source: trunk/source/processes/electromagnetic/xrays/src/G4SynchrotronRadiation.cc@ 1339

Last change on this file since 1339 was 1337, checked in by garnier, 15 years ago

tag geant4.9.4 beta 1 + modifs locales
File size: 15.3 KB
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1//
2// ********************************************************************
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4// * *
5// * The Geant4 software is copyright of the Copyright Holders of *
6// * the Geant4 Collaboration. It is provided under the terms and *
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14// * regarding this software system or assume any liability for its *
15// * use. Please see the license in the file LICENSE and URL above *
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17// * *
18// * This code implementation is the result of the scientific and *
19// * technical work of the GEANT4 collaboration. *
20// * By using, copying, modifying or distributing the software (or *
21// * any work based on the software) you agree to acknowledge its *
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23// * acceptance of all terms of the Geant4 Software license. *
24// ********************************************************************
25//
26//
27// $Id: G4SynchrotronRadiation.cc,v 1.6 2010/06/16 15:34:15 gcosmo Exp $
28// GEANT4 tag $Name: geant4-09-04-beta-01 $
29//
30// --------------------------------------------------------------
31// GEANT 4 class implementation file
32// CERN Geneva Switzerland
33//
34// History: first implementation,
35// 21-5-98 V.Grichine
36// 28-05-01, V.Ivanchenko minor changes to provide ANSI -wall compilation
37// 04.03.05, V.Grichine: get local field interface
38// 18-05-06 H. Burkhardt: Energy spectrum from function rather than table
39//
40//
41//
42//
43///////////////////////////////////////////////////////////////////////////
44
45#include "G4SynchrotronRadiation.hh"
46#include "G4UnitsTable.hh"
47
48///////////////////////////////////////////////////////////////////////
49//
50// Constructor
51//
52
53G4SynchrotronRadiation::G4SynchrotronRadiation(const G4String& processName,
54 G4ProcessType type):G4VDiscreteProcess (processName, type),
55 theGamma (G4Gamma::Gamma() ),
56 theElectron ( G4Electron::Electron() ),
57 thePositron ( G4Positron::Positron() )
58{
59 G4TransportationManager* transportMgr =
60 G4TransportationManager::GetTransportationManager();
61
62 fFieldPropagator = transportMgr->GetPropagatorInField();
63
64 fLambdaConst = std::sqrt(3.0)*electron_mass_c2/
65 (2.5*fine_structure_const*eplus*c_light) ;
66 fEnergyConst = 1.5*c_light*c_light*eplus*hbar_Planck/electron_mass_c2 ;
67 verboseLevel=1;
68}
69
70/////////////////////////////////////////////////////////////////////////
71//
72// Destructor
73//
74
75G4SynchrotronRadiation::~G4SynchrotronRadiation()
76{
77 ;
78}
79
80/////////////////////////////// METHODS /////////////////////////////////
81//
82//
83// Production of synchrotron X-ray photon
84// GEANT4 internal units.
85//
86
87
88G4double
89G4SynchrotronRadiation::GetMeanFreePath( const G4Track& trackData,
90 G4double,
91 G4ForceCondition* condition)
92{
93 // gives the MeanFreePath in GEANT4 internal units
94 G4double MeanFreePath;
95
96 const G4DynamicParticle* aDynamicParticle = trackData.GetDynamicParticle();
97
98 *condition = NotForced ;
99
100 G4double gamma = aDynamicParticle->GetTotalEnergy()/
101 aDynamicParticle->GetMass();
102
103 G4double particleCharge = aDynamicParticle->GetDefinition()->GetPDGCharge();
104
105 if ( gamma < 1.0e3 ) MeanFreePath = DBL_MAX;
106 else
107 {
108
109 G4ThreeVector FieldValue;
110 const G4Field* pField = 0;
111
112 G4FieldManager* fieldMgr=0;
113 G4bool fieldExertsForce = false;
114
115 if( (particleCharge != 0.0) )
116 {
117 fieldMgr = fFieldPropagator->FindAndSetFieldManager( trackData.GetVolume() );
118
119 if ( fieldMgr != 0 )
120 {
121 // If the field manager has no field, there is no field !
122
123 fieldExertsForce = ( fieldMgr->GetDetectorField() != 0 );
124 }
125 }
126 if ( fieldExertsForce )
127 {
128 pField = fieldMgr->GetDetectorField() ;
129 G4ThreeVector globPosition = trackData.GetPosition();
130
131 G4double globPosVec[3], FieldValueVec[3];
132
133 globPosVec[0] = globPosition.x();
134 globPosVec[1] = globPosition.y();
135 globPosVec[2] = globPosition.z();
136
137 pField->GetFieldValue( globPosVec, FieldValueVec );
138
139 FieldValue = G4ThreeVector( FieldValueVec[0],
140 FieldValueVec[1],
141 FieldValueVec[2] );
142
143
144
145 G4ThreeVector unitMomentum = aDynamicParticle->GetMomentumDirection();
146 G4ThreeVector unitMcrossB = FieldValue.cross(unitMomentum) ;
147 G4double perpB = unitMcrossB.mag() ;
148
149 if( perpB > 0.0 ) MeanFreePath = fLambdaConst/perpB;
150 else MeanFreePath = DBL_MAX;
151
152 static G4bool FirstTime=true;
153 if(verboseLevel > 0 && FirstTime)
154 {
155 G4cout << "G4SynchrotronRadiation::GetMeanFreePath :" << '\n' << std::setprecision(4)
156 << " MeanFreePath = " << G4BestUnit(MeanFreePath, "Length")
157 << G4endl;
158 if(verboseLevel > 1)
159 {
160 G4ThreeVector pvec=aDynamicParticle->GetMomentum();
161 G4double Btot=FieldValue.getR();
162 G4double ptot=pvec.getR();
163 G4double rho= ptot / (MeV * c_light * Btot ); // full bending radius
164 G4double Theta=unitMomentum.theta(FieldValue); // angle between particle and field
165 G4cout
166 << " B = " << Btot/tesla << " Tesla"
167 << " perpB = " << perpB/tesla << " Tesla"
168 << " Theta = " << Theta << " std::sin(Theta)=" << std::sin(Theta) << '\n'
169 << " ptot = " << G4BestUnit(ptot,"Energy")
170 << " rho = " << G4BestUnit(rho,"Length")
171 << G4endl;
172 }
173 FirstTime=false;
174 }
175 }
176 else MeanFreePath = DBL_MAX;
177
178
179 }
180
181 return MeanFreePath;
182}
183
184////////////////////////////////////////////////////////////////////////////////
185//
186//
187
188G4VParticleChange*
189G4SynchrotronRadiation::PostStepDoIt(const G4Track& trackData,
190 const G4Step& stepData )
191
192{
193 aParticleChange.Initialize(trackData);
194
195 const G4DynamicParticle* aDynamicParticle=trackData.GetDynamicParticle();
196
197 G4double gamma = aDynamicParticle->GetTotalEnergy()/
198 (aDynamicParticle->GetMass() );
199
200 if(gamma <= 1.0e3 )
201 {
202 return G4VDiscreteProcess::PostStepDoIt(trackData,stepData);
203 }
204 G4double particleCharge = aDynamicParticle->GetDefinition()->GetPDGCharge();
205
206 G4ThreeVector FieldValue;
207 const G4Field* pField = 0 ;
208
209 G4FieldManager* fieldMgr=0;
210 G4bool fieldExertsForce = false;
211
212 if( (particleCharge != 0.0) )
213 {
214 fieldMgr = fFieldPropagator->FindAndSetFieldManager( trackData.GetVolume() );
215 if ( fieldMgr != 0 )
216 {
217 // If the field manager has no field, there is no field !
218
219 fieldExertsForce = ( fieldMgr->GetDetectorField() != 0 );
220 }
221 }
222 if ( fieldExertsForce )
223 {
224 pField = fieldMgr->GetDetectorField() ;
225 G4ThreeVector globPosition = trackData.GetPosition() ;
226 G4double globPosVec[3], FieldValueVec[3] ;
227 globPosVec[0] = globPosition.x() ;
228 globPosVec[1] = globPosition.y() ;
229 globPosVec[2] = globPosition.z() ;
230
231 pField->GetFieldValue( globPosVec, FieldValueVec ) ;
232 FieldValue = G4ThreeVector( FieldValueVec[0],
233 FieldValueVec[1],
234 FieldValueVec[2] );
235
236 G4ThreeVector unitMomentum = aDynamicParticle->GetMomentumDirection();
237 G4ThreeVector unitMcrossB = FieldValue.cross(unitMomentum);
238 G4double perpB = unitMcrossB.mag() ;
239 if(perpB > 0.0)
240 {
241 // M-C of synchrotron photon energy
242
243 G4double energyOfSR = GetRandomEnergySR(gamma,perpB);
244
245 // check against insufficient energy
246
247 if( energyOfSR <= 0.0 )
248 {
249 return G4VDiscreteProcess::PostStepDoIt(trackData,stepData);
250 }
251 G4double kineticEnergy = aDynamicParticle->GetKineticEnergy();
252 G4ParticleMomentum
253 particleDirection = aDynamicParticle->GetMomentumDirection();
254
255 // M-C of its direction
256
257 G4double Teta = G4UniformRand()/gamma ; // Very roughly
258
259 G4double Phi = twopi * G4UniformRand() ;
260
261 G4double dirx = std::sin(Teta)*std::cos(Phi) ,
262 diry = std::sin(Teta)*std::sin(Phi) ,
263 dirz = std::cos(Teta) ;
264
265 G4ThreeVector gammaDirection ( dirx, diry, dirz);
266 gammaDirection.rotateUz(particleDirection);
267
268 // polarization of new gamma
269
270 // G4double sx = std::cos(Teta)*std::cos(Phi);
271 // G4double sy = std::cos(Teta)*std::sin(Phi);
272 // G4double sz = -std::sin(Teta);
273
274 G4ThreeVector gammaPolarization = FieldValue.cross(gammaDirection);
275 gammaPolarization = gammaPolarization.unit();
276
277 // (sx, sy, sz);
278 // gammaPolarization.rotateUz(particleDirection);
279
280 // create G4DynamicParticle object for the SR photon
281
282 G4DynamicParticle* aGamma= new G4DynamicParticle ( theGamma,
283 gammaDirection,
284 energyOfSR );
285 aGamma->SetPolarization( gammaPolarization.x(),
286 gammaPolarization.y(),
287 gammaPolarization.z() );
288
289
290 aParticleChange.SetNumberOfSecondaries(1);
291 aParticleChange.AddSecondary(aGamma);
292
293 // Update the incident particle
294
295 G4double newKinEnergy = kineticEnergy - energyOfSR ;
296 aParticleChange.ProposeLocalEnergyDeposit (0.);
297
298 if (newKinEnergy > 0.)
299 {
300 aParticleChange.ProposeMomentumDirection( particleDirection );
301 aParticleChange.ProposeEnergy( newKinEnergy );
302 }
303 else
304 {
305 aParticleChange.ProposeEnergy( 0. );
306 }
307 }
308 }
309 return G4VDiscreteProcess::PostStepDoIt(trackData,stepData);
310}
311
312
313/////////////////////////////////////////////////////////////////////////////////
314//
315//
316
317G4double G4SynchrotronRadiation::InvSynFracInt(G4double x)
318// direct generation
319{
320 // from 0 to 0.7
321 const G4double aa1=0 ,aa2=0.7;
322 const G4int ncheb1=27;
323 static const G4double cheb1[] =
324 { 1.22371665676046468821,0.108956475422163837267,0.0383328524358594396134,0.00759138369340257753721,
325 0.00205712048644963340914,0.000497810783280019308661,0.000130743691810302187818,0.0000338168760220395409734,
326 8.97049680900520817728e-6,2.38685472794452241466e-6,6.41923109149104165049e-7,1.73549898982749277843e-7,
327 4.72145949240790029153e-8,1.29039866111999149636e-8,3.5422080787089834182e-9,9.7594757336403784905e-10,
328 2.6979510184976065731e-10,7.480422622550977077e-11,2.079598176402699913e-11,5.79533622220841193e-12,
329 1.61856011449276096e-12,4.529450993473807e-13,1.2698603951096606e-13,3.566117394511206e-14,1.00301587494091e-14,
330 2.82515346447219e-15,7.9680747949792e-16};
331 // from 0.7 to 0.9132260271183847
332 const G4double aa3=0.9132260271183847;
333 const G4int ncheb2=27;
334 static const G4double cheb2[] =
335 { 1.1139496701107756,0.3523967429328067,0.0713849171926623,0.01475818043595387,0.003381255637322462,
336 0.0008228057599452224,0.00020785506681254216,0.00005390169253706556,0.000014250571923902464,3.823880733161044e-6,
337 1.0381966089136036e-6,2.8457557457837253e-7,7.86223332179956e-8,2.1866609342508474e-8,6.116186259857143e-9,
338 1.7191233618437565e-9,4.852755117740807e-10,1.3749966961763457e-10,3.908961987062447e-11,1.1146253766895824e-11,
339 3.1868887323415814e-12,9.134319791300977e-13,2.6211077371181566e-13,7.588643377757906e-14,2.1528376972619e-14,
340 6.030906040404772e-15,1.9549163926819867e-15};
341 // Chebyshev with exp/log scale
342 // a = -Log[1 - SynFracInt[1]]; b = -Log[1 - SynFracInt[7]];
343 const G4double aa4=2.4444485538746025480,aa5=9.3830728608909477079;
344 const G4int ncheb3=28;
345 static const G4double cheb3[] =
346 { 1.2292683840435586977,0.160353449247864455879,-0.0353559911947559448721,0.00776901561223573936985,
347 -0.00165886451971685133259,0.000335719118906954279467,-0.0000617184951079161143187,9.23534039743246708256e-6,
348 -6.06747198795168022842e-7,-3.07934045961999778094e-7,1.98818772614682367781e-7,-8.13909971567720135413e-8,
349 2.84298174969641838618e-8,-9.12829766621316063548e-9,2.77713868004820551077e-9,-8.13032767247834023165e-10,
350 2.31128525568385247392e-10,-6.41796873254200220876e-11,1.74815310473323361543e-11,-4.68653536933392363045e-12,
351 1.24016595805520752748e-12,-3.24839432979935522159e-13,8.44601465226513952994e-14,-2.18647276044246803998e-14,
352 5.65407548745690689978e-15,-1.46553625917463067508e-15,3.82059606377570462276e-16,-1.00457896653436912508e-16};
353 const G4double aa6=33.122936966163038145;
354 const G4int ncheb4=27;
355 static const G4double cheb4[] =
356 {1.69342658227676741765,0.0742766400841232319225,-0.019337880608635717358,0.00516065527473364110491,
357 -0.00139342012990307729473,0.000378549864052022522193,-0.000103167085583785340215,0.0000281543441271412178337,
358 -7.68409742018258198651e-6,2.09543221890204537392e-6,-5.70493140367526282946e-7,1.54961164548564906446e-7,
359 -4.19665599629607704794e-8,1.13239680054166507038e-8,-3.04223563379021441863e-9,8.13073745977562957997e-10,
360 -2.15969415476814981374e-10,5.69472105972525594811e-11,-1.48844799572430829499e-11,3.84901514438304484973e-12,
361 -9.82222575944247161834e-13,2.46468329208292208183e-13,-6.04953826265982691612e-14,1.44055805710671611984e-14,
362 -3.28200813577388740722e-15,6.96566359173765367675e-16,-1.294122794852896275e-16};
363
364 if(x<aa2) return x*x*x*Chebyshev(aa1,aa2,cheb1,ncheb1,x);
365 else if(x<aa3) return Chebyshev(aa2,aa3,cheb2,ncheb2,x);
366 else if(x<1-0.0000841363)
367 { G4double y=-std::log(1-x);
368 return y*Chebyshev(aa4,aa5,cheb3,ncheb3,y);
369 }
370 else
371 { G4double y=-std::log(1-x);
372 return y*Chebyshev(aa5,aa6,cheb4,ncheb4,y);
373 }
374}
375
376G4double G4SynchrotronRadiation::GetRandomEnergySR(G4double gamma, G4double perpB)
377{
378
379 G4double Ecr=fEnergyConst*gamma*gamma*perpB;
380
381 static G4bool FirstTime=true;
382 if(verboseLevel > 0 && FirstTime)
383 { G4double Emean=8./(15.*std::sqrt(3.))*Ecr; // mean photon energy
384 G4double E_rms=std::sqrt(211./675.)*Ecr; // rms of photon energy distribution
385 G4cout << "G4SynchrotronRadiation::GetRandomEnergySR :" << '\n' << std::setprecision(4)
386 << " Ecr = " << G4BestUnit(Ecr,"Energy") << '\n'
387 << " Emean = " << G4BestUnit(Emean,"Energy") << '\n'
388 << " E_rms = " << G4BestUnit(E_rms,"Energy") << G4endl;
389 FirstTime=false;
390 }
391
392 G4double energySR=Ecr*InvSynFracInt(G4UniformRand());
393 return energySR;
394}
395
396
397void G4SynchrotronRadiation::BuildPhysicsTable(const G4ParticleDefinition& part)
398{
399 if(0 < verboseLevel && &part==theElectron ) PrintInfoDefinition();
400}
401
402void G4SynchrotronRadiation::PrintInfoDefinition() // not yet called, usually called from BuildPhysicsTable
403{
404 G4String comments ="Incoherent Synchrotron Radiation\n";
405 G4cout << G4endl << GetProcessName() << ": " << comments
406 << " good description for long magnets at all energies" << G4endl;
407}
408
409///////////////////// end of G4SynchrotronRadiation.cc
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