/*
$Log$
+Revision 1.14 1999/11/02 17:15:54 fca
+Correct ansi scoping not accepted by HP compilers
+
+Revision 1.13 1999/11/02 17:14:51 fca
+Correct ansi scoping not accepted by HP compilers
+
+Revision 1.12 1999/11/02 16:35:56 fca
+New version of TRD introduced
+
+Revision 1.11 1999/11/01 20:41:51 fca
+Added protections against using the wrong version of FRAME
+
+Revision 1.10 1999/09/29 09:24:35 fca
+Introduction of the Copyright and cvs Log
+
*/
///////////////////////////////////////////////////////////////////////////////
// //
-// Transition Radiation Detector version 1 -- coarse simulation //
-// This version has two detector arms, leaving the space in front of the //
-// HMPID and PHOS empty //
+// Transition Radiation Detector version 2 -- slow simulator //
// //
//Begin_Html
/*
-<img src="picts/AliTRDv1Class.gif">
+<img src="picts/AliTRDfullClass.gif">
*/
//End_Html
// //
///////////////////////////////////////////////////////////////////////////////
#include <TMath.h>
-#include <TRandom.h>
#include <TVector.h>
+#include <TRandom.h>
#include "AliTRDv1.h"
+#include "AliTRDmatrix.h"
#include "AliRun.h"
#include "AliMC.h"
#include "AliConst.h"
-
+
ClassImp(AliTRDv1)
//_____________________________________________________________________________
:AliTRD(name, title)
{
//
- // Standard constructor for the Transition Radiation Detector version 1
+ // Standard constructor for Transition Radiation Detector version 2
//
- fIdSens = 0;
- fHitsOn = 0;
+ fIdSens = 0;
- fIdSpace1 = 0;
- fIdSpace2 = 0;
- fIdSpace3 = 0;
+ fIdChamber1 = 0;
+ fIdChamber2 = 0;
+ fIdChamber3 = 0;
- fIdChamber1 = 0;
- fIdChamber2 = 0;
- fIdChamber3 = 0;
+ fSensSelect = 0;
+ fSensPlane = 0;
+ fSensChamber = 0;
+ fSensSector = 0;
+
+ fGasGain = 0;
+ fNoise = 0;
+ fChipGain = 0;
+ fADCoutRange = 0;
+ fADCinRange = 0;
+ fADCthreshold = 0;
+
+ fDiffusionT = 0;
+ fDiffusionL = 0;
+
+ fClusMaxThresh = 0;
+ fClusSigThresh = 0;
+ fClusMethod = 0;
+
+ fDeltaE = NULL;
+
+ SetBufferSize(128000);
+
+}
+
+//_____________________________________________________________________________
+AliTRDv1::~AliTRDv1()
+{
+
+ if (fDeltaE) delete fDeltaE;
}
void AliTRDv1::CreateGeometry()
{
//
- // Create the GEANT geometry for the Transition Radiation Detector - Version 1
- // This version covers only part of the azimuth.
- //
- // Author: Christoph Blume (C.Blume@gsi.de) 20/07/99
+ // Create the GEANT geometry for the Transition Radiation Detector - Version 2
+ // This version covers the full azimuth.
//
- Float_t xpos, ypos, zpos;
-
// Check that FRAME is there otherwise we have no place where to put the TRD
AliModule* FRAME = gAlice->GetModule("FRAME");
if (!FRAME) return;
// Define the chambers
AliTRD::CreateGeometry();
- // Position the the TRD-sectors only in one TRD-volume in the spaceframe
- xpos = 0.;
- ypos = 0.;
- zpos = 0.;
- gMC->Gspos("TRD ",1,"BTR1",xpos,ypos,zpos,0,"ONLY");
-
}
//_____________________________________________________________________________
void AliTRDv1::CreateMaterials()
{
//
- // Create materials for the Transition Radiation Detector version 1
+ // Create materials for the Transition Radiation Detector version 2
//
AliTRD::CreateMaterials();
}
+//_____________________________________________________________________________
+void AliTRDv1::Diffusion(Float_t driftlength, Float_t *xyz)
+{
+ //
+ // Applies the diffusion smearing to the position of a single electron
+ //
+
+ if ((driftlength > 0) &&
+ (driftlength < kDrThick)) {
+ Float_t driftSqrt = TMath::Sqrt(driftlength);
+ Float_t sigmaT = driftSqrt * fDiffusionT;
+ Float_t sigmaL = driftSqrt * fDiffusionL;
+ xyz[0] = gRandom->Gaus(xyz[0], sigmaL);
+ xyz[1] = gRandom->Gaus(xyz[1], sigmaT);
+ xyz[2] = gRandom->Gaus(xyz[2], sigmaT);
+ }
+ else {
+ xyz[0] = 0.0;
+ xyz[1] = 0.0;
+ xyz[2] = 0.0;
+ }
+
+}
+
+//_____________________________________________________________________________
+void AliTRDv1::Hits2Digits()
+{
+ //
+ // Creates TRD digits from hits. This procedure includes the following:
+ // - Diffusion
+ // - Gas gain including fluctuations
+ // - Pad-response (simple Gaussian approximation)
+ // - Electronics noise
+ // - Electronics gain
+ // - Digitization
+ // - ADC threshold
+ // The corresponding parameter can be adjusted via the various Set-functions.
+ // If these parameters are not explicitly set, default values are used (see
+ // Init-function).
+ // To produce digits from a root-file with TRD-hits use the
+ // slowDigitsCreate.C macro.
+ //
+
+ printf("AliTRDv1::Hits2Digits -- Start creating digits\n");
+
+ ///////////////////////////////////////////////////////////////
+ // Parameter
+ ///////////////////////////////////////////////////////////////
+
+ // Converts number of electrons to fC
+ const Float_t el2fC = 1.602E-19 * 1.0E15;
+
+ ///////////////////////////////////////////////////////////////
+
+ Int_t nBytes = 0;
+
+ Int_t iRow;
+
+ AliTRDhit *TRDhit;
+
+ // Get the pointer to the hit tree
+ TTree *HitTree = gAlice->TreeH();
+ // Get the pointer to the digits tree
+ TTree *DigitsTree = gAlice->TreeD();
+
+ // Get the number of entries in the hit tree
+ // (Number of primary particles creating a hit somewhere)
+ Int_t nTrack = (Int_t) HitTree->GetEntries();
+
+ Int_t chamBeg = 0;
+ Int_t chamEnd = kNcham;
+ if (fSensChamber) chamEnd = chamBeg = fSensChamber;
+ Int_t planBeg = 0;
+ Int_t planEnd = kNplan;
+ if (fSensPlane) planEnd = planBeg = fSensPlane;
+ Int_t sectBeg = 0;
+ Int_t sectEnd = kNsect;
+ if (fSensSector) sectEnd = sectBeg = fSensSector;
+
+ // Loop through all the chambers
+ for (Int_t icham = chamBeg; icham < chamEnd; icham++) {
+ for (Int_t iplan = planBeg; iplan < planEnd; iplan++) {
+ for (Int_t isect = sectBeg; isect < sectEnd; isect++) {
+
+ Int_t nDigits = 0;
+
+ printf("AliTRDv1::Hits2Digits -- Digitizing chamber %d, plane %d, sector %d\n"
+ ,icham+1,iplan+1,isect+1);
+
+ // Create a detector matrix to keep the signal and track numbers
+ AliTRDmatrix *matrix = new AliTRDmatrix(fRowMax[iplan][icham][isect]
+ ,fColMax[iplan]
+ ,fTimeMax
+ ,isect+1,icham+1,iplan+1);
+
+ // Loop through all entries in the tree
+ for (Int_t iTrack = 0; iTrack < nTrack; iTrack++) {
+
+ gAlice->ResetHits();
+ nBytes += HitTree->GetEvent(iTrack);
+
+ // Get the number of hits in the TRD created by this particle
+ Int_t nHit = fHits->GetEntriesFast();
+
+ // Loop through the TRD hits
+ for (Int_t iHit = 0; iHit < nHit; iHit++) {
+
+ if (!(TRDhit = (AliTRDhit *) fHits->UncheckedAt(iHit)))
+ continue;
+
+ Float_t x = TRDhit->fX;
+ Float_t y = TRDhit->fY;
+ Float_t z = TRDhit->fZ;
+ Float_t q = TRDhit->fQ;
+ Int_t track = TRDhit->fTrack;
+ Int_t plane = TRDhit->fPlane;
+ Int_t sector = TRDhit->fSector;
+ Int_t chamber = TRDhit->fChamber;
+
+ if ((sector != isect+1) ||
+ (plane != iplan+1) ||
+ (chamber != icham+1))
+ continue;
+
+ // Rotate the sectors on top of each other
+ Float_t phi = 2.0 * kPI / (Float_t) kNsect
+ * ((Float_t) sector - 0.5);
+ Float_t xRot = -x * TMath::Cos(phi) + y * TMath::Sin(phi);
+ Float_t yRot = x * TMath::Sin(phi) + y * TMath::Cos(phi);
+ Float_t zRot = z;
+
+ // The hit position in pad coordinates (center pad)
+ // The pad row (z-direction)
+ Int_t rowH = (Int_t) ((zRot - fRow0[iplan][icham][isect]) / fRowPadSize);
+ // The pad column (rphi-direction)
+ Int_t colH = (Int_t) ((yRot - fCol0[iplan] ) / fColPadSize);
+ // The time bucket
+ Int_t timeH = (Int_t) ((xRot - fTime0[iplan] ) / fTimeBinSize);
+
+ // Array to sum up the signal in a box surrounding the
+ // hit postition
+ const Int_t timeBox = 5;
+ const Int_t colBox = 7;
+ const Int_t rowBox = 5;
+ Float_t signalSum[rowBox][colBox][timeBox];
+ for (iRow = 0; iRow < rowBox; iRow++ ) {
+ for (Int_t iCol = 0; iCol < colBox; iCol++ ) {
+ for (Int_t iTime = 0; iTime < timeBox; iTime++) {
+ signalSum[iRow][iCol][iTime] = 0;
+ }
+ }
+ }
+
+ // Loop over all electrons of this hit
+ Int_t nEl = (Int_t) q;
+ for (Int_t iEl = 0; iEl < nEl; iEl++) {
+
+ // Apply the diffusion smearing
+ Float_t driftlength = xRot - fTime0[iplan];
+ Float_t xyz[3];
+ xyz[0] = xRot;
+ xyz[1] = yRot;
+ xyz[2] = zRot;
+ Diffusion(driftlength,xyz);
+
+ // At this point absorption effects that depend on the
+ // driftlength could be taken into account.
+
+ // The electron position and the distance to the hit position
+ // in pad units
+ // The pad row (z-direction)
+ Int_t rowE = (Int_t) ((xyz[2] - fRow0[iplan][icham][isect]) / fRowPadSize);
+ Int_t rowD = rowH - rowE;
+ // The pad column (rphi-direction)
+ Int_t colE = (Int_t) ((xyz[1] - fCol0[iplan] ) / fColPadSize);
+ Int_t colD = colH - colE;
+ // The time bucket
+ Int_t timeE = (Int_t) ((xyz[0] - fTime0[iplan] ) / fTimeBinSize);
+ Int_t timeD = timeH - timeE;
+
+ // Apply the gas gain including fluctuations
+ Int_t signal = (Int_t) (-fGasGain * TMath::Log(gRandom->Rndm()));
+
+ // The distance of the electron to the center of the pad
+ // in units of pad width
+ Float_t dist = (xyz[1] - fCol0[iplan] - (colE + 0.5) * fColPadSize)
+ / fColPadSize;
+
+ // Sum up the signal in the different pixels
+ // and apply the pad response
+ Int_t rowIdx = rowD + (Int_t) ( rowBox / 2);
+ Int_t colIdx = colD + (Int_t) ( colBox / 2);
+ Int_t timeIdx = timeD + (Int_t) (timeBox / 2);
+ signalSum[rowIdx][colIdx-1][timeIdx] += PadResponse(dist-1.) * signal;
+ signalSum[rowIdx][colIdx ][timeIdx] += PadResponse(dist ) * signal;
+ signalSum[rowIdx][colIdx+1][timeIdx] += PadResponse(dist+1.) * signal;
+
+ }
+
+ // Add the padcluster to the detector matrix
+ for (iRow = 0; iRow < rowBox; iRow++ ) {
+ for (Int_t iCol = 0; iCol < colBox; iCol++ ) {
+ for (Int_t iTime = 0; iTime < timeBox; iTime++) {
+
+ Int_t rowB = rowH + iRow - (Int_t) ( rowBox / 2);
+ Int_t colB = colH + iCol - (Int_t) ( colBox / 2);
+ Int_t timeB = timeH + iTime - (Int_t) (timeBox / 2);
+
+ Float_t signalB = signalSum[iRow][iCol][iTime];
+ if (signalB > 0.0) {
+ matrix->AddSignal(rowB,colB,timeB,signalB);
+ if (!(matrix->AddTrack(rowB,colB,timeB,track)))
+ printf(" More than three tracks in a pixel!\n");
+ }
+
+ }
+ }
+ }
+
+ }
+
+ }
+
+ // Create the hits for this chamber
+ for (Int_t iRow = 0; iRow < fRowMax[iplan][icham][isect]; iRow++ ) {
+ for (Int_t iCol = 0; iCol < fColMax[iplan] ; iCol++ ) {
+ for (Int_t iTime = 0; iTime < fTimeMax ; iTime++) {
+
+ Float_t signalAmp = matrix->GetSignal(iRow,iCol,iTime);
+
+ // Add the noise
+ signalAmp = TMath::Max(gRandom->Gaus(signalAmp,fNoise),(Float_t) 0.0);
+ // Convert to fC
+ signalAmp *= el2fC;
+ // Convert to mV
+ signalAmp *= fChipGain;
+ // Convert to ADC counts
+ Int_t adc = (Int_t) (signalAmp * (fADCoutRange / fADCinRange));
+
+ // Apply threshold on ADC value
+ if (adc > fADCthreshold) {
+
+ Int_t trackSave[3];
+ for (Int_t ii = 0; ii < 3; ii++) {
+ trackSave[ii] = matrix->GetTrack(iRow,iCol,iTime,ii);
+ }
+
+ Int_t digits[7];
+ digits[0] = matrix->GetSector();
+ digits[1] = matrix->GetChamber();
+ digits[2] = matrix->GetPlane();
+ digits[3] = iRow;
+ digits[4] = iCol;
+ digits[5] = iTime;
+ digits[6] = adc;
+
+ // Add this digit to the TClonesArray
+ AddDigit(trackSave,digits);
+ nDigits++;
+
+ }
+
+ }
+ }
+ }
+
+ printf("AliTRDv1::Hits2Digits -- Number of digits found: %d\n",nDigits);
+
+ // Clean up
+ delete matrix;
+
+ }
+ }
+ }
+
+ // Fill the digits-tree
+ printf("AliTRDv1::Hits2Digits -- Fill the digits tree\n");
+ DigitsTree->Fill();
+
+}
+
+//_____________________________________________________________________________
+void AliTRDv1::Digits2Clusters()
+{
+
+ //
+ // Method to convert AliTRDdigits created by AliTRDv1::Hits2Digits()
+ // into AliTRDclusters
+ // To produce cluster from a root-file with TRD-digits use the
+ // slowClusterCreate.C macro.
+ //
+
+ Int_t row;
+
+ printf("AliTRDv1::Digits2Clusters -- Start creating clusters\n");
+
+ AliTRDdigit *TRDdigit;
+ TClonesArray *TRDDigits;
+
+ // Parameters
+ Float_t maxThresh = fClusMaxThresh; // threshold value for maximum
+ Float_t signalThresh = fClusSigThresh; // threshold value for digit signal
+ Int_t clusteringMethod = fClusMethod; // clustering method option (for testing)
+
+ const Float_t epsilon = 0.01; // iteration limit for unfolding procedure
+
+ // Get the pointer to the digits tree
+ TTree *DigitTree = gAlice->TreeD();
+ // Get the pointer to the cluster tree
+ TTree *ClusterTree = gAlice->TreeD();
+
+ // Get the pointer to the digits container
+ TRDDigits = Digits();
+
+ Int_t chamBeg = 0;
+ Int_t chamEnd = kNcham;
+ if (fSensChamber) chamEnd = chamBeg = fSensChamber;
+ Int_t planBeg = 0;
+ Int_t planEnd = kNplan;
+ if (fSensPlane) planEnd = planBeg = fSensPlane;
+ Int_t sectBeg = 0;
+ Int_t sectEnd = kNsect;
+ if (fSensSector) sectEnd = sectBeg = fSensSector;
+
+ // Import the digit tree
+ gAlice->ResetDigits();
+ Int_t nbytes=0;
+ nbytes += DigitTree->GetEvent(1);
+
+ // Get the number of digits in the detector
+ Int_t nTRDDigits = TRDDigits->GetEntriesFast();
+
+ // *** Start clustering *** in every chamber
+ for (Int_t icham = chamBeg; icham < chamEnd; icham++) {
+ for (Int_t iplan = planBeg; iplan < planEnd; iplan++) {
+ for (Int_t isect = sectBeg; isect < sectEnd; isect++) {
+
+ Int_t nClusters = 0;
+ printf("AliTRDv1::Digits2Clusters -- Finding clusters in chamber %d, plane %d, sector %d\n"
+ ,icham+1,iplan+1,isect+1);
+
+ // Create a detector matrix to keep maxima
+ AliTRDmatrix *digitMatrix = new AliTRDmatrix(fRowMax[iplan][icham][isect]
+ ,fColMax[iplan]
+ ,fTimeMax,isect+1
+ ,icham+1,iplan+1);
+ // Create a matrix to contain maximum flags
+ AliTRDmatrix *maximaMatrix = new AliTRDmatrix(fRowMax[iplan][icham][isect]
+ ,fColMax[iplan]
+ ,fTimeMax
+ ,isect+1,icham+1,iplan+1);
+
+ // Loop through all TRD digits
+ for (Int_t iTRDDigits = 0; iTRDDigits < nTRDDigits; iTRDDigits++) {
+
+ // Get the information for this digit
+ TRDdigit = (AliTRDdigit*) TRDDigits->UncheckedAt(iTRDDigits);
+ Int_t signal = TRDdigit->fSignal;
+ Int_t sector = TRDdigit->fSector;
+ Int_t chamber = TRDdigit->fChamber;
+ Int_t plane = TRDdigit->fPlane;
+ Int_t row = TRDdigit->fRow;
+ Int_t col = TRDdigit->fCol;
+ Int_t time = TRDdigit->fTime;
+
+ Int_t track[3];
+ for (Int_t iTrack = 0; iTrack < 3; iTrack++) {
+ track[iTrack] = TRDdigit->AliDigit::fTracks[iTrack];
+ }
+
+ if ((sector != isect+1) ||
+ (plane != iplan+1) ||
+ (chamber != icham+1))
+ continue;
+
+ // Fill the detector matrix
+ if (signal > signalThresh) {
+ digitMatrix->SetSignal(row,col,time,signal);
+ for (Int_t iTrack = 0; iTrack < 3; iTrack++) {
+ if (track[iTrack] > 0) {
+ digitMatrix->AddTrack(row,col,time,track[iTrack]);
+ }
+ }
+ }
+
+ }
+
+ // Loop chamber and find maxima in digitMatrix
+ for (row = 0; row < fRowMax[iplan][icham][isect]; row++) {
+ for (Int_t col = 1; col < fColMax[iplan] ; col++) {
+ for (Int_t time = 0; time < fTimeMax ; time++) {
+
+ if (digitMatrix->GetSignal(row,col,time)
+ < digitMatrix->GetSignal(row,col - 1,time)) {
+ // really maximum?
+ if (col > 1) {
+ if (digitMatrix->GetSignal(row,col - 2,time)
+ < digitMatrix->GetSignal(row,col - 1,time)) {
+ // yes, so set maximum flag
+ maximaMatrix->SetSignal(row,col - 1,time,1);
+ }
+ else maximaMatrix->SetSignal(row,col - 1,time,0);
+ }
+ }
+
+ } // time
+ } // col
+ } // row
+
+ // now check maxima and calculate cluster position
+ for (row = 0; row < fRowMax[iplan][icham][isect]; row++) {
+ for (Int_t col = 1; col < fColMax[iplan] ; col++) {
+ for (Int_t time = 0; time < fTimeMax ; time++) {
+
+ if ((maximaMatrix->GetSignal(row,col,time) > 0)
+ && (digitMatrix->GetSignal(row,col,time) > maxThresh)) {
+
+ Int_t clusters[5] = {0}; // cluster-object data
+
+ Float_t ratio = 0; // ratio resulting from unfolding
+ Float_t padSignal[5] = {0}; // signals on max and neighbouring pads
+ Float_t clusterSignal[3] = {0}; // signals from cluster
+ Float_t clusterPos[3] = {0}; // cluster in ALICE refFrame coords
+ Float_t clusterPads[6] = {0}; // cluster pad info
+
+ // setting values
+ clusters[0] = isect+1; // = isect ????
+ clusters[1] = icham+1; // = ichamber ????
+ clusters[2] = iplan+1; // = iplane ????
+ clusters[3] = time;
+
+ clusterPads[0] = icham+1;
+ clusterPads[1] = isect+1;
+ clusterPads[2] = iplan+1;
+
+ for (Int_t iPad = 0; iPad < 3; iPad++) {
+ clusterSignal[iPad] = digitMatrix->GetSignal(row,col-1+iPad,time);
+ }
+
+ // neighbouring maximum on right side?
+ if (col < fColMax[iplan] - 2) {
+ if (maximaMatrix->GetSignal(row,col + 2,time) > 0) {
+ for (Int_t iPad = 0; iPad < 5; iPad++) {
+ padSignal[iPad] = digitMatrix->GetSignal(row,col-1+iPad,time);
+ }
+
+ // unfold:
+ ratio = Unfold(epsilon, padSignal);
+
+ // set signal on overlapping pad to ratio
+ clusterSignal[2] *= ratio;
+ }
+ }
+
+ switch (clusteringMethod) {
+ case 1:
+ // method 1: simply center of mass
+ clusterPads[3] = row + 0.5;
+ clusterPads[4] = col - 0.5 + (clusterSignal[2] - clusterSignal[0]) /
+ (clusterSignal[1] + clusterSignal[2] + clusterSignal[3]);
+ clusterPads[5] = time + 0.5;
+
+ nClusters++;
+ break;
+ case 2:
+ // method 2: integral gauss fit on 3 pads
+ TH1F *hPadCharges = new TH1F("hPadCharges", "Charges on center 3 pads"
+ , 5, -1.5, 3.5);
+ for (Int_t iCol = -1; iCol <= 3; iCol++) {
+ if (clusterSignal[iCol] < 1) clusterSignal[iCol] = 1;
+ hPadCharges->Fill(iCol, clusterSignal[iCol]);
+ }
+ hPadCharges->Fit("gaus", "IQ", "SAME", -0.5, 2.5);
+ TF1 *fPadChargeFit = hPadCharges->GetFunction("gaus");
+ Double_t colMean = fPadChargeFit->GetParameter(1);
+
+ clusterPads[3] = row + 0.5;
+ clusterPads[4] = col - 1.5 + colMean;
+ clusterPads[5] = time + 0.5;
+
+ delete hPadCharges;
+
+ nClusters++;
+ break;
+ }
+
+ Float_t clusterCharge = clusterSignal[0]
+ + clusterSignal[1]
+ + clusterSignal[2];
+ clusters[4] = (Int_t)clusterCharge;
+
+ Int_t trackSave[3];
+ for (Int_t iTrack = 0; iTrack < 3; iTrack++) {
+ trackSave[iTrack] = digitMatrix->GetTrack(row,col,time,iTrack);
+ }
+
+ // Calculate cluster position in ALICE refFrame coords
+ // and set array clusterPos to calculated values
+ Pads2XYZ(clusterPads, clusterPos);
+
+ // Add cluster to reconstruction tree
+ AddCluster(trackSave,clusters,clusterPos);
+
+ }
+
+ } // time
+ } // col
+ } // row
+
+ printf("AliTRDv1::Digits2Clusters -- Number of clusters found: %d\n",nClusters);
+
+ delete digitMatrix;
+ delete maximaMatrix;
+
+ } // isect
+ } // iplan
+ } // icham
+
+ // Fill the cluster-tree
+ printf("AliTRDv1::Digits2Clusters -- Total number of clusters found: %d\n"
+ ,fClusters->GetEntries());
+ printf("AliTRDv1::Digits2Clusters -- Fill the cluster tree\n");
+ ClusterTree->Fill();
+
+}
+
//_____________________________________________________________________________
void AliTRDv1::Init()
{
//
- // Initialise the Transition Radiation Detector after the geometry is built
+ // Initialise Transition Radiation Detector after geometry has been built.
+ // Includes the default settings of all parameter for the digitization.
//
AliTRD::Init();
- for (Int_t i = 0; i < 80; i++) printf("*");
- printf("\n");
-
- // Identifier of the sensitive volume (amplification region)
- fIdSens = gMC->VolId("UL06");
+ printf(" Slow simulator\n");
+ if (fSensPlane)
+ printf(" Only plane %d is sensitive\n",fSensPlane);
+ if (fSensChamber)
+ printf(" Only chamber %d is sensitive\n",fSensChamber);
+ if (fSensSector)
+ printf(" Only sector %d is sensitive\n",fSensSector);
- // Identifier of the TRD-spaceframe volumina
- fIdSpace1 = gMC->VolId("B028");
- fIdSpace2 = gMC->VolId("B029");
- fIdSpace3 = gMC->VolId("B030");
+ // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
+ const Float_t kPoti = 12.1;
+ // Maximum energy (50 keV);
+ const Float_t kEend = 50000.0;
+ // Ermilova distribution for the delta-ray spectrum
+ Float_t Poti = TMath::Log(kPoti);
+ Float_t Eend = TMath::Log(kEend);
+ fDeltaE = new TF1("deltae",Ermilova,Poti,Eend,0);
+
+ // Identifier of the sensitive volume (drift region)
+ fIdSens = gMC->VolId("UL05");
// Identifier of the TRD-driftchambers
fIdChamber1 = gMC->VolId("UCIO");
fIdChamber2 = gMC->VolId("UCIM");
fIdChamber3 = gMC->VolId("UCII");
+ // The default parameter for the digitization
+ if (!(fGasGain)) fGasGain = 2.0E3;
+ if (!(fNoise)) fNoise = 3000.;
+ if (!(fChipGain)) fChipGain = 10.;
+ if (!(fADCoutRange)) fADCoutRange = 255.;
+ if (!(fADCinRange)) fADCinRange = 2000.;
+ if (!(fADCthreshold)) fADCthreshold = 1;
+
+ // Transverse and longitudinal diffusion coefficients (Xe/Isobutane)
+ if (!(fDiffusionT)) fDiffusionT = 0.060;
+ if (!(fDiffusionL)) fDiffusionL = 0.017;
+
+ // The default parameter for the clustering
+ if (!(fClusMaxThresh)) fClusMaxThresh = 5.0;
+ if (!(fClusSigThresh)) fClusSigThresh = 2.0;
+ if (!(fClusMethod)) fClusMethod = 1;
+
+ for (Int_t i = 0; i < 80; i++) printf("*");
+ printf("\n");
+
}
//_____________________________________________________________________________
-void AliTRDv1::StepManager()
+Float_t AliTRDv1::PadResponse(Float_t x)
{
//
- // Procedure called at every step in the TRD
- // Fast simulator. If switched on, a hit is produced when a track
- // crosses the border between amplification region and pad plane.
+ // The pad response for the chevron pads.
+ // We use a simple Gaussian approximation which should be good
+ // enough for our purpose.
//
- Int_t vol[3];
- Int_t iIdSens, icSens;
- Int_t iIdSpace, icSpace;
- Int_t iIdChamber, icChamber;
+ // The parameters for the response function
+ const Float_t aa = 0.8872;
+ const Float_t bb = -0.00573;
+ const Float_t cc = 0.454;
+ const Float_t cc2 = cc*cc;
+
+ Float_t pr = aa * (bb + TMath::Exp(-x*x / (2. * cc2)));
- Int_t secMap1[10] = { 3, 7, 8, 9, 10, 11, 2, 1, 18, 17 };
- Int_t secMap2[ 5] = { 16, 15, 14, 13, 12 };
- Int_t secMap3[ 3] = { 5, 6, 4 };
+ return (pr);
+
+}
- Float_t hits[4];
+//_____________________________________________________________________________
+void AliTRDv1::SetSensPlane(Int_t iplane)
+{
+ //
+ // Defines the hit-sensitive plane (1-6)
+ //
- TLorentzVector p;
+ if ((iplane < 0) || (iplane > 6)) {
+ printf("Wrong input value: %d\n",iplane);
+ printf("Use standard setting\n");
+ fSensPlane = 0;
+ fSensSelect = 0;
+ return;
+ }
+
+ fSensSelect = 1;
+ fSensPlane = iplane;
+
+}
+
+//_____________________________________________________________________________
+void AliTRDv1::SetSensChamber(Int_t ichamber)
+{
+ //
+ // Defines the hit-sensitive chamber (1-5)
+ //
+
+ if ((ichamber < 0) || (ichamber > 5)) {
+ printf("Wrong input value: %d\n",ichamber);
+ printf("Use standard setting\n");
+ fSensChamber = 0;
+ fSensSelect = 0;
+ return;
+ }
+
+ fSensSelect = 1;
+ fSensChamber = ichamber;
+
+}
+
+//_____________________________________________________________________________
+void AliTRDv1::SetSensSector(Int_t isector)
+{
+ //
+ // Defines the hit-sensitive sector (1-18)
+ //
+
+ if ((isector < 0) || (isector > 18)) {
+ printf("Wrong input value: %d\n",isector);
+ printf("Use standard setting\n");
+ fSensSector = 0;
+ fSensSelect = 0;
+ return;
+ }
+
+ fSensSelect = 1;
+ fSensSector = isector;
+
+}
+
+//_____________________________________________________________________________
+void AliTRDv1::StepManager()
+{
+ //
+ // Called at every step in the Transition Radiation Detector version 2.
+ // Slow simulator. Every charged track produces electron cluster as hits
+ // along its path across the drift volume. The step size is set acording
+ // to Bethe-Bloch. The energy distribution of the delta electrons follows
+ // a spectrum taken from Ermilova et al.
+ //
+
+ Int_t iIdSens, icSens;
+ Int_t iIdSpace, icSpace;
+ Int_t iIdChamber, icChamber;
+ Int_t vol[3];
+ Int_t iPid;
+
+ Float_t hits[4];
+ Float_t random[1];
+ Float_t charge;
+ Float_t aMass;
+
+ Double_t pTot;
+ Double_t qTot;
+ Double_t eDelta;
+ Double_t betaGamma, pp;
+
+ TLorentzVector pos, mom;
TClonesArray &lhits = *fHits;
- // Writing out hits enabled?
- if (!(fHitsOn)) return;
+ const Double_t kBig = 1.0E+12;
+
+ // Ionization energy
+ const Float_t kWion = 22.04;
+ // Maximum energy for e+ e- g for the step-size calculation
+ const Float_t kPTotMax = 0.002;
+ // Plateau value of the energy-loss for electron in xenon
+ // taken from: Allison + Comb, Ann. Rev. Nucl. Sci. (1980), 30, 253
+ //const Double_t kPlateau = 1.70;
+ // the averaged value (26/3/99)
+ const Float_t kPlateau = 1.55;
+ // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
+ const Float_t kPrim = 48.0;
+ // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
+ const Float_t kPoti = 12.1;
+
+ // Set the maximum step size to a very large number for all
+ // neutral particles and those outside the driftvolume
+ gMC->SetMaxStep(kBig);
- // Use only charged tracks and count them only once per volume
- if (gMC->TrackCharge() &&
- gMC->IsTrackExiting()) {
-
- // Check on sensitive volume
+ // Use only charged tracks
+ if (( gMC->TrackCharge() ) &&
+ (!gMC->IsTrackStop() ) &&
+ (!gMC->IsTrackDisappeared())) {
+
+ // Inside a sensitive volume?
iIdSens = gMC->CurrentVolID(icSens);
if (iIdSens == fIdSens) {
- gMC->TrackPosition(p);
- for (Int_t i = 0; i < 3; i++) hits[i] = p[i];
- // No charge created
- hits[3] = 0;
-
iIdSpace = gMC->CurrentVolOffID(4,icSpace );
iIdChamber = gMC->CurrentVolOffID(1,icChamber);
+ // Calculate the energy of the delta-electrons
+ eDelta = TMath::Exp(fDeltaE->GetRandom()) - kPoti;
+ eDelta = TMath::Max(eDelta,0.0);
+
+ // The number of secondary electrons created
+ qTot = (Double_t) ((Int_t) (eDelta / kWion) + 1);
+
+ // The hit coordinates and charge
+ gMC->TrackPosition(pos);
+ hits[0] = pos[0];
+ hits[1] = pos[1];
+ hits[2] = pos[2];
+ hits[3] = qTot;
+
// The sector number
- if (iIdSpace == fIdSpace1)
- vol[0] = secMap1[icSpace-1];
- else if (iIdSpace == fIdSpace2)
- vol[0] = secMap2[icSpace-1];
- else if (iIdSpace == fIdSpace3)
- vol[0] = secMap3[icSpace-1];
+ Float_t phi = pos[1] != 0 ? TMath::Atan2(pos[0],pos[1]) : (pos[0] > 0 ? 180. : 0.);
+ vol[0] = ((Int_t) (phi / 20)) + 1;
// The chamber number
// 1: outer left
// The plane number
vol[2] = icChamber - TMath::Nint((Float_t) (icChamber / 7)) * 6;
- new(lhits[fNhits++]) AliTRDhit(fIshunt,gAlice->CurrentTrack(),vol,hits);
+ // Check on selected volumes
+ Int_t addthishit = 1;
+ if (fSensSelect) {
+ if ((fSensPlane) && (vol[2] != fSensPlane )) addthishit = 0;
+ if ((fSensChamber) && (vol[1] != fSensChamber)) addthishit = 0;
+ if ((fSensSector) && (vol[0] != fSensSector )) addthishit = 0;
+ }
+
+ // Add this hit
+ if (addthishit) {
+
+ new(lhits[fNhits++]) AliTRDhit(fIshunt,gAlice->CurrentTrack(),vol,hits);
+
+ // The energy loss according to Bethe Bloch
+ gMC->TrackMomentum(mom);
+ pTot = mom.Rho();
+ iPid = gMC->TrackPid();
+ if ( (iPid > 3) ||
+ ((iPid <= 3) && (pTot < kPTotMax))) {
+ aMass = gMC->TrackMass();
+ betaGamma = pTot / aMass;
+ pp = kPrim * BetheBloch(betaGamma);
+ // Take charge > 1 into account
+ charge = gMC->TrackCharge();
+ if (TMath::Abs(charge) > 1) pp = pp * charge*charge;
+ }
+ // Electrons above 20 Mev/c are at the plateau
+ else {
+ pp = kPrim * kPlateau;
+ }
+
+ // Calculate the maximum step size for the next tracking step
+ if (pp > 0) {
+ do
+ gMC->Rndm(random,1);
+ while ((random[0] == 1.) || (random[0] == 0.));
+ gMC->SetMaxStep( - TMath::Log(random[0]) / pp);
+ }
+
+ }
+ else {
+ // set step size to maximal value
+ gMC->SetMaxStep(kBig);
+ }
}
- }
+ }
+
+}
+
+//_____________________________________________________________________________
+Double_t AliTRDv1::BetheBloch(Double_t bg)
+{
+ //
+ // Parametrization of the Bethe-Bloch-curve
+ // The parametrization is the same as for the TPC and is taken from Lehrhaus.
+ //
+
+ // This parameters have been adjusted to averaged values from GEANT
+ const Double_t kP1 = 7.17960e-02;
+ const Double_t kP2 = 8.54196;
+ const Double_t kP3 = 1.38065e-06;
+ const Double_t kP4 = 5.30972;
+ const Double_t kP5 = 2.83798;
+
+ // This parameters have been adjusted to Xe-data found in:
+ // Allison & Cobb, Ann. Rev. Nucl. Sci. (1980), 30, 253
+ //const Double_t kP1 = 0.76176E-1;
+ //const Double_t kP2 = 10.632;
+ //const Double_t kP3 = 3.17983E-6;
+ //const Double_t kP4 = 1.8631;
+ //const Double_t kP5 = 1.9479;
+
+ if (bg > 0) {
+ Double_t yy = bg / TMath::Sqrt(1. + bg*bg);
+ Double_t aa = TMath::Power(yy,kP4);
+ Double_t bb = TMath::Power((1./bg),kP5);
+ bb = TMath::Log(kP3 + bb);
+ return ((kP2 - aa - bb)*kP1 / aa);
+ }
+ else
+ return 0;
+
+}
+
+//_____________________________________________________________________________
+Double_t Ermilova(Double_t *x, Double_t *)
+{
+ //
+ // Calculates the delta-ray energy distribution according to Ermilova.
+ // Logarithmic scale !
+ //
+
+ Double_t energy;
+ Double_t dpos;
+ Double_t dnde;
+
+ Int_t pos1, pos2;
+
+ const Int_t nV = 31;
+
+ Float_t vxe[nV] = { 2.3026, 2.9957, 3.4012, 3.6889, 3.9120
+ , 4.0943, 4.2485, 4.3820, 4.4998, 4.6052
+ , 4.7005, 5.0752, 5.2983, 5.7038, 5.9915
+ , 6.2146, 6.5221, 6.9078, 7.3132, 7.6009
+ , 8.0064, 8.5172, 8.6995, 8.9872, 9.2103
+ , 9.4727, 9.9035,10.3735,10.5966,10.8198
+ ,11.5129 };
+
+ Float_t vye[nV] = { 80.0 , 31.0 , 23.3 , 21.1 , 21.0
+ , 20.9 , 20.8 , 20.0 , 16.0 , 11.0
+ , 8.0 , 6.0 , 5.2 , 4.6 , 4.0
+ , 3.5 , 3.0 , 1.4 , 0.67 , 0.44
+ , 0.3 , 0.18 , 0.12 , 0.08 , 0.056
+ , 0.04 , 0.023, 0.015, 0.011, 0.01
+ , 0.004 };
+
+ energy = x[0];
+
+ // Find the position
+ pos1 = pos2 = 0;
+ dpos = 0;
+ do {
+ dpos = energy - vxe[pos2++];
+ }
+ while (dpos > 0);
+ pos2--;
+ if (pos2 > nV) pos2 = nV;
+ pos1 = pos2 - 1;
+
+ // Differentiate between the sampling points
+ dnde = (vye[pos1] - vye[pos2]) / (vxe[pos2] - vxe[pos1]);
+
+ return dnde;
+
+}
+
+//_____________________________________________________________________________
+void AliTRDv1::Pads2XYZ(Float_t *pads, Float_t *pos)
+{
+ // Method to convert pad coordinates (row,col,time)
+ // into ALICE reference frame coordinates (x,y,z)
+
+ Int_t chamber = (Int_t) pads[0]; // chamber info (1-5)
+ Int_t sector = (Int_t) pads[1]; // sector info (1-18)
+ Int_t plane = (Int_t) pads[2]; // plane info (1-6)
+
+ Int_t icham = chamber - 1; // chamber info (0-4)
+ Int_t isect = sector - 1; // sector info (0-17)
+ Int_t iplan = plane - 1; // plane info (0-5)
+
+ Float_t padRow = pads[3]; // Pad Row position
+ Float_t padCol = pads[4]; // Pad Column position
+ Float_t timeSlice = pads[5]; // Time "position"
+
+ // calculate (x,y) position in rotated chamber
+ Float_t yRot = fCol0[iplan] + padCol * fColPadSize;
+ Float_t xRot = fTime0[iplan] + timeSlice * fTimeBinSize;
+ // calculate z-position:
+ Float_t z = fRow0[iplan][icham][isect] + padRow * fRowPadSize;
+
+ /**
+ rotate chamber back to original position
+ 1. mirror at y-axis, 2. rotate back to position (-phi)
+ / cos(phi) -sin(phi) \ / -1 0 \ / -cos(phi) -sin(phi) \
+ \ sin(phi) cos(phi) / * \ 0 1 / = \ -sin(phi) cos(phi) /
+ **/
+ //Float_t phi = 2*kPI / kNsect * ((Float_t) sector - 0.5);
+ //Float_t x = -xRot * TMath::Cos(phi) - yRot * TMath::Sin(phi);
+ //Float_t y = -xRot * TMath::Sin(phi) + yRot * TMath::Cos(phi);
+ Float_t phi = 2*kPI / kNsect * ((Float_t) sector - 0.5);
+ Float_t x = -xRot * TMath::Cos(phi) + yRot * TMath::Sin(phi);
+ Float_t y = xRot * TMath::Sin(phi) + yRot * TMath::Cos(phi);
+
+ // Setting values
+ pos[0] = x;
+ pos[1] = y;
+ pos[2] = z;
+
+}
+
+//_____________________________________________________________________________
+Float_t AliTRDv1::Unfold(Float_t eps, Float_t* padSignal)
+{
+ // Method to unfold neighbouring maxima.
+ // The charge ratio on the overlapping pad is calculated
+ // until there is no more change within the range given by eps.
+ // The resulting ratio is then returned to the calling method.
+
+ Int_t itStep = 0; // count iteration steps
+
+ Float_t ratio = 0.5; // start value for ratio
+ Float_t prevRatio = 0; // store previous ratio
+
+ Float_t newLeftSignal[3] = {0}; // array to store left cluster signal
+ Float_t newRightSignal[3] = {0}; // array to store right cluster signal
+
+ // start iteration:
+ while ((TMath::Abs(prevRatio - ratio) > eps) && (itStep < 10)) {
+
+ itStep++;
+ prevRatio = ratio;
+
+ // cluster position according to charge ratio
+ Float_t maxLeft = (ratio*padSignal[2] - padSignal[0]) /
+ (padSignal[0] + padSignal[1] + ratio*padSignal[2]);
+ Float_t maxRight = (padSignal[4] - (1-ratio)*padSignal[2]) /
+ ((1-ratio)*padSignal[2] + padSignal[3] + padSignal[4]);
+
+ // set cluster charge ratio
+ Float_t ampLeft = padSignal[1];
+ Float_t ampRight = padSignal[3];
+
+ // apply pad response to parameters
+ newLeftSignal[0] = ampLeft*PadResponse(-1 - maxLeft);
+ newLeftSignal[1] = ampLeft*PadResponse( 0 - maxLeft);
+ newLeftSignal[2] = ampLeft*PadResponse( 1 - maxLeft);
+
+ newRightSignal[0] = ampRight*PadResponse(-1 - maxRight);
+ newRightSignal[1] = ampRight*PadResponse( 0 - maxRight);
+ newRightSignal[2] = ampRight*PadResponse( 1 - maxRight);
+
+ // calculate new overlapping ratio
+ ratio = newLeftSignal[2]/(newLeftSignal[2] + newRightSignal[0]);
+
+ }
+
+ return ratio;
}
+
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