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geant4/source/processes/electromagnetic/standard/src/G4IonFluctuations.cc
T
Gabriele Cosmo d93e1e39a9 Import Geant4 7.1.0 source tree
2016-06-09 12:11:21 +02:00

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//
// ********************************************************************
// * DISCLAIMER *
// * *
// * The following disclaimer summarizes all the specific disclaimers *
// * of contributors to this software. The specific disclaimers,which *
// * govern, are listed with their locations in: *
// * http://cern.ch/geant4/license *
// * *
// * Neither the authors of this software system, nor their employing *
// * institutes,nor the agencies providing financial support for this *
// * work make any representation or warranty, express or implied, *
// * regarding this software system or assume any liability for its *
// * use. *
// * *
// * This code implementation is the intellectual property of the *
// * GEANT4 collaboration. *
// * By copying, distributing or modifying the Program (or any work *
// * based on the Program) you indicate your acceptance of this *
// * statement, and all its terms. *
// ********************************************************************
//
// $Id: G4IonFluctuations.cc,v 1.2 2004/12/01 19:37:14 vnivanch Exp $
// GEANT4 tag $Name: geant4-07-01 $
//
// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name: G4IonFluctuation
//
// Author: Vladimir Ivanchenko
//
// Creation date: 03.01.2002
//
// Modifications:
//
// 28-12-02 add method Dispersion (V.Ivanchenko)
// 07-02-03 change signature (V.Ivanchenko)
// 13-02-03 Add name (V.Ivanchenko)
// 23-05-03 Add control on parthalogical cases (V.Ivanchenko)
// 16-10-03 Changed interface to Initialisation (V.Ivanchenko)
//
// Class Description:
//
// -------------------------------------------------------------------
//
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
#include "G4IonFluctuations.hh"
#include "Randomize.hh"
#include "G4Poisson.hh"
#include "G4Material.hh"
#include "G4DynamicParticle.hh"
#include "G4ParticleDefinition.hh"
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
using namespace std;
G4IonFluctuations::G4IonFluctuations(const G4String& nam)
:G4VEmFluctuationModel(nam),
particle(0),
minNumberInteractionsBohr(10.0),
theBohrBeta2(50.0*keV/proton_mass_c2),
minFraction(0.2),
xmin(0.2),
minLoss(0.001*eV)
{}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4IonFluctuations::~G4IonFluctuations()
{}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
void G4IonFluctuations::InitialiseMe(const G4ParticleDefinition* part)
{
particle = part;
particleMass = part->GetPDGMass();
charge = part->GetPDGCharge()/eplus;
chargeSquare = charge*charge;
chargeSqRatio = 1.0;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4double G4IonFluctuations::SampleFluctuations(const G4Material* material,
const G4DynamicParticle* dp,
G4double& tmax,
G4double& length,
G4double& meanLoss)
{
if(meanLoss <= minLoss) return meanLoss;
if(dp->GetDefinition() != particle) {
particle = dp->GetDefinition();
charge = particle->GetPDGCharge()/eplus;
}
G4double siga = Dispersion(material,dp,tmax,length);
G4double loss = meanLoss;
G4double navr = minNumberInteractionsBohr;
// Gaussian fluctuation
G4bool gauss = true;
if (meanLoss >= minNumberInteractionsBohr*tmax) {
navr = meanLoss*meanLoss/siga;
if (navr < minNumberInteractionsBohr) gauss = false;
}
if(gauss) {
// Increase fluctuations for big fractional energy loss
//G4cout << "siga= " << siga << G4endl;
if ( meanLoss > minFraction*kineticEnergy ) {
G4double gam = (kineticEnergy - meanLoss)/particleMass + 1.0;
G4double b2 = 1.0 - 1.0/(gam*gam);
if(b2 < xmin*beta2) b2 = xmin*beta2;
G4double x = b2/beta2;
G4double x3 = 1.0/(x*x*x);
siga *= 0.25*(1.0 + x)*(x3 + (1.0/b2 - 0.5)/(1.0/beta2 - 0.5) );
}
// G4cout << "siga= " << siga << G4endl;
siga = sqrt(siga);
G4double lossmax = meanLoss+meanLoss;
do {
loss = G4RandGauss::shoot(meanLoss,siga);
} while (0.0 > loss || loss > lossmax);
// Poisson fluctuations
} else {
G4double n = (G4double)(G4Poisson(navr));
loss = meanLoss*n/navr;
}
// G4cout << "meanLoss= " << meanLoss << " loss= " << loss << G4endl;
return loss;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4double G4IonFluctuations::Dispersion(
const G4Material* material,
const G4DynamicParticle* dp,
G4double& tmax,
G4double& length)
{
particleMass = dp->GetMass();
G4double q = dp->GetCharge()/eplus;
chargeSquare = q*q;
chargeSqRatio = chargeSquare/(charge*charge);
G4double electronDensity = material->GetElectronDensity();
kineticEnergy = dp->GetKineticEnergy();
// G4cout << "e= " << kineticEnergy << " m= " << particleMass
// << " tmax= " << tmax << " l= " << length << " q^2= " << chargeSquare << G4endl;
G4double gam = kineticEnergy/particleMass + 1.0;
beta2 = 1.0 - 1.0/(gam*gam);
G4double siga = (1.0/beta2 - 0.5)*tmax*length*electronDensity*twopi_mc2_rcl2*chargeSquare;
// G4cout << "siga= " << siga << G4endl;
// Low velocity - additional ion charge fluctuations according to
// Q.Yang et al., NIM B61(1991)149-155.
G4double zeff = electronDensity/(material->GetTotNbOfAtomsPerVolume());
//G4cout << "siga= " << siga << " zeff= " << zeff << G4endl;
if ( beta2 < 3.0*theBohrBeta2*zeff ) {
G4double a = CoeffitientA (zeff);
G4double b = CoeffitientB (material, zeff);
// G4cout << "a= " << a << " b= " << b << G4endl;
siga *= (a*chargeSqRatio + b);
} else {
// H.Geissel et al. NIM B, 195 (2002) 3.
siga *= RelativisticFactor(material, zeff);
}
return siga;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4double G4IonFluctuations::CoeffitientA(G4double& zeff)
{
// The aproximation of energy loss fluctuations
// Q.Yang et al., NIM B61(1991)149-155.
// Reduced energy in MeV/AMU
G4double energy = kineticEnergy * amu_c2/(particleMass*MeV) ;
static G4double a[96][4] = {
{-0.3291, -0.8312, 0.2460, -1.0220},
{-0.5615, -0.5898, 0.5205, -0.7258},
{-0.5280, -0.4981, 0.5519, -0.5865},
{-0.5125, -0.4625, 0.5660, -0.5190},
{-0.5127, -0.8595, 0.5626, -0.8721},
{-0.5174, -1.1930, 0.5565, -1.1980},
{-0.5179, -1.1850, 0.5560, -1.2070},
{-0.5209, -0.9355, 0.5590, -1.0250},
{-0.5255, -0.7766, 0.5720, -0.9412},
{-0.5776, -0.6665, 0.6598, -0.8484},
{-0.6013, -0.6045, 0.7321, -0.7671},
{-0.5781, -0.5518, 0.7605, -0.6919},
{-0.5587, -0.4981, 0.7835, -0.6195},
{-0.5466, -0.4656, 0.7978, -0.5771},
{-0.5406, -0.4690, 0.8031, -0.5718},
{-0.5391, -0.5061, 0.8024, -0.5974},
{-0.5380, -0.6483, 0.7962, -0.6970},
{-0.5355, -0.7722, 0.7962, -0.7839},
{-0.5329, -0.7720, 0.7988, -0.7846},
{-0.5335, -0.7671, 0.7984, -0.7933},
{-0.5324, -0.7612, 0.7998, -0.8031},
{-0.5305, -0.7300, 0.8031, -0.7990},
{-0.5307, -0.7178, 0.8049, -0.8216},
{-0.5248, -0.6621, 0.8165, -0.7919},
{-0.5180, -0.6502, 0.8266, -0.7986},
{-0.5084, -0.6408, 0.8396, -0.8048},
{-0.4967, -0.6331, 0.8549, -0.8093},
{-0.4861, -0.6508, 0.8712, -0.8432},
{-0.4700, -0.6186, 0.8961, -0.8132},
{-0.4545, -0.5720, 0.9227, -0.7710},
{-0.4404, -0.5226, 0.9481, -0.7254},
{-0.4288, -0.4778, 0.9701, -0.6850},
{-0.4199, -0.4425, 0.9874, -0.6539},
{-0.4131, -0.4188, 0.9998, -0.6332},
{-0.4089, -0.4057, 1.0070, -0.6218},
{-0.4039, -0.3913, 1.0150, -0.6107},
{-0.3987, -0.3698, 1.0240, -0.5938},
{-0.3977, -0.3608, 1.0260, -0.5852},
{-0.3972, -0.3600, 1.0260, -0.5842},
{-0.3985, -0.3803, 1.0200, -0.6013},
{-0.3985, -0.3979, 1.0150, -0.6168},
{-0.3968, -0.3990, 1.0160, -0.6195},
{-0.3971, -0.4432, 1.0050, -0.6591},
{-0.3944, -0.4665, 1.0010, -0.6825},
{-0.3924, -0.5109, 0.9921, -0.7235},
{-0.3882, -0.5158, 0.9947, -0.7343},
{-0.3838, -0.5125, 0.9999, -0.7370},
{-0.3786, -0.4976, 1.0090, -0.7310},
{-0.3741, -0.4738, 1.0200, -0.7155},
{-0.3969, -0.4496, 1.0320, -0.6982},
{-0.3663, -0.4297, 1.0430, -0.6828},
{-0.3630, -0.4120, 1.0530, -0.6689},
{-0.3597, -0.3964, 1.0620, -0.6564},
{-0.3555, -0.3809, 1.0720, -0.6454},
{-0.3525, -0.3607, 1.0820, -0.6289},
{-0.3505, -0.3465, 1.0900, -0.6171},
{-0.3397, -0.3570, 1.1020, -0.6384},
{-0.3314, -0.3552, 1.1130, -0.6441},
{-0.3235, -0.3531, 1.1230, -0.6498},
{-0.3150, -0.3483, 1.1360, -0.6539},
{-0.3060, -0.3441, 1.1490, -0.6593},
{-0.2968, -0.3396, 1.1630, -0.6649},
{-0.2935, -0.3225, 1.1760, -0.6527},
{-0.2797, -0.3262, 1.1940, -0.6722},
{-0.2704, -0.3202, 1.2100, -0.6770},
{-0.2815, -0.3227, 1.2480, -0.6775},
{-0.2880, -0.3245, 1.2810, -0.6801},
{-0.3034, -0.3263, 1.3270, -0.6778},
{-0.2936, -0.3215, 1.3430, -0.6835},
{-0.3282, -0.3200, 1.3980, -0.6650},
{-0.3260, -0.3070, 1.4090, -0.6552},
{-0.3511, -0.3074, 1.4470, -0.6442},
{-0.3501, -0.3064, 1.4500, -0.6442},
{-0.3490, -0.3027, 1.4550, -0.6418},
{-0.3487, -0.3048, 1.4570, -0.6447},
{-0.3478, -0.3074, 1.4600, -0.6483},
{-0.3501, -0.3283, 1.4540, -0.6669},
{-0.3494, -0.3373, 1.4550, -0.6765},
{-0.3485, -0.3373, 1.4570, -0.6774},
{-0.3462, -0.3300, 1.4630, -0.6728},
{-0.3462, -0.3225, 1.4690, -0.6662},
{-0.3453, -0.3094, 1.4790, -0.6553},
{-0.3844, -0.3134, 1.5240, -0.6412},
{-0.3848, -0.3018, 1.5310, -0.6303},
{-0.3862, -0.2955, 1.5360, -0.6237},
{-0.4262, -0.2991, 1.5860, -0.6115},
{-0.4278, -0.2910, 1.5900, -0.6029},
{-0.4303, -0.2817, 1.5940, -0.5927},
{-0.4315, -0.2719, 1.6010, -0.5829},
{-0.4359, -0.2914, 1.6050, -0.6010},
{-0.4365, -0.2982, 1.6080, -0.6080},
{-0.4253, -0.3037, 1.6120, -0.6150},
{-0.4335, -0.3245, 1.6160, -0.6377},
{-0.4307, -0.3292, 1.6210, -0.6447},
{-0.4284, -0.3204, 1.6290, -0.6380},
{-0.4227, -0.3217, 1.6360, -0.6438}
} ;
G4int iz = (G4int)zeff - 2 ;
if( 0 > iz ) iz = 0 ;
if(95 < iz ) iz = 95 ;
G4double q = 1.0 / (1.0 + a[iz][0]*pow(energy,a[iz][1])+
+ a[iz][2]*pow(energy,a[iz][3])) ;
return q ;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4double G4IonFluctuations::CoeffitientB(const G4Material* material, G4double& zeff)
{
// The aproximation of energy loss fluctuations
// Q.Yang et al., NIM B61(1991)149-155.
// Reduced energy in MeV/AMU
G4double energy = kineticEnergy *amu_c2/(particleMass*MeV) ;
G4int i = 0 ;
G4double factor = 1.0 ;
// The index of set of parameters i = 0 for protons(hadrons) in gases
// 1 for protons(hadrons) in solids
// 2 for ions in atomic gases
// 3 for ions in molecular gases
// 4 for ions in solids
static G4double b[5][4] = {
{0.1014, 0.3700, 0.9642, 3.987},
{0.1955, 0.6941, 2.522, 1.040},
{0.05058, 0.08975, 0.1419, 10.80},
{0.05009, 0.08660, 0.2751, 3.787},
{0.01273, 0.03458, 0.3951, 3.812}
} ;
// protons (hadrons)
if(1.5 > charge) {
if( kStateGas != material->GetState() ) i = 1 ;
// ions
} else {
factor = charge * pow(charge/zeff, 0.3333) ;
if( kStateGas == material->GetState() ) {
energy /= (charge * sqrt(charge)) ;
if(1 == (material->GetNumberOfElements())) {
i = 2 ;
} else {
i = 3 ;
}
} else {
energy /= (charge * sqrt(charge*zeff)) ;
i = 4 ;
}
}
G4double x = b[i][2] * (1.0 - exp( - energy * b[i][3] )) ;
G4double q = factor * x * b[i][0] /
((energy - b[i][1])*(energy - b[i][1]) + x*x) ;
return q ;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4double G4IonFluctuations::RelativisticFactor(const G4Material*, G4double& zeff)
{
// H.Geissel et al. NIM B, 195 (2002) 3.
G4double factor = 1.0 + 0.667*theBohrBeta2*(1.0 - beta2)
* log(2.0*electron_mass_c2/(5.0*charge*eV))
/ ((1.0 - 0.5*beta2)*beta2*zeff) ;
factor *= (1.0 + 1.415e-4*chargeSquare/beta2);
// G4cout << "factor= " << factor << G4endl;
return factor;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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