source: trunk/source/processes/hadronic/cross_sections/src/G4EMDissociationCrossSection.cc @ 1253

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35//
36// %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
37//
38// MODULE:              G4EMDissociationCrossSection.cc
39//
40// Version:             B.1
41// Date:                15/04/04
42// Author:              P R Truscott
43// Organisation:        QinetiQ Ltd, UK
44// Customer:            ESA/ESTEC, NOORDWIJK
45// Contract:            17191/03/NL/LvH
46//
47// %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
48//
49// CHANGE HISTORY
50// --------------
51//
52// 17 October 2003, P R Truscott, QinetiQ Ltd, UK
53// Created.
54//
55// 15 March 2004, P R Truscott, QinetiQ Ltd, UK
56// Beta release
57//
58// 30. May 2005, J.P. Wellisch removed a compilation warning on gcc 3.4 for gant4 7.1.
59//
60// %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
61////////////////////////////////////////////////////////////////////////////////
62//
63#include "G4EMDissociationCrossSection.hh"
64#include "G4PhysicsFreeVector.hh"
65#include "G4ParticleTable.hh"
66#include "G4IonTable.hh"
67#include "globals.hh"
68////////////////////////////////////////////////////////////////////////////////
69//
70G4EMDissociationCrossSection::G4EMDissociationCrossSection ()
71{
72//
73//
74// This function makes use of the class which can sample the virtual photon
75// spectrum, G4EMDissociationSpectrum.
76//
77  thePhotonSpectrum = new G4EMDissociationSpectrum();
78//
79//
80// Define other constants.
81//
82  r0      = 1.18 * fermi;
83  J       = 36.8 * MeV;
84  Qprime  = 17.0 * MeV;
85  epsilon = 0.0768;
86  xd      = 0.25;
87}
88////////////////////////////////////////////////////////////////////////////////
89//
90G4EMDissociationCrossSection::~G4EMDissociationCrossSection()
91{
92  delete thePhotonSpectrum;
93}
94///////////////////////////////////////////////////////////////////////////////
95//
96G4bool G4EMDissociationCrossSection::IsZAApplicable
97(const G4DynamicParticle* theDynamicParticle, G4double /*ZZ*/, G4double AA)
98{
99//
100// The condition for the applicability of this class is that the projectile
101// must be an ion and the target must have more than one nucleon.  In reality
102// the value of A for either the projectile or target could be much higher,
103// since for cases where both he projectile and target are medium to small
104// Z, the probability of the EMD process is, I think, VERY small.
105//
106  if (G4ParticleTable::GetParticleTable()->GetIonTable()->
107    IsIon(theDynamicParticle->GetDefinition()) && AA > 1.0)
108    return true;
109  else
110    return false;
111}
112
113G4bool G4EMDissociationCrossSection::IsApplicable
114  (const G4DynamicParticle* theDynamicParticle, const G4Element* theElement)
115{
116  return IsZAApplicable(theDynamicParticle, 0., theElement->GetN());
117}
118
119//////////////////////////////////////////////////////////////////////////////
120//
121G4double G4EMDissociationCrossSection::GetCrossSection
122  (const G4DynamicParticle* theDynamicParticle, const G4Element* theElement,
123   G4double temperature)
124{
125  G4int nIso = theElement->GetNumberOfIsotopes();
126  G4double crossSection = 0;
127     
128  if (nIso) {
129    G4double sig;
130    G4IsotopeVector* isoVector = theElement->GetIsotopeVector();
131    G4double* abundVector = theElement->GetRelativeAbundanceVector();
132    G4double ZZ;
133    G4double AA;
134     
135    for (G4int i = 0; i < nIso; i++) {
136      ZZ = G4double( (*isoVector)[i]->GetZ() );
137      AA = G4double( (*isoVector)[i]->GetN() );
138      sig = GetIsoZACrossSection(theDynamicParticle, ZZ, AA, temperature);
139      crossSection += sig*abundVector[i];
140    }
141   
142  } else {
143    crossSection =
144      GetIsoZACrossSection(theDynamicParticle, theElement->GetZ(), 
145                           theElement->GetN(), temperature);
146  }
147   
148  return crossSection;
149}
150
151
152G4double G4EMDissociationCrossSection::GetIsoZACrossSection
153  (const G4DynamicParticle *theDynamicParticle, G4double ZZ, G4double AA,
154   G4double /*temperature*/)
155{
156//
157//
158// Get relevant information about the projectile and target (A, Z) and
159// velocity of the projectile.
160//
161  G4ParticleDefinition *definitionP = theDynamicParticle->GetDefinition();
162  G4double AP   = definitionP->GetBaryonNumber();
163  G4double ZP   = definitionP->GetPDGCharge();
164  G4double b    = theDynamicParticle->Get4Momentum().beta();
165//  G4double bsq  = b * b;
166 
167  G4double AT   = AA;
168  G4double ZT   = ZZ;
169  G4double bmin = thePhotonSpectrum->GetClosestApproach(AP, ZP, AT, ZT, b);
170//
171//
172// Calculate the cross-section for the projectile and then the target.  The
173// information is returned in a G4PhysicsFreeVector, which separates out the
174// cross-sections for the E1 and E2 moments of the virtual photon field, and
175// the energies (GDR and GQR).
176//
177  G4PhysicsFreeVector *theProjectileCrossSections = 
178    GetCrossSectionForProjectile (AP, ZP, AT, ZT, b, bmin);
179  G4double crossSection =
180    (*theProjectileCrossSections)[0]+(*theProjectileCrossSections)[1];
181  delete theProjectileCrossSections;
182  G4PhysicsFreeVector *theTargetCrossSections = 
183    GetCrossSectionForTarget (AP, ZP, AT, ZT, b, bmin);
184  crossSection += 
185    (*theTargetCrossSections)[0]+(*theTargetCrossSections)[1];
186  delete theTargetCrossSections;
187
188  return crossSection;
189}
190////////////////////////////////////////////////////////////////////////////////
191//
192G4PhysicsFreeVector *
193  G4EMDissociationCrossSection::GetCrossSectionForProjectile (G4double AP,
194  G4double ZP, G4double /* AT */, G4double ZT, G4double b, G4double bmin)
195{
196//
197//
198// Use Wilson et al's approach to calculate the cross-sections due to the E1
199// and E2 moments of the field at the giant dipole and quadrupole resonances
200// respectively,  Note that the algorithm is traditionally applied to the
201// EMD break-up of the projectile in the field of the target, as is implemented
202// here.
203//
204// Initialise variables and calculate the energies for the GDR and GQR.
205//
206  G4double AProot3 = std::pow(AP,1.0/3.0);
207  G4double u       = 3.0 * J / Qprime / AProot3;
208  G4double R0      = r0 * AProot3;
209  G4double E_GDR  = hbarc / std::sqrt(0.7*amu_c2*R0*R0/8.0/J*
210    (1.0 + u - (1.0 + epsilon + 3.0*u)/(1.0 + epsilon + u)*epsilon));
211  G4double E_GQR  = 63.0 * MeV / AProot3;
212//
213//
214// Determine the virtual photon spectra at these energies.
215//
216  G4double ZTsq = ZT * ZT;
217  G4double nE1 = ZTsq *
218    thePhotonSpectrum->GetGeneralE1Spectrum(E_GDR, b, bmin);
219  G4double nE2 = ZTsq *
220    thePhotonSpectrum->GetGeneralE2Spectrum(E_GQR, b, bmin);
221//
222//
223// Now calculate the cross-section of the projectile for interaction with the
224// E1 and E2 fields.
225//
226  G4double sE1 = 60.0 * millibarn * MeV * (AP-ZP)*ZP/AP;
227  G4double sE2 = 0.22 * microbarn / MeV * ZP * AProot3 * AProot3;
228  if (AP > 100.0)     sE2 *= 0.9;
229  else if (AP > 40.0) sE2 *= 0.6;
230  else                sE2 *= 0.3;
231//
232//
233// ... and multiply with the intensity of the virtual photon spectra to get
234// the probability of interaction.
235//
236  G4PhysicsFreeVector *theCrossSectionVector = new G4PhysicsFreeVector(2);
237  theCrossSectionVector->PutValue(0, E_GDR, sE1*nE1);
238  theCrossSectionVector->PutValue(1, E_GQR, sE2*nE2*E_GQR*E_GQR);
239 
240  return theCrossSectionVector;
241}
242////////////////////////////////////////////////////////////////////////////////
243//
244G4PhysicsFreeVector *
245  G4EMDissociationCrossSection::GetCrossSectionForTarget (G4double AP,
246  G4double ZP, G4double AT, G4double ZT, G4double b, G4double bmin)
247{
248//
249//
250// This is a cheaky little member function to calculate the probability of
251// EMD for the target in the field of the projectile ... just by reversing the
252// A and Z's for the participants.
253//
254  return GetCrossSectionForProjectile (AT, ZT, AP, ZP, b, bmin);
255}
256////////////////////////////////////////////////////////////////////////////////
257//
258G4double
259  G4EMDissociationCrossSection::GetWilsonProbabilityForProtonDissociation
260  (G4double A, G4double Z)
261{
262//
263//
264// This is a simple algorithm to choose whether a proton or neutron is ejected
265// from the nucleus in the EMD interaction.
266//
267  G4double p = 0.0;
268  if (Z < 6.0)
269    p = 0.5;
270  else if (Z < 8.0)
271    p = 0.6;
272  else if (Z < 14.0)
273    p = 0.7;
274  else
275  {
276    G4double p1 = (G4double) Z / (G4double) A;
277    G4double p2 = 1.95*std::exp(-0.075*Z);
278    if (p1 < p2) p = p1;
279    else         p = p2;
280  }
281
282  return p;
283}
284////////////////////////////////////////////////////////////////////////////////
285//
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