source: trunk/source/processes/hadronic/cross_sections/src/G4EMDissociationCrossSection.cc @ 1347

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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
59//               geant4 7.1.
60// 09 November 2010, V.Ivanchenko make class applicable for Hydrogen but
61//                   set cross section for Hydrogen to zero 
62//
63// %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
64//////////////////////////////////////////////////////////////////////////////
65//
66#include "G4EMDissociationCrossSection.hh"
67#include "G4PhysicsFreeVector.hh"
68#include "G4ParticleTable.hh"
69#include "G4IonTable.hh"
70#include "G4HadTmpUtil.hh"
71#include "globals.hh"
72
73
74G4EMDissociationCrossSection::G4EMDissociationCrossSection ()
75{
76//
77// This function makes use of the class which can sample the virtual photon
78// spectrum, G4EMDissociationSpectrum.
79//
80  thePhotonSpectrum = new G4EMDissociationSpectrum();
81//
82//
83// Define other constants.
84//
85  r0      = 1.18 * fermi;
86  J       = 36.8 * MeV;
87  Qprime  = 17.0 * MeV;
88  epsilon = 0.0768;
89  xd      = 0.25;
90}
91//////////////////////////////////////////////////////////////////////////////
92//
93G4EMDissociationCrossSection::~G4EMDissociationCrossSection()
94{
95  delete thePhotonSpectrum;
96}
97/////////////////////////////////////////////////////////////////////////////
98//
99G4bool
100G4EMDissociationCrossSection::IsIsoApplicable(const G4DynamicParticle* theDynamicParticle,
101                                              G4int /*ZZ*/, G4int/* AA*/)
102{
103//
104// The condition for the applicability of this class is that the projectile
105// must be an ion and the target must have more than one nucleon.  In reality
106// the value of A for either the projectile or target could be much higher,
107// since for cases where both he projectile and target are medium to small
108// Z, the probability of the EMD process is, I think, VERY small.
109//
110  if (G4ParticleTable::GetParticleTable()->GetIonTable()->
111      IsIon(theDynamicParticle->GetDefinition()) /*&& AA > 1*/)
112    return true;
113  else
114    return false;
115}
116
117G4bool G4EMDissociationCrossSection::IsApplicable
118  (const G4DynamicParticle* theDynamicParticle, const G4Element* theElement)
119{
120  return IsIsoApplicable(theDynamicParticle, 0, G4lrint(theElement->GetN()));
121}
122
123//////////////////////////////////////////////////////////////////////////////
124//
125G4double G4EMDissociationCrossSection::GetCrossSection
126  (const G4DynamicParticle* theDynamicParticle, const G4Element* theElement,
127   G4double temperature)
128{
129  G4int nIso = theElement->GetNumberOfIsotopes();
130  G4double crossSection = 0;
131
132  // VI protection for Hydrogen
133  if(theElement->GetZ() < 1.5) { return crossSection; }
134     
135  if (nIso) {
136    G4double sig;
137    G4IsotopeVector* isoVector = theElement->GetIsotopeVector();
138    G4double* abundVector = theElement->GetRelativeAbundanceVector();
139    G4int ZZ;
140    G4int AA;
141     
142    for (G4int i = 0; i < nIso; i++) {
143      ZZ = (*isoVector)[i]->GetZ();
144      AA = (*isoVector)[i]->GetN();
145      sig = GetZandACrossSection(theDynamicParticle, ZZ, AA, temperature);
146      crossSection += sig*abundVector[i];
147    }
148   
149  } else {
150    G4int ZZ = G4lrint(theElement->GetZ());
151    G4int AA = G4lrint(theElement->GetN());
152    crossSection = GetZandACrossSection(theDynamicParticle, ZZ, AA, temperature);
153  }
154   
155  return crossSection;
156}
157
158
159G4double
160G4EMDissociationCrossSection::GetZandACrossSection(const G4DynamicParticle *theDynamicParticle,
161                                                   G4int ZZ, G4int AA, G4double /*temperature*/)
162{
163  // VI protection for Hydrogen
164  if(ZZ <= 1) { return 0.0; }
165
166//
167// Get relevant information about the projectile and target (A, Z) and
168// velocity of the projectile.
169//
170  G4ParticleDefinition *definitionP = theDynamicParticle->GetDefinition();
171  G4double AP   = definitionP->GetBaryonNumber();
172  G4double ZP   = definitionP->GetPDGCharge();
173  G4double b    = theDynamicParticle->Get4Momentum().beta();
174//  G4double bsq  = b * b;
175 
176  G4double AT   = AA;
177  G4double ZT   = ZZ;
178  G4double bmin = thePhotonSpectrum->GetClosestApproach(AP, ZP, AT, ZT, b);
179//
180//
181// Calculate the cross-section for the projectile and then the target.  The
182// information is returned in a G4PhysicsFreeVector, which separates out the
183// cross-sections for the E1 and E2 moments of the virtual photon field, and
184// the energies (GDR and GQR).
185//
186  G4PhysicsFreeVector *theProjectileCrossSections = 
187    GetCrossSectionForProjectile (AP, ZP, AT, ZT, b, bmin);
188  G4double crossSection =
189    (*theProjectileCrossSections)[0]+(*theProjectileCrossSections)[1];
190  delete theProjectileCrossSections;
191  G4PhysicsFreeVector *theTargetCrossSections = 
192    GetCrossSectionForTarget (AP, ZP, AT, ZT, b, bmin);
193  crossSection += 
194    (*theTargetCrossSections)[0]+(*theTargetCrossSections)[1];
195  delete theTargetCrossSections;
196
197  return crossSection;
198}
199////////////////////////////////////////////////////////////////////////////////
200//
201G4PhysicsFreeVector *
202  G4EMDissociationCrossSection::GetCrossSectionForProjectile (G4double AP,
203  G4double ZP, G4double /* AT */, G4double ZT, G4double b, G4double bmin)
204{
205//
206//
207// Use Wilson et al's approach to calculate the cross-sections due to the E1
208// and E2 moments of the field at the giant dipole and quadrupole resonances
209// respectively,  Note that the algorithm is traditionally applied to the
210// EMD break-up of the projectile in the field of the target, as is implemented
211// here.
212//
213// Initialise variables and calculate the energies for the GDR and GQR.
214//
215  G4double AProot3 = std::pow(AP,1.0/3.0);
216  G4double u       = 3.0 * J / Qprime / AProot3;
217  G4double R0      = r0 * AProot3;
218  G4double E_GDR  = hbarc / std::sqrt(0.7*amu_c2*R0*R0/8.0/J*
219    (1.0 + u - (1.0 + epsilon + 3.0*u)/(1.0 + epsilon + u)*epsilon));
220  G4double E_GQR  = 63.0 * MeV / AProot3;
221//
222//
223// Determine the virtual photon spectra at these energies.
224//
225  G4double ZTsq = ZT * ZT;
226  G4double nE1 = ZTsq *
227    thePhotonSpectrum->GetGeneralE1Spectrum(E_GDR, b, bmin);
228  G4double nE2 = ZTsq *
229    thePhotonSpectrum->GetGeneralE2Spectrum(E_GQR, b, bmin);
230//
231//
232// Now calculate the cross-section of the projectile for interaction with the
233// E1 and E2 fields.
234//
235  G4double sE1 = 60.0 * millibarn * MeV * (AP-ZP)*ZP/AP;
236  G4double sE2 = 0.22 * microbarn / MeV * ZP * AProot3 * AProot3;
237  if (AP > 100.0)     sE2 *= 0.9;
238  else if (AP > 40.0) sE2 *= 0.6;
239  else                sE2 *= 0.3;
240//
241//
242// ... and multiply with the intensity of the virtual photon spectra to get
243// the probability of interaction.
244//
245  G4PhysicsFreeVector *theCrossSectionVector = new G4PhysicsFreeVector(2);
246  theCrossSectionVector->PutValue(0, E_GDR, sE1*nE1);
247  theCrossSectionVector->PutValue(1, E_GQR, sE2*nE2*E_GQR*E_GQR);
248 
249  return theCrossSectionVector;
250}
251
252////////////////////////////////////////////////////////////////////////////////
253//
254G4PhysicsFreeVector *
255  G4EMDissociationCrossSection::GetCrossSectionForTarget (G4double AP,
256  G4double ZP, G4double AT, G4double ZT, G4double b, G4double bmin)
257{
258//
259// This is a cheaky little member function to calculate the probability of
260// EMD for the target in the field of the projectile ... just by reversing the
261// A and Z's for the participants.
262//
263  return GetCrossSectionForProjectile (AT, ZT, AP, ZP, b, bmin);
264}
265
266
267G4double
268G4EMDissociationCrossSection::GetWilsonProbabilityForProtonDissociation(G4double A,
269                                                                        G4double Z)
270{
271//
272// This is a simple algorithm to choose whether a proton or neutron is ejected
273// from the nucleus in the EMD interaction.
274//
275  G4double p = 0.0;
276  if (Z < 6.0)
277    p = 0.5;
278  else if (Z < 8.0)
279    p = 0.6;
280  else if (Z < 14.0)
281    p = 0.7;
282  else
283  {
284    G4double p1 = (G4double) Z / (G4double) A;
285    G4double p2 = 1.95*std::exp(-0.075*Z);
286    if (p1 < p2) p = p1;
287    else         p = p2;
288  }
289
290  return p;
291}
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