Gabriele Cosmo
179 lines
6.7 KiB
C++
179 lines
6.7 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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//
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#ifndef G4EffectiveCharge_h
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#define G4EffectiveCharge_h
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#include "G4Material.hh"
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class G4EffectiveCharge
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{
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public:
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G4double GetCharge(const G4Material* material, G4double kineticEnergy,
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G4double particleMass, G4double ionCharge);
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};
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inline G4double G4EffectiveCharge::GetCharge(const G4Material* material, G4double kineticEnergy,
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G4double particleMass, G4double ionCharge)
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{
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// This is cut and paste with minor changes from low_energy electromagnetic to avoid coupling.
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// A design iteration is necessary for next time, to generate a process utility.
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// Original Author: V Ivanchenko.
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// The aproximation of ion effective charge from:
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// J.F.Ziegler, J.P. Biersack, U. Littmark
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// The Stopping and Range of Ions in Matter,
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// Vol.1, Pergamon Press, 1985
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// Fast ions or hadrons
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G4double reducedEnergy = kineticEnergy * proton_mass_c2/particleMass ;
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if( (reducedEnergy > ionCharge * 10.0 * MeV) ||
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(ionCharge < 1.5) ) return ionCharge ;
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static G4double vFermi[92] = {
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1.0309, 0.15976, 0.59782, 1.0781, 1.0486, 1.0, 1.058, 0.93942, 0.74562, 0.3424,
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0.45259, 0.71074, 0.90519, 0.97411, 0.97184, 0.89852, 0.70827, 0.39816, 0.36552, 0.62712,
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0.81707, 0.9943, 1.1423, 1.2381, 1.1222, 0.92705, 1.0047, 1.2, 1.0661, 0.97411,
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0.84912, 0.95, 1.0903, 1.0429, 0.49715, 0.37755, 0.35211, 0.57801, 0.77773, 1.0207,
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1.029, 1.2542, 1.122, 1.1241, 1.0882, 1.2709, 1.2542, 0.90094, 0.74093, 0.86054,
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0.93155, 1.0047, 0.55379, 0.43289, 0.32636, 0.5131, 0.695, 0.72591, 0.71202, 0.67413,
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0.71418, 0.71453, 0.5911, 0.70263, 0.68049, 0.68203, 0.68121, 0.68532, 0.68715, 0.61884,
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0.71801, 0.83048, 1.1222, 1.2381, 1.045, 1.0733, 1.0953, 1.2381, 1.2879, 0.78654,
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0.66401, 0.84912, 0.88433, 0.80746, 0.43357, 0.41923, 0.43638, 0.51464, 0.73087, 0.81065,
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1.9578, 1.0257} ;
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static G4double lFactor[92] = {
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1.0, 1.0, 1.1, 1.06, 1.01, 1.03, 1.04, 0.99, 0.95, 0.9,
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0.82, 0.81, 0.83, 0.88, 1.0, 0.95, 0.97, 0.99, 0.98, 0.97,
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0.98, 0.97, 0.96, 0.93, 0.91, 0.9, 0.88, 0.9, 0.9, 0.9,
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0.9, 0.85, 0.9, 0.9, 0.91, 0.92, 0.9, 0.9, 0.9, 0.9,
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0.9, 0.88, 0.9, 0.88, 0.88, 0.9, 0.9, 0.88, 0.9, 0.9,
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0.9, 0.9, 0.96, 1.2, 0.9, 0.88, 0.88, 0.85, 0.9, 0.9,
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0.92, 0.95, 0.99, 1.03, 1.05, 1.07, 1.08, 1.1, 1.08, 1.08,
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1.08, 1.08, 1.09, 1.09, 1.1, 1.11, 1.12, 1.13, 1.14, 1.15,
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1.17, 1.2, 1.18, 1.17, 1.17, 1.16, 1.16, 1.16, 1.16, 1.16,
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1.16, 1.16} ;
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static G4double c[6] = {0.2865, 0.1266, -0.001429,
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0.02402,-0.01135, 0.001475} ;
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// get elements in the actual material,
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const G4ElementVector* theElementVector = material->GetElementVector() ;
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const G4double* theAtomicNumDensityVector =
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material->GetAtomicNumDensityVector() ;
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const G4int NumberOfElements = material->GetNumberOfElements() ;
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// loop for the elements in the material
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// to find out average values Z, vF, lF
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G4double z = 0.0, vF = 0.0, lF = 0.0, norm = 0.0 ;
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if( 1 == NumberOfElements )
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{
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z = material->GetZ() ;
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G4int iz = G4int(z) - 1 ;
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if(iz < 0) iz = 0 ;
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else if(iz > 91) iz = 91 ;
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vF = vFermi[iz] ;
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lF = lFactor[iz] ;
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}
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else
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{
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for (G4int iel=0; iel<NumberOfElements; iel++)
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{
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const G4Element* element = (*theElementVector)[iel] ;
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G4double z2 = element->GetZ() ;
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const G4double weight = theAtomicNumDensityVector[iel] ;
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norm += weight ;
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z += z2 * weight ;
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G4int iz = G4int(z2) - 1 ;
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if(iz < 0) iz = 0 ;
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else if(iz > 91) iz =91 ;
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vF += vFermi[iz] * weight ;
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lF += lFactor[iz] * weight ;
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}
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z /= norm ;
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vF /= norm ;
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lF /= norm ;
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}
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// Helium ion case
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if( ionCharge < 2.5 )
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{
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G4double theHeMassAMU(4.0026);
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G4double e = log(std::max(1.0, kineticEnergy / (keV*theHeMassAMU) )) ;
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G4double x = c[0] ;
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G4double y = 1.0 ;
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for (G4int i=1; i<6; i++)
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{
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y *= e ;
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x += y * c[i] ;
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}
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G4double q = 7.6 - e ;
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q = 1.0 + ( 0.007 + 0.00005 * z ) * exp( -q*q ) ;
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return sqrt(4.0 * q * q * (1.0 - exp(-x))) ;
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// Heavy ion case
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}
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else
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{
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// v1 is ion velocity in vF unit
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G4double v1 = sqrt( reducedEnergy / (25.0 * keV) )/ vF ;
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G4double y ;
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G4double z13 = pow(ionCharge, 0.3333) ;
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// Faster than Fermi velocity
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if ( v1 > 1.0 )
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{
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y = vF * v1 * ( 1.0 + 0.2 / (v1*v1) ) / (z13*z13) ;
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// Slower than Fermi velocity
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}
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else
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{
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y = 0.6923 * vF * (1.0 + 2.0*v1*v1/3.0 + v1*v1*v1*v1/15.0) / (z13*z13) ;
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}
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G4double y3 = pow(y, 0.3) ;
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G4double q = 1.0 - exp( 0.803*y3 - 1.3167*y3*y3 -
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0.38157*y - 0.008983*y*y ) ;
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if( q < 0.0 ) q = 0.0 ;
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G4double s = 7.6 - log(std::max(1.0, reducedEnergy/keV)) ;
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s = 1.0 + ( 0.18 + 0.0015 * z ) * exp( -s*s )/ (ionCharge*ionCharge) ;
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// Screen length according to
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// J.F.Ziegler and J.M.Manoyan, The stopping of ions in compaunds,
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// Nucl. Inst. & Meth. in Phys. Res. B35 (1988) 215-228.
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G4double lambda = 10.0 * vF * pow(1.0-q, 0.6667) / (z13 * (6.0 + q)) ;
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G4double qeff = ionCharge * s *
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( q + 0.5*(1.0-q) * log(1.0 + lambda*lambda) / (vF*vF) ) ;
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if( 1.0 > qeff ) qeff = 1.0 ;
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return sqrt(qeff) ;
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}
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}
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#endif
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