* 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
-// _________________________________________________________________
+/// \class AliTPCSpaceCharge
+/// \brief The class calculates the space point distortions due to a rotational
+///
+/// symmetric space charge distribution with the TPC drift volume.
+///
+/// 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.
+///
+/// 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.
+///
+/// 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
+/// ![Picture from ROOT macro](AliTPCSpaceCharge_cxx_82e9c78.png)
+///
+/// \author Jim Thomas, Stefan Rossegger
+/// \date 23/08/2010
#include "AliTPCROC.h"
#include "AliTPCSpaceCharge.h"
+/// \cond CLASSIMP
ClassImp(AliTPCSpaceCharge)
+/// \endcond
AliTPCSpaceCharge::AliTPCSpaceCharge()
: AliTPCCorrection("SpaceCharge2D","Space Charge 2D"),
//
// default constructor
//
-
+
}
AliTPCSpaceCharge::~AliTPCSpaceCharge() {
- //
- // default destructor
- //
+ /// default destructor
+
}
void AliTPCSpaceCharge::Init() {
- //
- // Initialization funtion
- //
-
+ /// Initialization funtion
+
AliMagF* magF= (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
if (!magF) AliError("Magneticd field - not initialized");
Double_t bzField = magF->SolenoidField()/10.; //field in T
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 ;
+ Double_t wt = -10.0 * (bzField*10) * vdrift / ezField ;
// Correction Terms for effective omegaTau; obtained by a laser calibration run
SetOmegaTauT1T2(wt,fT1,fT2);
}
void AliTPCSpaceCharge::Update(const TTimeStamp &/*timeStamp*/) {
- //
- // Update function
- //
+ /// Update function
+
AliMagF* magF= (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
if (!magF) AliError("Magneticd field - not initialized");
Double_t bzField = magF->SolenoidField()/10.; //field in T
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 ;
+ Double_t wt = -10.0 * (bzField*10) * vdrift / ezField ;
// Correction Terms for effective omegaTau; obtained by a laser calibration run
SetOmegaTauT1T2(wt,fT1,fT2);
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
- //
+ /// 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
-
+ Int_t order = 1 ; // FIXME: hardcoded? Linear interpolation = 1, Quadratic = 2
+
Double_t intEr, intEphi, intdEz;
Double_t r, phi, z ;
Int_t sign;
} 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;
+ 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 );
+ 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
+ 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
- //
+ /// 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 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.
+
+ // 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 ;
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++ ) {
+ 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 ) ) ;
+ 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++ ) {
+ 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
+ // 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] ;
+ 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 ) {
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) +
+ 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) +
+ saveEr[1] = arrayErOverEz(ilow+1,jlow) +
(arrayErOverEz(ilow+1,jlow+1)-arrayErOverEz(ilow+1,jlow))*(z-zedList[jlow])/gridSizeZ ;
- saveEz[0] = arrayDeltaEz(ilow,jlow) +
+ saveEz[0] = arrayDeltaEz(ilow,jlow) +
(arrayDeltaEz(ilow,jlow+1)-arrayDeltaEz(ilow,jlow))*(z-zedList[jlow])/gridSizeZ ;
- saveEz[1] = arrayDeltaEz(ilow+1,jlow) +
+ 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
- //
+ /// 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());
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() ...");
}