source: trunk/source/processes/electromagnetic/xrays/src/G4SynchrotronRadiation.cc@ 1036

Last change on this file since 1036 was 1007, checked in by garnier, 17 years ago

update to geant4.9.2
File size: 15.2 KB
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1//
2// ********************************************************************
3// * License and Disclaimer *
4// * *
5// * The Geant4 software is copyright of the Copyright Holders of *
6// * the Geant4 Collaboration. It is provided under the terms and *
7// * conditions of the Geant4 Software License, included in the file *
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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 *
16// * for the full disclaimer and the limitation of liability. *
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 1.5 2006/06/29 19:56:15 gunter Exp $
28// GEANT4 tag $Name: geant4-09-02 $
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 "G4Integrator.hh"
47#include "G4UnitsTable.hh"
48
49using namespace std;
50
51///////////////////////////////////////////////////////////////////////
52//
53// Constructor
54//
55
56G4SynchrotronRadiation::G4SynchrotronRadiation(const G4String& processName,
57 G4ProcessType type):G4VDiscreteProcess (processName, type),
58 theGamma (G4Gamma::Gamma() ),
59 theElectron ( G4Electron::Electron() ),
60 thePositron ( G4Positron::Positron() )
61{
62 G4TransportationManager* transportMgr =
63 G4TransportationManager::GetTransportationManager();
64
65 fFieldPropagator = transportMgr->GetPropagatorInField();
66
67 fLambdaConst = sqrt(3.0)*electron_mass_c2/
68 (2.5*fine_structure_const*eplus*c_light) ;
69 fEnergyConst = 1.5*c_light*c_light*eplus*hbar_Planck/electron_mass_c2 ;
70 verboseLevel=1;
71}
72
73/////////////////////////////////////////////////////////////////////////
74//
75// Destructor
76//
77
78G4SynchrotronRadiation::~G4SynchrotronRadiation()
79{
80 ;
81}
82
83/////////////////////////////// METHODS /////////////////////////////////
84//
85//
86// Production of synchrotron X-ray photon
87// GEANT4 internal units.
88//
89
90
91G4double
92G4SynchrotronRadiation::GetMeanFreePath( const G4Track& trackData,
93 G4double,
94 G4ForceCondition* condition)
95{
96 // gives the MeanFreePath in GEANT4 internal units
97 G4double MeanFreePath;
98
99 const G4DynamicParticle* aDynamicParticle = trackData.GetDynamicParticle();
100
101 *condition = NotForced ;
102
103 G4double gamma = aDynamicParticle->GetTotalEnergy()/
104 aDynamicParticle->GetMass();
105
106 G4double particleCharge = aDynamicParticle->GetDefinition()->GetPDGCharge();
107
108 if ( gamma < 1.0e3 ) MeanFreePath = DBL_MAX;
109 else
110 {
111
112 G4ThreeVector FieldValue;
113 const G4Field* pField = 0;
114
115 G4FieldManager* fieldMgr=0;
116 G4bool fieldExertsForce = false;
117
118 if( (particleCharge != 0.0) )
119 {
120 fieldMgr = fFieldPropagator->FindAndSetFieldManager( trackData.GetVolume() );
121
122 if ( fieldMgr != 0 )
123 {
124 // If the field manager has no field, there is no field !
125
126 fieldExertsForce = ( fieldMgr->GetDetectorField() != 0 );
127 }
128 }
129 if ( fieldExertsForce )
130 {
131 pField = fieldMgr->GetDetectorField() ;
132 G4ThreeVector globPosition = trackData.GetPosition();
133
134 G4double globPosVec[3], FieldValueVec[3];
135
136 globPosVec[0] = globPosition.x();
137 globPosVec[1] = globPosition.y();
138 globPosVec[2] = globPosition.z();
139
140 pField->GetFieldValue( globPosVec, FieldValueVec );
141
142 FieldValue = G4ThreeVector( FieldValueVec[0],
143 FieldValueVec[1],
144 FieldValueVec[2] );
145
146
147
148 G4ThreeVector unitMomentum = aDynamicParticle->GetMomentumDirection();
149 G4ThreeVector unitMcrossB = FieldValue.cross(unitMomentum) ;
150 G4double perpB = unitMcrossB.mag() ;
151
152 if( perpB > 0.0 ) MeanFreePath = fLambdaConst/perpB;
153 else MeanFreePath = DBL_MAX;
154
155 static G4bool FirstTime=true;
156 if(verboseLevel > 0 && FirstTime)
157 {
158 G4cout << "G4SynchrotronRadiation::GetMeanFreePath :" << '\n' << std::setprecision(4)
159 << " MeanFreePath = " << G4BestUnit(MeanFreePath, "Length")
160 << G4endl;
161 if(verboseLevel > 1)
162 {
163 G4ThreeVector pvec=aDynamicParticle->GetMomentum();
164 G4double Btot=FieldValue.getR();
165 G4double ptot=pvec.getR();
166 G4double rho= ptot / (MeV * c_light * Btot ); // full bending radius
167 G4double Theta=unitMomentum.theta(FieldValue); // angle between particle and field
168 G4cout
169 << " B = " << Btot/tesla << " Tesla"
170 << " perpB = " << perpB/tesla << " Tesla"
171 << " Theta = " << Theta << " sin(Theta)=" << sin(Theta) << '\n'
172 << " ptot = " << G4BestUnit(ptot,"Energy")
173 << " rho = " << G4BestUnit(rho,"Length")
174 << G4endl;
175 }
176 FirstTime=false;
177 }
178 }
179 else MeanFreePath = DBL_MAX;
180
181
182 }
183
184 return MeanFreePath;
185}
186
187////////////////////////////////////////////////////////////////////////////////
188//
189//
190
191G4VParticleChange*
192G4SynchrotronRadiation::PostStepDoIt(const G4Track& trackData,
193 const G4Step& stepData )
194
195{
196 aParticleChange.Initialize(trackData);
197
198 const G4DynamicParticle* aDynamicParticle=trackData.GetDynamicParticle();
199
200 G4double gamma = aDynamicParticle->GetTotalEnergy()/
201 (aDynamicParticle->GetMass() );
202
203 if(gamma <= 1.0e3 )
204 {
205 return G4VDiscreteProcess::PostStepDoIt(trackData,stepData);
206 }
207 G4double particleCharge = aDynamicParticle->GetDefinition()->GetPDGCharge();
208
209 G4ThreeVector FieldValue;
210 const G4Field* pField = 0 ;
211
212 G4FieldManager* fieldMgr=0;
213 G4bool fieldExertsForce = false;
214
215 if( (particleCharge != 0.0) )
216 {
217 fieldMgr = fFieldPropagator->FindAndSetFieldManager( trackData.GetVolume() );
218 if ( fieldMgr != 0 )
219 {
220 // If the field manager has no field, there is no field !
221
222 fieldExertsForce = ( fieldMgr->GetDetectorField() != 0 );
223 }
224 }
225 if ( fieldExertsForce )
226 {
227 pField = fieldMgr->GetDetectorField() ;
228 G4ThreeVector globPosition = trackData.GetPosition() ;
229 G4double globPosVec[3], FieldValueVec[3] ;
230 globPosVec[0] = globPosition.x() ;
231 globPosVec[1] = globPosition.y() ;
232 globPosVec[2] = globPosition.z() ;
233
234 pField->GetFieldValue( globPosVec, FieldValueVec ) ;
235 FieldValue = G4ThreeVector( FieldValueVec[0],
236 FieldValueVec[1],
237 FieldValueVec[2] );
238
239 G4ThreeVector unitMomentum = aDynamicParticle->GetMomentumDirection();
240 G4ThreeVector unitMcrossB = FieldValue.cross(unitMomentum);
241 G4double perpB = unitMcrossB.mag() ;
242 if(perpB > 0.0)
243 {
244 // M-C of synchrotron photon energy
245
246 G4double energyOfSR = GetRandomEnergySR(gamma,perpB);
247
248 // check against insufficient energy
249
250 if( energyOfSR <= 0.0 )
251 {
252 return G4VDiscreteProcess::PostStepDoIt(trackData,stepData);
253 }
254 G4double kineticEnergy = aDynamicParticle->GetKineticEnergy();
255 G4ParticleMomentum
256 particleDirection = aDynamicParticle->GetMomentumDirection();
257
258 // M-C of its direction
259
260 G4double Teta = G4UniformRand()/gamma ; // Very roughly
261
262 G4double Phi = twopi * G4UniformRand() ;
263
264 G4double dirx = sin(Teta)*cos(Phi) ,
265 diry = sin(Teta)*sin(Phi) ,
266 dirz = cos(Teta) ;
267
268 G4ThreeVector gammaDirection ( dirx, diry, dirz);
269 gammaDirection.rotateUz(particleDirection);
270
271 // polarization of new gamma
272
273 // G4double sx = cos(Teta)*cos(Phi);
274 // G4double sy = cos(Teta)*sin(Phi);
275 // G4double sz = -sin(Teta);
276
277 G4ThreeVector gammaPolarization = FieldValue.cross(gammaDirection);
278 gammaPolarization = gammaPolarization.unit();
279
280 // (sx, sy, sz);
281 // gammaPolarization.rotateUz(particleDirection);
282
283 // create G4DynamicParticle object for the SR photon
284
285 G4DynamicParticle* aGamma= new G4DynamicParticle ( theGamma,
286 gammaDirection,
287 energyOfSR );
288 aGamma->SetPolarization( gammaPolarization.x(),
289 gammaPolarization.y(),
290 gammaPolarization.z() );
291
292
293 aParticleChange.SetNumberOfSecondaries(1);
294 aParticleChange.AddSecondary(aGamma);
295
296 // Update the incident particle
297
298 G4double newKinEnergy = kineticEnergy - energyOfSR ;
299 aParticleChange.ProposeLocalEnergyDeposit (0.);
300
301 if (newKinEnergy > 0.)
302 {
303 aParticleChange.ProposeMomentumDirection( particleDirection );
304 aParticleChange.ProposeEnergy( newKinEnergy );
305 }
306 else
307 {
308 aParticleChange.ProposeEnergy( 0. );
309 }
310 }
311 }
312 return G4VDiscreteProcess::PostStepDoIt(trackData,stepData);
313}
314
315
316/////////////////////////////////////////////////////////////////////////////////
317//
318//
319
320G4double G4SynchrotronRadiation::InvSynFracInt(G4double x)
321// direct generation
322{
323 // from 0 to 0.7
324 const G4double aa1=0 ,aa2=0.7;
325 const G4int ncheb1=27;
326 static const G4double cheb1[] =
327 { 1.22371665676046468821,0.108956475422163837267,0.0383328524358594396134,0.00759138369340257753721,
328 0.00205712048644963340914,0.000497810783280019308661,0.000130743691810302187818,0.0000338168760220395409734,
329 8.97049680900520817728e-6,2.38685472794452241466e-6,6.41923109149104165049e-7,1.73549898982749277843e-7,
330 4.72145949240790029153e-8,1.29039866111999149636e-8,3.5422080787089834182e-9,9.7594757336403784905e-10,
331 2.6979510184976065731e-10,7.480422622550977077e-11,2.079598176402699913e-11,5.79533622220841193e-12,
332 1.61856011449276096e-12,4.529450993473807e-13,1.2698603951096606e-13,3.566117394511206e-14,1.00301587494091e-14,
333 2.82515346447219e-15,7.9680747949792e-16};
334 // from 0.7 to 0.9132260271183847
335 const G4double aa3=0.9132260271183847;
336 const G4int ncheb2=27;
337 static const G4double cheb2[] =
338 { 1.1139496701107756,0.3523967429328067,0.0713849171926623,0.01475818043595387,0.003381255637322462,
339 0.0008228057599452224,0.00020785506681254216,0.00005390169253706556,0.000014250571923902464,3.823880733161044e-6,
340 1.0381966089136036e-6,2.8457557457837253e-7,7.86223332179956e-8,2.1866609342508474e-8,6.116186259857143e-9,
341 1.7191233618437565e-9,4.852755117740807e-10,1.3749966961763457e-10,3.908961987062447e-11,1.1146253766895824e-11,
342 3.1868887323415814e-12,9.134319791300977e-13,2.6211077371181566e-13,7.588643377757906e-14,2.1528376972619e-14,
343 6.030906040404772e-15,1.9549163926819867e-15};
344 // Chebyshev with exp/log scale
345 // a = -Log[1 - SynFracInt[1]]; b = -Log[1 - SynFracInt[7]];
346 const G4double aa4=2.4444485538746025480,aa5=9.3830728608909477079;
347 const G4int ncheb3=28;
348 static const G4double cheb3[] =
349 { 1.2292683840435586977,0.160353449247864455879,-0.0353559911947559448721,0.00776901561223573936985,
350 -0.00165886451971685133259,0.000335719118906954279467,-0.0000617184951079161143187,9.23534039743246708256e-6,
351 -6.06747198795168022842e-7,-3.07934045961999778094e-7,1.98818772614682367781e-7,-8.13909971567720135413e-8,
352 2.84298174969641838618e-8,-9.12829766621316063548e-9,2.77713868004820551077e-9,-8.13032767247834023165e-10,
353 2.31128525568385247392e-10,-6.41796873254200220876e-11,1.74815310473323361543e-11,-4.68653536933392363045e-12,
354 1.24016595805520752748e-12,-3.24839432979935522159e-13,8.44601465226513952994e-14,-2.18647276044246803998e-14,
355 5.65407548745690689978e-15,-1.46553625917463067508e-15,3.82059606377570462276e-16,-1.00457896653436912508e-16};
356 const G4double aa6=33.122936966163038145;
357 const G4int ncheb4=27;
358 static const G4double cheb4[] =
359 {1.69342658227676741765,0.0742766400841232319225,-0.019337880608635717358,0.00516065527473364110491,
360 -0.00139342012990307729473,0.000378549864052022522193,-0.000103167085583785340215,0.0000281543441271412178337,
361 -7.68409742018258198651e-6,2.09543221890204537392e-6,-5.70493140367526282946e-7,1.54961164548564906446e-7,
362 -4.19665599629607704794e-8,1.13239680054166507038e-8,-3.04223563379021441863e-9,8.13073745977562957997e-10,
363 -2.15969415476814981374e-10,5.69472105972525594811e-11,-1.48844799572430829499e-11,3.84901514438304484973e-12,
364 -9.82222575944247161834e-13,2.46468329208292208183e-13,-6.04953826265982691612e-14,1.44055805710671611984e-14,
365 -3.28200813577388740722e-15,6.96566359173765367675e-16,-1.294122794852896275e-16};
366
367 if(x<aa2) return x*x*x*Chebyshev(aa1,aa2,cheb1,ncheb1,x);
368 else if(x<aa3) return Chebyshev(aa2,aa3,cheb2,ncheb2,x);
369 else if(x<1-0.0000841363)
370 { G4double y=-log(1-x);
371 return y*Chebyshev(aa4,aa5,cheb3,ncheb3,y);
372 }
373 else
374 { G4double y=-log(1-x);
375 return y*Chebyshev(aa5,aa6,cheb4,ncheb4,y);
376 }
377}
378
379G4double G4SynchrotronRadiation::GetRandomEnergySR(G4double gamma, G4double perpB)
380{
381
382 G4double Ecr=fEnergyConst*gamma*gamma*perpB;
383
384 static G4bool FirstTime=true;
385 if(verboseLevel > 0 && FirstTime)
386 { G4double Emean=8./(15.*sqrt(3.))*Ecr; // mean photon energy
387 G4double E_rms=sqrt(211./675.)*Ecr; // rms of photon energy distribution
388 G4cout << "G4SynchrotronRadiation::GetRandomEnergySR :" << '\n' << std::setprecision(4)
389 << " Ecr = " << G4BestUnit(Ecr,"Energy") << '\n'
390 << " Emean = " << G4BestUnit(Emean,"Energy") << '\n'
391 << " E_rms = " << G4BestUnit(E_rms,"Energy") << G4endl;
392 FirstTime=false;
393 }
394
395 G4double energySR=Ecr*InvSynFracInt(G4UniformRand());
396 return energySR;
397}
398
399
400void G4SynchrotronRadiation::BuildPhysicsTable(const G4ParticleDefinition& part)
401{
402 if(0 < verboseLevel && &part==theElectron ) PrintInfoDefinition();
403}
404
405void G4SynchrotronRadiation::PrintInfoDefinition() // not yet called, usually called from BuildPhysicsTable
406{
407 G4String comments ="Incoherent Synchrotron Radiation\n";
408 G4cout << G4endl << GetProcessName() << ": " << comments
409 << " good description for long magnets at all energies" << G4endl;
410}
411
412///////////////////// end of G4SynchrotronRadiation.cc
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