Gabriele Cosmo
115 lines
4.8 KiB
C++
115 lines
4.8 KiB
C++
//
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// ********************************************************************
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// * DISCLAIMER *
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// * *
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// * The following disclaimer summarizes all the specific disclaimers *
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// * of contributors to this software. The specific disclaimers,which *
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// * govern, are listed with their locations in: *
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// * http://cern.ch/geant4/license *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. *
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// * *
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// * This code implementation is the intellectual property of the *
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// * GEANT4 collaboration. *
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// * By copying, distributing or modifying the Program (or any work *
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// * based on the Program) you indicate your acceptance of this *
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// * statement, and all its terms. *
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// ********************************************************************
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//
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//
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//////////////////////////////////////////////////////////////////////////
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// Matt.Dobbs@Cern.CH, December 1999
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// November 2000, updated to use Pythia 6.1
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// example of generating events with Pythia
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// using HepMC/PythiaWrapper.h
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// Events are read into the HepMC event record from the FORTRAN HEPEVT
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// common block using the IO_HEPEVT strategy and then output to file in
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// ascii format using the IO_Ascii strategy.
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//////////////////////////////////////////////////////////////////////////
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// To Compile: go to the HepMC directory and type:
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// gmake examples/example_MyPythia.exe
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//
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// In this example the precision and number of entries for the HEPEVT
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// fortran common block are explicitly defined to correspond to those
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// used in the Pythia version of the HEPEVT common block.
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//
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// If you get funny output from HEPEVT in your own code, probably you have
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// set these values incorrectly!
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//
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#include <iostream>
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#include "HepMC/PythiaWrapper.h"
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#include "HepMC/IO_HEPEVT.h"
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#include "HepMC/IO_Ascii.h"
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#include "HepMC/GenEvent.h"
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int main() {
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//
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//........................................HEPEVT
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// Pythia 6.1 uses HEPEVT with 4000 entries and 8-byte floating point
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// numbers. We need to explicitly pass this information to the
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// HEPEVT_Wrapper.
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//
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HepMC::HEPEVT_Wrapper::set_max_number_entries(4000);
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HepMC::HEPEVT_Wrapper::set_sizeof_real(8);
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//
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//........................................PYTHIA INITIALIZATIONS
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// (Some platforms may require the initialization of pythia PYDATA block
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// data as external - if you get pythia initialization errors try
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// commenting in/out the below call to initpydata() )
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// initpydata();
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//
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// Select W+gamma process (process number 20)
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// (here we have to be careful of C/F77 differences: arrays in C
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// start at 0, F77 at 1, so we need to subtract 1 from the process #)
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pysubs.msel=0;
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pysubs.msub[20-1] = 1;
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// set random number seed (mandatory!)
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pydatr.mrpy[0]=55122 ;
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// Tell Pythia not to write multiple copies of particles in event record.
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pypars.mstp[128-1] = 2;
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// Example of setting a Pythia parameter: set the top mass
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pydat2.pmas[1-1][6-1]= 175;
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//
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// Call pythia initialization
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call_pyinit( "CMS", "p", "p", 14000. );
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//........................................HepMC INITIALIZATIONS
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//
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// Instantiate an IO strategy for reading from HEPEVT.
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HepMC::IO_HEPEVT hepevtio;
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//
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// Instantial an IO strategy to write the data to file - it uses the
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// same ParticleDataTable
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HepMC::IO_Ascii ascii_io("example_MyPythia.dat",std::ios::out);
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//
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//........................................EVENT LOOP
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for ( int i = 1; i <= 10; i++ ) {
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if ( i%50==1 ) std::cout << "Processing Event Number "
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<< i << std::endl;
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call_pyevnt(); // generate one event with Pythia
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// pythia pyhepc routine converts common PYJETS in common HEPEVT
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call_pyhepc( 1 );
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HepMC::GenEvent* evt = hepevtio.read_next_event();
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// add some information to the event
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evt->set_event_number(i);
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evt->set_signal_process_id(20);
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// write the event out to the ascii file
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ascii_io << evt;
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// we also need to delete the created event from memory
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delete evt;
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}
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//........................................TERMINATION
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// write out some information from Pythia to the screen
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call_pystat( 1 );
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return 0;
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}
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