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[ALICE3] adding trapezoidal disk option for FT3; fixing overlaps in FT3 and TOF #15158

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[ALICE3] adding trapezoidal disk option for FT3; fixing overlaps in FT3 and TOF #15158

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26e1d34
adding trapezoidal disk option for FT3; fixing overlaps in FT3 OT mod…
Mar 13, 2026
32420a7
Please consider the following formatting changes
alibuild Mar 13, 2026
adc5c98
Merge pull request #1 from alibuild/alibot-cleanup-15158
altsybee Mar 13, 2026
77de2ae
Merge branch 'dev' into dev
njacazio Mar 13, 2026
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18 changes: 7 additions & 11 deletions Detectors/Upgrades/ALICE3/FT3/base/include/FT3Base/FT3BaseParam.h
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Expand Up @@ -19,20 +19,16 @@ namespace o2
{
namespace ft3
{

// **
// ** Parameters for FT3 base configuration
// **

enum FT3Geometry {
Default = 0,
Telescope = 1
// Parameters for FT3 (ML and OT disks)
enum eFT3Layout {
kCylindrical = 0,
kTrapezoidal,
kSegmented,
};

struct FT3BaseParam : public o2::conf::ConfigurableParamHelper<FT3BaseParam> {
// Geometry Builder parameters

Int_t geoModel = FT3Geometry::Default;
eFT3Layout layoutFT3 = kSegmented;
int nTrapezoidalSegments = 32; // for the simple trapezoidal disks

// FT3Geometry::Telescope parameters
Int_t nLayers = 10;
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3 changes: 2 additions & 1 deletion Detectors/Upgrades/ALICE3/FT3/base/include/FT3Base/GeometryTGeo.h
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Expand Up @@ -94,6 +94,7 @@ class GeometryTGeo : public o2::itsmft::GeometryTGeo
static const char* getFT3LayerPattern() { return sLayerName.c_str(); }
static const char* getFT3ChipPattern() { return sChipName.c_str(); }
static const char* getFT3SensorPattern() { return sSensorName.c_str(); }
static const char* getFT3PassivePattern() { return sPassiveName.c_str(); }

static const char* composeSymNameFT3(Int_t d) { return Form("%s_%d", o2::detectors::DetID(o2::detectors::DetID::FT3).getName(), d); }
static const char* composeSymNameLayer(Int_t d, Int_t lr);
Expand All @@ -105,8 +106,8 @@ class GeometryTGeo : public o2::itsmft::GeometryTGeo
static std::string sVolumeName; ///< Mother volume name
static std::string sLayerName; ///< Layer name
static std::string sChipName; ///< Chip name

static std::string sSensorName; ///< Sensor name
static std::string sPassiveName; ///< Passive material name

private:
static std::unique_ptr<o2::ft3::GeometryTGeo> sInstance; ///< singletone instance
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3 changes: 2 additions & 1 deletion Detectors/Upgrades/ALICE3/FT3/base/src/GeometryTGeo.cxx
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Expand Up @@ -52,8 +52,9 @@ std::unique_ptr<o2::ft3::GeometryTGeo> GeometryTGeo::sInstance;
std::string GeometryTGeo::sVolumeName = "FT3V"; ///< Mother volume name
std::string GeometryTGeo::sInnerVolumeName = "FT3Inner"; ///< Mother inner volume name
std::string GeometryTGeo::sLayerName = "FT3Layer"; ///< Layer name
std::string GeometryTGeo::sChipName = "FT3Chip"; ///< Sensor name
std::string GeometryTGeo::sChipName = "FT3Chip"; ///< Chip name
std::string GeometryTGeo::sSensorName = "FT3Sensor"; ///< Sensor name
std::string GeometryTGeo::sPassiveName = "FT3Passive"; ///< Passive material name

//__________________________________________________________________________
GeometryTGeo::GeometryTGeo(bool build, int loadTrans) : o2::itsmft::GeometryTGeo(DetID::FT3)
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1 change: 1 addition & 0 deletions Detectors/Upgrades/ALICE3/FT3/simulation/include/FT3Simulation/FT3Layer.h
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Expand Up @@ -86,6 +86,7 @@ class FT3Layer : public TObject
Double_t mOuterRadius; ///< Outer radius of this layer
Double_t mZ; ///< Z position of the layer
Double_t mChipThickness; ///< Chip thickness
Double_t mSensorThickness; ///< Sensor thickness
Double_t mx2X0; ///< Layer material budget x/X0

ClassDefOverride(FT3Layer, 0); // ALICE 3 EndCaps geometry
Expand Down
16 changes: 1 addition & 15 deletions Detectors/Upgrades/ALICE3/FT3/simulation/src/Detector.cxx
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Expand Up @@ -356,21 +356,7 @@ Detector::Detector(bool active)
mTrackData(),
mHits(o2::utils::createSimVector<o2::itsmft::Hit>())
{

// FT3 Base configuration parameters
auto& ft3BaseParam = FT3BaseParam::Instance();

switch (ft3BaseParam.geoModel) {
case Default:
buildFT3ScopingV3(); // v3 Dec 25
break;
case Telescope:
buildBasicFT3(ft3BaseParam); // BasicFT3 = Parametrized telescopic detector (equidistant layers)
break;
default:
LOG(fatal) << "Invalid Geometry.\n";
break;
}
buildFT3ScopingV3(); // v3 Dec 25
}

//_________________________________________________________________________________________________
Expand Down
140 changes: 128 additions & 12 deletions Detectors/Upgrades/ALICE3/FT3/simulation/src/FT3Layer.cxx
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Expand Up @@ -16,22 +16,17 @@

#include "FT3Simulation/FT3Layer.h"
#include "FT3Base/GeometryTGeo.h"

#include <fairlogger/Logger.h> // for LOG
#include "FT3Base/FT3BaseParam.h"

#include <TGeoManager.h> // for TGeoManager, gGeoManager
#include <TGeoMatrix.h> // for TGeoCombiTrans, TGeoRotation, etc
#include <TGeoTube.h> // for TGeoTube, TGeoTubeSeg
#include <TGeoArb8.h> // for TGeoTrap
#include <TGeoVolume.h> // for TGeoVolume, TGeoVolumeAssembly
#include <TGeoCompositeShape.h> // for TGeoCompositeShape
#include "TMathBase.h" // for Abs
#include <TMath.h> // for Sin, RadToDeg, DegToRad, Cos, Tan, etc

#include <TGeoBBox.h>
#include <string>
#include <cstdio> // for snprintf
#include <cmath>

class TGeoMedium;

using namespace TMath;
Expand Down Expand Up @@ -68,6 +63,7 @@ FT3Layer::FT3Layer(Int_t layerDirection, Int_t layerNumber, std::string layerNam
mOuterRadius = rOut;
const double Si_X0 = 9.5;
mChipThickness = Layerx2X0 * Si_X0;
mSensorThickness = 0.005; // assume 50 microns of active thickness (for sensor volumes for trapezoidal disks)

// Sanity checks
if (std::isnan(mZ)) {
Expand Down Expand Up @@ -232,10 +228,130 @@ void FT3Layer::createSeparationLayer(TGeoVolume* motherVolume, const std::string

void FT3Layer::createLayer(TGeoVolume* motherVolume)
{
auto& ft3Params = FT3BaseParam::Instance();

if (mLayerNumber < 0) {
LOG(fatal) << "Invalid layer number " << mLayerNumber << " for FT3 layer.";
}
if (mIsMiddleLayer) { // ML disks

LOG(info) << "FT3: ft3Params.layoutFT3 = " << ft3Params.layoutFT3;

// ### options for ML and OT disk layout
if (ft3Params.layoutFT3 == kTrapezoidal || (mIsMiddleLayer && ft3Params.layoutFT3 == kSegmented)) {
// trapezoidal ML+OT disks
// (disks with TGeoTubes doesn'n work properly in ACTS, due to polar coordinates on TGeoTube sides)

// (!) Currently (March 12, 2026), only OT disks are segmented --> use Trapezoidal option for ML disks as a simplified segmentation
// To be changed to "true" paving with modules, as for the OT disks

std::string chipName = o2::ft3::GeometryTGeo::getFT3ChipPattern() + std::to_string(mLayerNumber);
std::string sensName = Form("%s_%d_%d", GeometryTGeo::getFT3SensorPattern(), mDirection, mLayerNumber);
std::string passiveName = o2::ft3::GeometryTGeo::getFT3PassivePattern() + std::to_string(mLayerNumber);

TGeoMedium* medSi = gGeoManager->GetMedium("FT3_SILICON$");
TGeoMedium* medAir = gGeoManager->GetMedium("FT3_AIR$");

TGeoTube* layer = new TGeoTube(mInnerRadius, mOuterRadius, mChipThickness / 2);
TGeoVolume* layerVol = new TGeoVolume(mLayerName.c_str(), layer, medAir);
layerVol->SetLineColor(kGray);

const int NtrapezoidalSegments = ft3Params.nTrapezoidalSegments;

const double dz = mChipThickness / 2;
const double dzSensor = mSensorThickness / 2;

const double dphi = 2.0 * TMath::Pi() / NtrapezoidalSegments;
double innerRadiusTrapezoidCorner = mInnerRadius / sin((TMath::Pi() - dphi) / 2); // to ensure that the trapezoid segments do not extend beyond the volume

const double rc = 0.5 * (innerRadiusTrapezoidCorner + mOuterRadius) * TMath::Cos(0.5 * dphi); // radius of tile center
const double h = 0.5 * (mOuterRadius - innerRadiusTrapezoidCorner) * TMath::Cos(0.5 * dphi); // half radial length

// chord lengths at inner/outer radii
const double bl = innerRadiusTrapezoidCorner * TMath::Sin(0.5 * dphi); // half lower base
const double tl = mOuterRadius * TMath::Sin(0.5 * dphi); // half upper base

// create trapezoids
for (int iTr = 0; iTr < NtrapezoidalSegments; ++iTr) {
// chip volume
auto trdShapeChip = new TGeoTrap(dz,
0.0, 0.0, // theta, phi
h, // h1
bl, // bl1
tl, // tl1
0.0, // alpha1
h, // h2
bl, // bl2
tl, // tl2
0.0); // alpha2
TGeoVolume* trapezoidChipVolume = new TGeoVolume(chipName.c_str(), trdShapeChip, medSi);
trapezoidChipVolume->SetLineColor(kCyan);
trapezoidChipVolume->SetTransparency(50);

// sensor volume
auto trdShapeSensor = new TGeoTrap(dzSensor,
0.0, 0.0, // theta, phi
h, // h1
bl, // bl1
tl, // tl1
0.0, // alpha1
h, // h2
bl, // bl2
tl, // tl2
0.0); // alpha2
TGeoVolume* trapezoidSensorVolume = new TGeoVolume(sensName.c_str(), trdShapeSensor, medSi);
trapezoidSensorVolume->SetLineColor(kYellow);

// placing sensor in chip:
const double zSensorInChip = (dz - dzSensor) * (mZ < 0 ? 1 : -1); // place sensor at the outer face of the chip, towards the incoming particles
TGeoCombiTrans* transSens = new TGeoCombiTrans();
transSens->SetTranslation(0, 0, zSensorInChip);
trapezoidChipVolume->AddNode(trapezoidSensorVolume, iTr, transSens);

// passive volume
auto trdShapePassive = new TGeoTrap(dz - dzSensor,
0.0, 0.0, // theta, phi
h, // h1
bl, // bl1
tl, // tl1
0.0, // alpha1
h, // h2
bl, // bl2
tl, // tl2
0.0); // alpha2
TGeoVolume* trapezoidPassiveVolume = new TGeoVolume(passiveName.c_str(), trdShapePassive, medSi);
trapezoidPassiveVolume->SetLineColor(kGray);

// placing passive volume in chip:
const double zPassiveInChip = (-dzSensor) * (mZ < 0 ? 1 : -1); // place passive volume at the outer face of the chip, towards the incoming particles
TGeoCombiTrans* transPassive = new TGeoCombiTrans();
transPassive->SetTranslation(0, 0, zPassiveInChip);
trapezoidChipVolume->AddNode(trapezoidPassiveVolume, iTr, transPassive);

// prepare placing of chip in layer:
const double phi_c = (iTr + 0.5) * dphi; // sector center
const double phi_deg = phi_c * 180.0 / TMath::Pi();

// center of tile
const double x = rc * TMath::Cos(phi_c);
const double y = rc * TMath::Sin(phi_c);
const double z = 0.0;

// local +Y should point radially outward
auto rot = new TGeoRotation();
rot->RotateZ(phi_deg - 90.0);
auto transf = new TGeoCombiTrans(x, y, z, rot);

layerVol->AddNode(trapezoidChipVolume, iTr, transf);
}

LOG(info) << "Inserting " << NtrapezoidalSegments << " trapezoidal segments (Rmin="
<< mInnerRadius << ", Rmax=" << mOuterRadius << ", z = " << mZ << "cm) inside " << layerVol->GetName();

auto* diskRotation = new TGeoRotation("TrapezoidalDiskRotation", 0, 0, 0);
auto* diskCombiTrans = new TGeoCombiTrans(0, 0, mZ, diskRotation);
motherVolume->AddNode(layerVol, 1, diskCombiTrans);
} else if (ft3Params.layoutFT3 == kCylindrical) {
// cylindrical ML+OT disks

std::string chipName = o2::ft3::GeometryTGeo::getFT3ChipPattern() + std::to_string(mLayerNumber),
sensName = Form("%s_%d_%d", GeometryTGeo::getFT3SensorPattern(), mDirection, mLayerNumber);
Expand Down Expand Up @@ -265,9 +381,7 @@ void FT3Layer::createLayer(TGeoVolume* motherVolume)

LOG(info) << "Inserting " << layerVol->GetName() << " inside " << motherVolume->GetName();
motherVolume->AddNode(layerVol, 1, FwdDiskCombiTrans);

} else { // OT disks

} else if (ft3Params.layoutFT3 == kSegmented) {
FT3Module module;

// layer structure
Expand All @@ -276,7 +390,7 @@ void FT3Layer::createLayer(TGeoVolume* motherVolume)
std::string separationLayerName = "FT3SeparationLayer" + std::to_string(mDirection) + std::to_string(mLayerNumber);

TGeoMedium* medAir = gGeoManager->GetMedium("FT3_AIR$");
TGeoTube* layer = new TGeoTube(mInnerRadius, mOuterRadius, 10 * mChipThickness / 2);
TGeoTube* layer = new TGeoTube(mInnerRadius, mOuterRadius, 12 * mChipThickness / 2); // additional "thickness factor" is to avoid sub-volumes crossing the mother layer
TGeoVolume* layerVol = new TGeoVolume(mLayerName.c_str(), layer, medAir);
layerVol->SetLineColor(kYellow + 2);

Expand All @@ -293,5 +407,7 @@ void FT3Layer::createLayer(TGeoVolume* motherVolume)

LOG(info) << "Inserting " << layerVol->GetName() << " inside " << motherVolume->GetName();
motherVolume->AddNode(layerVol, 1, FwdDiskCombiTrans);
} else {
LOG(fatal) << "Unknown FT3 layout option: " << static_cast<int>(ft3Params.layoutFT3);
}
}
10 changes: 5 additions & 5 deletions Detectors/Upgrades/ALICE3/IOTOF/simulation/src/Detector.cxx
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Expand Up @@ -96,10 +96,10 @@ void Detector::configLayers(bool itof, bool otof, bool ftof, bool btof, std::str
}
if (itof) { // iTOF
const std::string name = GeometryTGeo::getITOFLayerPattern();
const int nStaves = itofSegmented ? 24 : 0; // number of staves in segmented case
const double staveWidth = itofSegmented ? 5.42 : 0.0; // cm
const double staveTiltAngle = itofSegmented ? 10.0 : 0.0; // degrees
const int modulesPerStave = itofSegmented ? 10 : 0; // number of modules per stave in segmented case
const int nStaves = itofSegmented ? 24 : 0; // number of staves in segmented case
const double staveWidth = itofSegmented ? 5.42 : 0.0; // cm
const double staveTiltAngle = itofSegmented ? 3.0 : 0.0; // degrees
const int modulesPerStave = itofSegmented ? 10 : 0; // number of modules per stave in segmented case
mITOFLayer = ITOFLayer(name,
dInnerTof.first, 0.f, dInnerTof.second, 0.f, x2x0, ITOFLayer::kBarrelSegmented,
nStaves, staveWidth, staveTiltAngle, modulesPerStave);
Expand All @@ -108,7 +108,7 @@ void Detector::configLayers(bool itof, bool otof, bool ftof, bool btof, std::str
const std::string name = GeometryTGeo::getOTOFLayerPattern();
const int nStaves = otofSegmented ? 62 : 0; // number of staves in segmented case
const double staveWidth = otofSegmented ? 9.74 : 0.0; // cm
const double staveTiltAngle = otofSegmented ? 5.0 : 0.0; // degrees
const double staveTiltAngle = otofSegmented ? 3.0 : 0.0; // degrees
const int modulesPerStave = otofSegmented ? 54 : 0; // number of modules per stave in segmented case
mOTOFLayer = OTOFLayer(name,
dOuterTof.first, 0.f, dOuterTof.second, 0.f, x2x0, OTOFLayer::kBarrelSegmented,
Expand Down
16 changes: 11 additions & 5 deletions Detectors/Upgrades/ALICE3/IOTOF/simulation/src/Layer.cxx
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Expand Up @@ -155,14 +155,17 @@ void ITOFLayer::createLayer(TGeoVolume* motherVolume)
case kBarrelSegmented: {
// First we create the volume for the whole layer, which will be used as mother volume for the segments
const double avgRadius = 0.5 * (mInnerRadius + mOuterRadius);
const double staveSizeX = mStaves.second; // cm
const double staveSizeY = mOuterRadius - mInnerRadius; // cm
const double staveSizeZ = mZLength; // cm
const double deltaForTilt = 0.5 * (std::sin(TMath::DegToRad() * mTiltAngle) * staveSizeX + std::cos(TMath::DegToRad() * mTiltAngle) * staveSizeY); // we increase the size of the layer to account for the tilt of the staves
const double staveSizeX = mStaves.second; // cm
const double staveSizeY = mOuterRadius - mInnerRadius; // cm
const double staveSizeZ = mZLength; // cm
const double rMargin = 0.2; // cm, a small margin to avoid layer extrusion by sub-volumes
const double deltaForTilt = rMargin + 0.5 * (std::sin(TMath::DegToRad() * mTiltAngle) * staveSizeX + std::cos(TMath::DegToRad() * mTiltAngle) * staveSizeY); // we increase the size of the layer to account for the tilt of the staves
TGeoTube* layer = new TGeoTube(mInnerRadius - deltaForTilt, mOuterRadius + deltaForTilt, mZLength / 2);
TGeoVolume* layerVol = new TGeoVolume(mLayerName.c_str(), layer, medAir);
setLayerStyle(layerVol);

LOGP(info, "iTOF kBarrelSegmented layout: stave tilt angle {}, layer tube rMin {}, rMax {}", mTiltAngle, mInnerRadius - deltaForTilt, mOuterRadius + deltaForTilt);

// Now we create the volume for a single stave
TGeoBBox* stave = new TGeoBBox(staveSizeX * 0.5, staveSizeY * 0.5, staveSizeZ * 0.5);
TGeoVolume* staveVol = new TGeoVolume(staveName, stave, medAir);
Expand Down Expand Up @@ -287,10 +290,13 @@ void OTOFLayer::createLayer(TGeoVolume* motherVolume)
case kBarrelSegmented: {
// First we create the volume for the whole layer, which will be used as mother volume for the segments
const double avgRadius = 0.5 * (mInnerRadius + mOuterRadius);
TGeoTube* layer = new TGeoTube(mInnerRadius, mOuterRadius, mZLength / 2);
const double rMargin = 0.8; // cm, a small margin to avoid layer extrusion by sub-volumes
TGeoTube* layer = new TGeoTube(mInnerRadius - rMargin, mOuterRadius + rMargin, mZLength / 2);
TGeoVolume* layerVol = new TGeoVolume(mLayerName.c_str(), layer, medAir);
setLayerStyle(layerVol);

LOGP(info, "oTOF kBarrelSegmented layout: stave tilt angle {}, layer tube rMin {}, rMax {}", mTiltAngle, mInnerRadius - rMargin, mOuterRadius + rMargin);

// Now we create the volume for a single stave
const double staveSizeX = mStaves.second; // cm
const double staveSizeY = mOuterRadius - mInnerRadius; // cm
Expand Down
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