1 | ////////////////////////////////////////////////////////////////////////// |
---|
2 | // Matt.Dobbs@Cern.CH, Feb 2000 |
---|
3 | // Example of building an event and a particle data table from scratch |
---|
4 | // This is meant to be of use for persons implementing HepMC inside a MC |
---|
5 | // event generator |
---|
6 | ////////////////////////////////////////////////////////////////////////// |
---|
7 | // To Compile: go to the HepMC directory and type: |
---|
8 | // gmake examples/example_BuildEventFromScratch.exe |
---|
9 | // |
---|
10 | |
---|
11 | #include <iostream> |
---|
12 | |
---|
13 | #include "HepMC/GenEvent.h" |
---|
14 | |
---|
15 | // in this example we use the HepMC namespace, so that we do not have to |
---|
16 | // precede all HepMC classes with HepMC:: |
---|
17 | |
---|
18 | // This example also shows how to use the CLHEP Lorentz vector with HepMC2 |
---|
19 | |
---|
20 | using namespace HepMC; |
---|
21 | |
---|
22 | int main() { |
---|
23 | // |
---|
24 | // In this example we will place the following event into HepMC "by hand" |
---|
25 | // |
---|
26 | // name status pdg_id parent Px Py Pz Energy Mass |
---|
27 | // 1 !p+! 3 2212 0,0 0.000 0.000 7000.000 7000.000 0.938 |
---|
28 | // 2 !p+! 3 2212 0,0 0.000 0.000-7000.000 7000.000 0.938 |
---|
29 | //========================================================================= |
---|
30 | // 3 !d! 3 1 1,1 0.750 -1.569 32.191 32.238 0.000 |
---|
31 | // 4 !u~! 3 -2 2,2 -3.047 -19.000 -54.629 57.920 0.000 |
---|
32 | // 5 !W-! 3 -24 1,2 1.517 -20.68 -20.605 85.925 80.799 |
---|
33 | // 6 !gamma! 1 22 1,2 -3.813 0.113 -1.833 4.233 0.000 |
---|
34 | // 7 !d! 1 1 5,5 -2.445 28.816 6.082 29.552 0.010 |
---|
35 | // 8 !u~! 1 -2 5,5 3.962 -49.498 -26.687 56.373 0.006 |
---|
36 | |
---|
37 | // now we build the graph, which will look like |
---|
38 | // p7 # |
---|
39 | // p1 / # |
---|
40 | // \v1__p3 p5---v4 # |
---|
41 | // \_v3_/ \ # |
---|
42 | // / \ p8 # |
---|
43 | // v2__p4 \ # |
---|
44 | // / p6 # |
---|
45 | // p2 # |
---|
46 | // # |
---|
47 | |
---|
48 | // First create the event container, with Signal Process 20, event number 1 |
---|
49 | // |
---|
50 | GenEvent* evt = new GenEvent( 20, 1 ); |
---|
51 | // define the units |
---|
52 | evt->use_units(HepMC::Units::GEV, HepMC::Units::MM); |
---|
53 | // |
---|
54 | // create vertex 1 and vertex 2, together with their inparticles |
---|
55 | GenVertex* v1 = new GenVertex(); |
---|
56 | evt->add_vertex( v1 ); |
---|
57 | v1->add_particle_in( new GenParticle( FourVector(0,0,7000,7000), |
---|
58 | 2212, 3 ) ); |
---|
59 | GenVertex* v2 = new GenVertex(); |
---|
60 | evt->add_vertex( v2 ); |
---|
61 | v2->add_particle_in( new GenParticle( FourVector(0,0,-7000,7000), |
---|
62 | 2212, 3 ) ); |
---|
63 | // |
---|
64 | // create the outgoing particles of v1 and v2 |
---|
65 | GenParticle* p3 = |
---|
66 | new GenParticle( FourVector(.750,-1.569,32.191,32.238), 1, 3 ); |
---|
67 | v1->add_particle_out( p3 ); |
---|
68 | GenParticle* p4 = |
---|
69 | new GenParticle( FourVector(-3.047,-19.,-54.629,57.920), -2, 3 ); |
---|
70 | v2->add_particle_out( p4 ); |
---|
71 | // |
---|
72 | // create v3 |
---|
73 | GenVertex* v3 = new GenVertex(); |
---|
74 | evt->add_vertex( v3 ); |
---|
75 | v3->add_particle_in( p3 ); |
---|
76 | v3->add_particle_in( p4 ); |
---|
77 | v3->add_particle_out( |
---|
78 | new GenParticle( FourVector(-3.813,0.113,-1.833,4.233 ), 22, 1 ) |
---|
79 | ); |
---|
80 | GenParticle* p5 = |
---|
81 | new GenParticle( FourVector(1.517,-20.68,-20.605,85.925), -24,3); |
---|
82 | v3->add_particle_out( p5 ); |
---|
83 | // |
---|
84 | // create v4 |
---|
85 | GenVertex* v4 = new GenVertex(FourVector(0.12,-0.3,0.05,0.004)); |
---|
86 | evt->add_vertex( v4 ); |
---|
87 | v4->add_particle_in( p5 ); |
---|
88 | v4->add_particle_out( |
---|
89 | new GenParticle( FourVector(-2.445,28.816,6.082,29.552), 1,1 ) |
---|
90 | ); |
---|
91 | v4->add_particle_out( |
---|
92 | new GenParticle( FourVector(3.962,-49.498,-26.687,56.373), -2,1 ) |
---|
93 | ); |
---|
94 | // |
---|
95 | // tell the event which vertex is the signal process vertex |
---|
96 | evt->set_signal_process_vertex( v3 ); |
---|
97 | // the event is complete, we now print it out to the screen |
---|
98 | evt->print(); |
---|
99 | |
---|
100 | // now clean-up by deleteing all objects from memory |
---|
101 | // |
---|
102 | // deleting the event deletes all contained vertices, and all particles |
---|
103 | // contained in those vertices |
---|
104 | delete evt; |
---|
105 | |
---|
106 | return 0; |
---|
107 | } |
---|