1 AliGenerator *AddMCGenAmpt(
2 Double_t Energy = 2760., // CM energy
3 Double_t bmin = 0.0, // minimum impact parameter
4 Double_t bmax = 20.0, // maximum impact parameter
5 Double_t ptHardMin = 3.0, // minimum pt hard (was 3.0 in previous AMPT productions)
6 Bool_t stringMelting = kTRUE, // string melting option
7 Bool_t useART = kTRUE, // use hadronic rescattering phase (ART)
8 Bool_t pAcollisions = kFALSE // pA instead of AA collisions
11 // User defined generator
13 gSystem->Load("libampt.so");
14 gSystem->Load("libTAmpt.so");
15 gSystem->Load("libEGPythia6");
16 gSystem->Load("libpythia6.so");
17 gSystem->Load("libAliPythia6.so");
20 AliGenAmpt *genAMPT = new AliGenAmpt(-1);
21 //=========================================================================
25 Int_t Flag_SM = 4; // flag for string melting: 1 = default, 4 = String Melting
26 Int_t NTmax = 150; // NTMAX: number of timesteps (Default = 150), to turn off ART set it to 3
27 Double_t mu = 3.2264; // parton screening mass in fm^(-1) (Default = 3.2264)
28 Double_t alpha_s = 1./3.; // change mu and alpha_s (Default = 1./3.) to vary scattering cross-section
29 // mu = 3.2 fm^-1 and alpha_s = 0.33 ==> sigma_{partonic} = 1.5mb
37 NTmax = 1500; // this was used in earlier productions for p-Pb
38 //=========================================================================
42 AliDecayer *decayer = new AliDecayerPythia();
43 genAMPT->SetForceDecay( kHadronicD );
44 genAMPT->SetDecayer( decayer );
45 //=========================================================================
48 genAMPT->SetEnergyCMS(Energy);
49 genAMPT->SetReferenceFrame("CMS");
50 genAMPT->SetProjectile("A", 208, 82);
52 genAMPT->SetTarget("P", 1, 1);
54 genAMPT->SetTarget("A", 208, 82);
55 genAMPT->SetPtHardMin (ptHardMin);
56 genAMPT->SetImpactParameterRange(bmin,bmax);
57 //=========================================================================
60 genAMPT->SetJetQuenching(0); // enable jet quenching
61 genAMPT->SetShadowing(1); // enable shadowing
62 genAMPT->SetDecaysOff(1); // neutral pion and heavy particle decays switched off
63 genAMPT->SetSpectators(0); // track spectators
64 genAMPT->SetIsoft(Flag_SM); // 4=string melting, 1=standard AMPT
65 genAMPT->SetXmu(mu); // parton xsection
66 genAMPT->SetNtMax(NTmax); // time bins
67 genAMPT->SetAlpha(alpha_s); // alpha =0.333
68 genAMPT->SetStringFrag(0.5,0.9); // string fragmentation parameters
69 genAMPT->SetIpop(1); // enable popcorn mechanism (net-baryon stopping)
70 //=========================================================================
72 // Boost into LHC lab frame
73 genAMPT->SetBoostLHC(1);
75 // randomize reaction plane
76 genAMPT->SetRandomReactionPlane(kTRUE);