[u/mrichter/AliRoot.git] / ZDC / AliGenZDC.cxx

/**************************************************************************
 * 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.                  *
 **************************************************************************/

/*
$Log$
Revision 1.5  2000/11/22 11:30:12  coppedis
Major code revision

Revision 1.4  2000/10/05 08:02:47  fca
Correction of the generator direction

Revision 1.3  2000/10/02 21:28:20  fca
Removal of useless dependecies via forward declarations

Revision 1.2  2000/07/11 11:12:34  fca
Some syntax corrections for non standard HP aCC

Revision 1.1  2000/07/10 13:58:01  fca
New version of ZDC from E.Scomparin & C.Oppedisano

Revision 1.7  2000/01/19 17:17:40  fca

Revision 1.6  1999/09/29 09:24:35  fca
Introduction of the Copyright and cvs Log

*/
#include <assert.h>

#include <TRandom.h>
#include <TLorentzVector.h>
#include <TVector3.h>
#include "TDatabasePDG.h"

#include "AliGenZDC.h"
#include "AliConst.h"
#include "AliPDG.h"
#include "AliRun.h"
#include "AliMCProcess.h"
 
ClassImp(AliGenZDC)
 
//_____________________________________________________________________________
AliGenZDC::AliGenZDC()
   :AliGenerator()
{
  //
  // Default constructor
  //
  fIpart = 0;
}

//_____________________________________________________________________________
AliGenZDC::AliGenZDC(Int_t npart)
   :AliGenerator(npart)
{
  //
  // Standard constructor
  //
  fName = "AliGenZDC";
  fTitle = "Generation of Test Particles for ZDCs";
  fIpart = kNeutron;
  fCosx  = 0.;
  fCosy  = 0.;
  fCosz  = 1.;
  fPseudoRapidity = 0.;
  fFermiflag = 1;
  // LHC values for beam divergence and crossing angle
  fBeamDiv = 0.000032;
  fBeamCrossAngle = 0.0001;
  fBeamCrossPlane = 2;
}

//_____________________________________________________________________________
void AliGenZDC::Init()
{
  printf("		AliGenZDC initialized with:\n");
  printf("   Fermi flag = %d, Beam Divergence = %f, Crossing Angle "
         "= %f, Crossing Plane = %d\n\n", fFermiflag, fBeamDiv, fBeamCrossAngle,
	 fBeamCrossPlane);
  //Initialize Fermi momentum distributions for Pb-Pb
  FermiTwoGaussian(207.,82.,fPp,fProbintp,fProbintn);
}  
  
//_____________________________________________________________________________
void AliGenZDC::Generate()
{
  //
  // Generate one trigger (n or p)
  //
  Int_t i;

  Double_t mass, pLab[3], fP0, ddp[3], dddp0, dddp[3];
  Float_t ptot = fPMin;
  Int_t nt;
  
  if(fPseudoRapidity==0.){ 
    pLab[0] = ptot*fCosx;
    pLab[1] = ptot*fCosy;
    pLab[2] = ptot*fCosz;
  }
  else{
    Float_t scang = 2*TMath::ATan(TMath::Exp(-(fPseudoRapidity)));
    pLab[0] = -ptot*TMath::Sin(scang);
    pLab[1] = 0.;
    pLab[2] = ptot*TMath::Cos(scang);
  }
  for(i=0; i<=2; i++){
     fPInit[i] = pLab[i];
     fP[i] = pLab[i];
  }
  
  // Beam divergence and crossing angle
  if(fBeamCrossAngle!=0.) {
    BeamDivCross(1,fBeamDiv,fBeamCrossAngle,fBeamCrossPlane,pLab);
    for(i=0; i<=2; i++){
       fP[i] = pLab[i];
    }
  }
  if(fBeamDiv!=0.) {
    BeamDivCross(0,fBeamDiv,fBeamCrossAngle,fBeamCrossPlane,pLab);
    for(i=0; i<=2; i++){
       fP[i] = pLab[i];
    }
  }

  // If required apply the Fermi momentum
  if(fFermiflag==1){
    if((fIpart==kProton) || (fIpart==kNeutron)){
      ExtractFermi(fIpart,fPp,fProbintp,fProbintn,ddp);
    }
    mass=gAlice->PDGDB()->GetParticle(fIpart)->Mass();
    fP0 = TMath::Sqrt(fP[0]*fP[0]+fP[1]*fP[1]+fP[2]*fP[2]+mass*mass);
    for(i=0; i<=2; i++){
       dddp[i] = ddp[i];
    }
    dddp0 = TMath::Sqrt(dddp[0]*dddp[0]+dddp[1]*dddp[1]+dddp[2]*dddp[2]+mass*mass);
    
    TVector3 b(fP[0]/fP0, fP[1]/fP0, fP[2]/fP0);
    TLorentzVector pFermi(dddp[0], dddp[1], dddp[2], dddp0);

    
    pFermi.Boost(b);

    for(i=0; i<=2; i++){
       fBoostP[i] = pFermi[i];
       fP[i] = pFermi[i];
    }

  }
  
  for(i=0; i<=2; i++){
     fPTrack[i] = fP[i];
  }
      
  Float_t polar[3] = {0,0,0};
//  printf("fPTrack = %f, %f, %f \n",fPTrack[0],fPTrack[1],fPTrack[2]);
  gAlice->SetTrack(fTrackIt,-1,fIpart,fPTrack,fOrigin.GetArray(),polar,0,
  		   kPPrimary,nt);
}

//_____________________________________________________________________________
void AliGenZDC::FermiTwoGaussian(Double_t A, Float_t Z, Double_t* fPp, Double_t*
  		fProbintp, Double_t* fProbintn)
{
//
// Momenta distributions according to the "double-gaussian"
// distribution (Ilinov) - equal for protons and neutrons
//
//   printf("		Initialization of Fermi momenta distribution\n");
   fProbintp[0] = 0;
   fProbintn[0] = 0;
   Double_t sig1 = 0.113;
   Double_t sig2 = 0.250;
   Double_t alfa = 0.18*(TMath::Power((A/12.),(Float_t)1/3));
   Double_t xk = (2*k2PI)/((1.+alfa)*(TMath::Power(k2PI,1.5)));
   
   for(Int_t i=1; i<=200; i++){
      Double_t p = i*0.005;
      fPp[i] = p;
      Double_t e1 = (p*p)/(2.*sig1*sig1);
      Double_t e2 = (p*p)/(2.*sig2*sig2);
      Double_t f1 = TMath::Exp(-(e1));
      Double_t f2 = TMath::Exp(-(e2));
      Double_t probp = xk*p*p*(f1/(TMath::Power(sig1,3.))+
                      alfa*f2/(TMath::Power(sig2,3.)))*0.005;
      fProbintp[i] = fProbintp[i-1] + probp;
      fProbintn[i] = fProbintp[i];
//      printf(" fProbintp[%d] = %f, fProbintp[%d] = %f\n",i,fProbintp[i],i,fProbintn[i]);
   }
} 
//_____________________________________________________________________________
void AliGenZDC::ExtractFermi(Int_t id, Double_t* fPp, Double_t* fProbintp,
                Double_t* fProbintn, Double_t* ddp)
{
//
// Compute Fermi momentum for spectator nucleons
//
//  printf("		Extraction of Fermi momentum\n");

  Int_t i;
  Float_t xx = gRandom->Rndm();
  assert ( id==kProton || id==kNeutron );
  if(id==kProton){
    for(i=0; i<=200; i++){
       if((xx>=fProbintp[i-1]) && (xx<fProbintp[i])) break;
       }
  }
  else {
    for(i=0; i<=200; i++){
       if((xx>=fProbintn[i-1]) && (xx<fProbintn[i])) break;
       }
   }
         Float_t pext = fPp[i]+0.001;
	 Float_t phi = k2PI*(gRandom->Rndm());
	 Float_t cost = (1.-2.*(gRandom->Rndm()));
	 Float_t tet = TMath::ACos(cost);
	 ddp[0] = pext*TMath::Sin(tet)*TMath::Cos(phi);
	 ddp[1] = pext*TMath::Sin(tet)*TMath::Sin(phi);
	 ddp[2] = pext*cost;
//  printf(" pFx = %f  pFy = %f  pFz = %f \n",ddp[0],ddp[1],ddp[2]); 
}

//_____________________________________________________________________________
void AliGenZDC::BeamDivCross(Int_t icross, Float_t fBeamDiv, Float_t fBeamCrossAngle, 
                Int_t fBeamCrossPlane, Double_t* pLab)
{
  Double_t tetpart, fipart, tetdiv=0, fidiv=0, angleSum[2], tetsum, fisum;
  Double_t rvec;

//  printf("		Beam divergence and crossing angle\n");
  Int_t i;
  Double_t pmq = 0.;
  for(i=0; i<=2; i++){
     pmq = pmq+pLab[i]*pLab[i];
  }
  Double_t pmod = TMath::Sqrt(pmq);

  if(icross==0){
    rvec = gRandom->Gaus(0.0,1.0);
    tetdiv = fBeamDiv * TMath::Abs(rvec);
    fidiv = (gRandom->Rndm())*k2PI;
  }
  else if(icross==1){
    if(fBeamCrossPlane==0.){
      tetdiv = 0.;
      fidiv = 0.;
    }
    else if(fBeamCrossPlane==1.){
      tetdiv = fBeamCrossAngle;
      fidiv = 0.;
    }
    else if(fBeamCrossPlane==2.){
      tetdiv = fBeamCrossAngle;
      fidiv = k2PI/4.;
    }
  }

  tetpart = TMath::ATan(TMath::Sqrt(pLab[0]*pLab[0]+pLab[1]*pLab[1])/pLab[2]);
  if(pLab[1]!=0. || pLab[0]!=0.){
    fipart = TMath::ATan2(pLab[1],pLab[0]);
  }
  else{
    fipart = 0.;
  }
  if(fipart<0.) {fipart = fipart+k2PI;}
  tetdiv = tetdiv*kRaddeg;
  fidiv = fidiv*kRaddeg;
  tetpart = tetpart*kRaddeg;
  fipart = fipart*kRaddeg;
  AddAngle(tetpart,fipart,tetdiv,fidiv,angleSum);
  tetsum = angleSum[0];
  fisum  = angleSum[1];
  tetsum = tetsum*kDegrad;
  fisum = fisum*kDegrad;
  pLab[0] = pmod*TMath::Sin(tetsum)*TMath::Cos(fisum);
  pLab[1] = pmod*TMath::Sin(tetsum)*TMath::Sin(fisum);
  pLab[2] = pmod*TMath::Cos(tetsum);
  for(i=0; i<=2; i++){
     fDivP[i] = pLab[i];
  }
}
  
//_____________________________________________________________________________
void  AliGenZDC::AddAngle(Double_t theta1, Double_t phi1, Double_t theta2,
  	       Double_t phi2, Double_t* angleSum)
{
  Double_t temp, conv, cx, cy, cz, ct1, st1, ct2, st2, cp1, sp1, cp2, sp2;
  Double_t rtetsum, tetsum, fisum;
  
  temp = -1.;
  conv = 180./TMath::ACos(temp);
  
  ct1 = TMath::Cos(theta1/conv);
  st1 = TMath::Sin(theta1/conv);
  cp1 = TMath::Cos(phi1/conv);
  sp1 = TMath::Sin(phi1/conv);
  ct2 = TMath::Cos(theta2/conv);
  st2 = TMath::Sin(theta2/conv);
  cp2 = TMath::Cos(phi2/conv);
  sp2 = TMath::Sin(phi2/conv);
  cx = ct1*cp1*st2*cp2+st1*cp1*ct2-sp1*st2*sp2;
  cy = ct1*sp1*st2*cp2+st1*sp1*ct2+cp1*st2*sp2;
  cz = ct1*ct2-st1*st2*cp2;
  
  rtetsum = TMath::ACos(cz);
  tetsum = conv*rtetsum;
  if(tetsum==0. || tetsum==180.){
    fisum = 0.;
    return;
  }
  temp = cx/TMath::Sin(rtetsum);
  if(temp>1.) temp=1.;
  if(temp<-1.) temp=-1.;
  fisum = conv*TMath::ACos(temp);
  if(cy<0) {fisum = 360.-fisum;}
  angleSum[0] = tetsum;
  angleSum[1] = fisum;
}
Commit	Line	Data
68ca986e	1	/**************************************************************************
	2	* Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
	3	* *
	4	* Author: The ALICE Off-line Project. *
	5	* Contributors are mentioned in the code where appropriate. *
	6	* *
	7	* Permission to use, copy, modify and distribute this software and its *
	8	* documentation strictly for non-commercial purposes is hereby granted *
	9	* without fee, provided that the above copyright notice appears in all *
	10	* copies and that both the copyright notice and this permission notice *
	11	* appear in the supporting documentation. The authors make no claims *
	12	* about the suitability of this software for any purpose. It is *
	13	* provided "as is" without express or implied warranty. *
	14	**************************************************************************/
	15
	16	/*
	17	$Log$
1de555dc	18	Revision 1.5 2000/11/22 11:30:12 coppedis
	19	Major code revision
	20
866ab5a2	21	Revision 1.4 2000/10/05 08:02:47 fca
	22	Correction of the generator direction
	23
699b37ac	24	Revision 1.3 2000/10/02 21:28:20 fca
	25	Removal of useless dependecies via forward declarations
	26
94de3818	27	Revision 1.2 2000/07/11 11:12:34 fca
	28	Some syntax corrections for non standard HP aCC
	29
c0ceba4c	30	Revision 1.1 2000/07/10 13:58:01 fca
	31	New version of ZDC from E.Scomparin & C.Oppedisano
	32
68ca986e	33	Revision 1.7 2000/01/19 17:17:40 fca
	34
	35	Revision 1.6 1999/09/29 09:24:35 fca
	36	Introduction of the Copyright and cvs Log
	37
	38	*/
94de3818	39	#include <assert.h>
94de3818	40
68ca986e	41	#include <TRandom.h>
	42	#include <TLorentzVector.h>
	43	#include <TVector3.h>
94de3818	44	#include "TDatabasePDG.h"
68ca986e	45
	46	#include "AliGenZDC.h"
	47	#include "AliConst.h"
	48	#include "AliPDG.h"
	49	#include "AliRun.h"
1de555dc	50	#include "AliMCProcess.h"
68ca986e	51
	52	ClassImp(AliGenZDC)
	53
	54	//_____________________________________________________________________________
	55	AliGenZDC::AliGenZDC()
	56	:AliGenerator()
	57	{
	58	//
	59	// Default constructor
	60	//
	61	fIpart = 0;
	62	}
	63
	64	//_____________________________________________________________________________
	65	AliGenZDC::AliGenZDC(Int_t npart)
	66	:AliGenerator(npart)
	67	{
	68	//
	69	// Standard constructor
	70	//
	71	fName = "AliGenZDC";
	72	fTitle = "Generation of Test Particles for ZDCs";
	73	fIpart = kNeutron;
	74	fCosx = 0.;
	75	fCosy = 0.;
	76	fCosz = 1.;
	77	fPseudoRapidity = 0.;
	78	fFermiflag = 1;
	79	// LHC values for beam divergence and crossing angle
	80	fBeamDiv = 0.000032;
	81	fBeamCrossAngle = 0.0001;
	82	fBeamCrossPlane = 2;
	83	}
	84
	85	//_____________________________________________________________________________
	86	void AliGenZDC::Init()
	87	{
866ab5a2	88	printf(" AliGenZDC initialized with:\n");
866ab5a2	89	printf(" Fermi flag = %d, Beam Divergence = %f, Crossing Angle "
68ca986e	90	"= %f, Crossing Plane = %d\n\n", fFermiflag, fBeamDiv, fBeamCrossAngle,
	91	fBeamCrossPlane);
	92	//Initialize Fermi momentum distributions for Pb-Pb
	93	FermiTwoGaussian(207.,82.,fPp,fProbintp,fProbintn);
	94	}
	95
	96	//_____________________________________________________________________________
	97	void AliGenZDC::Generate()
	98	{
	99	//
	100	// Generate one trigger (n or p)
	101	//
c0ceba4c	102	Int_t i;
c0ceba4c	103
866ab5a2	104	Double_t mass, pLab[3], fP0, ddp[3], dddp0, dddp[3];
68ca986e	105	Float_t ptot = fPMin;
	106	Int_t nt;
	107
866ab5a2	108	if(fPseudoRapidity==0.){
68ca986e	109	pLab[0] = ptot*fCosx;
	110	pLab[1] = ptot*fCosy;
	111	pLab[2] = ptot*fCosz;
	112	}
	113	else{
	114	Float_t scang = 2*TMath::ATan(TMath::Exp(-(fPseudoRapidity)));
	115	pLab[0] = -ptot*TMath::Sin(scang);
	116	pLab[1] = 0.;
	117	pLab[2] = ptot*TMath::Cos(scang);
	118	}
c0ceba4c	119	for(i=0; i<=2; i++){
866ab5a2	120	fPInit[i] = pLab[i];
68ca986e	121	fP[i] = pLab[i];
	122	}
	123
	124	// Beam divergence and crossing angle
866ab5a2	125	if(fBeamCrossAngle!=0.) {
	126	BeamDivCross(1,fBeamDiv,fBeamCrossAngle,fBeamCrossPlane,pLab);
	127	for(i=0; i<=2; i++){
	128	fP[i] = pLab[i];
	129	}
	130	}
	131	if(fBeamDiv!=0.) {
	132	BeamDivCross(0,fBeamDiv,fBeamCrossAngle,fBeamCrossPlane,pLab);
	133	for(i=0; i<=2; i++){
	134	fP[i] = pLab[i];
	135	}
	136	}
	137
68ca986e	138	// If required apply the Fermi momentum
	139	if(fFermiflag==1){
	140	if((fIpart==kProton) \|\| (fIpart==kNeutron)){
	141	ExtractFermi(fIpart,fPp,fProbintp,fProbintn,ddp);
	142	}
94de3818	143	mass=gAlice->PDGDB()->GetParticle(fIpart)->Mass();
866ab5a2	144	fP0 = TMath::Sqrt(fP[0]fP[0]+fP[1]fP[1]+fP[2]fP[2]+massmass);
c0ceba4c	145	for(i=0; i<=2; i++){
68ca986e	146	dddp[i] = ddp[i];
	147	}
	148	dddp0 = TMath::Sqrt(dddp[0]dddp[0]+dddp[1]dddp[1]+dddp[2]dddp[2]+massmass);
	149
866ab5a2	150	TVector3 b(fP[0]/fP0, fP[1]/fP0, fP[2]/fP0);
68ca986e	151	TLorentzVector pFermi(dddp[0], dddp[1], dddp[2], dddp0);
68ca986e	152
68ca986e	153
	154	pFermi.Boost(b);
	155
c0ceba4c	156	for(i=0; i<=2; i++){
68ca986e	157	fBoostP[i] = pFermi[i];
866ab5a2	158	fP[i] = pFermi[i];
68ca986e	159	}
	160
	161	}
866ab5a2	162
	163	for(i=0; i<=2; i++){
	164	fPTrack[i] = fP[i];
	165	}
	166
68ca986e	167	Float_t polar[3] = {0,0,0};
866ab5a2	168	// printf("fPTrack = %f, %f, %f \n",fPTrack[0],fPTrack[1],fPTrack[2]);
866ab5a2	169	gAlice->SetTrack(fTrackIt,-1,fIpart,fPTrack,fOrigin.GetArray(),polar,0,
1de555dc	170	kPPrimary,nt);
68ca986e	171	}
	172
	173	//_____________________________________________________________________________
	174	void AliGenZDC::FermiTwoGaussian(Double_t A, Float_t Z, Double_t* fPp, Double_t*
	175	fProbintp, Double_t* fProbintn)
	176	{
	177	//
	178	// Momenta distributions according to the "double-gaussian"
	179	// distribution (Ilinov) - equal for protons and neutrons
	180	//
	181	// printf(" Initialization of Fermi momenta distribution\n");
	182	fProbintp[0] = 0;
	183	fProbintn[0] = 0;
	184	Double_t sig1 = 0.113;
	185	Double_t sig2 = 0.250;
	186	Double_t alfa = 0.18*(TMath::Power((A/12.),(Float_t)1/3));
	187	Double_t xk = (2k2PI)/((1.+alfa)(TMath::Power(k2PI,1.5)));
	188
	189	for(Int_t i=1; i<=200; i++){
	190	Double_t p = i*0.005;
	191	fPp[i] = p;
68ca986e	192	Double_t e1 = (pp)/(2.sig1*sig1);
	193	Double_t e2 = (pp)/(2.sig2*sig2);
	194	Double_t f1 = TMath::Exp(-(e1));
	195	Double_t f2 = TMath::Exp(-(e2));
	196	Double_t probp = xkpp*(f1/(TMath::Power(sig1,3.))+
	197	alfaf2/(TMath::Power(sig2,3.)))0.005;
68ca986e	198	fProbintp[i] = fProbintp[i-1] + probp;
	199	fProbintn[i] = fProbintp[i];
	200	// printf(" fProbintp[%d] = %f, fProbintp[%d] = %f\n",i,fProbintp[i],i,fProbintn[i]);
	201	}
	202	}
	203	//_____________________________________________________________________________
	204	void AliGenZDC::ExtractFermi(Int_t id, Double_t* fPp, Double_t* fProbintp,
	205	Double_t* fProbintn, Double_t* ddp)
	206	{
	207	//
	208	// Compute Fermi momentum for spectator nucleons
	209	//
866ab5a2	210	// printf(" Extraction of Fermi momentum\n");
866ab5a2	211
68ca986e	212	Int_t i;
68ca986e	213	Float_t xx = gRandom->Rndm();
699b37ac	214	assert ( id==kProton \|\| id==kNeutron );
68ca986e	215	if(id==kProton){
	216	for(i=0; i<=200; i++){
	217	if((xx>=fProbintp[i-1]) && (xx<fProbintp[i])) break;
	218	}
	219	}
94de3818	220	else {
68ca986e	221	for(i=0; i<=200; i++){
	222	if((xx>=fProbintn[i-1]) && (xx<fProbintn[i])) break;
	223	}
	224	}
	225	Float_t pext = fPp[i]+0.001;
	226	Float_t phi = k2PI*(gRandom->Rndm());
	227	Float_t cost = (1.-2.*(gRandom->Rndm()));
	228	Float_t tet = TMath::ACos(cost);
	229	ddp[0] = pextTMath::Sin(tet)TMath::Cos(phi);
	230	ddp[1] = pextTMath::Sin(tet)TMath::Sin(phi);
	231	ddp[2] = pext*cost;
866ab5a2	232	// printf(" pFx = %f pFy = %f pFz = %f \n",ddp[0],ddp[1],ddp[2]);
68ca986e	233	}
	234
	235	//_____________________________________________________________________________
	236	void AliGenZDC::BeamDivCross(Int_t icross, Float_t fBeamDiv, Float_t fBeamCrossAngle,
	237	Int_t fBeamCrossPlane, Double_t* pLab)
	238	{
866ab5a2	239	Double_t tetpart, fipart, tetdiv=0, fidiv=0, angleSum[2], tetsum, fisum;
68ca986e	240	Double_t rvec;
c0ceba4c	241
866ab5a2	242	// printf(" Beam divergence and crossing angle\n");
c0ceba4c	243	Int_t i;
68ca986e	244	Double_t pmq = 0.;
c0ceba4c	245	for(i=0; i<=2; i++){
68ca986e	246	pmq = pmq+pLab[i]*pLab[i];
	247	}
	248	Double_t pmod = TMath::Sqrt(pmq);
68ca986e	249
68ca986e	250	if(icross==0){
	251	rvec = gRandom->Gaus(0.0,1.0);
	252	tetdiv = fBeamDiv * TMath::Abs(rvec);
	253	fidiv = (gRandom->Rndm())*k2PI;
	254	}
	255	else if(icross==1){
	256	if(fBeamCrossPlane==0.){
	257	tetdiv = 0.;
	258	fidiv = 0.;
	259	}
	260	else if(fBeamCrossPlane==1.){
	261	tetdiv = fBeamCrossAngle;
	262	fidiv = 0.;
	263	}
	264	else if(fBeamCrossPlane==2.){
	265	tetdiv = fBeamCrossAngle;
	266	fidiv = k2PI/4.;
	267	}
	268	}
866ab5a2	269
	270	tetpart = TMath::ATan(TMath::Sqrt(pLab[0]pLab[0]+pLab[1]pLab[1])/pLab[2]);
	271	if(pLab[1]!=0. \|\| pLab[0]!=0.){
	272	fipart = TMath::ATan2(pLab[1],pLab[0]);
68ca986e	273	}
	274	else{
	275	fipart = 0.;
	276	}
	277	if(fipart<0.) {fipart = fipart+k2PI;}
68ca986e	278	tetdiv = tetdiv*kRaddeg;
	279	fidiv = fidiv*kRaddeg;
	280	tetpart = tetpart*kRaddeg;
	281	fipart = fipart*kRaddeg;
	282	AddAngle(tetpart,fipart,tetdiv,fidiv,angleSum);
	283	tetsum = angleSum[0];
	284	fisum = angleSum[1];
68ca986e	285	tetsum = tetsum*kDegrad;
	286	fisum = fisum*kDegrad;
	287	pLab[0] = pmodTMath::Sin(tetsum)TMath::Cos(fisum);
	288	pLab[1] = pmodTMath::Sin(tetsum)TMath::Sin(fisum);
	289	pLab[2] = pmod*TMath::Cos(tetsum);
c0ceba4c	290	for(i=0; i<=2; i++){
68ca986e	291	fDivP[i] = pLab[i];
	292	}
	293	}
	294
	295	//_____________________________________________________________________________
	296	void AliGenZDC::AddAngle(Double_t theta1, Double_t phi1, Double_t theta2,
	297	Double_t phi2, Double_t* angleSum)
	298	{
	299	Double_t temp, conv, cx, cy, cz, ct1, st1, ct2, st2, cp1, sp1, cp2, sp2;
	300	Double_t rtetsum, tetsum, fisum;
	301
	302	temp = -1.;
	303	conv = 180./TMath::ACos(temp);
	304
	305	ct1 = TMath::Cos(theta1/conv);
	306	st1 = TMath::Sin(theta1/conv);
	307	cp1 = TMath::Cos(phi1/conv);
	308	sp1 = TMath::Sin(phi1/conv);
	309	ct2 = TMath::Cos(theta2/conv);
	310	st2 = TMath::Sin(theta2/conv);
	311	cp2 = TMath::Cos(phi2/conv);
	312	sp2 = TMath::Sin(phi2/conv);
	313	cx = ct1cp1st2cp2+st1cp1ct2-sp1st2*sp2;
	314	cy = ct1sp1st2cp2+st1sp1ct2+cp1st2*sp2;
	315	cz = ct1ct2-st1st2*cp2;
	316
	317	rtetsum = TMath::ACos(cz);
	318	tetsum = conv*rtetsum;
	319	if(tetsum==0. \|\| tetsum==180.){
	320	fisum = 0.;
	321	return;
	322	}
	323	temp = cx/TMath::Sin(rtetsum);
	324	if(temp>1.) temp=1.;
	325	if(temp<-1.) temp=-1.;
	326	fisum = conv*TMath::ACos(temp);
	327	if(cy<0) {fisum = 360.-fisum;}
68ca986e	328	angleSum[0] = tetsum;
	329	angleSum[1] = fisum;
	330	}
	331