Adding the macro to generate the file with space charge map.

Given file is later used to generate the Space charge correction class.

diff --git a/TPC/Upgrade/macros/makeSpaceChargeMap.C b/TPC/Upgrade/macros/makeSpaceChargeMap.C
new file mode 100644 (file)
index 0000000..c1146e6
--- /dev/null
+++ b/TPC/Upgrade/macros/makeSpaceChargeMap.C
@@ -0,0 +1,127 @@
+//
+// Origin: Christian Lippman, CERN, Christian.Lippmann@cern.ch
+//
+
+int makeSpaceChargeMap(Double_t multiplicity = 950., Double_t intRate = 5e4, Double_t eps = 10.,
+                      Double_t gasfactor = 1., string filename = "SpaceChargeMap.root") {
+  //
+  // Charge distribution is splitted into two (RZ and RPHI) in order to speed up
+  // the needed calculation time. It is dumped to 
+  //
+  // Explanation of variables:
+  // 1) multiplicity: charghed particle dn/deta for top 80% centrality (660 for 2011,
+  //    expect 950 for full energy)
+  // 2) intRate: Total interaction rate (e.g. 50kHz for the upgrade)
+  // 3) eps: Number of backdrifting ions per primary electron (0 for MWPC, e.g.10 for GEM)
+  // 4) gasfactor: Use different gas. E.g. Ar/CO2 has twice the primary ionization, ion drift
+  //    velocity factor 2.5 slower, so  gasfactor = 5.
+  //
+
+  TFile *f = new TFile(filename.c_str(), "RECREATE");
+  
+  // some grid, not too coarse
+  Int_t nr   = 350;
+  Int_t nphi = 180;
+  Int_t nz   = 500;
+
+  const Double_t fgkIFCRadius=  83.5;     // radius which renders the "18 rod manifold"
+  const Double_t fgkOFCRadius= 254.5;     // Mean Radius of the Outer Field Cage
+  const Double_t fgke0 = 8.854187817e-12; // vacuum permittivity [A·s/(V·m)]
+
+  Double_t dr = (fgkOFCRadius-fgkIFCRadius)/(nr+1);
+  Double_t dphi = TMath::TwoPi()/(nphi+1);
+  Double_t dz = 500./(nz+1);
+  Double_t safty = 0.; // due to a root bug which does not interpolate the boundary ..
+  // .. (first and last bin) correctly
+
+  // Charge distribution in ZR (rotational symmetric) ------------------
+
+  TH2F *histoZR = new TH2F("chargeZR", "chargeZR",
+                           nr, fgkIFCRadius-dr-safty, fgkOFCRadius+dr+safty,
+                           nz, -250-dz-safty, 250+dz+safty);
+ 
+  for (Int_t ir=1;ir<=nr;++ir) {
+    Double_t rp = histoZR->GetXaxis()->GetBinCenter(ir);
+    for (Int_t iz=1;iz<=nz;++iz) {
+      Double_t zp = histoZR->GetYaxis()->GetBinCenter(iz);
+      
+      // recalculation to meter
+      Double_t lZ = 2.5; // approx. TPC drift length
+      Double_t rpM = rp/100.; // in [m]
+      Double_t zpM = TMath::Abs(zp/100.); // in [m]
+ 
+      // calculation of "scaled" parameters
+      Double_t a = multiplicity*intRate/76628;
+      //Double_t charge = gasfactor * ( a / (rpM*rpM) * (1 - zpM/lZ) ); // charge in [C/m^3/e0], no IBF
+      Double_t charge = gasfactor * ( a / (rpM*rpM) * (1 - zpM/lZ + 2*eps/3) ); // charge in [C/m^3/e0], with IBF
+
+      charge = charge*fgke0;          // [C/m^3]
+
+      // from MC simulation (Stefan)
+      // for 50kHz
+      Double_t kon = (2.62243e-09); // charge in [C/m^3]
+      // Add to normal charge: gain 2000 with {0.25,0.5%) ion feedback
+      //charge += eps*(kon/(rpM*rpM));
+
+      if (zp<0) charge *= 0.9; // Slightly less on C side due to front absorber
+
+      histoZR->SetBinContent(ir, iz, charge); 
+    }
+  }
+    
+  histoZR->Write("SpaceChargeInRZ");
+
+  // Charge distribution in RPhi (e.g. Floating GG wire) ------------
+  
+  TH3F *histoRPhi = new TH3F("chargeRPhi", "chargeRPhi",
+                             nr, fgkIFCRadius-dr-safty, fgkOFCRadius+dr+safty,
+                             nphi, 0-dphi-safty, TMath::TwoPi()+dphi+safty,
+                             2, -1, 1); // z part - to allow A and C side differences
+  
+  // some 'arbitrary' GG leaks
+  Int_t   nGGleaks = 5;
+  Double_t secPosA[5]    = {3,6,6,11,13};         // sector
+  Double_t radialPosA[5] = {125,100,160,200,230}; // radius in cm
+  Double_t secPosC[5]    = {1,8,12,15,15};        // sector
+  Double_t radialPosC[5] = {245,120,140,120,190}; // radius in cm
+
+  for (Int_t ir=1;ir<=nr;++ir) {
+    Double_t rp = histoRPhi->GetXaxis()->GetBinCenter(ir);
+    for (Int_t iphi=1;iphi<=nphi;++iphi) {
+      Double_t phip = histoRPhi->GetYaxis()->GetBinCenter(iphi);
+      for (Int_t iz=1;iz<=2;++iz) {
+        Double_t zp = histoRPhi->GetZaxis()->GetBinCenter(iz);
+        
+        Double_t charge = 0;
+        
+        for (Int_t igg = 0; igg<nGGleaks; igg++) { // loop over GG leaks
+          
+          // A side
+          Double_t secPos = secPosA[igg]; 
+          Double_t radialPos = radialPosA[igg];
+
+          if (zp<0) { // C side
+            secPos = secPosC[igg]; 
+            radialPos = radialPosC[igg];
+          }
+
+          // some 'arbitrary' GG leaks
+          if (  (phip<(TMath::Pi()/9*(secPos+1)) && phip>(TMath::Pi()/9*secPos) ) ) { // sector slice
+            if ( rp>(radialPos-2.5) && rp<(radialPos+2.5))  // 5 cm slice
+              //charge = 300;
+             charge = 0.;
+         }
+          
+        }               
+       
+        charge = charge*fgke0; // [C/m^3]
+        histoRPhi->SetBinContent(ir,iphi,iz,charge); 
+      }
+    }
+  }
+
+  histoRPhi->Write("SpaceChargeInRPhi");
+
+  f->Close();
+  
+}