EffC++ warnings corrected.
[u/mrichter/AliRoot.git] / LHC / AliLhcProcessIBS.cxx
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11141716 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
803d1ab0 16/* $Id$ */
11141716 17
21aa51f2 18//
19// Realisation of AliLhcProcess for the fast simulation of the
20// Intra Beam Scattering process
21// in transverse and longitudinal direction.
22// Author: Andreas Morsch
23// andreas.morsch@cern.ch
24//
25
11141716 26#include "AliLhcProcessIBS.h"
27#include "AliLHC.h"
28#include "AliLhcIRegion.h"
29#include "AliLhcBeam.h"
30
31#include <TF1.h>
32#include <TMath.h>
33#include <TCanvas.h>
34#include <TGraph.h>
35#include <TMultiGraph.h>
36
37ClassImp(AliLhcProcessIBS)
38
39 Double_t func(Double_t *x, Double_t *par);
40
41AliLhcProcessIBS::AliLhcProcessIBS(AliLHC* lhc, const char* name, const char* title)
42 :AliLhcProcess(lhc,name,title)
43{
44// Constructor
45}
46
47
48AliLhcProcessIBS::~AliLhcProcessIBS()
49{
50// Destructor
51
52}
53
54void AliLhcProcessIBS::Init()
55{
56 // Initialization
57 const Float_t r0=1.535e-16;
58
59 printf("\n Initializing Process %s", GetName());
60 printf("\n ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^");
61
62 fIRegions = fAccelerator->IRegions();
63
64 for (Int_t i = 0; i < 2; i++) {
65 fBeam[i] = fAccelerator->Beam(i);
66 fR[i] = r0*fBeam[i]->Z()*fBeam[i]->Z()/fBeam[i]->A();
67 fE[i] = 0.938*fBeam[i]->A();
68 }
69}
70
71void AliLhcProcessIBS::Evolve(Float_t dt)
72{
21aa51f2 73//
74// Evolve by one time step dt
11141716 75 printf("\n Here process %s %f:", GetName(), dt);
76 for (Int_t i=0; i<2; i++) {
77 // Density
78 Float_t sige = fBeam[i]->EnergySpread();
79 Float_t avbeta = fAccelerator->AverageBeta();
80 Float_t avd = fAccelerator->AverageDisp();
81
82 Float_t gamma = fBeam[i]->Gamma();
83 Float_t epsx = fBeam[i]->Emittance()*gamma;
84 Float_t epsy = epsx;
85 Float_t epse = fBeam[i]->LongEmittance();
86 Float_t sigxb = TMath::Sqrt(epsx/gamma*avbeta);
87 Float_t sigx = TMath::Sqrt(sigxb*sigxb+(avd*avd*sige*sige));
88 Float_t ssigx = TMath::Sqrt(epsx/gamma/avbeta);
89 Float_t sigy = sigx;
90 Float_t ssigy = ssigx;
91
92 Float_t asd = fBeam[i]->N()*fR[i]*fR[i]*fE[i]/
93 (16.*TMath::Pi()*gamma*epsx*epsy*epse);
94
95 // impact parameter
96 Float_t d = sige*avd/sigx;
97 //
98 Float_t at = sige*TMath::Sqrt(1.-d*d)/(gamma*ssigx);
99 Float_t bt = sige*TMath::Sqrt(1.-d*d)/(gamma*ssigy);
100 Float_t ct = sige*TMath::Sqrt(1.-d*d)*TMath::Sqrt(4.*sigy/fR[i]);
101 //
102 Double_t par[3];
103 par[0] = at;
104 par[1] = bt;
105 par[2] = ct;
106 TF1 *fct = new TF1("func",func, 0., 1., 3);
107
108 Float_t f = (Float_t) 8.0*TMath::Pi()*
109 fct->Integral(0., 1., par, 1.e-5);
110 //
111 fTaux = 1./(asd*f*(d*d-at*at/2.));
112 fTaue = 1./(asd*f*(1.-d*d));
113 // printf("\n taux, taue %f %f", taux, taue);
114 // Float_t tauy = -2./at*at/asd/f;
115 fBeam[i]->IncreaseEmittance(dt/fTaux, dt/fTaue);
116 }
117
118}
119
120void AliLhcProcessIBS::SetMonitor(Int_t n)
121{
122 // Initialize Monitor
123 if (fTauxArray) delete fTauxArray;
124 if (fTaueArray) delete fTaueArray;
125 fTauxArray = new Float_t[n];
126 fTaueArray = new Float_t[n];
127 fNmax = n;
128}
129
130void AliLhcProcessIBS::Record()
131{
132 // Record monitor quantities
133 fTauxArray[fAccelerator->Nt()] = fTaux/3600.;
134 fTaueArray[fAccelerator->Nt()] = fTaue/3600.;
135}
136
137
138void AliLhcProcessIBS::DrawPlots()
139{
140 // Draw monitor plots
141 Float_t* t = fAccelerator->TimeA();
142
143 TH1 *t1 = new TH1F("t1","Hor. IBS growth time",fNmax,0,t[fNmax]);
144 t1->SetMinimum(0);
145 t1->SetMaximum(fTauxArray[fNmax]*1.1);
146 t1->SetStats(0);
147 t1->GetXaxis()->SetTitle("t (h)");
148 t1->GetYaxis()->SetTitle("tau_x (t)");
149
150 TH1 *t2 = new TH1F("t2","Long. IBS growth time",fNmax,0,t[fNmax]);
151 t2->SetMinimum(0);
152 t2->SetMaximum(fTaueArray[fNmax]*1.1);
153 t2->SetStats(0);
154 t2->GetXaxis()->SetTitle("t (h)");
155 t2->GetYaxis()->SetTitle("tau_l (t)");
156
157 TGraph* grTaux = new TGraph(fNmax, fAccelerator->TimeA(), fTauxArray);
158 grTaux->SetHistogram(t1);
159
160 TGraph* grTaue = new TGraph(fNmax, fAccelerator->TimeA(), fTaueArray);
161 grTaue->SetHistogram(t2);
162 grTaue->SetLineStyle(2);
163
164 TMultiGraph* mg = new TMultiGraph();
165 mg->Add(grTaux);
166 mg->Add(grTaue);
167
168 TCanvas *c3 = new TCanvas("c3","IBS", 200, 10, 700, 500);
169 c3->SetGrid();
170 mg->Draw("AC");
171 mg->GetXaxis()->SetTitle("t (h)");
172 mg->GetYaxis()->SetTitle("IBS Growth Time (h)");
173 mg->Draw("AC");
174}
175
176
177
178
179
e76f229f 180AliLhcProcessIBS& AliLhcProcessIBS::operator=(const AliLhcProcessIBS & /*rhs*/)
11141716 181{
182// Assignment operator
183 return *this;
184}
185
186Double_t func(Double_t *x, Double_t *par)
187{
188 Double_t a = par[0];
189 Double_t b = par[1];
190 Double_t cc = par[2];
191
21aa51f2 192 const Double_t kbc = 0.5772;
11141716 193 Double_t xx = x[0];
194 Double_t x2=xx*xx;
195 Double_t x1=1.0-x2;
196 Double_t p=1.0/TMath::Sqrt(x2+a*a*x1);
197 Double_t q=1.0/TMath::Sqrt(x2+b*b*x1);
21aa51f2 198 return (1.0-3.0*x2)*p*q*(2.0*TMath::Log(0.5*cc*(p+q))-kbc);
11141716 199}
200