1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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 **************************************************************************/
18 Revision 1.1 2003/04/10 08:48:13 morsch
24 #include "AliFastGlauber.h"
33 ClassImp(AliFastGlauber)
35 TF1* AliFastGlauber::fWSb = NULL;
36 TF2* AliFastGlauber::fWSbz = NULL;
37 TF1* AliFastGlauber::fWSz = NULL;
38 TF1* AliFastGlauber::fWSta = NULL;
39 TF2* AliFastGlauber::fWStarfi = NULL;
40 TF1* AliFastGlauber::fWStaa = NULL;
41 TF1* AliFastGlauber::fWSgeo = NULL;
42 TF1* AliFastGlauber::fWSbinary = NULL;
43 TF1* AliFastGlauber::fWSN = NULL;
44 Float_t AliFastGlauber::fbMax = 0.;
46 AliFastGlauber::AliFastGlauber()
48 // Default Constructor
51 SetWoodSaxonParameters(6.624, 0.549, 0.00, 7.69e-4);
52 SetHardCrossSection();
56 void AliFastGlauber::Init(Int_t mode)
62 fWSb = new TF1("WSb", WSb, 0, fbMax, 4);
63 fWSb->SetParameter(0, fWSr0);
64 fWSb->SetParameter(1, fWSd);
65 fWSb->SetParameter(2, fWSw);
66 fWSb->SetParameter(3, fWSn);
68 fWSbz = new TF2("WSbz", WSbz, 0, fbMax, 4);
69 fWSbz->SetParameter(0, fWSr0);
70 fWSbz->SetParameter(1, fWSd);
71 fWSbz->SetParameter(2, fWSw);
72 fWSbz->SetParameter(3, fWSn);
74 fWSz = new TF1("WSz", WSz, 0, fbMax, 5);
75 fWSz->SetParameter(0, fWSr0);
76 fWSz->SetParameter(1, fWSd);
77 fWSz->SetParameter(2, fWSw);
78 fWSz->SetParameter(3, fWSn);
83 fWSta = new TF1("WSta", WSta, 0., fbMax, 0);
88 fWStarfi = new TF2("WStarfi", WStarfi, 0., fbMax, 0., TMath::Pi(), 1);
89 fWStarfi->SetParameter(0, 0.);
90 fWStarfi->SetNpx(200);
96 fWStaa = new TF1("WStaa", WStaa, 0., fbMax, 0);
99 TFile* f = new TFile("$(ALICE_ROOT)/FASTSIM/data/glauberPbPb.root");
100 fWStaa = (TF1*) f->Get("WStaa");
104 // Geometrical Cross-Section
106 fWSgeo = new TF1("WSgeo", WSgeo, 0., fbMax, 0);
109 // Hard cross section (~ binary collisions)
111 fWSbinary = new TF1("WSbinary", WSbinary, 0., fbMax, 1);
112 fWSbinary->SetParameter(0, fSigmaHard); // mb
113 fWSbinary->SetNpx(100);
115 // Hard collisions per event
117 fWSN = new TF1("WSN", WSN, 0., fbMax, 1);
121 void AliFastGlauber::DrawWSb()
124 // Draw Wood-Saxon Nuclear Density Function
126 TCanvas *c1 = new TCanvas("c1","Wood Saxon",400,10,600,700);
131 void AliFastGlauber::DrawOverlap()
134 // Draw Overlap Function
136 TCanvas *c2 = new TCanvas("c2","Overlap",400,10,600,700);
141 void AliFastGlauber::DrawThickness()
144 // Draw Thickness Function
146 TCanvas *c3 = new TCanvas("c3","Thickness",400,10,600,700);
151 void AliFastGlauber::DrawGeo()
154 // Draw Geometrical Cross-Section
156 TCanvas *c3 = new TCanvas("c3","Geometrical Cross-Section",400,10,600,700);
161 void AliFastGlauber::DrawBinary()
164 // Draw Wood-Saxon Nuclear Density Function
166 TCanvas *c4 = new TCanvas("c4","Binary Cross-Section",400,10,600,700);
171 void AliFastGlauber::DrawN()
174 // Draw Binaries per event
176 TCanvas *c5 = new TCanvas("c5","Binaries per event",400,10,600,700);
181 void AliFastGlauber::DrawKernel()
186 TCanvas *c6 = new TCanvas("c6","Kernel",400,10,600,700);
191 Double_t AliFastGlauber::WSb(Double_t* x, Double_t* par)
194 // Woods-Saxon Parameterisation
195 // as a function of radius
198 Double_t r0 = par[0];
203 Double_t y = n * (1.+w*(xx/r0)*(xx/r0))/(1.+TMath::Exp((xx-r0)/d));
207 Double_t AliFastGlauber::WSbz(Double_t* x, Double_t* par)
210 // Wood Saxon Parameterisation
211 // as a function of z and b
215 Double_t r0 = par[0];
219 Double_t xx = TMath::Sqrt(bb*bb+zz*zz);
220 Double_t y = n * (1.+w*(xx/r0)*(xx/r0))/(1.+TMath::Exp((xx-r0)/d));
224 Double_t AliFastGlauber::WSz(Double_t* x, Double_t* par)
227 // Wood Saxon Parameterisation
228 // as a function of z for fixed b
230 Double_t bb = par[4];
232 Double_t r0 = par[0];
236 Double_t xx = TMath::Sqrt(bb*bb+zz*zz);
237 Double_t y = n * (1.+w*(xx/r0)*(xx/r0))/(1.+TMath::Exp((xx-r0)/d));
238 // if (y < 1.e-6) y = 0;
242 Double_t AliFastGlauber::WSta(Double_t* x, Double_t* par)
245 // Thickness function
248 fWSz->SetParameter(4, b);
249 Double_t y = 2. * fWSz->Integral(0., fbMax);
255 Double_t AliFastGlauber::WStarfi(Double_t* x, Double_t* par)
258 // Kernel for overlap function
263 Double_t r2 = TMath::Sqrt(r1 * r1 + b * b - 2. * r1 * b * TMath::Cos(phi));
264 Double_t y = r1 * fWSta->Eval(r1) * fWSta->Eval(r2);
269 Double_t AliFastGlauber::WStaa(Double_t* x, Double_t* par)
275 fWStarfi->SetParameter(0, b);
285 Double_t y = 2. * fWStarfi->IntegralMultiple(2, al, bl, 0.001, err);
286 printf("WStaa: %f %f %f\n", b, y, err);
292 for (Int_t i = 0; i < 100000; i++)
294 Double_t phi = TMath::Pi() * gRandom->Rndm();
295 Double_t b1 = fbMax * gRandom->Rndm();
296 y += fWStarfi->Eval(b1, phi);
298 y *= 2. * 0.1 * 208. * 208. * TMath::Pi() * fbMax / 100000.;
302 Double_t AliFastGlauber::WSgeo(Double_t* x, Double_t* par)
305 // Geometrical Cross-Section
308 Double_t taa = fWStaa->Eval(b);
309 const Double_t sigma = 55.6; // mbarn
311 Double_t y = 2. * TMath::Pi() * b * (1. - TMath::Exp(- sigma * taa)); // fm
316 Double_t AliFastGlauber::WSbinary(Double_t* x, Double_t* par)
319 // Geometrical Cross-Section
322 Double_t sigma = par[0];
323 Double_t taa = fWStaa->Eval(b);
325 Double_t y = 2. * TMath::Pi() * b * sigma * taa; // fm
329 Double_t AliFastGlauber::WSN(Double_t* x, Double_t* par)
332 // Geometrical Cross-Section
335 Double_t y = fWSbinary->Eval(b)/fWSgeo->Eval(b);
339 void AliFastGlauber::SimulateTrigger(Int_t n)
344 TH1F* mbtH = new TH1F("mbtH", "MB Trigger b-Distribution", 100, 0., 20.);
345 TH1F* hdtH = new TH1F("hdtH", "Hard Trigger b-Distribution", 100, 0., 20.);
346 TH1F* mbmH = new TH1F("mbmH", "MB Trigger Multiplicity Distribution", 100, 0., 8000.);
347 TH1F* hdmH = new TH1F("hdmH", "Hard Trigger Multiplicity Distribution", 100, 0., 8000.);
349 mbtH->SetXTitle("b [fm]");
350 hdtH->SetXTitle("b [fm]");
351 mbmH->SetXTitle("Multiplicity");
352 hdmH->SetXTitle("Multiplicity");
354 TCanvas *c0 = new TCanvas("c0","Trigger Simulation",400,10,600,700);
356 TCanvas *c1 = new TCanvas("c1","Trigger Simulation",400,10,600,700);
362 for (Int_t iev = 0; iev < n; iev++)
365 GetRandom(b, p, mult);
368 mbmH->Fill(mult, 1.);
385 void AliFastGlauber::GetRandom(Float_t& b, Float_t& p, Float_t& mult)
388 // Gives back a random impact parameter, hard trigger probability and multiplicity
390 b = fWSgeo->GetRandom();
391 Float_t mu = fWSN->Eval(b);
392 p = 1.-TMath::Exp(-mu);
393 mult = 6000./fWSN->Eval(1.) * mu;
396 Float_t AliFastGlauber::GetRandomImpactParameter(Float_t bmin, Float_t bmax)
399 // Gives back a random impact parameter in the range bmin .. bmax
403 while(b < bmin || b > bmax)
404 b = fWSgeo->GetRandom();
408 Double_t AliFastGlauber::CrossSection(Double_t b1, Double_t b2)
411 // Return cross-section integrated from b1 to b2
414 return fWSgeo->Integral(b1, b2)/100.;
417 Double_t AliFastGlauber::FractionOfHardCrossSection(Double_t b1, Double_t b2)
420 // Return raction of hard cross-section integrated from b1 to b2
423 return fWSbinary->Integral(b1, b2)/fWSbinary->Integral(0., 100.);
427 Double_t AliFastGlauber::Binaries(Double_t b)
430 // Return number of binary collisions normalized to 1 at b=0
433 return fWSN->Eval(b)/fWSN->Eval(0.);