[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.                  *
 **************************************************************************/

/* $Id$ */

#include <assert.h>

#include <TDatabasePDG.h>
#include <TLorentzVector.h>
#include <TMCProcess.h>
#include <TPDGCode.h>
#include <TRandom.h>
#include <TVector3.h>

#include "AliConst.h"
#include "AliGenZDC.h"
#include "AliRun.h"
#include "AliMC.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;
  
  Int_t i, j;
  for(i=0; i<201; i++){
     fProbintp[i] = 0;
     fProbintn[i] = 0;
  }
  for(j=0; j<3; j++) fPp[i] = 0;
  fDebugOpt = 0;
}

//_____________________________________________________________________________
void AliGenZDC::Init()
{
  printf("\n\n		AliGenZDC initialization:\n");
  printf("   Particle: %d, Track cosines: x = %f, y = %f, z = %f \n", 
  	 fIpart,fCosx,fCosy,fCosz);
  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.,fPp,fProbintp,fProbintn);
}  
  
//_____________________________________________________________________________
void AliGenZDC::Generate()
{
  //
  // Generate one trigger (n or p)
  //
  Int_t i;

  Double_t Mass, pLab[3], fP0, fP[3], fBoostP[3], ddp[3], dddp0, dddp[3]; 
  Float_t  fPTrack[3], 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++) fP[i] = pLab[i];  
  if(fDebugOpt == 1){
    printf("\n\n		Particle momentum before divergence and crossing\n");
    for(i=0; i<=2; i++)printf(" 	pLab[%d] = %f\n",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};
  gAlice->GetMCApp()->PushTrack(fTrackIt,-1,fIpart,fPTrack,fOrigin.GetArray(),polar,0,
  		   kPPrimary,nt);
  if(fDebugOpt == 1){
    printf("\n\n		Track momentum:\n");
    printf("\n	 fPTrack = %f, %f, %f \n",fPTrack[0],fPTrack[1],fPTrack[2]);
  }
}

//_____________________________________________________________________________
void AliGenZDC::FermiTwoGaussian(Float_t A, Double_t *fPp, 
                Double_t *fProbintp, Double_t *fProbintn)
{
//
// Momenta distributions according to the "double-gaussian"
// distribution (Ilinov) - equal for protons and neutrons
//

   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];
   }
   if(fDebugOpt == 1){
     printf("\n\n		Initialization of Fermi momenta distribution \n");
     //for(Int_t i=0; i<=200; i++)
     //   printf(" fProbintp[%d] = %f, fProbintn[%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
//
  
  Int_t i;
  Float_t xx = gRandom->Rndm();
  assert ( id==kProton || id==kNeutron );
  if(id==kProton){
    for(i=1; 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;

  if(fDebugOpt == 1){
    printf("\n\n		Extraction of Fermi momentum\n");
    printf("\n 	pxFermi = %f  pyFermi = %f  pzFermi = %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;

  Int_t sign=0;
  if(pLab[2]>=0.)  sign=1;
  else sign=-1;
  Double_t pmq = 0.;
  Int_t i;
  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);
  if(sign==1) pLab[2] = pmod*TMath::Cos(tetsum);
  else pLab[2] = -pmod*TMath::Cos(tetsum);
  if(fDebugOpt == 1){
    printf("\n\n		Beam divergence and crossing angle\n");
    for(i=0; i<=2; i++)printf(" 	pLab[%d] = %f\n",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
88cb7938	16	/* $Id$ */
116cbefd	17
94de3818	18	#include <assert.h>
94de3818	19
116cbefd	20	#include <TDatabasePDG.h>
68ca986e	21	#include <TLorentzVector.h>
116cbefd	22	#include <TMCProcess.h>
	23	#include <TPDGCode.h>
	24	#include <TRandom.h>
68ca986e	25	#include <TVector3.h>
68ca986e	26
68ca986e	27	#include "AliConst.h"
116cbefd	28	#include "AliGenZDC.h"
68ca986e	29	#include "AliRun.h"
5d12ce38	30	#include "AliMC.h"
68ca986e	31
	32	ClassImp(AliGenZDC)
	33
	34	//_____________________________________________________________________________
	35	AliGenZDC::AliGenZDC()
	36	:AliGenerator()
	37	{
	38	//
	39	// Default constructor
	40	//
	41	fIpart = 0;
	42	}
	43
	44	//_____________________________________________________________________________
	45	AliGenZDC::AliGenZDC(Int_t npart)
	46	:AliGenerator(npart)
	47	{
	48	//
	49	// Standard constructor
	50	//
	51	fName = "AliGenZDC";
	52	fTitle = "Generation of Test Particles for ZDCs";
	53	fIpart = kNeutron;
	54	fCosx = 0.;
	55	fCosy = 0.;
	56	fCosz = 1.;
	57	fPseudoRapidity = 0.;
5a881c97	58
68ca986e	59	fFermiflag = 1;
	60	// LHC values for beam divergence and crossing angle
	61	fBeamDiv = 0.000032;
	62	fBeamCrossAngle = 0.0001;
	63	fBeamCrossPlane = 2;
5a881c97	64
	65	Int_t i, j;
	66	for(i=0; i<201; i++){
	67	fProbintp[i] = 0;
	68	fProbintn[i] = 0;
	69	}
c294be39	70	for(j=0; j<3; j++) fPp[i] = 0;
5a881c97	71	fDebugOpt = 0;
68ca986e	72	}
	73
	74	//_____________________________________________________________________________
	75	void AliGenZDC::Init()
	76	{
c294be39	77	printf("\n\n AliGenZDC initialization:\n");
	78	printf(" Particle: %d, Track cosines: x = %f, y = %f, z = %f \n",
	79	fIpart,fCosx,fCosy,fCosz);
	80	printf(" Fermi flag = %d, Beam divergence = %f, Crossing angle "
	81	"= %f, Crossing plane = %d\n\n", fFermiflag, fBeamDiv, fBeamCrossAngle,
68ca986e	82	fBeamCrossPlane);
5a881c97	83
68ca986e	84	//Initialize Fermi momentum distributions for Pb-Pb
f5cb71ad	85	FermiTwoGaussian(207.,fPp,fProbintp,fProbintn);
68ca986e	86	}
	87
	88	//_____________________________________________________________________________
	89	void AliGenZDC::Generate()
	90	{
	91	//
	92	// Generate one trigger (n or p)
	93	//
c0ceba4c	94	Int_t i;
c0ceba4c	95
5a881c97	96	Double_t Mass, pLab[3], fP0, fP[3], fBoostP[3], ddp[3], dddp0, dddp[3];
5a881c97	97	Float_t fPTrack[3], ptot = fPMin;
68ca986e	98	Int_t nt;
68ca986e	99
866ab5a2	100	if(fPseudoRapidity==0.){
68ca986e	101	pLab[0] = ptot*fCosx;
	102	pLab[1] = ptot*fCosy;
	103	pLab[2] = ptot*fCosz;
	104	}
	105	else{
	106	Float_t scang = 2*TMath::ATan(TMath::Exp(-(fPseudoRapidity)));
	107	pLab[0] = -ptot*TMath::Sin(scang);
	108	pLab[1] = 0.;
	109	pLab[2] = ptot*TMath::Cos(scang);
	110	}
c294be39	111	for(i=0; i<=2; i++) fP[i] = pLab[i];
	112	if(fDebugOpt == 1){
	113	printf("\n\n Particle momentum before divergence and crossing\n");
	114	for(i=0; i<=2; i++)printf(" pLab[%d] = %f\n",i,pLab[i]);
68ca986e	115	}
	116
	117	// Beam divergence and crossing angle
866ab5a2	118	if(fBeamCrossAngle!=0.) {
866ab5a2	119	BeamDivCross(1,fBeamDiv,fBeamCrossAngle,fBeamCrossPlane,pLab);
c294be39	120	for(i=0; i<=2; i++) fP[i] = pLab[i];
866ab5a2	121	}
	122	if(fBeamDiv!=0.) {
	123	BeamDivCross(0,fBeamDiv,fBeamCrossAngle,fBeamCrossPlane,pLab);
c294be39	124	for(i=0; i<=2; i++) fP[i] = pLab[i];
866ab5a2	125	}
866ab5a2	126
68ca986e	127	// If required apply the Fermi momentum
68ca986e	128	if(fFermiflag==1){
c294be39	129	if((fIpart==kProton) \|\| (fIpart==kNeutron))
68ca986e	130	ExtractFermi(fIpart,fPp,fProbintp,fProbintn,ddp);
5a881c97	131	Mass=gAlice->PDGDB()->GetParticle(fIpart)->Mass();
5a881c97	132	fP0 = TMath::Sqrt(fP[0]fP[0]+fP[1]fP[1]+fP[2]fP[2]+MassMass);
c294be39	133	for(i=0; i<=2; i++) dddp[i] = ddp[i];
5a881c97	134	dddp0 = TMath::Sqrt(dddp[0]dddp[0]+dddp[1]dddp[1]+dddp[2]dddp[2]+MassMass);
68ca986e	135
866ab5a2	136	TVector3 b(fP[0]/fP0, fP[1]/fP0, fP[2]/fP0);
68ca986e	137	TLorentzVector pFermi(dddp[0], dddp[1], dddp[2], dddp0);
68ca986e	138
68ca986e	139	pFermi.Boost(b);
c0ceba4c	140	for(i=0; i<=2; i++){
68ca986e	141	fBoostP[i] = pFermi[i];
866ab5a2	142	fP[i] = pFermi[i];
68ca986e	143	}
	144
	145	}
866ab5a2	146
c294be39	147	for(i=0; i<=2; i++) fPTrack[i] = fP[i];
866ab5a2	148
68ca986e	149	Float_t polar[3] = {0,0,0};
5d12ce38	150	gAlice->GetMCApp()->PushTrack(fTrackIt,-1,fIpart,fPTrack,fOrigin.GetArray(),polar,0,
1de555dc	151	kPPrimary,nt);
5a881c97	152	if(fDebugOpt == 1){
	153	printf("\n\n Track momentum:\n");
	154	printf("\n fPTrack = %f, %f, %f \n",fPTrack[0],fPTrack[1],fPTrack[2]);
	155	}
68ca986e	156	}
	157
	158	//_____________________________________________________________________________
f5cb71ad	159	void AliGenZDC::FermiTwoGaussian(Float_t A, Double_t *fPp,
5a881c97	160	Double_t fProbintp, Double_t fProbintn)
68ca986e	161	{
	162	//
	163	// Momenta distributions according to the "double-gaussian"
	164	// distribution (Ilinov) - equal for protons and neutrons
	165	//
5a881c97	166
68ca986e	167	fProbintp[0] = 0;
	168	fProbintn[0] = 0;
	169	Double_t sig1 = 0.113;
	170	Double_t sig2 = 0.250;
	171	Double_t alfa = 0.18*(TMath::Power((A/12.),(Float_t)1/3));
	172	Double_t xk = (2k2PI)/((1.+alfa)(TMath::Power(k2PI,1.5)));
	173
	174	for(Int_t i=1; i<=200; i++){
	175	Double_t p = i*0.005;
	176	fPp[i] = p;
68ca986e	177	Double_t e1 = (pp)/(2.sig1*sig1);
	178	Double_t e2 = (pp)/(2.sig2*sig2);
	179	Double_t f1 = TMath::Exp(-(e1));
	180	Double_t f2 = TMath::Exp(-(e2));
	181	Double_t probp = xkpp*(f1/(TMath::Power(sig1,3.))+
	182	alfaf2/(TMath::Power(sig2,3.)))0.005;
68ca986e	183	fProbintp[i] = fProbintp[i-1] + probp;
68ca986e	184	fProbintn[i] = fProbintp[i];
5a881c97	185	}
	186	if(fDebugOpt == 1){
	187	printf("\n\n Initialization of Fermi momenta distribution \n");
c294be39	188	//for(Int_t i=0; i<=200; i++)
c294be39	189	// printf(" fProbintp[%d] = %f, fProbintn[%d] = %f\n",i,fProbintp[i],i,fProbintn[i]);
68ca986e	190	}
	191	}
	192	//_____________________________________________________________________________
5a881c97	193	void AliGenZDC::ExtractFermi(Int_t id, Double_t fPp, Double_t fProbintp,
5a881c97	194	Double_t fProbintn, Double_t ddp)
68ca986e	195	{
	196	//
	197	// Compute Fermi momentum for spectator nucleons
	198	//
5a881c97	199
68ca986e	200	Int_t i;
68ca986e	201	Float_t xx = gRandom->Rndm();
699b37ac	202	assert ( id==kProton \|\| id==kNeutron );
68ca986e	203	if(id==kProton){
0ff3ad02	204	for(i=1; i<=200; i++){
68ca986e	205	if((xx>=fProbintp[i-1]) && (xx<fProbintp[i])) break;
	206	}
	207	}
94de3818	208	else {
68ca986e	209	for(i=0; i<=200; i++){
	210	if((xx>=fProbintn[i-1]) && (xx<fProbintn[i])) break;
	211	}
	212	}
	213	Float_t pext = fPp[i]+0.001;
	214	Float_t phi = k2PI*(gRandom->Rndm());
	215	Float_t cost = (1.-2.*(gRandom->Rndm()));
	216	Float_t tet = TMath::ACos(cost);
	217	ddp[0] = pextTMath::Sin(tet)TMath::Cos(phi);
	218	ddp[1] = pextTMath::Sin(tet)TMath::Sin(phi);
	219	ddp[2] = pext*cost;
5a881c97	220
	221	if(fDebugOpt == 1){
	222	printf("\n\n Extraction of Fermi momentum\n");
	223	printf("\n pxFermi = %f pyFermi = %f pzFermi = %f \n",ddp[0],ddp[1],ddp[2]);
	224	}
68ca986e	225	}
	226
	227	//_____________________________________________________________________________
	228	void AliGenZDC::BeamDivCross(Int_t icross, Float_t fBeamDiv, Float_t fBeamCrossAngle,
5a881c97	229	Int_t fBeamCrossPlane, Double_t *pLab)
68ca986e	230	{
866ab5a2	231	Double_t tetpart, fipart, tetdiv=0, fidiv=0, angleSum[2], tetsum, fisum;
68ca986e	232	Double_t rvec;
c0ceba4c	233
c294be39	234	Int_t sign=0;
	235	if(pLab[2]>=0.) sign=1;
	236	else sign=-1;
68ca986e	237	Double_t pmq = 0.;
c294be39	238	Int_t i;
c294be39	239	for(i=0; i<=2; i++) pmq = pmq+pLab[i]*pLab[i];
68ca986e	240	Double_t pmod = TMath::Sqrt(pmq);
68ca986e	241
68ca986e	242	if(icross==0){
	243	rvec = gRandom->Gaus(0.0,1.0);
	244	tetdiv = fBeamDiv * TMath::Abs(rvec);
	245	fidiv = (gRandom->Rndm())*k2PI;
	246	}
	247	else if(icross==1){
	248	if(fBeamCrossPlane==0.){
	249	tetdiv = 0.;
	250	fidiv = 0.;
	251	}
	252	else if(fBeamCrossPlane==1.){
	253	tetdiv = fBeamCrossAngle;
	254	fidiv = 0.;
	255	}
	256	else if(fBeamCrossPlane==2.){
	257	tetdiv = fBeamCrossAngle;
736c9b58	258	fidiv = k2PI/4.;
68ca986e	259	}
68ca986e	260	}
866ab5a2	261
866ab5a2	262	tetpart = TMath::ATan(TMath::Sqrt(pLab[0]pLab[0]+pLab[1]pLab[1])/pLab[2]);
c294be39	263	if(pLab[1]!=0. \|\| pLab[0]!=0.) fipart = TMath::ATan2(pLab[1],pLab[0]);
c294be39	264	else fipart = 0.;
68ca986e	265	if(fipart<0.) {fipart = fipart+k2PI;}
68ca986e	266	tetdiv = tetdiv*kRaddeg;
	267	fidiv = fidiv*kRaddeg;
	268	tetpart = tetpart*kRaddeg;
	269	fipart = fipart*kRaddeg;
	270	AddAngle(tetpart,fipart,tetdiv,fidiv,angleSum);
	271	tetsum = angleSum[0];
	272	fisum = angleSum[1];
68ca986e	273	tetsum = tetsum*kDegrad;
	274	fisum = fisum*kDegrad;
	275	pLab[0] = pmodTMath::Sin(tetsum)TMath::Cos(fisum);
	276	pLab[1] = pmodTMath::Sin(tetsum)TMath::Sin(fisum);
c294be39	277	if(sign==1) pLab[2] = pmod*TMath::Cos(tetsum);
c294be39	278	else pLab[2] = -pmod*TMath::Cos(tetsum);
5a881c97	279	if(fDebugOpt == 1){
5a881c97	280	printf("\n\n Beam divergence and crossing angle\n");
c294be39	281	for(i=0; i<=2; i++)printf(" pLab[%d] = %f\n",i,pLab[i]);
68ca986e	282	}
	283	}
	284
	285	//_____________________________________________________________________________
	286	void AliGenZDC::AddAngle(Double_t theta1, Double_t phi1, Double_t theta2,
5a881c97	287	Double_t phi2, Double_t *angleSum)
68ca986e	288	{
	289	Double_t temp, conv, cx, cy, cz, ct1, st1, ct2, st2, cp1, sp1, cp2, sp2;
	290	Double_t rtetsum, tetsum, fisum;
	291
	292	temp = -1.;
	293	conv = 180./TMath::ACos(temp);
	294
	295	ct1 = TMath::Cos(theta1/conv);
	296	st1 = TMath::Sin(theta1/conv);
	297	cp1 = TMath::Cos(phi1/conv);
	298	sp1 = TMath::Sin(phi1/conv);
	299	ct2 = TMath::Cos(theta2/conv);
	300	st2 = TMath::Sin(theta2/conv);
	301	cp2 = TMath::Cos(phi2/conv);
	302	sp2 = TMath::Sin(phi2/conv);
	303	cx = ct1cp1st2cp2+st1cp1ct2-sp1st2*sp2;
	304	cy = ct1sp1st2cp2+st1sp1ct2+cp1st2*sp2;
	305	cz = ct1ct2-st1st2*cp2;
	306
	307	rtetsum = TMath::ACos(cz);
	308	tetsum = conv*rtetsum;
	309	if(tetsum==0. \|\| tetsum==180.){
	310	fisum = 0.;
	311	return;
	312	}
	313	temp = cx/TMath::Sin(rtetsum);
	314	if(temp>1.) temp=1.;
	315	if(temp<-1.) temp=-1.;
	316	fisum = conv*TMath::ACos(temp);
	317	if(cy<0) {fisum = 360.-fisum;}
68ca986e	318	angleSum[0] = tetsum;
	319	angleSum[1] = fisum;
	320	}
	321