include/Geant4/G4INCLCoulombNonRelativistic.hh

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0025 //
0026 // INCL++ intra-nuclear cascade model
0027 // Alain Boudard, CEA-Saclay, France
0028 // Joseph Cugnon, University of Liege, Belgium
0029 // Jean-Christophe David, CEA-Saclay, France
0030 // Pekka Kaitaniemi, CEA-Saclay, France, and Helsinki Institute of Physics, Finland
0031 // Sylvie Leray, CEA-Saclay, France
0032 // Davide Mancusi, CEA-Saclay, France
0033 //
0034 #define INCLXX_IN_GEANT4_MODE 1
0035
0036 #include "globals.hh"
0037
0038 /** \file G4INCLCoulombNonRelativistic.hh
0039  * \brief Class for non-relativistic Coulomb distortion.
0040  *
0041  * \date 14 February 2011
0042  * \author Davide Mancusi
0043  */
0044
0045 #ifndef G4INCLCOULOMBNONRELATIVISTIC_HH_
0046 #define G4INCLCOULOMBNONRELATIVISTIC_HH_
0047
0048 #include "G4INCLParticle.hh"
0049 #include "G4INCLNucleus.hh"
0050 #include "G4INCLICoulomb.hh"
0051 #include "G4INCLCoulombNone.hh"
0052 #include "G4INCLGlobals.hh"
0053
0054 namespace G4INCL {
0055
0056   class CoulombNonRelativistic : public ICoulomb {
0057     public:
0058       CoulombNonRelativistic() {}
0059       virtual ~CoulombNonRelativistic() {}
0060
0061       /** \brief Modify the momentum of the particle and position it on the
0062        *         surface of the nucleus.
0063        *
0064        * This method performs non-relativistic distortion.
0065        *
0066        * \param p incoming particle
0067        * \param n distorting nucleus
0068        **/
0069       ParticleEntryAvatar *bringToSurface(Particle * const p, Nucleus * const n) const;
0070
0071       /** \brief Modify the momentum of the incoming cluster and position it on
0072        *         the surface of the nucleus.
0073        *
0074        * This method performs non-relativistic distortion. The momenta of the
0075        * particles that compose the cluster are also distorted.
0076        *
0077        * \param c incoming cluster
0078        * \param n distorting nucleus
0079        **/
0080       IAvatarList bringToSurface(Cluster * const c, Nucleus * const n) const;
0081
0082       /** \brief Modify the momenta of the outgoing particles.
0083        *
0084        * This method performs non-relativistic distortion.
0085        *
0086        * \param pL list of outgoing particles
0087        * \param n distorting nucleus
0088        */
0089       void distortOut(ParticleList const &pL, Nucleus const * const n) const;
0090
0091       /** \brief Return the maximum impact parameter for Coulomb-distorted
0092        *         trajectories. **/
0093       G4double maxImpactParameter(ParticleSpecies const &p, const G4double kinE, Nucleus const *
0094           const n) const;
0095
0096     private:
0097       /// \brief Return the minimum distance of approach in a head-on collision (b=0).
0098       G4double minimumDistance(ParticleSpecies const &p, const G4double kineticEnergy, Nucleus const * const n) const {
0099         const G4double particleMass = ParticleTable::getTableSpeciesMass(p);
0100         const G4double nucleusMass = n->getTableMass();
0101         const G4double reducedMass = particleMass*nucleusMass/(particleMass+nucleusMass);
0102         const G4double kineticEnergyInCM = kineticEnergy * reducedMass / particleMass;
0103         const G4double theMinimumDistance = ( kineticEnergyInCM <= 0.0 ? 0.0 :
0104                 PhysicalConstants::eSquared * p.theZ * n->getZ() * particleMass
0105                 / (kineticEnergyInCM * reducedMass) );
0106         INCL_DEBUG("Minimum distance of approach due to Coulomb = " << theMinimumDistance << '\n');
0107         return theMinimumDistance;
0108       }
0109
0110       /// \brief Return the minimum distance of approach in a head-on collision (b=0).
0111       G4double minimumDistance(Particle const * const p, Nucleus const * const n) const {
0112         return minimumDistance(p->getSpecies(), p->getKineticEnergy(), n);
0113       }
0114
0115       /** \brief Perform Coulomb deviation
0116        *
0117        * Modifies the entrance angle of the particle and its impact parameter.
0118        * Can be applied to Particles and Clusters.
0119        *
0120        * The trajectory for an asymptotic impact parameter \f$b\f$ is
0121        * parametrised as follows:
0122        * \f[
0123        * r(\theta) = \frac{(1-e^2)r_0/2}{1-e \sin(\theta-\theta_R/2)},
0124        * \f]
0125        * here \f$e\f$ is the hyperbola eccentricity:
0126        * \f[
0127        * e = \sqrt{1+4b^2/r_0^2};
0128        * \f]
0129        * \f$\theta_R\f$ is the Rutherford scattering angle:
0130        * \f[
0131        * \theta_R = \pi - 2\arctan\left(\frac{2b}{r_0}\right)
0132        * \f]
0133        * \f$\theta\f$ ranges from \f$\pi\f$ (initial state) to \f$\theta_R\f$
0134        * (scattered particle) and \f$r_0\f$ is the minimum distance of approach
0135        * in a head-on collision (see the minimumDistance() method).
0136        *
0137        * \param p pointer to the Particle
0138        * \param n pointer to the Nucleus
0139        * \return false if below the barrier
0140        */
0141       G4bool coulombDeviation(Particle * const p, Nucleus const * const n) const;
0142
0143       /** \brief Get the Coulomb radius for a given particle
0144        *
0145        * That's the radius of the sphere that the Coulomb trajectory of the
0146        * incoming particle should intersect. The intersection point is used to
0147        * determine the effective impact parameter of the trajectory and the new
0148        * entrance angle.
0149        *
0150        * If the particle is not a Cluster, the Coulomb radius reduces to the
0151        * surface radius. We use a parametrisation for d, t, He3 and alphas. For
0152        * heavier clusters we fall back to the surface radius.
0153        *
0154        * \param p the particle species
0155        * \param n the deflecting nucleus
0156        * \return Coulomb radius
0157        */
0158       G4double getCoulombRadius(ParticleSpecies const &p, Nucleus const * const n) const;
0159
0160       /// \brief Internal CoulombNone slave to generate the avatars
0161       CoulombNone theCoulombNoneSlave;
0162   };
0163 }
0164
0165 #endif /* G4INCLCOULOMBNONRELATIVISTIC_HH_ */