G4INCLBinaryCollisionAvatar.cc

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//
// INCL++ intra-nuclear cascade model
// Alain Boudard, CEA-Saclay, France
// Joseph Cugnon, University of Liege, Belgium
// Jean-Christophe David, CEA-Saclay, France
// Pekka Kaitaniemi, CEA-Saclay, France, and Helsinki Institute of Physics, Finland
// Sylvie Leray, CEA-Saclay, France
// Davide Mancusi, CEA-Saclay, France
//
#define INCLXX_IN_GEANT4_MODE 1
 
#include "globals.hh"
 
/*
 * G4INCLBinaryCollisionAvatar.cc
 *
 *  \date Jun 5, 2009
 * \author Pekka Kaitaniemi
 */
 
#include "G4INCLBinaryCollisionAvatar.hh"
#include "G4INCLElasticChannel.hh"
#include "G4INCLRecombinationChannel.hh"
#include "G4INCLDeltaProductionChannel.hh"
#include "G4INCLNNToMultiPionsChannel.hh"
#include "G4INCLNNToNNEtaChannel.hh"
#include "G4INCLNDeltaEtaProductionChannel.hh"
#include "G4INCLNNEtaToMultiPionsChannel.hh"
#include "G4INCLNNToNNOmegaChannel.hh"
#include "G4INCLNDeltaOmegaProductionChannel.hh"
#include "G4INCLNNOmegaToMultiPionsChannel.hh"
#include "G4INCLCrossSections.hh"
#include "G4INCLKinematicsUtils.hh"
#include "G4INCLRandom.hh"
#include "G4INCLParticleTable.hh"
#include "G4INCLPauliBlocking.hh"
#include "G4INCLPiNElasticChannel.hh"
#include "G4INCLPiNToDeltaChannel.hh"
#include "G4INCLPiNToMultiPionsChannel.hh"
#include "G4INCLPiNToEtaChannel.hh"
#include "G4INCLPiNToOmegaChannel.hh"
#include "G4INCLEtaNElasticChannel.hh"
#include "G4INCLEtaNToPiNChannel.hh"
#include "G4INCLEtaNToPiPiNChannel.hh"
#include "G4INCLOmegaNElasticChannel.hh"
#include "G4INCLOmegaNToPiNChannel.hh"
#include "G4INCLNNToNLKChannel.hh"
#include "G4INCLNNToNSKChannel.hh"
#include "G4INCLNNToNLKpiChannel.hh"
#include "G4INCLNNToNSKpiChannel.hh"
#include "G4INCLNNToNLK2piChannel.hh"
#include "G4INCLNNToNSK2piChannel.hh"
#include "G4INCLNNToNNKKbChannel.hh"
#include "G4INCLNNToMissingStrangenessChannel.hh"
#include "G4INCLNDeltaToNLKChannel.hh"
#include "G4INCLNDeltaToNSKChannel.hh"
#include "G4INCLNDeltaToDeltaLKChannel.hh"
#include "G4INCLNDeltaToDeltaSKChannel.hh"
#include "G4INCLNDeltaToNNKKbChannel.hh"
#include "G4INCLNpiToLKChannel.hh"
#include "G4INCLNpiToSKChannel.hh"
#include "G4INCLNpiToLKpiChannel.hh"
#include "G4INCLNpiToSKpiChannel.hh"
#include "G4INCLNpiToLK2piChannel.hh"
#include "G4INCLNpiToSK2piChannel.hh"
#include "G4INCLNpiToNKKbChannel.hh"
#include "G4INCLNpiToMissingStrangenessChannel.hh"
#include "G4INCLNKElasticChannel.hh"
#include "G4INCLNKToNKChannel.hh"
#include "G4INCLNKToNKpiChannel.hh"
#include "G4INCLNKToNK2piChannel.hh"
#include "G4INCLNKbElasticChannel.hh"
#include "G4INCLNKbToNKbChannel.hh"
#include "G4INCLNKbToNKbpiChannel.hh"
#include "G4INCLNKbToNKb2piChannel.hh"
#include "G4INCLNKbToLpiChannel.hh"
#include "G4INCLNKbToL2piChannel.hh"
#include "G4INCLNKbToSpiChannel.hh"
#include "G4INCLNKbToS2piChannel.hh"
#include "G4INCLNYElasticChannel.hh"
#include "G4INCLNLToNSChannel.hh"
#include "G4INCLNSToNLChannel.hh"
#include "G4INCLNSToNSChannel.hh"
#include "G4INCLOmegaNToPiPiNChannel.hh"
#include "G4INCLStore.hh"
#include "G4INCLBook.hh"
#include "G4INCLLogger.hh"
#include <string>
#include <sstream>
// #include <cassert>
 
namespace G4INCL {
 
  // WARNING: if you update the default cutNN value, make sure you update the
  // cutNNSquared variable, too.
  G4ThreadLocal G4double BinaryCollisionAvatar::cutNN = 1910.0;
  G4ThreadLocal G4double BinaryCollisionAvatar::cutNNSquared = 3648100.0; // 1910.0 * 1910.0
  G4ThreadLocal G4double BinaryCollisionAvatar::bias = 1.;
 
  BinaryCollisionAvatar::BinaryCollisionAvatar(G4double time, G4double crossSection,
      G4INCL::Nucleus *n, G4INCL::Particle *p1, G4INCL::Particle *p2)
    : InteractionAvatar(time, n, p1, p2), theCrossSection(crossSection),
    isParticle1Spectator(false),
    isParticle2Spectator(false),
    isElastic(false),
    isStrangeProduction(false)
  {
    setType(CollisionAvatarType);
  }
 
  BinaryCollisionAvatar::~BinaryCollisionAvatar() {
  }
 
  G4INCL::IChannel* BinaryCollisionAvatar::getChannel() {
    // We already check cutNN at avatar creation time, but we have to check it
    // again here. For composite projectiles, we might have created independent
    // avatars with no cutNN before any collision took place.
    if(particle1->isNucleon()
        && particle2->isNucleon()
        && theNucleus->getStore()->getBook().getAcceptedCollisions()!=0) {
      const G4double energyCM2 = KinematicsUtils::squareTotalEnergyInCM(particle1, particle2);
      // Below a certain cut value we don't do anything:
      if(energyCM2 < cutNNSquared) {
        INCL_DEBUG("CM energy = sqrt(" << energyCM2 << ") MeV < std::sqrt(" << cutNNSquared
            << ") MeV = cutNN" << "; returning a NULL channel" << '\n');
        InteractionAvatar::restoreParticles();
        return NULL;
      }
    }
 
    ThreeVector minimumDistance = particle1->getPosition();
    minimumDistance -= particle2->getPosition();
    const G4double betaDotX = boostVector.dot(minimumDistance);
    const G4double minDist = Math::tenPi*(minimumDistance.mag2() + betaDotX*betaDotX / (1.-boostVector.mag2()));
    if(minDist > theCrossSection) {
      INCL_DEBUG("CM distance of approach is too small: " << minDist << ">" <<
        theCrossSection <<"; returning a NULL channel" << '\n');
      InteractionAvatar::restoreParticles();
      return NULL;
    }
 
    G4double bias_apply = 1.;
    if(bias != 1.) bias_apply = Particle::getBiasFromVector(Particle::MergeVectorBias(particle1,particle2)) * bias;
 
    if(particle1->isNucleon() && particle2->isNucleon()) {
 
      G4double NLKProductionCX = CrossSections::NNToNLK(particle1, particle2)*bias_apply;
      G4double NSKProductionCX = CrossSections::NNToNSK(particle1, particle2)*bias_apply;
      G4double NLKpiProductionCX = CrossSections::NNToNLKpi(particle1, particle2)*bias_apply;
      G4double NSKpiProductionCX = CrossSections::NNToNSKpi(particle1, particle2)*bias_apply;
      G4double NLK2piProductionCX = CrossSections::NNToNLK2pi(particle1, particle2)*bias_apply;
      G4double NSK2piProductionCX = CrossSections::NNToNSK2pi(particle1, particle2)*bias_apply;
      G4double NNKKbProductionCX = CrossSections::NNToNNKKb(particle1, particle2)*bias_apply;
      G4double NNMissingCX = CrossSections::NNToMissingStrangeness(particle1, particle2)*bias_apply;
      
      const G4double UnStrangeProdCX = CrossSections::elastic(particle1, particle2) + CrossSections::NNToNDelta(particle1, particle2) + CrossSections::NNToxPiNN(1,particle1, particle2)
                                   + CrossSections::NNToxPiNN(2,particle1, particle2) + CrossSections::NNToxPiNN(3,particle1, particle2) + CrossSections::NNToxPiNN(4,particle1, particle2)
                                   + CrossSections::NNToNNEtaExclu(particle1, particle2) + CrossSections::NNToNDeltaEta(particle1, particle2) + CrossSections::NNToNNEtaxPi(1,particle1, particle2)
                                   + CrossSections::NNToNNEtaxPi(2,particle1, particle2) +  CrossSections::NNToNNEtaxPi(3,particle1, particle2) + CrossSections::NNToNNEtaxPi(4,particle1, particle2)
                                   + CrossSections::NNToNNOmegaExclu(particle1, particle2) + CrossSections::NNToNDeltaOmega(particle1, particle2) + CrossSections::NNToNNOmegaxPi(1,particle1, particle2)
                                   + CrossSections::NNToNNOmegaxPi(2,particle1, particle2) + CrossSections::NNToNNOmegaxPi(3,particle1, particle2) + CrossSections::NNToNNOmegaxPi(4,particle1, particle2);
      const G4double StrangenessProdCX = (NLKProductionCX + NSKProductionCX + NLKpiProductionCX + NSKpiProductionCX + NLK2piProductionCX + NSK2piProductionCX + NNKKbProductionCX + NNMissingCX)/bias_apply;
      
      G4double counterweight = (1. - bias_apply * StrangenessProdCX / (StrangenessProdCX + UnStrangeProdCX))/(1. - StrangenessProdCX / (StrangenessProdCX + UnStrangeProdCX));
 
      if(counterweight < 0.5) {
         counterweight = 0.5;
         bias_apply = 0.5*UnStrangeProdCX/StrangenessProdCX+1;
         NLKProductionCX = CrossSections::NNToNLK(particle1, particle2)*bias_apply;
         NSKProductionCX = CrossSections::NNToNSK(particle1, particle2)*bias_apply;
         NLKpiProductionCX = CrossSections::NNToNLKpi(particle1, particle2)*bias_apply;
         NSKpiProductionCX = CrossSections::NNToNSKpi(particle1, particle2)*bias_apply;
         NLK2piProductionCX = CrossSections::NNToNLK2pi(particle1, particle2)*bias_apply;
         NSK2piProductionCX = CrossSections::NNToNSK2pi(particle1, particle2)*bias_apply;
         NNKKbProductionCX = CrossSections::NNToNNKKb(particle1, particle2)*bias_apply;
         NNMissingCX = CrossSections::NNToMissingStrangeness(particle1, particle2)*bias_apply;
      }
      
      
      const G4double elasticCX = CrossSections::elastic(particle1, particle2)*counterweight;
      const G4double deltaProductionCX = CrossSections::NNToNDelta(particle1, particle2)*counterweight;
      const G4double onePiProductionCX = CrossSections::NNToxPiNN(1,particle1, particle2)*counterweight;
      const G4double twoPiProductionCX = CrossSections::NNToxPiNN(2,particle1, particle2)*counterweight;
      const G4double threePiProductionCX = CrossSections::NNToxPiNN(3,particle1, particle2)*counterweight;
      const G4double fourPiProductionCX = CrossSections::NNToxPiNN(4,particle1, particle2)*counterweight;
      
      const G4double etaProductionCX = CrossSections::NNToNNEtaExclu(particle1, particle2)*counterweight;
      const G4double etadeltaProductionCX = CrossSections::NNToNDeltaEta(particle1, particle2)*counterweight;
      const G4double etaonePiProductionCX = CrossSections::NNToNNEtaxPi(1,particle1, particle2)*counterweight;
      const G4double etatwoPiProductionCX = CrossSections::NNToNNEtaxPi(2,particle1, particle2)*counterweight;
      const G4double etathreePiProductionCX = CrossSections::NNToNNEtaxPi(3,particle1, particle2)*counterweight;
      const G4double etafourPiProductionCX = CrossSections::NNToNNEtaxPi(4,particle1, particle2)*counterweight;
      const G4double omegaProductionCX = CrossSections::NNToNNOmegaExclu(particle1, particle2)*counterweight;
      const G4double omegadeltaProductionCX = CrossSections::NNToNDeltaOmega(particle1, particle2)*counterweight;
      const G4double omegaonePiProductionCX = CrossSections::NNToNNOmegaxPi(1,particle1, particle2)*counterweight;
      const G4double omegatwoPiProductionCX = CrossSections::NNToNNOmegaxPi(2,particle1, particle2)*counterweight;
      const G4double omegathreePiProductionCX = CrossSections::NNToNNOmegaxPi(3,particle1, particle2)*counterweight;
      const G4double omegafourPiProductionCX = CrossSections::NNToNNOmegaxPi(4,particle1, particle2)*counterweight;
      
      const G4double totCX=CrossSections::total(particle1, particle2);
      
// assert(std::fabs(totCX-elasticCX-deltaProductionCX-onePiProductionCX-twoPiProductionCX-threePiProductionCX-fourPiProductionCX-NLKProductionCX-NSKProductionCX-NLKpiProductionCX-NSKpiProductionCX-NLK2piProductionCX-NSK2piProductionCX-NNKKbProductionCX-NNMissingCX-etaProductionCX-etadeltaProductionCX-etaonePiProductionCX-etatwoPiProductionCX-etathreePiProductionCX-etafourPiProductionCX-omegaProductionCX-omegadeltaProductionCX-omegaonePiProductionCX-omegatwoPiProductionCX-omegathreePiProductionCX-omegafourPiProductionCX) < 0.5);
 
      const G4double rChannel=Random::shoot() * totCX;
 
      if(elasticCX > rChannel) {
// Elastic NN channel
        isElastic = true;
        INCL_DEBUG("NN interaction: elastic channel chosen" << '\n');
        weight = counterweight;
        return new ElasticChannel(particle1, particle2);
      } else if((elasticCX + deltaProductionCX) > rChannel) {
        isElastic = false;
// NN -> N Delta channel is chosen
        INCL_DEBUG("NN interaction: Delta channel chosen" << '\n');
        weight = counterweight;
        return new DeltaProductionChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX > rChannel) {
        isElastic = false;
// NN -> PiNN channel is chosen
        INCL_DEBUG("NN interaction: one Pion channel chosen" << '\n');
        weight = counterweight;
        return new NNToMultiPionsChannel(1,particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX > rChannel) {
        isElastic = false;
// NN -> 2PiNN channel is chosen
        INCL_DEBUG("NN interaction: two Pions channel chosen" << '\n');
        weight = counterweight;
        return new NNToMultiPionsChannel(2,particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX > rChannel) {
        isElastic = false;
// NN -> 3PiNN channel is chosen
        INCL_DEBUG("NN interaction: three Pions channel chosen" << '\n');
        weight = counterweight;
        return new NNToMultiPionsChannel(3,particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX > rChannel) {
              isElastic = false;
// NN -> 4PiNN channel is chosen
              INCL_DEBUG("NN interaction: four Pions channel chosen" << '\n');
              weight = counterweight;
              return new NNToMultiPionsChannel(4,particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX > rChannel) {
       isElastic = false;
// NN -> NNEta channel is chosen
       INCL_DEBUG("NN interaction: Eta channel chosen" << '\n');
       weight = counterweight;
       return new NNToNNEtaChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX + etadeltaProductionCX > rChannel) {
       isElastic = false;
// NN -> N Delta Eta channel is chosen
       INCL_DEBUG("NN interaction: Delta Eta channel chosen" << '\n');
       weight = counterweight;
       return new NDeltaEtaProductionChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX + etadeltaProductionCX + etaonePiProductionCX > rChannel) {
       isElastic = false;
// NN -> EtaPiNN channel is chosen
       INCL_DEBUG("NN interaction: Eta + one Pion channel chosen" << '\n');
       weight = counterweight;
       return new NNEtaToMultiPionsChannel(1,particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX + etadeltaProductionCX + etaonePiProductionCX + etatwoPiProductionCX > rChannel) {
       isElastic = false;
// NN -> Eta2PiNN channel is chosen
       INCL_DEBUG("NN interaction: Eta + two Pions channel chosen" << '\n');
       weight = counterweight;
       return new NNEtaToMultiPionsChannel(2,particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX + etadeltaProductionCX + etaonePiProductionCX + etatwoPiProductionCX + etathreePiProductionCX > rChannel) {
       isElastic = false;
// NN -> Eta3PiNN channel is chosen
       INCL_DEBUG("NN interaction: Eta + three Pions channel chosen" << '\n');
       weight = counterweight;
       return new NNEtaToMultiPionsChannel(3,particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX + etadeltaProductionCX + etaonePiProductionCX + etatwoPiProductionCX + etathreePiProductionCX + etafourPiProductionCX > rChannel) {
       isElastic = false;
// NN -> Eta4PiNN channel is chosen
       INCL_DEBUG("NN interaction: Eta + four Pions channel chosen" << '\n');
       weight = counterweight;
       return new NNEtaToMultiPionsChannel(4,particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX + etadeltaProductionCX + etaonePiProductionCX + etatwoPiProductionCX + etathreePiProductionCX + etafourPiProductionCX
                          + omegaProductionCX > rChannel) {
       isElastic = false;
// NN -> NNOmega channel is chosen
       INCL_DEBUG("NN interaction: Omega channel chosen" << '\n');
       weight = counterweight;
       return new NNToNNOmegaChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX + etadeltaProductionCX + etaonePiProductionCX + etatwoPiProductionCX + etathreePiProductionCX + etafourPiProductionCX
                          + omegaProductionCX + omegadeltaProductionCX > rChannel) {
       isElastic = false;
// NN -> N Delta Omega channel is chosen
       INCL_DEBUG("NN interaction: Delta Omega channel chosen" << '\n');
       weight = counterweight;
       return new NDeltaOmegaProductionChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX + etadeltaProductionCX + etaonePiProductionCX + etatwoPiProductionCX + etathreePiProductionCX + etafourPiProductionCX
                          + omegaProductionCX + omegadeltaProductionCX + omegaonePiProductionCX > rChannel) {
       isElastic = false;
// NN -> OmegaPiNN channel is chosen
       INCL_DEBUG("NN interaction: Omega + one Pion channel chosen" << '\n');
       weight = counterweight;
       return new NNOmegaToMultiPionsChannel(1,particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX + etadeltaProductionCX + etaonePiProductionCX + etatwoPiProductionCX + etathreePiProductionCX + etafourPiProductionCX
                          + omegaProductionCX + omegadeltaProductionCX + omegaonePiProductionCX + omegatwoPiProductionCX > rChannel) {
       isElastic = false;
// NN -> Omega2PiNN channel is chosen
       INCL_DEBUG("NN interaction: Omega + two Pions channel chosen" << '\n');
       weight = counterweight;
       return new NNOmegaToMultiPionsChannel(2,particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX + etadeltaProductionCX + etaonePiProductionCX + etatwoPiProductionCX + etathreePiProductionCX + etafourPiProductionCX
                          + omegaProductionCX + omegadeltaProductionCX + omegaonePiProductionCX + omegatwoPiProductionCX + omegathreePiProductionCX > rChannel) {
       isElastic = false;
// NN -> Omega3PiNN channel is chosen
       INCL_DEBUG("NN interaction: Omega + three Pions channel chosen" << '\n');
       weight = counterweight;
       return new NNOmegaToMultiPionsChannel(3,particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX + etadeltaProductionCX + etaonePiProductionCX + etatwoPiProductionCX + etathreePiProductionCX + etafourPiProductionCX
                          + omegaProductionCX + omegadeltaProductionCX + omegaonePiProductionCX + omegatwoPiProductionCX + omegathreePiProductionCX + omegafourPiProductionCX > rChannel) {
       isElastic = false;
// NN -> Omega4PiNN channel is chosen
       INCL_DEBUG("NN interaction: Omega + four Pions channel chosen" << '\n');
       weight = counterweight;
       return new NNOmegaToMultiPionsChannel(4,particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX + etadeltaProductionCX + etaonePiProductionCX + etatwoPiProductionCX + etathreePiProductionCX + etafourPiProductionCX
                          + omegaProductionCX + omegadeltaProductionCX + omegaonePiProductionCX + omegatwoPiProductionCX + omegathreePiProductionCX + omegafourPiProductionCX
                          + NLKProductionCX > rChannel) {
        isElastic = false;
        isStrangeProduction = true;
// NN -> NLK channel is chosen
        INCL_DEBUG("NN interaction: NLK channel chosen" << '\n');
        weight = bias_apply;
        return new NNToNLKChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX + etadeltaProductionCX + etaonePiProductionCX + etatwoPiProductionCX + etathreePiProductionCX + etafourPiProductionCX
                          + omegaProductionCX + omegadeltaProductionCX + omegaonePiProductionCX + omegatwoPiProductionCX + omegathreePiProductionCX + omegafourPiProductionCX
                          + NLKProductionCX + NLKpiProductionCX > rChannel) {
        isElastic = false;
        isStrangeProduction = true;
// NN -> NLKpi channel is chosen
        INCL_DEBUG("NN interaction: NLKpi channel chosen" << '\n');
        weight = bias_apply;
        return new NNToNLKpiChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX + etadeltaProductionCX + etaonePiProductionCX + etatwoPiProductionCX + etathreePiProductionCX + etafourPiProductionCX
                          + omegaProductionCX + omegadeltaProductionCX + omegaonePiProductionCX + omegatwoPiProductionCX + omegathreePiProductionCX + omegafourPiProductionCX
                          + NLKProductionCX + NLKpiProductionCX + NLK2piProductionCX > rChannel) {
        isElastic = false;
        isStrangeProduction = true;
// NN -> NLK2pi channel is chosen
        INCL_DEBUG("NN interaction: NLK2pi channel chosen" << '\n');
        weight = bias_apply;
        return new NNToNLK2piChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX + etadeltaProductionCX + etaonePiProductionCX + etatwoPiProductionCX + etathreePiProductionCX + etafourPiProductionCX
                          + omegaProductionCX + omegadeltaProductionCX + omegaonePiProductionCX + omegatwoPiProductionCX + omegathreePiProductionCX + omegafourPiProductionCX
                          + NLKProductionCX + NLKpiProductionCX + NLK2piProductionCX + NSKProductionCX > rChannel) {
        isElastic = false;
        isStrangeProduction = true;
// NN -> NSK channel is chosen
        INCL_DEBUG("NN interaction: NSK channel chosen" << '\n');
        weight = bias_apply;
        return new NNToNSKChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX + etadeltaProductionCX + etaonePiProductionCX + etatwoPiProductionCX + etathreePiProductionCX + etafourPiProductionCX
                          + omegaProductionCX + omegadeltaProductionCX + omegaonePiProductionCX + omegatwoPiProductionCX + omegathreePiProductionCX + omegafourPiProductionCX
                          + NLKProductionCX + NLKpiProductionCX + NLK2piProductionCX + NSKProductionCX + NSKpiProductionCX > rChannel) {
        isElastic = false;
        isStrangeProduction = true;
// NN -> NSKpi channel is chosen
        INCL_DEBUG("NN interaction: NSKpi channel chosen" << '\n');
        weight = bias_apply;
        return new NNToNSKpiChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX + etadeltaProductionCX + etaonePiProductionCX + etatwoPiProductionCX + etathreePiProductionCX + etafourPiProductionCX
                          + omegaProductionCX + omegadeltaProductionCX + omegaonePiProductionCX + omegatwoPiProductionCX + omegathreePiProductionCX + omegafourPiProductionCX
                          + NLKProductionCX + NLKpiProductionCX + NLK2piProductionCX + NSKProductionCX + NSKpiProductionCX + NSK2piProductionCX > rChannel) {
        isElastic = false;
        isStrangeProduction = true;
// NN -> NSK2pi channel is chosen
        INCL_DEBUG("NN interaction: NSK2pi channel chosen" << '\n');
        weight = bias_apply;
        return new NNToNSK2piChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX + etadeltaProductionCX + etaonePiProductionCX + etatwoPiProductionCX + etathreePiProductionCX + etafourPiProductionCX
                          + omegaProductionCX + omegadeltaProductionCX + omegaonePiProductionCX + omegatwoPiProductionCX + omegathreePiProductionCX + omegafourPiProductionCX
                          + NLKProductionCX + NLKpiProductionCX + NLK2piProductionCX + NSKProductionCX + NSKpiProductionCX + NSK2piProductionCX + NNKKbProductionCX > rChannel) {
        isElastic = false;
        isStrangeProduction = true;
// NN -> NNKKb channel is chosen
        INCL_DEBUG("NN interaction: NNKKb channel chosen" << '\n');
        weight = bias_apply;
        return new NNToNNKKbChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + fourPiProductionCX
                          + etaProductionCX + etadeltaProductionCX + etaonePiProductionCX + etatwoPiProductionCX + etathreePiProductionCX + etafourPiProductionCX
                          + omegaProductionCX + omegadeltaProductionCX + omegaonePiProductionCX + omegatwoPiProductionCX + omegathreePiProductionCX + omegafourPiProductionCX
                          + NLKProductionCX + NLKpiProductionCX + NLK2piProductionCX + NSKProductionCX + NSKpiProductionCX + NSK2piProductionCX + NNKKbProductionCX + NNMissingCX> rChannel) {
        isElastic = false;
        isStrangeProduction = true;
// NN -> Missing Strangeness channel is chosen
        INCL_DEBUG("NN interaction: Missing Strangeness channel chosen" << '\n');
        weight = bias_apply;
        return new NNToMissingStrangenessChannel(particle1, particle2);
      } else {
        INCL_WARN("inconsistency within the NN Cross Sections (sum!=inelastic)" << '\n');
        if(NNMissingCX>0.) {
            INCL_WARN("Returning an Missing Strangeness channel" << '\n');
            weight = bias_apply;
            isElastic = false;
            isStrangeProduction = true;
            return new NNToNNKKbChannel(particle1, particle2);
        } else if(NNKKbProductionCX>0.) {
            INCL_WARN("Returning an NNKKb channel" << '\n');
            weight = bias_apply;
            isElastic = false;
            isStrangeProduction = true;
            return new NNToNNKKbChannel(particle1, particle2);
        } else if(NSK2piProductionCX>0.) {
            INCL_WARN("Returning an NSK2pi channel" << '\n');
            weight = bias_apply;
            isElastic = false;
            isStrangeProduction = true;
            return new NNToNSK2piChannel(particle1, particle2);
        } else if(NSKpiProductionCX>0.) {
            INCL_WARN("Returning an NSKpi channel" << '\n');
            weight = bias_apply;
            isElastic = false;
            isStrangeProduction = true;
            return new NNToNSKpiChannel(particle1, particle2);
        } else if(NSKProductionCX>0.) {
            INCL_WARN("Returning an NSK channel" << '\n');
            weight = bias_apply;
            isElastic = false;
            isStrangeProduction = true;
            return new NNToNSKChannel(particle1, particle2);
        } else if(NLK2piProductionCX>0.) {
            INCL_WARN("Returning an NLK2pi channel" << '\n');
            weight = bias_apply;
            isElastic = false;
            isStrangeProduction = true;
            return new NNToNLK2piChannel(particle1, particle2);
        } else if(NLKpiProductionCX>0.) {
            INCL_WARN("Returning an NLKpi channel" << '\n');
            weight = bias_apply;
            isElastic = false;
            isStrangeProduction = true;
            return new NNToNLKpiChannel(particle1, particle2);
        } else if(NLKProductionCX>0.) {
            INCL_WARN("Returning an NLK channel" << '\n');
            weight = bias_apply;
            isElastic = false;
            isStrangeProduction = true;
            return new NNToNLKChannel(particle1, particle2);
        } else if(omegafourPiProductionCX>0.) {
            INCL_WARN("Returning an Omega + four Pions channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new NNOmegaToMultiPionsChannel(4,particle1, particle2);
        } else if(omegathreePiProductionCX>0.) {
            INCL_WARN("Returning an Omega + three Pions channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new NNOmegaToMultiPionsChannel(3,particle1, particle2);
        } else if(omegatwoPiProductionCX>0.) {
            INCL_WARN("Returning an Omega + two Pions channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new NNOmegaToMultiPionsChannel(2,particle1, particle2);
        } else if(omegaonePiProductionCX>0.) {
            INCL_WARN("Returning an Omega + one Pion channel" << '\n');
            weight = counterweight;
            isElastic = false;
         return new NNOmegaToMultiPionsChannel(1,particle1, particle2);
        } else if(omegadeltaProductionCX>0.) {
            INCL_WARN("Returning an Omega + Delta channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new NDeltaOmegaProductionChannel(particle1, particle2);
        } else if(omegaProductionCX>0.) {
            INCL_WARN("Returning an Omega channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new NNToNNOmegaChannel(particle1, particle2);
        } else if(etafourPiProductionCX>0.) {
            INCL_WARN("Returning an Eta + four Pions channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new NNEtaToMultiPionsChannel(4,particle1, particle2);
        } else if(etathreePiProductionCX>0.) {
            INCL_WARN("Returning an Eta + threev channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new NNEtaToMultiPionsChannel(3,particle1, particle2);
        } else if(etatwoPiProductionCX>0.) {
            INCL_WARN("Returning an Eta + two Pions channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new NNEtaToMultiPionsChannel(2,particle1, particle2);
        } else if(etaonePiProductionCX>0.) {
            INCL_WARN("Returning an Eta + one Pion channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new NNEtaToMultiPionsChannel(1,particle1, particle2);
        } else if(etadeltaProductionCX>0.) {
            INCL_WARN("Returning an Eta + Delta channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new NDeltaEtaProductionChannel(particle1, particle2);
        } else if(etaProductionCX>0.) {
            INCL_WARN("Returning an Eta channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new NNToNNEtaChannel(particle1, particle2);
        } else if(fourPiProductionCX>0.) {
            INCL_WARN("Returning a 4pi channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new NNToMultiPionsChannel(4,particle1, particle2);
        } else if(threePiProductionCX>0.) {
            INCL_WARN("Returning a 3pi channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new NNToMultiPionsChannel(3,particle1, particle2);
        } else if(twoPiProductionCX>0.) {
            INCL_WARN("Returning a 2pi channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new NNToMultiPionsChannel(2,particle1, particle2);
        } else if(onePiProductionCX>0.) {
            INCL_WARN("Returning a 1pi channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new NNToMultiPionsChannel(1,particle1, particle2);
        } else if(deltaProductionCX>0.) {
            INCL_WARN("Returning a delta-production channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new DeltaProductionChannel(particle1, particle2);
        } else {
            INCL_WARN("Returning an elastic channel" << '\n');
            weight = counterweight;
            isElastic = true;
            return new ElasticChannel(particle1, particle2);
        }
      }
 
    }
    else if((particle1->isNucleon() && particle2->isDelta()) ||
                 (particle1->isDelta() && particle2->isNucleon())) {
          
          G4double NLKProductionCX = CrossSections::NDeltaToNLK(particle1, particle2)*bias_apply;
          G4double NSKProductionCX = CrossSections::NDeltaToNSK(particle1, particle2)*bias_apply;
          G4double DeltaLKProductionCX = CrossSections::NDeltaToDeltaLK(particle1, particle2)*bias_apply;
          G4double DeltaSKProductionCX = CrossSections::NDeltaToDeltaSK(particle1, particle2)*bias_apply;
          G4double NNKKbProductionCX = CrossSections::NDeltaToNNKKb(particle1, particle2)*bias_apply;
          
          const G4double UnStrangeProdCX = CrossSections::elastic(particle1, particle2) + CrossSections::NDeltaToNN(particle1, particle2);
          const G4double StrangenessProdCX = (NLKProductionCX + NSKProductionCX + DeltaLKProductionCX + DeltaSKProductionCX + NNKKbProductionCX)/bias_apply;
          
          G4double counterweight = (1. - bias_apply * StrangenessProdCX / (StrangenessProdCX + UnStrangeProdCX))/(1. - StrangenessProdCX / (StrangenessProdCX + UnStrangeProdCX));
 
          if(counterweight < 0.5){
             counterweight = 0.5;
             bias_apply = 0.5*UnStrangeProdCX/StrangenessProdCX+1;
             
             NLKProductionCX = CrossSections::NDeltaToNLK(particle1, particle2)*bias_apply;
             NSKProductionCX = CrossSections::NDeltaToNSK(particle1, particle2)*bias_apply;
             DeltaLKProductionCX = CrossSections::NDeltaToDeltaLK(particle1, particle2)*bias_apply;
             DeltaSKProductionCX = CrossSections::NDeltaToDeltaSK(particle1, particle2)*bias_apply;
             NNKKbProductionCX = CrossSections::NDeltaToNNKKb(particle1, particle2)*bias_apply;
          }
      
          G4double elasticCX = CrossSections::elastic(particle1, particle2)*counterweight;
          G4double recombinationCX = CrossSections::NDeltaToNN(particle1, particle2)*counterweight;
          
          const G4double rChannel=Random::shoot() * (StrangenessProdCX + UnStrangeProdCX);
 
          if(elasticCX > rChannel) {
            isElastic = true;
// Elastic N Delta channel
             INCL_DEBUG("NDelta interaction: elastic channel chosen" << '\n');
             weight = counterweight;
             return new ElasticChannel(particle1, particle2);
          } else if (elasticCX + recombinationCX > rChannel){
            isElastic = false;
// Recombination
// NDelta -> NN channel is chosen
             INCL_DEBUG("NDelta interaction: recombination channel chosen" << '\n');
             weight = counterweight;
             return new RecombinationChannel(particle1, particle2);
          } else if (elasticCX + recombinationCX + NLKProductionCX > rChannel){
            isElastic = false;
            isStrangeProduction = true;
// NDelta -> NLK channel is chosen
             INCL_DEBUG("NDelta interaction: NLK channel chosen" << '\n');
             weight = bias_apply;
             return new NDeltaToNLKChannel(particle1, particle2);
          } else if (elasticCX + recombinationCX + NLKProductionCX + NSKProductionCX > rChannel){
            isElastic = false;
            isStrangeProduction = true;
// NDelta -> NSK channel is chosen
             INCL_DEBUG("NDelta interaction: NSK channel chosen" << '\n');
             weight = bias_apply;
             return new NDeltaToNSKChannel(particle1, particle2);
          } else if (elasticCX + recombinationCX + NLKProductionCX + NSKProductionCX + DeltaLKProductionCX > rChannel){
            isElastic = false;
            isStrangeProduction = true;
// NDelta -> DeltaLK channel is chosen
             INCL_DEBUG("NDelta interaction: DeltaLK channel chosen" << '\n');
             weight = bias_apply;
             return new NDeltaToDeltaLKChannel(particle1, particle2);
          } else if (elasticCX + recombinationCX + NLKProductionCX + NSKProductionCX + DeltaLKProductionCX + DeltaSKProductionCX > rChannel){
            isElastic = false;
            isStrangeProduction = true;
// NDelta -> DeltaSK channel is chosen
             INCL_DEBUG("NDelta interaction: DeltaSK channel chosen" << '\n');
             weight = bias_apply;
             return new NDeltaToDeltaSKChannel(particle1, particle2);
          } else if (elasticCX + recombinationCX + NLKProductionCX + NSKProductionCX + DeltaLKProductionCX + DeltaSKProductionCX + NNKKbProductionCX > rChannel){
            isElastic = false;
            isStrangeProduction = true;
// NDelta -> NNKKb channel is chosen
             INCL_DEBUG("NDelta interaction: NNKKb channel chosen" << '\n');
             weight = bias_apply;
             return new NDeltaToNNKKbChannel(particle1, particle2);
          }
          else{
             INCL_ERROR("rChannel > (StrangenessProdCX + UnStrangeProdCX) in NDelta interaction: return an elastic channel" << '\n');
             weight = counterweight;
             isElastic = true;
             return new ElasticChannel(particle1, particle2);
          }
 
    } else if(particle1->isDelta() && particle2->isDelta()) {
        isElastic = true;
        INCL_DEBUG("DeltaDelta interaction: elastic channel chosen" << '\n');
        return new ElasticChannel(particle1, particle2);
 
    } else if(isPiN) {
      
      G4double LKProdCX = CrossSections::NpiToLK(particle1,particle2)*bias_apply;
      G4double SKProdCX = CrossSections::NpiToSK(particle1,particle2)*bias_apply;
      G4double LKpiProdCX = CrossSections::NpiToLKpi(particle1,particle2)*bias_apply;
      G4double SKpiProdCX = CrossSections::NpiToSKpi(particle1,particle2)*bias_apply;
      G4double LK2piProdCX = CrossSections::NpiToLK2pi(particle1,particle2)*bias_apply;
      G4double SK2piProdCX = CrossSections::NpiToSK2pi(particle1,particle2)*bias_apply;
      G4double NKKbProdCX = CrossSections::NpiToNKKb(particle1,particle2)*bias_apply;
      G4double MissingCX = CrossSections::NpiToMissingStrangeness(particle1,particle2)*bias_apply;
      
      const G4double UnStrangeProdCX = CrossSections::elastic(particle1, particle2) + CrossSections::piNToDelta(particle1, particle2)
                                   + CrossSections::piNToxPiN(2,particle1, particle2) + CrossSections::piNToxPiN(3,particle1, particle2) + CrossSections::piNToxPiN(4,particle1, particle2)
                                   + CrossSections::piNToEtaN(particle1, particle2) + CrossSections::piNToOmegaN(particle1, particle2);
      const G4double StrangenessProdCX = (LKProdCX + SKProdCX + LKpiProdCX + SKpiProdCX + LK2piProdCX + SK2piProdCX + NKKbProdCX + MissingCX)/bias_apply;
      
      G4double counterweight = (1. - bias_apply * StrangenessProdCX / (StrangenessProdCX + UnStrangeProdCX))/(1. - StrangenessProdCX / (StrangenessProdCX + UnStrangeProdCX));
      
      if(counterweight < 0.5) {
         counterweight = 0.5;
         bias_apply = 0.5*UnStrangeProdCX/StrangenessProdCX+1;
         LKProdCX = CrossSections::NpiToLK(particle1,particle2)*bias_apply;
         SKProdCX = CrossSections::NpiToSK(particle1,particle2)*bias_apply;
         LKpiProdCX = CrossSections::NpiToLKpi(particle1,particle2)*bias_apply;
         SKpiProdCX = CrossSections::NpiToSKpi(particle1,particle2)*bias_apply;
         LK2piProdCX = CrossSections::NpiToLK2pi(particle1,particle2)*bias_apply;
         SK2piProdCX = CrossSections::NpiToSK2pi(particle1,particle2)*bias_apply;
         NKKbProdCX = CrossSections::NpiToNKKb(particle1,particle2)*bias_apply;
         MissingCX = CrossSections::NpiToMissingStrangeness(particle1,particle2)*bias_apply;
      }
      
      
      const G4double elasticCX = CrossSections::elastic(particle1, particle2)*counterweight;
      const G4double deltaProductionCX = CrossSections::piNToDelta(particle1, particle2)*counterweight;
      const G4double onePiProductionCX = CrossSections::piNToxPiN(2,particle1, particle2)*counterweight;
      const G4double twoPiProductionCX = CrossSections::piNToxPiN(3,particle1, particle2)*counterweight;
         const G4double threePiProductionCX = CrossSections::piNToxPiN(4,particle1, particle2)*counterweight;
         const G4double etaProductionCX = CrossSections::piNToEtaN(particle1, particle2)*counterweight;
         const G4double omegaProductionCX = CrossSections::piNToOmegaN(particle1, particle2)*counterweight;
      
      const G4double totCX=CrossSections::total(particle1, particle2);
      
// assert(std::fabs(totCX-elasticCX-deltaProductionCX-onePiProductionCX-twoPiProductionCX-threePiProductionCX-etaProductionCX-omegaProductionCX-LKProdCX-SKProdCX-LKpiProdCX-SKpiProdCX-LK2piProdCX-SK2piProdCX-NKKbProdCX-MissingCX) < 0.15);
 
      const G4double rChannel=Random::shoot() * totCX;
 
      if(elasticCX > rChannel) {
        isElastic = true;
// Elastic PiN channel
        INCL_DEBUG("PiN interaction: elastic channel chosen" << '\n');
        weight = counterweight;
        return new PiNElasticChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX > rChannel) {
        isElastic = false;
// PiN -> Delta channel is chosen
        INCL_DEBUG("PiN interaction: Delta channel chosen" << '\n');
        weight = counterweight;
        return new PiNToDeltaChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX > rChannel) {
        isElastic = false;
// PiN -> PiNPi channel is chosen
        INCL_DEBUG("PiN interaction: one Pion channel chosen" << '\n');
        weight = counterweight;
        return new PiNToMultiPionsChannel(2,particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX > rChannel) {
        isElastic = false;
// PiN -> PiN2Pi channel is chosen
        INCL_DEBUG("PiN interaction: two Pions channel chosen" << '\n');
        weight = counterweight;
        return new PiNToMultiPionsChannel(3,particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX > rChannel) {
        isElastic = false;
// PiN -> PiN3Pi channel is chosen
        INCL_DEBUG("PiN interaction: three Pions channel chosen" << '\n');
        weight = counterweight;
        return new PiNToMultiPionsChannel(4,particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + etaProductionCX > rChannel) {
        isElastic = false;
// PiN -> EtaN channel is chosen
        INCL_DEBUG("PiN interaction: Eta channel chosen" << '\n');
        weight = counterweight;
        return new PiNToEtaChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + etaProductionCX+ omegaProductionCX > rChannel) {
        isElastic = false;
// PiN -> OmegaN channel is chosen
        INCL_DEBUG("PiN interaction: Omega channel chosen" << '\n');
        weight = counterweight;
        return new PiNToOmegaChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + etaProductionCX+ omegaProductionCX
                          + LKProdCX > rChannel) {
        isElastic = false;
        isStrangeProduction = true;
// PiN -> LK channel is chosen
        INCL_DEBUG("PiN interaction: LK channel chosen" << '\n');
        weight = bias_apply;
        return new NpiToLKChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + etaProductionCX+ omegaProductionCX
                          + LKProdCX + SKProdCX > rChannel) {
        isElastic = false;
        isStrangeProduction = true;
// PiN -> SK channel is chosen
        INCL_DEBUG("PiN interaction: SK channel chosen" << '\n');
        weight = bias_apply;
        return new NpiToSKChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + etaProductionCX+ omegaProductionCX
                          + LKProdCX + SKProdCX + LKpiProdCX > rChannel) {
        isElastic = false;
        isStrangeProduction = true;
// PiN -> LKpi channel is chosen
        INCL_DEBUG("PiN interaction: LKpi channel chosen" << '\n');
        weight = bias_apply;
        return new NpiToLKpiChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + etaProductionCX+ omegaProductionCX
                          + LKProdCX + SKProdCX + LKpiProdCX + SKpiProdCX > rChannel) {
        isElastic = false;
        isStrangeProduction = true;
// PiN -> SKpi channel is chosen
        INCL_DEBUG("PiN interaction: SKpi channel chosen" << '\n');
        weight = bias_apply;
        return new NpiToSKpiChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + etaProductionCX+ omegaProductionCX
                          + LKProdCX + SKProdCX + LKpiProdCX + SKpiProdCX + LK2piProdCX > rChannel) {
        isElastic = false;
        isStrangeProduction = true;
// PiN -> LK2pi channel is chosen
        INCL_DEBUG("PiN interaction: LK2pi channel chosen" << '\n');
        weight = bias_apply;
        return new NpiToLK2piChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + etaProductionCX+ omegaProductionCX
                          + LKProdCX + SKProdCX + LKpiProdCX + SKpiProdCX + LK2piProdCX + SK2piProdCX > rChannel) {
        isElastic = false;
        isStrangeProduction = true;
// PiN -> SK2pi channel is chosen
        INCL_DEBUG("PiN interaction: SK2pi channel chosen" << '\n');
        weight = bias_apply;
        return new NpiToSK2piChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + etaProductionCX+ omegaProductionCX
                          + LKProdCX + SKProdCX + LKpiProdCX + SKpiProdCX + LK2piProdCX + SK2piProdCX + NKKbProdCX > rChannel) {
        isElastic = false;
        isStrangeProduction = true;
// PiN -> NKKb channel is chosen
        INCL_DEBUG("PiN interaction: NKKb channel chosen" << '\n');
        weight = bias_apply;
        return new NpiToNKKbChannel(particle1, particle2);
      } else if(elasticCX + deltaProductionCX + onePiProductionCX + twoPiProductionCX + threePiProductionCX + etaProductionCX+ omegaProductionCX
                          + LKProdCX + SKProdCX + LKpiProdCX + SKpiProdCX + LK2piProdCX + SK2piProdCX + NKKbProdCX + MissingCX> rChannel) {
        isElastic = false;
        isStrangeProduction = true;
// PiN -> Missinge Strangeness channel is chosen
        INCL_DEBUG("PiN interaction: Missinge Strangeness channel chosen" << '\n');
        weight = bias_apply;
        return new NpiToMissingStrangenessChannel(particle1, particle2);
      }
      else {
         INCL_WARN("inconsistency within the PiN Cross Sections (sum!=inelastic)" << '\n');
         if(MissingCX>0.) {
            INCL_WARN("Returning a Missinge Strangeness channel" << '\n');
            weight = bias_apply;
            isElastic = false;
            isStrangeProduction = true;
            return new NpiToMissingStrangenessChannel(particle1, particle2);
        } else if(NKKbProdCX>0.) {
            INCL_WARN("Returning a NKKb channel" << '\n');
            weight = bias_apply;
            isElastic = false;
            isStrangeProduction = true;
            return new NpiToNKKbChannel(particle1, particle2);
        } else if(SK2piProdCX>0.) {
            INCL_WARN("Returning a SK2pi channel" << '\n');
            weight = bias_apply;
            isElastic = false;
            isStrangeProduction = true;
            return new NpiToSK2piChannel(particle1, particle2);
        } else if(LK2piProdCX>0.) {
            INCL_WARN("Returning a LK2pi channel" << '\n');
            weight = bias_apply;
            isElastic = false;
            isStrangeProduction = true;
            return new NpiToLK2piChannel(particle1, particle2);
        } else if(SKpiProdCX>0.) {
            INCL_WARN("Returning a SKpi channel" << '\n');
            weight = bias_apply;
            isElastic = false;
            isStrangeProduction = true;
            return new NpiToSKpiChannel(particle1, particle2);
        } else if(LKpiProdCX>0.) {
            INCL_WARN("Returning a LKpi channel" << '\n');
            weight = bias_apply;
            isElastic = false;
            isStrangeProduction = true;
            return new NpiToLKpiChannel(particle1, particle2);
        } else if(SKProdCX>0.) {
            INCL_WARN("Returning a SK channel" << '\n');
            weight = bias_apply;
            isElastic = false;
            isStrangeProduction = true;
            return new NpiToSKChannel(particle1, particle2);
        } else if(LKProdCX>0.) {
            INCL_WARN("Returning a LK channel" << '\n');
            weight = bias_apply;
            isElastic = false;
            isStrangeProduction = true;
            return new NpiToLKChannel(particle1, particle2);
        } else if(omegaProductionCX>0.) {
            INCL_WARN("Returning a Omega channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new PiNToOmegaChannel(particle1, particle2);
        } else if(etaProductionCX>0.) {
            INCL_WARN("Returning a Eta channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new PiNToEtaChannel(particle1, particle2);
        } else if(threePiProductionCX>0.) {
            INCL_WARN("Returning a 3pi channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new PiNToMultiPionsChannel(4,particle1, particle2);
        } else if(twoPiProductionCX>0.) {
            INCL_WARN("Returning a 2pi channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new PiNToMultiPionsChannel(3,particle1, particle2);
        } else if(onePiProductionCX>0.) {
            INCL_WARN("Returning a 1pi channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new PiNToMultiPionsChannel(2,particle1, particle2);
        } else if(deltaProductionCX>0.) {
            INCL_WARN("Returning a delta-production channel" << '\n');
            weight = counterweight;
            isElastic = false;
            return new PiNToDeltaChannel(particle1, particle2);
        } else {
            INCL_WARN("Returning an elastic channel" << '\n');
            weight = counterweight;
            isElastic = true;
            return new PiNElasticChannel(particle1, particle2);
        }
      }
    } else if ((particle1->isNucleon() && particle2->isEta()) || (particle2->isNucleon() && particle1->isEta())) {
 
                    const G4double elasticCX = CrossSections::elastic(particle1, particle2);
                    const G4double onePiProductionCX = CrossSections::etaNToPiN(particle1, particle2);
                    const G4double twoPiProductionCX = CrossSections::etaNToPiPiN(particle1, particle2);
                    const G4double totCX=CrossSections::total(particle1, particle2);
// assert(std::fabs(totCX-elasticCX-onePiProductionCX-twoPiProductionCX)<1.);
                    
                    const G4double rChannel=Random::shoot() * totCX;
                                        
                    if(elasticCX > rChannel) {
// Elastic EtaN channel
                        isElastic = true;
                        INCL_DEBUG("EtaN interaction: elastic channel chosen" << '\n');
                        return new EtaNElasticChannel(particle1, particle2);
                    } else if(elasticCX + onePiProductionCX > rChannel) {
                        isElastic = false;
// EtaN -> EtaPiN channel is chosen
                        INCL_DEBUG("EtaN interaction: PiN channel chosen" << '\n');
                        return new EtaNToPiNChannel(particle1, particle2);
                    } else if(elasticCX + onePiProductionCX + twoPiProductionCX > rChannel) {
                        isElastic = false;
// EtaN -> EtaPiPiN channel is chosen
                        INCL_DEBUG("EtaN interaction: PiPiN channel chosen" << '\n');
                        return new EtaNToPiPiNChannel(particle1, particle2);
                    }
 
                    else {
                        INCL_WARN("inconsistency within the EtaN Cross Sections (sum!=inelastic)" << '\n');
                        if(twoPiProductionCX>0.) {
                            INCL_WARN("Returning a PiPiN channel" << '\n');
                            isElastic = false;
                            return new EtaNToPiPiNChannel(particle1, particle2);
                        } else if(onePiProductionCX>0.) {
                            INCL_WARN("Returning a PiN channel" << '\n');
                            isElastic = false;
                            return new EtaNToPiNChannel(particle1, particle2);
                        } else {
                            INCL_WARN("Returning an elastic channel" << '\n');
                            isElastic = true;
                            return new EtaNElasticChannel(particle1, particle2);
                        }
                    }
                                    
    } else if ((particle1->isNucleon() && particle2->isOmega()) || (particle2->isNucleon() && particle1->isOmega())) {
     
                    const G4double elasticCX = CrossSections::elastic(particle1, particle2);
                    const G4double onePiProductionCX = CrossSections::omegaNToPiN(particle1, particle2);
                    const G4double twoPiProductionCX = CrossSections::omegaNToPiPiN(particle1, particle2);
                    const G4double totCX=CrossSections::total(particle1, particle2);
// assert(std::fabs(totCX-elasticCX-onePiProductionCX-twoPiProductionCX)<1.);
                    
                    const G4double rChannel=Random::shoot() * totCX;
     
                    if(elasticCX > rChannel) {
// Elastic OmegaN channel
                        isElastic = true;
                        INCL_DEBUG("OmegaN interaction: elastic channel chosen" << '\n');
                        return new OmegaNElasticChannel(particle1, particle2);
                    } else if(elasticCX + onePiProductionCX > rChannel) {
                        isElastic = false;
// OmegaN -> PiN channel is chosen
            INCL_DEBUG("OmegaN interaction: PiN channel chosen" << '\n');
            return new OmegaNToPiNChannel(particle1, particle2);
                    } else if(elasticCX + onePiProductionCX + twoPiProductionCX > rChannel) {
                        isElastic = false;
// OmegaN -> PiPiN channel is chosen
                        INCL_DEBUG("OmegaN interaction: PiPiN channel chosen" << '\n');
                        return new OmegaNToPiPiNChannel(particle1, particle2);
                    }
                    else {
                        INCL_WARN("inconsistency within the OmegaN Cross Sections (sum!=inelastic)" << '\n');
                        if(twoPiProductionCX>0.) {
                            INCL_WARN("Returning a PiPiN channel" << '\n');
                            isElastic = false;
                            return new OmegaNToPiPiNChannel(particle1, particle2);
                        } else if(onePiProductionCX>0.) {
                            INCL_WARN("Returning a PiN channel" << '\n');
                            isElastic = false;
                            return new OmegaNToPiNChannel(particle1, particle2);
                        } else {
                            INCL_WARN("Returning an elastic channel" << '\n');
                            isElastic = true;
                            return new OmegaNElasticChannel(particle1, particle2);
                        }
                    }
    } else if ((particle1->isNucleon() && particle2->isKaon()) || (particle2->isNucleon() && particle1->isKaon())) {
        const G4double elasticCX = CrossSections::elastic(particle1,particle2);
        const G4double quasielasticCX = CrossSections::NKToNK(particle1,particle2);
        const G4double NKToNKpiCX = CrossSections::NKToNKpi(particle1,particle2);
        const G4double NKToNK2piCX = CrossSections::NKToNK2pi(particle1,particle2);
        const G4double totCX=CrossSections::total(particle1, particle2);
// assert(std::fabs(totCX-elasticCX-quasielasticCX-NKToNKpiCX-NKToNK2piCX)<0.1);
        
        const G4double rChannel=Random::shoot() * totCX;
        if(elasticCX > rChannel){
// Elastic KN channel is chosen
            isElastic = true;
            INCL_DEBUG("KN interaction: elastic channel chosen" << '\n');
            return new NKElasticChannel(particle1, particle2);
        } else if(elasticCX + quasielasticCX > rChannel){
// Quasi-elastic KN channel is chosen
            isElastic = false; // true ??
            INCL_DEBUG("KN interaction: quasi-elastic channel chosen" << '\n');
            return new NKToNKChannel(particle1, particle2);
        } else if(elasticCX + quasielasticCX + NKToNKpiCX > rChannel){
// KN -> NKpi channel is chosen
            isElastic = false;
            INCL_DEBUG("KN interaction: NKpi channel chosen" << '\n');
            return new NKToNKpiChannel(particle1, particle2);
        } else if(elasticCX + quasielasticCX + NKToNKpiCX + NKToNK2piCX > rChannel){
// KN -> NK2pi channel is chosen
            isElastic = false;
            INCL_DEBUG("KN interaction: NK2pi channel chosen" << '\n');
            return new NKToNK2piChannel(particle1, particle2);
        } else {
            INCL_WARN("inconsistency within the KN Cross Sections (sum!=inelastic)" << '\n');
            if(NKToNK2piCX>0.) {
                INCL_WARN("Returning a NKToNK2pi channel" << '\n');
                isElastic = false;
                return new NKToNK2piChannel(particle1, particle2);
            } else if(NKToNKpiCX>0.) {
                INCL_WARN("Returning a NKToNKpi channel" << '\n');
                isElastic = false;
                return new NKToNKpiChannel(particle1, particle2);
            } else if(quasielasticCX>0.) {
                INCL_WARN("Returning a quasi-elastic channel" << '\n');
                isElastic = false; // true ??
                return new NKToNKChannel(particle1, particle2);
            } else {
                INCL_WARN("Returning an elastic channel" << '\n');
                isElastic = true;
                return new NKElasticChannel(particle1, particle2);
            }
        }    
    } else if ((particle1->isNucleon() && particle2->isAntiKaon()) || (particle2->isNucleon() && particle1->isAntiKaon())) {
        const G4double elasticCX = CrossSections::elastic(particle1,particle2);
        const G4double quasielasticCX = CrossSections::NKbToNKb(particle1,particle2);
        const G4double NKbToNKbpiCX = CrossSections::NKbToNKbpi(particle1,particle2);
        const G4double NKbToNKb2piCX = CrossSections::NKbToNKb2pi(particle1,particle2);
        const G4double NKbToLpiCX = CrossSections::NKbToLpi(particle1,particle2);
        const G4double NKbToL2piCX = CrossSections::NKbToL2pi(particle1,particle2);
        const G4double NKbToSpiCX = CrossSections::NKbToSpi(particle1,particle2);
        const G4double NKbToS2piCX = CrossSections::NKbToS2pi(particle1,particle2);
        const G4double totCX=CrossSections::total(particle1, particle2);
// assert(std::fabs(totCX-elasticCX-quasielasticCX-NKbToNKbpiCX-NKbToNKb2piCX-NKbToLpiCX-NKbToL2piCX-NKbToSpiCX-NKbToS2piCX)<0.1);
        
        const G4double rChannel=Random::shoot() * totCX;
        if(elasticCX > rChannel){
// Elastic KbN channel is chosen
            isElastic = true;
            INCL_DEBUG("KbN interaction: elastic channel chosen" << '\n');
            return new NKbElasticChannel(particle1, particle2);
        } else if(elasticCX + quasielasticCX > rChannel){
// Quasi-elastic KbN channel is chosen
            isElastic = false; // true ??
            INCL_DEBUG("KbN interaction: quasi-elastic channel chosen" << '\n');
            return new NKbToNKbChannel(particle1, particle2);
        } else if(elasticCX + quasielasticCX + NKbToNKbpiCX > rChannel){
// KbN -> NKbpi channel is chosen
            isElastic = false;
            INCL_DEBUG("KbN interaction: NKbpi channel chosen" << '\n');
            return new NKbToNKbpiChannel(particle1, particle2);
        } else if(elasticCX + quasielasticCX + NKbToNKbpiCX + NKbToNKb2piCX > rChannel){
// KbN -> NKb2pi channel is chosen
            isElastic = false;
            INCL_DEBUG("KbN interaction: NKb2pi channel chosen" << '\n');
            return new NKbToNKb2piChannel(particle1, particle2);
        } else if(elasticCX + quasielasticCX + NKbToNKbpiCX + NKbToNKb2piCX + NKbToLpiCX > rChannel){
// KbN -> Lpi channel is chosen
            isElastic = false;
            INCL_DEBUG("KbN interaction: Lpi channel chosen" << '\n');
            return new NKbToLpiChannel(particle1, particle2);
        } else if(elasticCX + quasielasticCX + NKbToNKbpiCX + NKbToNKb2piCX + NKbToLpiCX + NKbToL2piCX > rChannel){
// KbN -> L2pi channel is chosen
            isElastic = false;
            INCL_DEBUG("KbN interaction: L2pi channel chosen" << '\n');
            return new NKbToL2piChannel(particle1, particle2);
        } else if(elasticCX + quasielasticCX + NKbToNKbpiCX + NKbToNKb2piCX + NKbToLpiCX + NKbToL2piCX + NKbToSpiCX > rChannel){
// KbN -> Spi channel is chosen
            isElastic = false;
            INCL_DEBUG("KbN interaction: Spi channel chosen" << '\n');
            return new NKbToSpiChannel(particle1, particle2);
        } else if(elasticCX + quasielasticCX + NKbToNKbpiCX + NKbToNKb2piCX + NKbToLpiCX + NKbToL2piCX + NKbToSpiCX + NKbToS2piCX > rChannel){
// KbN -> S2pi channel is chosen
            isElastic = false;
            INCL_DEBUG("KbN interaction: S2pi channel chosen" << '\n');
            return new NKbToS2piChannel(particle1, particle2);
        } else {
            INCL_WARN("inconsistency within the KbN Cross Sections (sum!=inelastic)" << '\n');
             if(NKbToS2piCX>0.) {
                INCL_WARN("Returning a NKbToS2pi channel" << '\n');
                isElastic = false;
                return new NKbToS2piChannel(particle1, particle2);
            } else if(NKbToSpiCX>0.) {
                INCL_WARN("Returning a NKbToSpi channel" << '\n');
                isElastic = false;
                return new NKbToSpiChannel(particle1, particle2);
            } else if(NKbToL2piCX>0.) {
                INCL_WARN("Returning a NKbToL2pi channel" << '\n');
                isElastic = false;
                return new NKbToL2piChannel(particle1, particle2);
            } else if(NKbToLpiCX>0.) {
                INCL_WARN("Returning a NKbToLpi channel" << '\n');
                isElastic = false;
                return new NKbToLpiChannel(particle1, particle2);
            } else if(NKbToNKb2piCX>0.) {
                INCL_WARN("Returning a NKbToNKb2pi channel" << '\n');
                isElastic = false;
                return new NKbToNKb2piChannel(particle1, particle2);
            } else if(NKbToNKbpiCX>0.) {
                INCL_WARN("Returning a NKbToNKbpi channel" << '\n');
                isElastic = false;
                return new NKbToNKbpiChannel(particle1, particle2);
            } else if(quasielasticCX>0.) {
                INCL_WARN("Returning a quasi-elastic channel" << '\n');
                isElastic = false; // true ??
                return new NKbToNKbChannel(particle1, particle2);
            } else {
                INCL_WARN("Returning an elastic channel" << '\n');
                isElastic = true;
                return new NKbElasticChannel(particle1, particle2);
            }
        }
    } else if ((particle1->isNucleon() && particle2->isLambda()) || (particle2->isNucleon() && particle1->isLambda())) {
        const G4double elasticCX = CrossSections::elastic(particle1,particle2);
        const G4double NLToNSCX = CrossSections::NLToNS(particle1,particle2);
        const G4double totCX=CrossSections::total(particle1, particle2);
// assert(std::fabs(totCX-elasticCX-NLToNSCX)<0.1);
        
        const G4double rChannel=Random::shoot() * totCX;
        if(elasticCX > rChannel){
// Elastic NLambda channel is chosen
            isElastic = true;
            INCL_DEBUG("NLambda interaction: elastic channel chosen" << '\n');
            return new NYElasticChannel(particle1, particle2);
        } else if(elasticCX + NLToNSCX > rChannel){
// Quasi-elastic NLambda channel is chosen
            isElastic = false; // true ??
            INCL_DEBUG("NLambda interaction: quasi-elastic channel chosen" << '\n');
            return new NLToNSChannel(particle1, particle2);
        } else {
            INCL_WARN("inconsistency within the NLambda Cross Sections (sum!=inelastic)" << '\n');
            if(NLToNSCX>0.) {
                INCL_WARN("Returning a quasi-elastic channel" << '\n');
                isElastic = false; // true ??
                return new NLToNSChannel(particle1, particle2);
            } else {
                INCL_WARN("Returning an elastic channel" << '\n');
                isElastic = true;
                return new NYElasticChannel(particle1, particle2);
            }
        }
    } else if ((particle1->isNucleon() && particle2->isSigma()) || (particle2->isNucleon() && particle1->isSigma())) {
        const G4double elasticCX = CrossSections::elastic(particle1,particle2);
        const G4double NSToNLCX = CrossSections::NSToNL(particle1,particle2);
        const G4double NSToNSCX = CrossSections::NSToNS(particle1,particle2);
        const G4double totCX=CrossSections::total(particle1, particle2);
// assert(std::fabs(totCX-elasticCX-NSToNLCX-NSToNSCX)<0.1);
        
        const G4double rChannel=Random::shoot() * totCX;
        if(elasticCX > rChannel){
// Elastic NSigma channel is chosen
            isElastic = true;
            INCL_DEBUG("NSigma interaction: elastic channel chosen" << '\n');
            return new NYElasticChannel(particle1, particle2);
        } else if(elasticCX + NSToNLCX > rChannel){
// NSigma -> NLambda channel is chosen
            isElastic = false; // true ??
            INCL_DEBUG("NSigma interaction: NLambda channel chosen" << '\n');
            return new NSToNLChannel(particle1, particle2);
        } else if(elasticCX + NSToNLCX + NSToNSCX > rChannel){
// NSigma -> NSigma quasi-elastic channel is chosen
            isElastic = false; // true ??
            INCL_DEBUG("NSigma interaction: NSigma quasi-elastic channel chosen" << '\n');
            return new NSToNSChannel(particle1, particle2);
        } else {
            INCL_WARN("inconsistency within the NSigma Cross Sections (sum!=inelastic)" << '\n');
            if(NSToNSCX>0.) {
                INCL_WARN("Returning a quasi-elastic channel" << '\n');
                isElastic = false; // true ??
                return new NSToNSChannel(particle1, particle2);
            } else if(NSToNLCX>0.) {
                INCL_WARN("Returning a NLambda channel" << '\n');
                isElastic = false; // true ??
                return new NSToNLChannel(particle1, particle2);
            } else {
                INCL_WARN("Returning an elastic channel" << '\n');
                isElastic = true;
                return new NYElasticChannel(particle1, particle2);
            }
        }
    }
 
    else {
      INCL_DEBUG("BinaryCollisionAvatar can only handle nucleons (for the moment)."
          << '\n'
          << particle1->print()
          << '\n'
          << particle2->print()
          << '\n');
      InteractionAvatar::restoreParticles();
      return NULL;
    }
  }
 
  void BinaryCollisionAvatar::preInteraction() {
    isParticle1Spectator = particle1->isTargetSpectator();
    isParticle2Spectator = particle2->isTargetSpectator();
    InteractionAvatar::preInteraction();
  }
 
  void BinaryCollisionAvatar::postInteraction(FinalState *fs) {
    // Call the postInteraction method of the parent class
    // (provides Pauli blocking and enforces energy conservation)
    InteractionAvatar::postInteraction(fs);
 
    switch(fs->getValidity()) {
      case PauliBlockedFS:
        theNucleus->getStore()->getBook().incrementBlockedCollisions();
        break;
      case NoEnergyConservationFS:
      case ParticleBelowFermiFS:
      case ParticleBelowZeroFS:
        break;
      case ValidFS:
        Book &theBook = theNucleus->getStore()->getBook();
        theBook.incrementAcceptedCollisions();
        
        if(theBook.getAcceptedCollisions() == 1) {
          // Store time and cross section of the first collision
          G4double t = theBook.getCurrentTime();
          theBook.setFirstCollisionTime(t);
          theBook.setFirstCollisionXSec(oldXSec);
          // Increase the number of Kaon by 1
          if(isStrangeProduction) theNucleus->setNumberOfKaon(theNucleus->getNumberOfKaon()+1);
          // Store position and momentum of the spectator on the first
          // collision
          if((isParticle1Spectator && isParticle2Spectator) || (!isParticle1Spectator && !isParticle2Spectator)) {
            INCL_ERROR("First collision must be within a target spectator and a non-target spectator");
          }
          if(isParticle1Spectator) {
            theBook.setFirstCollisionSpectatorPosition(backupParticle1->getPosition().mag());
            theBook.setFirstCollisionSpectatorMomentum(backupParticle1->getMomentum().mag());
          } else {
            theBook.setFirstCollisionSpectatorPosition(backupParticle2->getPosition().mag());
            theBook.setFirstCollisionSpectatorMomentum(backupParticle2->getMomentum().mag());
          }
 
          // Store the elasticity of the first collision
          theBook.setFirstCollisionIsElastic(isElastic);
        }
    }
    return;
  }
 
  std::string BinaryCollisionAvatar::dump() const {
    std::stringstream ss;
    ss << "(avatar " << theTime <<" 'nn-collision" << '\n'
      << "(list " << '\n'
      << particle1->dump()
      << particle2->dump()
      << "))" << '\n';
    return ss.str();
  }
 
}