Gabriele Cosmo
122 lines
4.8 KiB
C++
122 lines
4.8 KiB
C++
//
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// ********************************************************************
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// * DISCLAIMER *
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// * *
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// * The following disclaimer summarizes all the specific disclaimers *
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// * of contributors to this software. The specific disclaimers,which *
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// * govern, are listed with their locations in: *
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// * http://cern.ch/geant4/license *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. *
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// * *
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// * This code implementation is the intellectual property of the *
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// * GEANT4 collaboration. *
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// * By copying, distributing or modifying the Program (or any work *
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// * based on the Program) you indicate your acceptance of this *
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// * statement, and all its terms. *
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// ********************************************************************
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//
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// Implementation of formulas in analogy to NASA technical paper 3621 by Tripathi, et al.
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#include "G4TripathiCrossSection.hh"
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#include "G4ParticleTable.hh"
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#include "G4IonTable.hh"
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#include "G4HadTmpUtil.hh"
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G4double G4TripathiCrossSection::
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GetCrossSection(const G4DynamicParticle* aPart,
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const G4Element*anEle, G4double )
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{
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G4double result = 0;
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const G4double targetAtomicNumber = anEle->GetN();
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const G4double nTargetProtons = anEle->GetZ();
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const G4double kineticEnergy = aPart->GetKineticEnergy()/MeV;
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const G4double nProjProtons = aPart->GetDefinition()->GetPDGCharge();
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const G4double projectileAtomicNumber = aPart->GetDefinition()->GetBaryonNumber();
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const G4double nuleonRadius=1.1E-15;
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const G4double myNuleonRadius=1.36E-15;
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// needs target mass
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G4double targetMass = G4ParticleTable::GetParticleTable()
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->GetIonTable()
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->GetIonMass(G4lrint(nTargetProtons), G4lrint(targetAtomicNumber));
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G4LorentzVector pTarget(0,0,0,targetMass);
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G4LorentzVector pProjectile(aPart->Get4Momentum());
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pTarget = pTarget+pProjectile;
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G4double E_cm = (pTarget.mag()-targetMass-pProjectile.m())/MeV;
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// done
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G4double r_rms_p = 0.6 * myNuleonRadius * pow(projectileAtomicNumber, 1./3.);
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G4double r_rms_t = 0.6 * myNuleonRadius * pow(targetAtomicNumber, 1./3.);
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// done
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G4double r_p = 1.29*r_rms_p/nuleonRadius ;
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G4double r_t = 1.29*r_rms_t/nuleonRadius;
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// done
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G4double Radius = r_p + r_t +
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1.2*(pow(targetAtomicNumber, 1./3.) + pow(projectileAtomicNumber, 1./3.))/
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pow(E_cm, 1./3.);
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//done
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G4double B = 1.44*nProjProtons*nTargetProtons/Radius;
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// done
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G4double Energy = kineticEnergy/projectileAtomicNumber;
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// done
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//
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// Note that this correction to G4TripathiCrossSection is just to accurately
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// reflect Tripathi's algorithm. However, if you're using alpha particles/protons
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// consider using the more accurate G4TripathiLightCrossSection, which
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// Tripathi developed specifically for light systems.
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//
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G4double D;
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if (nProjProtons==1 && projectileAtomicNumber==1)
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{
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D = 2.05;
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}
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else if (nProjProtons==2 && projectileAtomicNumber==4)
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{
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D = 2.77-(8.0E-3*targetAtomicNumber)+(1.8E-5*targetAtomicNumber*targetAtomicNumber)
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- 0.8/(1+exp((250.-Energy)/75.));
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}
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else
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{
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//
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// This is the original value used in the G4TripathiCrossSection implementation,
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// and was used for all projectile/target conditions. I'm not touching this,
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// althoughJudging from Tripathi's paper, this is valid for cases where the
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// nucleon density changes little with A.
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//
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D = 1.75;
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}
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// done
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G4double C_E = D * (1-exp(-Energy/40.)) - 0.292*exp(-Energy/792.)*cos(0.229*pow(Energy, 0.453));
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// done
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G4double S = pow(projectileAtomicNumber, 1./3.)*pow(targetAtomicNumber, 1./3.)/
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(pow(projectileAtomicNumber, 1./3.) + pow(targetAtomicNumber, 1./3.));
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// done
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G4double deltaE = 1.85*S + 0.16*S/pow(E_cm,1./3.) - C_E +
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0.91*(targetAtomicNumber-2.*nTargetProtons)*nProjProtons/
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(targetAtomicNumber*projectileAtomicNumber);
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// done
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result = pi * nuleonRadius*nuleonRadius *
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pow(( pow(targetAtomicNumber, 1./3.) +
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pow(projectileAtomicNumber, 1./3.) + deltaE),2.) * (1-B/E_cm);
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if(result < 0) result = 0;
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return result*m2;
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}
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