+++ /dev/null
-/**************************************************************************
- * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
- * *
- * Author: The ALICE Off-line Project. *
- * Contributors are mentioned in the code where appropriate. *
- * *
- * Permission to use, copy, modify and distribute this software and its *
- * documentation strictly for non-commercial purposes is hereby granted *
- * without fee, provided that the above copyright notice appears in all *
- * copies and that both the copyright notice and this permission notice *
- * appear in the supporting documentation. The authors make no claims *
- * about the suitability of this software for any purpose. It is *
- * provided "as is" without express or implied warranty. *
- **************************************************************************/
-
-// _________________________________________________________________
-//
-// Begin_Html
-// <h2> AliTPCSpaceCharge class </h2>
-// The class calculates the space point distortions due to a rotational
-// symmetric space charge distribution with the TPC drift volume.
-// <p>
-// The class uses the PoissonRelaxation2D to calculate the resulting
-// electrical field inhomogeneities in the (r,z)-plane. Then, the
-// Langevin-integral formalism is used to calculate the space point distortions.
-// <p>
-// The class assumes, that the distortions scales linearly with the magnitude
-// of the space charge distribution $\rho(r,z)$. The in here assumed distribution is
-// $$\rho(r,z) = \frac{(A-B\,z)}{r^2} $$ wherein the factors A and B scale with the
-// event multiplicity and the interaction rate.
-// <p>
-// The scaling factor can be set via the function SetCorrectionFactor. An example of
-// the shape of the distortions is given below.
-//
-// MI modification - 22.05.2013
-// As an optional input the Space charge histogram RZ is used in case it is provided
-// - using the SetInputSpaceCharge function
-//
-// End_Html
-//
-// Begin_Macro(source)
-// {
-// gROOT->SetStyle("Plain"); gStyle->SetPalette(1);
-// TCanvas *c2 = new TCanvas("cAliTPCSpaceCharge","cAliTPCSpaceCharge",500,300);
-// AliTPCSpaceCharge sc;
-// sc.SetOmegaTauT1T2(-0.32,1,1); // B=0.5 Tesla
-// sc.SetCorrectionFactor(0.0015);
-// sc.CreateHistoDRinZR(0.)->Draw("surf2");
-// return c2;
-// }
-// End_Macro
-//
-// Begin_Html
-// <p>
-// Date: 23/08/2010 <br>
-// Authors: Jim Thomas, Stefan Rossegger
-// End_Html
-// _________________________________________________________________
-
-
-
-#include "AliMagF.h"
-#include "TGeoGlobalMagField.h"
-#include "AliTPCcalibDB.h"
-#include "AliTPCParam.h"
-#include "AliLog.h"
-#include "TMatrixD.h"
-#include "TH2.h"
-
-#include "TMath.h"
-#include "AliTPCROC.h"
-#include "AliTPCSpaceCharge.h"
-
-ClassImp(AliTPCSpaceCharge)
-
-AliTPCSpaceCharge::AliTPCSpaceCharge()
- : AliTPCCorrection("SpaceCharge2D","Space Charge 2D"),
- fC0(0.),fC1(0.),fCorrectionFactor(0.001),fSpaceChargeHistogram(0),
- fInitLookUp(kFALSE)
-{
- //
- // default constructor
- //
-
-}
-
-AliTPCSpaceCharge::~AliTPCSpaceCharge() {
- //
- // default destructor
- //
-}
-
-
-
-void AliTPCSpaceCharge::Init() {
- //
- // Initialization funtion
- //
-
- AliMagF* magF= (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
- if (!magF) AliError("Magneticd field - not initialized");
- Double_t bzField = magF->SolenoidField()/10.; //field in T
- AliTPCParam *param= AliTPCcalibDB::Instance()->GetParameters();
- if (!param) AliError("Parameters - not initialized");
- Double_t vdrift = param->GetDriftV()/1000000.; // [cm/us] // From dataBase: to be updated: per second (ideally)
- Double_t ezField = 400; // [V/cm] // to be updated: never (hopefully)
- Double_t wt = -10.0 * (bzField*10) * vdrift / ezField ;
- // Correction Terms for effective omegaTau; obtained by a laser calibration run
- SetOmegaTauT1T2(wt,fT1,fT2);
-
- InitSpaceChargeDistortion(); // fill the look up table
-}
-
-void AliTPCSpaceCharge::Update(const TTimeStamp &/*timeStamp*/) {
- //
- // Update function
- //
- AliMagF* magF= (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
- if (!magF) AliError("Magneticd field - not initialized");
- Double_t bzField = magF->SolenoidField()/10.; //field in T
- AliTPCParam *param= AliTPCcalibDB::Instance()->GetParameters();
- if (!param) AliError("Parameters - not initialized");
- Double_t vdrift = param->GetDriftV()/1000000.; // [cm/us] // From dataBase: to be updated: per second (ideally)
- Double_t ezField = 400; // [V/cm] // to be updated: never (hopefully)
- Double_t wt = -10.0 * (bzField*10) * vdrift / ezField ;
- // Correction Terms for effective omegaTau; obtained by a laser calibration run
- SetOmegaTauT1T2(wt,fT1,fT2);
-
- // SetCorrectionFactor(1.); // should come from some database
-
-}
-
-
-
-void AliTPCSpaceCharge::GetCorrection(const Float_t x[],const Short_t roc,Float_t dx[]) {
- //
- // Calculates the correction due the Space Charge effect within the TPC drift volume
- //
-
- if (!fInitLookUp) {
- AliInfo("Lookup table was not initialized! Perform the inizialisation now ...");
- InitSpaceChargeDistortion();
- }
- Int_t order = 1 ; // FIXME: hardcoded? Linear interpolation = 1, Quadratic = 2
-
- Double_t intEr, intEphi, intdEz;
- Double_t r, phi, z ;
- Int_t sign;
-
- r = TMath::Sqrt( x[0]*x[0] + x[1]*x[1] ) ;
- phi = TMath::ATan2(x[1],x[0]) ;
- if ( phi < 0 ) phi += TMath::TwoPi() ; // Table uses phi from 0 to 2*Pi
- z = x[2] ; // Create temporary copy of x[2]
-
- if ( (roc%36) < 18 ) {
- sign = 1; // (TPC A side)
- } else {
- sign = -1; // (TPC C side)
- }
-
- if ( sign==1 && z < fgkZOffSet ) z = fgkZOffSet; // Protect against discontinuity at CE
- if ( sign==-1 && z > -fgkZOffSet ) z = -fgkZOffSet; // Protect against discontinuity at CE
-
-
- if ( (sign==1 && z<0) || (sign==-1 && z>0) ) // just a consistency check
- AliError("ROC number does not correspond to z coordinate! Calculation of distortions is most likely wrong!");
-
- // Efield is symmetric in phi - 2D calculation
- intEphi = 0.0;
- // Get the E field integrals
- Interpolate2DEdistortion( order, r, z, fLookUpErOverEz, intEr );
- // Get DeltaEz field integral
- Interpolate2DEdistortion( order, r, z, fLookUpDeltaEz, intdEz );
-
-
- // Calculate distorted position
- if ( r > 0.0 ) {
- phi = phi + fCorrectionFactor *( fC0*intEphi - fC1*intEr ) / r;
- r = r + fCorrectionFactor *( fC0*intEr + fC1*intEphi );
- }
- Double_t dz = intdEz*fCorrectionFactor;
-
- // Calculate correction in cartesian coordinates
- dx[0] = - (r * TMath::Cos(phi) - x[0]);
- dx[1] = - (r * TMath::Sin(phi) - x[1]);
- dx[2] = - dz; // z distortion - (internally scaled with driftvelocity dependency
- // on the Ez field
-
-}
-
-void AliTPCSpaceCharge::InitSpaceChargeDistortion() {
- //
- // Initialization of the Lookup table which contains the solutions of the
- // poisson problem
- //
-
- const Float_t gridSizeR = (fgkOFCRadius-fgkIFCRadius) / (kRows-1) ;
- const Float_t gridSizeZ = fgkTPCZ0 / (kColumns-1) ;
-
- TMatrixD voltArray(kRows,kColumns); // dummy boundary vectors
- TMatrixD chargeDensity(kRows,kColumns); // charge
- TMatrixD arrayErOverEz(kRows,kColumns); // solution in Er
- TMatrixD arrayDeltaEz(kRows,kColumns); // solution in Ez
-
- Double_t rList[kRows], zedList[kColumns] ;
-
- // Fill arrays with initial conditions. V on the boundary and ChargeDensity in the volume.
- for ( Int_t j = 0 ; j < kColumns ; j++ ) {
- Double_t zed = j*gridSizeZ ;
- zedList[j] = zed ;
- for ( Int_t i = 0 ; i < kRows ; i++ ) {
- Double_t radius = fgkIFCRadius + i*gridSizeR ;
- rList[i] = radius ;
- voltArray(i,j) = 0; // Initialize voltArray to zero - not used in this class
- chargeDensity(i,j) = 0; // Initialize ChargeDensity to zero
- }
- }
-
- // Fill the initial conditions
- for ( Int_t j = 1 ; j < kColumns-1 ; j++ ) {
- Double_t zed = j*gridSizeZ ;
- for ( Int_t i = 1 ; i < kRows-1 ; i++ ) {
- Double_t radius = fgkIFCRadius + i*gridSizeR ;
-
- Double_t zterm = (fgkTPCZ0-zed) * (fgkOFCRadius*fgkOFCRadius - fgkIFCRadius*fgkIFCRadius) / fgkTPCZ0 ;
- // for 1/R**2 charge density in the TPC; then integrated in Z due to drifting ions
- chargeDensity(i,j) = zterm / ( TMath::Log(fgkOFCRadius/fgkIFCRadius) * ( radius*radius ) ) ;
- }
- }
- // Fill the initial space charge in case histogram exist
- if (fSpaceChargeHistogram){
- for ( Int_t j = 1 ; j < kColumns-1 ; j++ ) {
- Double_t zed = j*gridSizeZ ;
- for ( Int_t i = 1 ; i < kRows-1 ; i++ ) {
- Double_t radius = fgkIFCRadius + i*gridSizeR ;
-
- Double_t zterm = (fgkTPCZ0-zed) * (fgkOFCRadius*fgkOFCRadius - fgkIFCRadius*fgkIFCRadius) / fgkTPCZ0 ;
- // for 1/R**2 charge density in the TPC; then integrated in Z due to drifting ions
- chargeDensity(i,j) = fSpaceChargeHistogram->Interpolate(radius,zed);
- }
- }
- }
-
-
- // Solve the electrosatic problem in 2D
-
- PoissonRelaxation2D( voltArray, chargeDensity, arrayErOverEz, arrayDeltaEz, kRows, kColumns, kIterations ) ;
-
- //Interpolate results onto standard grid for Electric Fields
- Int_t ilow=0, jlow=0 ;
- Double_t z,r;
- Float_t saveEr[2], saveEz[2] ;
- for ( Int_t i = 0 ; i < kNZ ; ++i ) {
- z = TMath::Abs( fgkZList[i] ) ; // assume symmetric behaviour on A and C side
- for ( Int_t j = 0 ; j < kNR ; ++j ) {
-
- // Linear interpolation !!
- r = fgkRList[j] ;
- Search( kRows, rList, r, ilow ) ; // Note switch - R in rows and Z in columns
- Search( kColumns, zedList, z, jlow ) ;
- if ( ilow < 0 ) ilow = 0 ; // check if out of range
- if ( jlow < 0 ) jlow = 0 ;
- if ( ilow + 1 >= kRows - 1 ) ilow = kRows - 2 ;
- if ( jlow + 1 >= kColumns - 1 ) jlow = kColumns - 2 ;
-
- saveEr[0] = arrayErOverEz(ilow,jlow) +
- (arrayErOverEz(ilow,jlow+1)-arrayErOverEz(ilow,jlow))*(z-zedList[jlow])/gridSizeZ ;
- saveEr[1] = arrayErOverEz(ilow+1,jlow) +
- (arrayErOverEz(ilow+1,jlow+1)-arrayErOverEz(ilow+1,jlow))*(z-zedList[jlow])/gridSizeZ ;
- saveEz[0] = arrayDeltaEz(ilow,jlow) +
- (arrayDeltaEz(ilow,jlow+1)-arrayDeltaEz(ilow,jlow))*(z-zedList[jlow])/gridSizeZ ;
- saveEz[1] = arrayDeltaEz(ilow+1,jlow) +
- (arrayDeltaEz(ilow+1,jlow+1)-arrayDeltaEz(ilow+1,jlow))*(z-zedList[jlow])/gridSizeZ ;
-
-
- fLookUpErOverEz[i][j] = saveEr[0] + (saveEr[1]-saveEr[0])*(r-rList[ilow])/gridSizeR ;
- fLookUpDeltaEz[i][j] = saveEz[0] + (saveEz[1]-saveEz[0])*(r-rList[ilow])/gridSizeR ;
-
- if (fgkZList[i]<0) fLookUpDeltaEz[i][j] *= -1; // C side is negative z
- }
- }
-
- fInitLookUp = kTRUE;
-
-}
-
-void AliTPCSpaceCharge::Print(const Option_t* option) const {
- //
- // Print function to check the settings of the boundary vectors
- // option=="a" prints the C0 and C1 coefficents for calibration purposes
- //
-
- TString opt = option; opt.ToLower();
- printf("%s\n",GetTitle());
- printf(" - Space Charge effects assuming a radial symmetric z over r^2 SC-distribution.\n");
- printf(" SC correction factor: %f \n",fCorrectionFactor);
-
- if (opt.Contains("a")) { // Print all details
- printf(" - T1: %1.4f, T2: %1.4f \n",fT1,fT2);
- printf(" - C1: %1.4f, C0: %1.4f \n",fC1,fC0);
- }
-
- if (!fInitLookUp) AliError("Lookup table was not initialized! You should do InitSpaceChargeDistortion() ...");
-
-}
git://git.uio.no / u / mrichter / AliRoot.git / blobdiff