/**************************************************************************
 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
 *                                                                        *
 * Author: The ALICE Off-line Project.                                    *
 * Contributors are mentioned in the code where appropriate.              *
 *                                                                        *
 * Permission to use, copy, modify and distribute this software and its   *
 * documentation strictly for non-commercial purposes is hereby granted   *
 * without fee, provided that the above copyright notice appears in all   *
 * copies and that both the copyright notice and this permission notice   *
 * appear in the supporting documentation. The authors make no claims     *
 * about the suitability of this software for any purpose. It is          *
 * provided "as is" without express or implied warranty.                  *
 **************************************************************************/

/* $Id$ */

#include "AliPythia.h"
#include "AliPythiaRndm.h"

ClassImp(AliPythia)

#ifndef WIN32
# define pyclus pyclus_
# define pycell pycell_
# define pyshow pyshow_
# define pyrobo pyrobo_
# define type_of_call
#else
# define pyclus PYCLUS
# define pycell PYCELL
# define pyrobo PYROBO
# define type_of_call _stdcall
#endif

extern "C" void type_of_call pyclus(Int_t & );
extern "C" void type_of_call pycell(Int_t & );
extern "C" void type_of_call pyshow(Int_t &, Int_t &, Double_t &);
extern "C" void type_of_call pyrobo(Int_t &, Int_t &, Double_t &, Double_t &, Double_t &, Double_t &, Double_t &);

//_____________________________________________________________________________

AliPythia* AliPythia::fgAliPythia=NULL;

AliPythia::AliPythia()
{
// Default Constructor
//
//  Set random number
    if (!AliPythiaRndm::GetPythiaRandom()) 
      AliPythiaRndm::SetPythiaRandom(GetRandom());

}

void AliPythia::ProcInit(Process_t process, Float_t energy, StrucFunc_t strucfunc)
{
// Initialise the process to generate 
    if (!AliPythiaRndm::GetPythiaRandom()) 
      AliPythiaRndm::SetPythiaRandom(GetRandom());
    
    fProcess = process;
    fEcms = energy;
    fStrucFunc = strucfunc;
//  don't decay p0
    SetMDCY(Pycomp(111),1,0);
//  select structure function 
    SetMSTP(52,2);
    SetMSTP(51,strucfunc);
//
// Pythia initialisation for selected processes//
//
// Make MSEL clean
//
    for (Int_t i=1; i<= 200; i++) {
	SetMSUB(i,0);
    }
//  select charm production
    switch (process) 
    {
    case kPyCharm:
	SetMSEL(4);
//
//  heavy quark masses

	SetPMAS(4,1,1.2);
	SetMSTU(16,2);
//
//    primordial pT
	SetMSTP(91,1);
	SetPARP(91,1.);
	SetPARP(93,5.);
//
	break;
    case kPyBeauty:
	SetMSEL(5);
	SetPMAS(5,1,4.75);
	SetMSTU(16,2);
	break;
    case kPyJpsi:
	SetMSEL(0);
// gg->J/Psi g
	SetMSUB(86,1);
	break;
    case kPyJpsiChi:
	SetMSEL(0);
// gg->J/Psi g
	SetMSUB(86,1);
// gg-> chi_0c g
	SetMSUB(87,1);
// gg-> chi_1c g
	SetMSUB(88,1);
// gg-> chi_2c g
	SetMSUB(89,1);	
	break;
    case kPyCharmUnforced:
	SetMSEL(0);
// gq->qg   
	SetMSUB(28,1);
// gg->qq
	SetMSUB(53,1);
// gg->gg
	SetMSUB(68,1);
	break;
    case kPyBeautyUnforced:
	SetMSEL(0);
// gq->qg   
	SetMSUB(28,1);
// gg->qq
	SetMSUB(53,1);
// gg->gg
	SetMSUB(68,1);
	break;
    case kPyMb:
// Minimum Bias pp-Collisions
//
//   
//      select Pythia min. bias model
	SetMSEL(0);
	SetMSUB(92,1);      // single diffraction AB-->XB
	SetMSUB(93,1);      // single diffraction AB-->AX
	SetMSUB(94,1);      // double diffraction
	SetMSUB(95,1);	    // low pt production
	SetMSTP(81,1);      // multiple interactions switched on
	SetMSTP(82,3);      // model with varying impact param. & a single Gaussian
	SetPARP(82,3.47);   // set value pT_0  for turn-off of the cross section of                  
                            // multiple interaction at a reference energy = 14000 GeV
	SetPARP(89,14000.); // reference energy for the above parameter
	SetPARP(90,0.174);  // set exponent for energy dependence of pT_0
    case kPyMbNonDiffr:
// Minimum Bias pp-Collisions
//
//   
//      select Pythia min. bias model
	SetMSEL(0);
	SetMSUB(95,1);	    // low pt production
	SetMSTP(81,1);      // multiple interactions switched on
	SetMSTP(82,3);      // model with varying impact param. & a single Gaussian
	SetPARP(82,3.47);   // set value pT_0  for turn-off of the cross section of                  
                            // multiple interaction at a reference energy = 14000 GeV
	SetPARP(89,14000.); // reference energy for the above parameter
	SetPARP(90,0.174);  // set exponent for energy dependence of pT_0
 
	break;
    case kPyJets:
//
//  QCD Jets
//
	SetMSEL(1);
	break;
    case kPyDirectGamma:
	SetMSEL(10);
	break;
    case kPyCharmPbPbMNR:
    case kPyD0PbPbMNR:
      // Tuning of Pythia parameters aimed to get a resonable agreement
      // between with the NLO calculation by Mangano, Nason, Ridolfi for the
      // c-cbar single inclusive and double differential distributions.
      // This parameter settings are meant to work with Pb-Pb collisions
      // (AliGenPythia::SetNuclei) and with kCTEQ4L PDFs.
      // To get a good agreement the minimum ptHard (AliGenPythia::SetPtHard)
      // has to be set to 2.1GeV. Example in ConfigCharmPPR.C.

      // All QCD processes
      SetMSEL(1);

      // No multiple interactions
      SetMSTP(81,0);
      SetPARP(81,0.0);
      SetPARP(82,0.0);

      // Initial/final parton shower on (Pythia default)
      SetMSTP(61,1);
      SetMSTP(71,1);

      // 2nd order alpha_s
      SetMSTP(2,2);

      // QCD scales
      SetMSTP(32,2);
      SetPARP(34,1.0);

      // Intrinsic <kT>
      SetMSTP(91,1);
      SetPARP(91,1.304);
      SetPARP(93,6.52);

      // Set c-quark mass
      SetPMAS(4,1,1.2);

      break;
    case kPyCharmpPbMNR:
    case kPyD0pPbMNR:
      // Tuning of Pythia parameters aimed to get a resonable agreement
      // between with the NLO calculation by Mangano, Nason, Ridolfi for the
      // c-cbar single inclusive and double differential distributions.
      // This parameter settings are meant to work with p-Pb collisions
      // (AliGenPythia::SetNuclei) and with kCTEQ4L PDFs.
      // To get a good agreement the minimum ptHard (AliGenPythia::SetPtHard)
      // has to be set to 2.1GeV. Example in ConfigCharmPPR.C.

      // All QCD processes
      SetMSEL(1);

      // No multiple interactions
      SetMSTP(81,0);
      SetPARP(81,0.0);
      SetPARP(82,0.0);

      // Initial/final parton shower on (Pythia default)
      SetMSTP(61,1);
      SetMSTP(71,1);

      // 2nd order alpha_s
      SetMSTP(2,2);

      // QCD scales
      SetMSTP(32,2);
      SetPARP(34,1.0);

      // Intrinsic <kT>
      SetMSTP(91,1);
      SetPARP(91,1.16);
      SetPARP(93,5.8);

      // Set c-quark mass
      SetPMAS(4,1,1.2);

      break;
    case kPyCharmppMNR:
    case kPyD0ppMNR:
      // Tuning of Pythia parameters aimed to get a resonable agreement
      // between with the NLO calculation by Mangano, Nason, Ridolfi for the
      // c-cbar single inclusive and double differential distributions.
      // This parameter settings are meant to work with pp collisions
      // (AliGenPythia::SetNuclei) and with kCTEQ4L PDFs.
      // To get a good agreement the minimum ptHard (AliGenPythia::SetPtHard)
      // has to be set to 2.1GeV. Example in ConfigCharmPPR.C.

      // All QCD processes
      SetMSEL(1);

      // No multiple interactions
      SetMSTP(81,0);
      SetPARP(81,0.0);
      SetPARP(82,0.0);

      // Initial/final parton shower on (Pythia default)
      SetMSTP(61,1);
      SetMSTP(71,1);

      // 2nd order alpha_s
      SetMSTP(2,2);

      // QCD scales
      SetMSTP(32,2);
      SetPARP(34,1.0);

      // Intrinsic <kT^2>
      SetMSTP(91,1);
      SetPARP(91,1.);
      SetPARP(93,5.);

      // Set c-quark mass
      SetPMAS(4,1,1.2);

      break;
    case kPyBeautyPbPbMNR:
      // Tuning of Pythia parameters aimed to get a resonable agreement
      // between with the NLO calculation by Mangano, Nason, Ridolfi for the
      // b-bbar single inclusive and double differential distributions.
      // This parameter settings are meant to work with Pb-Pb collisions
      // (AliGenPythia::SetNuclei) and with kCTEQ4L PDFs.
      // To get a good agreement the minimum ptHard (AliGenPythia::SetPtHard)
      // has to be set to 2.75GeV. Example in ConfigBeautyPPR.C.

      // All QCD processes
      SetMSEL(1);

      // No multiple interactions
      SetMSTP(81,0);
      SetPARP(81,0.0);
      SetPARP(82,0.0);

      // Initial/final parton shower on (Pythia default)
      SetMSTP(61,1);
      SetMSTP(71,1);

      // 2nd order alpha_s
      SetMSTP(2,2);

      // QCD scales
      SetMSTP(32,2);
      SetPARP(34,1.0);
      SetPARP(67,1.0);
      SetPARP(71,1.0);

      // Intrinsic <kT>
      SetMSTP(91,1);
      SetPARP(91,2.035);
      SetPARP(93,10.17);

      // Set b-quark mass
      SetPMAS(5,1,4.75);

      break;
    case kPyBeautypPbMNR:
      // Tuning of Pythia parameters aimed to get a resonable agreement
      // between with the NLO calculation by Mangano, Nason, Ridolfi for the
      // b-bbar single inclusive and double differential distributions.
      // This parameter settings are meant to work with p-Pb collisions
      // (AliGenPythia::SetNuclei) and with kCTEQ4L PDFs.
      // To get a good agreement the minimum ptHard (AliGenPythia::SetPtHard)
      // has to be set to 2.75GeV. Example in ConfigBeautyPPR.C.

      // All QCD processes
      SetMSEL(1);

      // No multiple interactions
      SetMSTP(81,0);
      SetPARP(81,0.0);
      SetPARP(82,0.0);

      // Initial/final parton shower on (Pythia default)
      SetMSTP(61,1);
      SetMSTP(71,1);

      // 2nd order alpha_s
      SetMSTP(2,2);

      // QCD scales
      SetMSTP(32,2);
      SetPARP(34,1.0);
      SetPARP(67,1.0);
      SetPARP(71,1.0);

      // Intrinsic <kT>
      SetMSTP(91,1);
      SetPARP(91,1.60);
      SetPARP(93,8.00);

      // Set b-quark mass
      SetPMAS(5,1,4.75);

      break;
    case kPyBeautyppMNR:
      // Tuning of Pythia parameters aimed to get a resonable agreement
      // between with the NLO calculation by Mangano, Nason, Ridolfi for the
      // b-bbar single inclusive and double differential distributions.
      // This parameter settings are meant to work with pp collisions
      // (AliGenPythia::SetNuclei) and with kCTEQ4L PDFs.
      // To get a good agreement the minimum ptHard (AliGenPythia::SetPtHard)
      // has to be set to 2.75GeV. Example in ConfigBeautyPPR.C.

      // All QCD processes
      SetMSEL(1);

      // No multiple interactions
      SetMSTP(81,0);
      SetPARP(81,0.0);
      SetPARP(82,0.0);

      // Initial/final parton shower on (Pythia default)
      SetMSTP(61,1);
      SetMSTP(71,1);

      // 2nd order alpha_s
      SetMSTP(2,2);

      // QCD scales
      SetMSTP(32,2);
      SetPARP(34,1.0);
      SetPARP(67,1.0);
      SetPARP(71,1.0);

      // Intrinsic <kT>
      SetMSTP(91,1);
      SetPARP(91,1.);
      SetPARP(93,5.);

      // Set b-quark mass
      SetPMAS(5,1,4.75);

      break;
    }
//
//  Initialize PYTHIA
    SetMSTP(41,1);   // all resonance decays switched on

    Initialize("CMS","p","p",fEcms);

}

Int_t AliPythia::CheckedLuComp(Int_t kf)
{
// Check Lund particle code (for debugging)
    Int_t kc=Pycomp(kf);
    printf("\n Lucomp kf,kc %d %d",kf,kc);
    return kc;
}

void AliPythia::SetNuclei(Int_t a1, Int_t a2)
{
// Treat protons as inside nuclei with mass numbers a1 and a2  
//    The MSTP array in the PYPARS common block is used to enable and 
//    select the nuclear structure functions. 
//    MSTP(52)  : (D=1) choice of proton and nuclear structure-function library
//            =1: internal PYTHIA acording to MSTP(51) 
//            =2: PDFLIB proton  s.f., with MSTP(51)  = 1000xNGROUP+NSET
//    If the following mass number both not equal zero, nuclear corrections of the stf are used.
//    MSTP(192) : Mass number of nucleus side 1
//    MSTP(193) : Mass number of nucleus side 2
    SetMSTP(52,2);
    SetMSTP(192, a1);
    SetMSTP(193, a2);  
}
	

AliPythia* AliPythia::Instance()
{ 
// Set random number generator 
    if (fgAliPythia) {
	return fgAliPythia;
    } else {
	fgAliPythia = new AliPythia();
	return fgAliPythia;
    }
}

void AliPythia::PrintParticles()
{ 
// Print list of particl properties
    Int_t np = 0;
    char*   name = new char[16];    
    for (Int_t kf=0; kf<1000000; kf++) {
	for (Int_t c = 1;  c > -2; c-=2) {
	    Int_t kc = Pycomp(c*kf);
	    if (kc) {
		Float_t mass  = GetPMAS(kc,1);
		Float_t width = GetPMAS(kc,2);	
		Float_t tau   = GetPMAS(kc,4);

		Pyname(kf,name);
	
		np++;
		
		printf("\n mass, width, tau: %6d %s %10.3f %10.3e %10.3e", 
		       c*kf, name, mass, width, tau);
	    }
	}
    }
    printf("\n Number of particles %d \n \n", np);
}

void  AliPythia::ResetDecayTable()
{
//  Set default values for pythia decay switches
    Int_t i;
    for (i = 1; i <  501; i++) SetMDCY(i,1,fDefMDCY[i]);
    for (i = 1; i < 2001; i++) SetMDME(i,1,fDefMDME[i]);
}

void  AliPythia::SetDecayTable()
{
//  Set default values for pythia decay switches
//
    Int_t i;
    for (i = 1; i <  501; i++) fDefMDCY[i] = GetMDCY(i,1);
    for (i = 1; i < 2001; i++) fDefMDME[i] = GetMDME(i,1);
}

void  AliPythia::Pyclus(Int_t& njet)
{
//  Call Pythia clustering algorithm
//
    pyclus(njet);
}

void  AliPythia::Pycell(Int_t& njet)
{
//  Call Pythia jet reconstruction algorithm
//
    pycell(njet);
}

void  AliPythia::Pyshow(Int_t ip1, Int_t ip2, Double_t qmax)
{
//  Call Pythia jet reconstruction algorithm
//
    Int_t numpart   = fPyjets->N;
    for (Int_t i = 0; i < numpart; i++)
    {
	if (fPyjets->K[2][i] == 7) ip1 = i+1;
	if (fPyjets->K[2][i] == 8) ip2 = i+1;
    }
    

    qmax = 2. * GetVINT(51);
    printf("Pyshow %d %d %f", ip1, ip2, qmax);
    
    pyshow(ip1, ip2, qmax);
}

void AliPythia::Pyrobo(Int_t imi, Int_t ima, Double_t the, Double_t phi, Double_t bex, Double_t bey, Double_t bez)
{
    pyrobo(imi, ima, the, phi, bex, bey, bez);
}



void  AliPythia::Quench()
{
//
//
//  Simple Jet Quenching routine:
//  =============================
//  The jet formed by all final state partons radiated by the parton created 
//  in the hard collisions is quenched by a factor z using:
//  (E + p_z)new = (1-z) (E + p_z)old
//
//   The lost momentum is first balanced by one gluon with virtuality > 0.   
//   Subsequently the gluon splits to yield two gluons with E = p.
//
    Float_t p0[2][5];
    Float_t p1[2][5];
    Float_t p2[2][5];
    Int_t   klast[2] = {-1, -1};
    Int_t   kglu[2];
    for (Int_t i = 0; i < 4; i++)
    {
	p0[0][i] = 0.;
	p0[1][i] = 0.;
	p1[0][i] = 0.;
	p1[1][i] = 0.;
	p2[0][i] = 0.;
	p2[1][i] = 0.;
    }

    Int_t numpart   = fPyjets->N;

    for (Int_t i = 0; i < numpart; i++)
    {
	Int_t imo =  fPyjets->K[2][i];
	Int_t kst =  fPyjets->K[0][i];
	Int_t pdg =  fPyjets->K[1][i];
	
//      Quarks and gluons only
	if (pdg != 21 && TMath::Abs(pdg) > 6) continue;

//      Particles from hard scattering only


	Float_t px = fPyjets->P[0][i];
	Float_t py = fPyjets->P[1][i];
	Float_t pz = fPyjets->P[2][i];
	Float_t e  = fPyjets->P[3][i];
	Float_t m  = fPyjets->P[4][i];
	Float_t pt = TMath::Sqrt(px * px + py * py);
//      Skip comment lines
	if (kst != 1 && kst != 2) continue;

	Float_t mt = TMath::Sqrt(px * px + py * py + m * m);

	//
	// Some cuts to be in a save kinematic region
	//
	if (imo != 7 && imo != 8) continue;
	Int_t index = imo - 7;
	klast[index] = i;
	
	p0[index][0] += px;
	p0[index][1] += py;
	p0[index][2] += pz;
	p0[index][3] += e;	
	
	//
	// Fix z
	//

	Float_t z       = 0.2;
	Float_t eppzOld = e + pz;
	Float_t empzOld = e - pz;


	//
	// Kinematics of the original parton
	// 

	Float_t eppzNew = (1. - z) * eppzOld;
	Float_t empzNew = empzOld - mt * mt * z / eppzOld;
	Float_t eNew0    = 0.5 * (eppzNew + empzNew);
	Float_t pzNew0   = 0.5 * (eppzNew - empzNew);
	//
        // Skip if pt too small
	// 
	if (m * m > eppzNew * empzNew) continue;
	Float_t ptNew    = TMath::Sqrt(eppzNew * empzNew - m * m);
	Float_t pxNew0   = ptNew / pt * px;
	Float_t pyNew0   = ptNew / pt * py;	

	p1[index][0] += pxNew0;
	p1[index][1] += pyNew0;
	p1[index][2] += pzNew0;
	p1[index][3] += eNew0;	
	//
	// Update event record
	//
	fPyjets->P[0][i] = pxNew0;
	fPyjets->P[1][i] = pyNew0;
	fPyjets->P[2][i] = pzNew0;
	fPyjets->P[3][i] = eNew0;
	
    }

    //
    // Gluons
    // 
    
    for (Int_t k = 0; k < 2; k++) 
    {
	for (Int_t j = 0; j < 4; j++) 
	{
	    p2[k][j] = p0[k][j] - p1[k][j];
	}
	p2[k][4] = p2[k][3] * p2[k][3] - p2[k][0] * p2[k][0] - p2[k][1] * p2[k][1] - p2[k][2] * p2[k][2];

	if (p2[k][4] > 0.)
	{

	    //
	    // Bring gluon back to mass shell via momentum scaling 
	    // (momentum will not be conserved, but energy)
	    //
	    // not used anymore
/*
	    Float_t psq   = p2[k][0] * p2[k][0] + p2[k][1] * p2[k][1] + p2[k][2] * p2[k][2];
	    Float_t fact  = TMath::Sqrt(1. + p2[k][4] / psq);
	    p2[k][0] *= fact;
	    p2[k][1] *= fact;
	    p2[k][2] *= fact;
	    p2[k][3]  = TMath::Sqrt(psq) * fact;
	    p2[k][4]  = 0.;
*/
	}
    }

    if (p2[0][4] > 0.) {
	p2[0][4] = TMath::Sqrt(p2[0][4]);
    } else {
	printf("Warning negative mass squared ! \n");
    }
    
    if (p2[1][4] > 0.) {
	p2[1][4] = TMath::Sqrt(p2[1][4]);
    } else {
	printf("Warning negative mass squared ! \n");
    }
    
    //
    // Add the gluons
    //
    
    
    for (Int_t i = 0; i < 2; i++) {
	Int_t ish, jmin, jmax, iGlu, iNew;
	Int_t in = klast[i];
	ish = 0;
	
	if (in == -1) continue;
	if (i == 1 && klast[1] > klast[0]) in += ish;
	
	jmin = in - 1;
	ish  = 1;

	if (p2[i][4] > 0) ish = 2;
	
	iGlu = in;
	iNew = in + ish;
	jmax = numpart + ish - 1;
 
	if (fPyjets->K[0][in-1] == 1 || fPyjets->K[0][in-1] == 21 || fPyjets->K[0][in-1] == 11) {
	    jmin = in;
	    iGlu = in + 1;
	    iNew = in;
	}

	kglu[i] = iGlu;
	
	for (Int_t j = jmax; j > jmin; j--)
	{
	    for (Int_t k = 0; k < 5; k++) {
		fPyjets->K[k][j] =  fPyjets->K[k][j-ish];
		fPyjets->P[k][j] =  fPyjets->P[k][j-ish];
		fPyjets->V[k][j] =  fPyjets->V[k][j-ish];
	    }
	} // end shifting
	numpart += ish;
	(fPyjets->N) += ish;
	
	if (ish == 1) {
	    fPyjets->P[0][iGlu] = p2[i][0];
	    fPyjets->P[1][iGlu] = p2[i][1];
	    fPyjets->P[2][iGlu] = p2[i][2];
	    fPyjets->P[3][iGlu] = p2[i][3];
	    fPyjets->P[4][iGlu] = p2[i][4];
	    
	    fPyjets->K[0][iGlu] = 2;
	    fPyjets->K[1][iGlu] = 21;	
	    fPyjets->K[2][iGlu] = fPyjets->K[2][iNew];
	    fPyjets->K[3][iGlu] = -1;	
	    fPyjets->K[4][iGlu] = -1;
	} else {
	    //
	    // Split gluon in rest frame.
	    //
	    Double_t bx =  p2[i][0] / p2[i][3];
	    Double_t by =  p2[i][1] / p2[i][3];
	    Double_t bz =  p2[i][2] / p2[i][3];
	    
	    Float_t pst  = p2[i][4] / 2.;
	    
	    Float_t cost = 2. * gRandom->Rndm() - 1.;
	    Float_t sint = TMath::Sqrt(1. - cost * cost);
	    Float_t phi = 2. * TMath::Pi() * gRandom->Rndm();
	    
	    Float_t pz1 =   pst * cost;
	    Float_t pz2 =  -pst * cost;
	    Float_t pt1 =   pst * sint;
	    Float_t pt2 =  -pst * sint;
	    Float_t px1 =   pt1 * TMath::Cos(phi);
	    Float_t py1 =   pt1 * TMath::Sin(phi);	    
	    Float_t px2 =   pt2 * TMath::Cos(phi);
	    Float_t py2 =   pt2 * TMath::Sin(phi);	    
	    
	    fPyjets->P[0][iGlu] = px1;
	    fPyjets->P[1][iGlu] = py1;
	    fPyjets->P[2][iGlu] = pz1;
	    fPyjets->P[3][iGlu] = pst;
	    fPyjets->P[4][iGlu] = 0.;
	    
	    fPyjets->K[0][iGlu] = 2;
	    fPyjets->K[1][iGlu] = 21;	
	    fPyjets->K[2][iGlu] = fPyjets->K[2][iNew];
	    fPyjets->K[3][iGlu] = -1;	
	    fPyjets->K[4][iGlu] = -1;

	    fPyjets->P[0][iGlu+1] = px2;
	    fPyjets->P[1][iGlu+1] = py2;
	    fPyjets->P[2][iGlu+1] = pz2;
	    fPyjets->P[3][iGlu+1] = pst;
	    fPyjets->P[4][iGlu+1] = 0.;
	    
	    fPyjets->K[0][iGlu+1] = 2;
	    fPyjets->K[1][iGlu+1] = 21;	
	    fPyjets->K[2][iGlu+1] = fPyjets->K[2][iNew];
	    fPyjets->K[3][iGlu+1] = -1;	
	    fPyjets->K[4][iGlu+1] = -1;
	    SetMSTU(1,0);
	    SetMSTU(2,0);

	    //
	    // Boost back
	    //
	    Pyrobo(iGlu + 1, iGlu + 2, 0., 0., bx, by, bz);

	}
    } // end adding gluons
} // end quench