eloss to Nelectrons

float Vbb = 0.0; ///< back bias absolute value for MFT (in Volt)
Expand Down
6 changes: 3 additions & 3 deletions Detectors/Upgrades/ALICE3/TRK/simulation/include/TRKSimulation/DigiParams.h
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Expand Up @@ -109,9 +109,9 @@ class DigiParams
float mStrobeLength = 0; ///< length of the strobe in ns (sig. over threshold checked in this window only)
double mTimeOffset = -2 * infTime; ///< time offset (in seconds!) to calculate ROFrame from hit time
int mROFrameBiasInBC = 0; ///< misalignment of the ROF start in BC
int mChargeThreshold = 150; ///< charge threshold in Nelectrons
int mMinChargeToAccount = 15; ///< minimum charge contribution to account
int mNSimSteps = 18; ///< number of steps in response simulation
int mChargeThreshold = 1; ///< charge threshold in Nelectrons
int mMinChargeToAccount = 1; ///< minimum charge contribution to account
int mNSimSteps = 25; ///< number of steps in response simulation
float mNSimStepsInv = 0; ///< its inverse

float mEnergyToNElectrons = 1. / 3.6e-9; // conversion of eloss to Nelectrons
Expand Down
43 changes: 14 additions & 29 deletions Detectors/Upgrades/ALICE3/TRK/simulation/src/Digitizer.cxx
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Expand Up @@ -62,29 +62,29 @@ void Digitizer::init()

/// setting scale factors to adapt to the APTS response function (adjusting pitch and Y shift)
// TODO: adjust Y shift when the geometry is improved
LOG(debug) << " Depth max: " << mChipSimRespVD->getDepthMax();
LOG(debug) << " Depth min: " << mChipSimRespVD->getDepthMin();
LOG(info) << " Depth max VD: " << mChipSimRespVD->getDepthMax();
LOG(info) << " Depth min VD: " << mChipSimRespVD->getDepthMin();

LOG(info) << " Depth max MLOT: " << mChipSimRespMLOT->getDepthMax();
LOG(info) << " Depth min MLOT: " << mChipSimRespMLOT->getDepthMin();

float thicknessVD = 0.0095; // cm --- hardcoded based on geometry currently present
float thicknessMLOT = 0.1; // cm --- hardcoded based on geometry currently present

mSimRespVDScaleX = o2::trk::constants::apts::pitchX / o2::trk::SegmentationChip::PitchRowVD;
mSimRespVDScaleZ = o2::trk::constants::apts::pitchZ / o2::trk::SegmentationChip::PitchColVD;
mSimRespVDScaleDepth = o2::trk::constants::apts::thickness / (thicknessVD); /// introducing this scaling factor because the silicon thickness for the moment is 1 mm -> rescale to 45 um which is the depth of the APTS response
// mSimRespVDShift = mChipSimRespVD->getDepthMax() - thicknessVD * mSimRespVDScaleDepth / 2.f; // the shift should be done considering the rescaling done to adapt to the wrong silicon thickness. TODO: remove the scaling factor for the depth when the silicon thickness match the simulated response
mSimRespVDShift = mChipSimRespVD->getDepthMax(); // the curved, rescaled, sensors have a width from 0 to -45. Must add 10 um (= max depth) to match the APTS response.
mSimRespVDShift = -mChipSimRespVD->getDepthMax(); // the curved, rescaled, sensors have a width from 0 to -45. Must add 10 um (= max depth) to match the APTS response.
mSimRespMLOTScaleX = o2::trk::constants::apts::pitchX / o2::trk::SegmentationChip::PitchRowMLOT;
mSimRespMLOTScaleZ = o2::trk::constants::apts::pitchZ / o2::trk::SegmentationChip::PitchColMLOT;
mSimRespMLOTScaleDepth = o2::trk::constants::apts::thickness / (thicknessMLOT); /// introducing this scaling factor because the silicon thickness for the moment is 1 mm -> rescale to 45 um which is the depth of the APTS response
mSimRespMLOTShift = mChipSimRespMLOT->getDepthMax() - thicknessMLOT * mSimRespMLOTScaleDepth / 2.f; // the shift should be done considering the rescaling done to adapt to the wrong silicon thickness. TODO: remove the scaling factor for the depth when the silicon thickness match the simulated response
mSimRespMLOTShift = mChipSimRespMLOT->getDepthMax() - thicknessMLOT / 2.f; // the shift should be done considering the rescaling done to adapt to the wrong silicon thickness. TODO: remove the scaling factor for the depth when the silicon thickness match the simulated response
mSimRespOrientation = false;

// importing the parameters from DPLDigitizerParam.h
auto& dOptTRK = DPLDigitizerParam<o2::detectors::DetID::TRK>::Instance();

LOGP(info, "TRK Digitizer is initialised.");
mParams.print();
LOGP(info, "VD shift = {} ; ML/OT shift = {} = {} - {}", mSimRespVDShift, mSimRespMLOTShift, mChipSimRespMLOT->getDepthMax(), thicknessMLOT * mSimRespMLOTScaleDepth / 2.f);
LOGP(info, "VD shift = {} ; ML/OT shift = {} = {} - {}", mSimRespVDShift, mSimRespMLOTShift, mChipSimRespMLOT->getDepthMax(), thicknessMLOT / 2.f);
LOGP(info, "VD pixel scale on x = {} ; z = {}", mSimRespVDScaleX, mSimRespVDScaleZ);
LOGP(info, "ML/OT pixel scale on x = {} ; z = {}", mSimRespMLOTScaleX, mSimRespMLOTScaleZ);
LOGP(info, "Response orientation: {}", mSimRespOrientation ? "flipped" : "normal");
Expand Down Expand Up @@ -115,8 +115,8 @@ void Digitizer::process(const std::vector<Hit>* hits, int evID, int srcID)
<< " cont.mode: " << isContinuous()
<< " Min/Max ROFrames " << mROFrameMin << "/" << mROFrameMax;

std::cout << "Printing segmentation info: " << std::endl;
SegmentationChip::Print();
// std::cout << "Printing segmentation info: " << std::endl;
// SegmentationChip::Print();

// // is there something to flush ?
if (mNewROFrame > mROFrameMin) {
Expand Down Expand Up @@ -335,13 +335,9 @@ void Digitizer::processHit(const o2::itsmft::Hit& hit, uint32_t& maxFr, int evID

//// adapting the depth (Y) of the chip to the APTS response maximum depth
LOG(debug) << "local original: startPos = " << xyzLocS << ", endPos = " << xyzLocE << std::endl;
if (subDetID == 0) {
xyzLocS.SetY(xyzLocS.Y() * mSimRespVDScaleDepth);
xyzLocE.SetY(xyzLocE.Y() * mSimRespVDScaleDepth);
} else {
xyzLocS.SetY(xyzLocS.Y() * mSimRespMLOTScaleDepth);
xyzLocE.SetY(xyzLocE.Y() * mSimRespMLOTScaleDepth);
}
xyzLocS.SetY(xyzLocS.Y());
xyzLocE.SetY(xyzLocE.Y());

LOG(debug) << "rescaled Y: startPos = " << xyzLocS << ", endPos = " << xyzLocE << std::endl;

math_utils::Vector3D<float> step(xyzLocE);
Expand Down Expand Up @@ -449,17 +445,6 @@ void Digitizer::processHit(const o2::itsmft::Hit& hit, uint32_t& maxFr, int evID
rspmat = resp->getResponse(mSimRespMLOTScaleX * (xyzLocS.X() - cRowPix), mSimRespMLOTScaleZ * (xyzLocS.Z() - cColPix), xyzLocS.Y(), flipRow, flipCol, rowMax, colMax);
}

float tempPitchX = 0, tempPitchZ = 0;
if (subDetID == 0) {
tempPitchX = Segmentation::PitchRowVD;
tempPitchZ = Segmentation::PitchColVD;
} else {
tempPitchX = Segmentation::PitchRowMLOT;
tempPitchZ = Segmentation::PitchColMLOT;
}
LOG(debug) << "X and Z inside pixel at start = " << (xyzLocS.X() - cRowPix) << " , " << (xyzLocS.Z() - cColPix) << ", rescaled: " << mSimRespMLOTScaleX * (xyzLocS.X() - cRowPix) << " , " << mSimRespMLOTScaleZ * (xyzLocS.Z() - cColPix);
LOG(debug) << "Hit inside pitch? X: " << ((xyzLocS.X() - cRowPix) < tempPitchX) << " Z: " << ((xyzLocS.Z() - cColPix) < tempPitchZ);

xyzLocS += step;

if (rspmat == nullptr) {
Expand All @@ -479,7 +464,7 @@ void Digitizer::processHit(const o2::itsmft::Hit& hit, uint32_t& maxFr, int evID
if (colDest < 0 || colDest >= colSpan) {
continue;
}
respMatrix[rowDest][colDest] += rspmat->getValue(irow, icol, mSimRespOrientation ? !flipRow : flipRow, flipCol);
respMatrix[rowDest][colDest] += rspmat->getValue(irow, icol, mSimRespOrientation ? !flipRow : flipRow, !flipCol);
}
}
}
Expand Down