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[u/mrichter/AliRoot.git] / TPC / AliTPCExBConical.cxx

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/// \class AliTPCExBConical
///
/// Calculates the space point distortions due to the conical shape of ALICE TPC.
///
/// Becasue of mechanical deformation ALICE TPC, chambers are misaligned in z direction
/// TPC has roughly conical shape
///
/// For the moment ONLY efective correction used - NOT EDGE EFFECT calcualted
///
/// The class allows "effective Omega Tau" corrections.
///
/// Example usage:
///
/// ~~~{.cxx}
/// AliTPCExBConical conical;
/// conical.SetOmegaTauT1T2(0.32,1.,1.); // values ideally from OCDB
/// conical.SetXConical(0.001);   // set conical in X direction (in rad)
/// // plot dRPhi distortions ...
/// conical.CreateHistoDRPhiinZR(1.,100,100)->Draw("surf2");
/// ~~~
///
/// \author Marian Ivanov, Jim Thomas, Magnus Mager, Stefan Rossegger
/// \date 02/05/2010

#include "AliMagF.h"
#include "TGeoGlobalMagField.h"
#include "AliTPCcalibDB.h"
#include "AliTPCParam.h"
#include "AliLog.h"

#include "TMath.h"
#include "AliTPCROC.h"
#include "AliTPCExBConical.h"
/// \cond CLASSIMP
ClassImp(AliTPCExBConical)
/// \endcond

AliTPCExBConical::AliTPCExBConical()
  : AliTPCCorrection("exb_conical","ExB conical"),
    fC1(0.),fC2(0.),fConicalFactor(0)
{
  //
  // default constructor
  //
  for (Int_t i=0; i<3; i++){
    fConicalA[i]= 0;  
    fConicalC[i]= 0;
  }
}

AliTPCExBConical::~AliTPCExBConical() {
  /// default destructor

}



void AliTPCExBConical::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);


}

void AliTPCExBConical::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);


}



void AliTPCExBConical::GetCorrection(const Float_t x[],const Short_t roc,Float_t dx[]) {
  /// Calculates the correction due conical shape

  AliTPCROC * calROC = AliTPCROC::Instance();
  const Double_t kRTPC0  =calROC->GetPadRowRadii(0,0);
  const Double_t kRTPC1  =calROC->GetPadRowRadii(36,calROC->GetNRows(36)-1);
  Float_t rmiddle=(kRTPC0+kRTPC1)/2.;
  //
  Double_t phi =TMath::ATan2(x[1],x[0]);
  Double_t r =TMath::Sqrt(x[1]*x[1]+x[0]*x[0]);
  Double_t dTheta=0;
  if (roc%36<18)  dTheta = fConicalA[0]+TMath::Cos(phi)*fConicalA[1]+TMath::Sin(phi)*fConicalA[2];
  if (roc%36>=18) {
    dTheta = fConicalC[0]+TMath::Cos(phi)*fConicalC[1]+TMath::Sin(phi)*fConicalC[2];
  }
  Double_t corr=dTheta*fConicalFactor;
  if (roc%36>=18) corr*=-1.;
  Double_t drphi=fC1*corr;
  Double_t dr   =fC2*corr;
  dx[0]= TMath::Cos(phi)*dr-TMath::Sin(phi)*drphi;
  dx[1]= TMath::Sin(phi)*dr+TMath::Cos(phi)*drphi;
  dx[2]= -0.001*dTheta*(r-rmiddle); // dtheta in mrad

}

void AliTPCExBConical::Print(const Option_t* option) const {
  /// Print function to check the settings (e.g. the conical in the X direction)
  /// option=="a" prints the C0 and C1 coefficents for calibration purposes

  TString opt = option; opt.ToLower();
  printf("%s:%s\n",GetTitle(), GetName());
  printf(" - T1: %1.4f, T2: %1.4f \n",fT1,fT2);  
  printf("Conical settings: Empirical: %1.5f mm/mrad\n",fConicalFactor);
  printf("Conical settings: A-Conical: %1.5f mrad:%1.5f mrad:%1.5f mrad \n",fConicalA[0],fConicalA[1],fConicalA[2]);
  printf("Conical settings: C-Conical: %1.5f mrad:%1.5f mrad:%1.5f mrad \n",fConicalC[0],fConicalC[1],fConicalC[2]);

}


void AliTPCExBConical::SetConicalA(Float_t conicalA[3]){
  /// set paramters of conical shape - A side - obtained from alignment

  fConicalA[0]= conicalA[0];  // constant
  fConicalA[1]= conicalA[1];  // cos 
  fConicalA[2]= conicalA[2];  // sin
}
void AliTPCExBConical::SetConicalC(Float_t conicalC[3]){
  /// set paramters of conical shape -C side obtained form the alignemnt

  fConicalC[0]= conicalC[0];  // constant
  fConicalC[1]= conicalC[1];  // cos 
  fConicalC[2]= conicalC[2];  // sin
}