| Geant4 Cross Reference |
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 *
8 // * LICENSE and available at http://cern.ch/geant4/license . These *
9 // * include a list of copyright holders. *
10 // * *
11 // * Neither the authors of this software system, nor their employing *
12 // * institutes,nor the agencies providing financial support for this *
13 // * work make any representation or warranty, express or implied, *
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 *
22 // * use in resulting scientific publications, and indicate your *
23 // * acceptance of all terms of the Geant4 Software license. *
24 // ********************************************************************
25 //
26 // INCL++ intra-nuclear cascade model
27 // Alain Boudard, CEA-Saclay, France
28 // Joseph Cugnon, University of Liege, Belgium
29 // Jean-Christophe David, CEA-Saclay, France
30 // Pekka Kaitaniemi, CEA-Saclay, France, and Helsinki Institute of Physics, Finland
31 // Sylvie Leray, CEA-Saclay, France
32 // Davide Mancusi, CEA-Saclay, France
33 //
34 #define INCLXX_IN_GEANT4_MODE 1
35
36 #include "globals.hh"
37
38 /** \file G4INCLCoulombNonRelativistic.hh
39 * \brief Class for non-relativistic Coulomb distortion.
40 *
41 * \date 14 February 2011
42 * \author Davide Mancusi
43 */
44
45 #ifndef G4INCLCOULOMBNONRELATIVISTIC_HH_
46 #define G4INCLCOULOMBNONRELATIVISTIC_HH_
47
48 #include "G4INCLParticle.hh"
49 #include "G4INCLNucleus.hh"
50 #include "G4INCLICoulomb.hh"
51 #include "G4INCLCoulombNone.hh"
52 #include "G4INCLGlobals.hh"
53
54 namespace G4INCL {
55
56 class CoulombNonRelativistic : public ICoulomb {
57 public:
58 CoulombNonRelativistic() {}
59 virtual ~CoulombNonRelativistic() {}
60
61 /** \brief Modify the momentum of the particle and position it on the
62 * surface of the nucleus.
63 *
64 * This method performs non-relativistic distortion.
65 *
66 * \param p incoming particle
67 * \param n distorting nucleus
68 **/
69 ParticleEntryAvatar *bringToSurface(Particle * const p, Nucleus * const n) const;
70
71 /** \brief Modify the momentum of the incoming cluster and position it on
72 * the surface of the nucleus.
73 *
74 * This method performs non-relativistic distortion. The momenta of the
75 * particles that compose the cluster are also distorted.
76 *
77 * \param c incoming cluster
78 * \param n distorting nucleus
79 **/
80 IAvatarList bringToSurface(Cluster * const c, Nucleus * const n) const;
81
82 /** \brief Modify the momenta of the outgoing particles.
83 *
84 * This method performs non-relativistic distortion.
85 *
86 * \param pL list of outgoing particles
87 * \param n distorting nucleus
88 */
89 void distortOut(ParticleList const &pL, Nucleus const * const n) const;
90
91 /** \brief Return the maximum impact parameter for Coulomb-distorted
92 * trajectories. **/
93 G4double maxImpactParameter(ParticleSpecies const &p, const G4double kinE, Nucleus const *
94 const n) const;
95
96 private:
97 /// \brief Return the minimum distance of approach in a head-on collision (b=0).
98 G4double minimumDistance(ParticleSpecies const &p, const G4double kineticEnergy, Nucleus const * const n) const {
99 const G4double particleMass = ParticleTable::getTableSpeciesMass(p);
100 const G4double nucleusMass = n->getTableMass();
101 const G4double reducedMass = particleMass*nucleusMass/(particleMass+nucleusMass);
102 const G4double kineticEnergyInCM = kineticEnergy * reducedMass / particleMass;
103 const G4double theMinimumDistance = ( kineticEnergyInCM <= 0.0 ? 0.0 :
104 PhysicalConstants::eSquared * p.theZ * n->getZ() * particleMass
105 / (kineticEnergyInCM * reducedMass) );
106 INCL_DEBUG("Minimum distance of approach due to Coulomb = " << theMinimumDistance << '\n');
107 return theMinimumDistance;
108 }
109
110 /// \brief Return the minimum distance of approach in a head-on collision (b=0).
111 G4double minimumDistance(Particle const * const p, Nucleus const * const n) const {
112 return minimumDistance(p->getSpecies(), p->getKineticEnergy(), n);
113 }
114
115 /** \brief Perform Coulomb deviation
116 *
117 * Modifies the entrance angle of the particle and its impact parameter.
118 * Can be applied to Particles and Clusters.
119 *
120 * The trajectory for an asymptotic impact parameter \f$b\f$ is
121 * parametrised as follows:
122 * \f[
123 * r(\theta) = \frac{(1-e^2)r_0/2}{1-e \sin(\theta-\theta_R/2)},
124 * \f]
125 * here \f$e\f$ is the hyperbola eccentricity:
126 * \f[
127 * e = \sqrt{1+4b^2/r_0^2};
128 * \f]
129 * \f$\theta_R\f$ is the Rutherford scattering angle:
130 * \f[
131 * \theta_R = \pi - 2\arctan\left(\frac{2b}{r_0}\right)
132 * \f]
133 * \f$\theta\f$ ranges from \f$\pi\f$ (initial state) to \f$\theta_R\f$
134 * (scattered particle) and \f$r_0\f$ is the minimum distance of approach
135 * in a head-on collision (see the minimumDistance() method).
136 *
137 * \param p pointer to the Particle
138 * \param n pointer to the Nucleus
139 * \return false if below the barrier
140 */
141 G4bool coulombDeviation(Particle * const p, Nucleus const * const n) const;
142
143 /** \brief Get the Coulomb radius for a given particle
144 *
145 * That's the radius of the sphere that the Coulomb trajectory of the
146 * incoming particle should intersect. The intersection point is used to
147 * determine the effective impact parameter of the trajectory and the new
148 * entrance angle.
149 *
150 * If the particle is not a Cluster, the Coulomb radius reduces to the
151 * surface radius. We use a parametrisation for d, t, He3 and alphas. For
152 * heavier clusters we fall back to the surface radius.
153 *
154 * \param p the particle species
155 * \param n the deflecting nucleus
156 * \return Coulomb radius
157 */
158 G4double getCoulombRadius(ParticleSpecies const &p, Nucleus const * const n) const;
159
160 /// \brief Internal CoulombNone slave to generate the avatars
161 CoulombNone theCoulombNoneSlave;
162 };
163 }
164
165 #endif /* G4INCLCOULOMBNONRELATIVISTIC_HH_ */
166