Moved Tao's code to TaoLEMuSR.

geant4/TaoLEMuSR/include/LEMuSRMuonDecayChannel.hh

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+//$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$//*
+//             LOW ENERGY MUON SPIN RELAXATION, ROTATION, RADIATION   Geant4 SIMULATION
+//  ID    : LEMuSRMuonDecayChannel.hh , v 1.0
+//  AUTHOR: Taofiq PARAISO based on G4MuonDecayChannel $Id$
+//  DATE  : 2004-07-13 11:15
+//                   
+//$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$//
+//
+//  &           &&&&&&&&&&                            &&&&&&&         &&&&&&&&
+//  &           &                                   &&      &&       &       &&
+//  &           &                   &      &       &                &       &&
+//  &           &&&&&&&            &      &         &&&&&&         &&&&&&&&  
+//  &           &                 &      &&                &      &      &&
+//  &           &                &&     &  &     &&      &&      &        &
+//  &&&&&&&&&&  &&&&&&&&&&      &  &&&&&    &&    &&&&&&&       &        &&   
+//                             &
+//                            &
+//                           &
+//                         &  
+//                          MUON DECAY CHANNEL.HH
+//$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$//
+
+/**
+ * The LEMuSRMuonDecayChannel class contains the implementation of the asymmetric muon decay. The process is applicable to muon (positive or negative) and muonium.
+ *
+ * It was inspired from the G4MuonDecayChannel method, which did not take into account the spin polarization of the muon.
+ * 
+ * One should notice that recent versions of Geant4 feature a G4MuonDecayChannelWithSpin class, whose role is identical to the class we are describing.
+ * 
+ * The two caracteristics of this process are 
+ * - The Michel spectrum for e+ energy distribution
+ *   \image html michel.gif Michel's Spectrum.
+ * - The cardioidal angular distribution as a function of the positron energy
+ *   \image html kardio.gif Cardioid.
+ * .
+ * The angular direction of the positron emission is in relation with the energy of 
+ * the positron. 
+ * The more energy the positron has, the smaller the angle of emission with respect 
+ * to the muon spin is. The V-A theory predicts the positron rate to be
+ * \f[ \mbox{d}\Gamma^2(w,\theta)= \frac{1}{\tau n(w)\left[1+ D(w)cos\theta \right]}\mbox{d}w \mbox{d}(\cos \theta),\f]
+ * \f$w\f$ being the ratio between the energy of the emitted positron and the 
+ * maximal energy, and \f$\theta\f$ the angle between the muon spin and the 
+ * positron momentum.
+ * 
+ * The distribution \f$n(w)\f$ along energy is given by the Michel's spectrum 
+ * \f[ n(w)= w^2(3-2w)\f] and the asymmetric factor is given by 
+ * \f[D(w) = \frac{2w-1}{3-2w}.\f] We assume, here, that the muons are fully 
+ * polarized. 
+ *
+ * The distribution along energies becomes, for \f$\Theta=0\f$, 
+ * \f[n(w)+n(w)D(w)= 2w^2\f]
+ * and for \f$\Theta = \pi\f$, 
+ * \f[n(w)-n(w)D(w)= 4(w^2-w^3)\f]
+ *
+ * The asymmetry can be derived integrating the rate \f$d\Gamma^2\f$, 
+ * and one should get
+ * \f[A(w_{min}, \Theta_0) = \frac{1+\cos\Theta_0}{6}\frac{1+2w_{min}^3-3w_{min}^4}{1-2w_{min}^3+w_{min}^4}\f]
+ * where \f$\Theta_0\f$ is the opening angle of the solid angle.
+ * This means that if one select all positron energies, \f$w_{min}\simeq 0\f$
+ * - \f$A \simeq\frac{1}{3}\f$ for small solid angles
+ * - \f$A \simeq\frac{1}{6}\f$ for large solid angles
+
+ */
+
+#ifndef LEMuSRMuonDecayChannel_h
+#define LEMuSRMuonDecayChannel_h 1
+
+
+#include "G4ios.hh"
+#include "globals.hh"
+#include "G4VDecayChannel.hh"
+#include "G4DynamicParticle.hh"
+#include "Randomize.hh"
+#include "G4ThreeVector.hh"
+#include "G4Transform3D.hh"
+
+class LEMuSRMuonDecayChannel : public G4VDecayChannel
+{
+
+  // Class Decription
+
+public:  
+  //!Constructor. 
+  LEMuSRMuonDecayChannel(const G4String& theParentName,
+		     G4double        theBR);
+  //! Destructor.
+  ~LEMuSRMuonDecayChannel();
+  
+ static LEMuSRMuonDecayChannel* pointer;
+ static LEMuSRMuonDecayChannel* GetInstance();
+
+
+void   finalize();
+
+public:  // With Description
+  //! \mm
+  virtual G4DecayProducts *DecayIt(G4double);     
+  HepRandomEngine* theEngine;
+  G4ThreeVector emomdir;  
+
+  //! Angles.
+  G4double alpha,sinalpha, cosalpha, delta, sindelta, cosdelta;
+  //! Sines and cosines.
+  G4double costheta, sintheta, phi, sinphi, cosphi, theta; 
+
+  inline G4double GetTheta(){return theta;};
+  inline G4double GetPhi(){return phi;};
+ 
+
+  //! Polarized decay
+  /*!
+   * Gets the muon polarization and launch the Decay it method. 
+  */
+  G4DecayProducts *DecayItPolarized(G4double,G4ThreeVector polar);
+
+
+private:
+
+ 
+};
+
+#endif