@brief Needed fot interface of Superchic_i to Superchic3.03 generator
@brief Needed fot interface of Superchic_i to Superchic3.03 generator
to store the umodified HEPEVT common.
This code was directly copied from Tailola_i package https://gitlab.cern.ch/atlas/athena/blob/21.6/Generators/Tauola_i/Tauola_i/Atlas_HEPEVT.h
with minor changes, original author list is following. This modified class takes into account the length of the array in hepevt parameteri nmxhep which is set to (nmxhep=4000) instead of HEPEVT standard event common which uses nmxhep=10000
@author Borut Paul Kersevan (BPK), June 2003
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@@ -75,9 +78,10 @@ private:
intm_dummy;
doublem_realdummy;
staticHEPEVT*s_atlas_HEPEVT;
// s_HEPEVT is needed access the umodified HEPEVT common block information
SuperChic 3 Monte Carlo event generator for central exclusive production
This interface package runs SuperChic MC Generator (v3.05) within Athena framework, and stores the events output into the transient store in HepMC format.
SuperChic MC event generator is dedicated for Central exclusive production (CEP) processes in high-energy hadron-hadron collisions (pp, pA, and AA beams) for both photon and QCD-initiated production. This documentation gives you some details about setting up the Superchic interface (which is prepared using the latest available Superchic version 3.05) and activating the module using the JobOptions.
In order to initialize and calculate input parameters like such as opacity,screening amplitude,sudakov factor, and skewed PDF the subroutine calcparam.F is used. To generate events superchicrun.F subroutine is used which inheritates from the superchic.f subroutine.
\section{Usage of Job Options}
The example job option file can be found under the following path.
{\bf Superchic\_i/share/jobOptions.Superchic.py }
Before running this script, first setup the athena
{\bf asetup 21.6,latest,AthGeneration,slc6 }
Above command sets up the latest AthGeneration cache.
The Superchic input parameters can be set from the job options service. The
default parameters initializes the Superchic for PbPb beams at center-of-mass energy per nucleon of 5.02 TeV for the light by light scattering process [$\gamma\gamma\rightarrow\gamma\gamma$ (process no. 59)].
{\bf All the parameters passed to Superchic are in the units specified
in the Superchic manual https://superchic.hepforge.org/superchic3.pdf }
The default jobOptions.Superchic.py file can be copied to your test run directory. The initialization parameters can be changed via the following line in the jobOptions.py
Each quoted string sets one parameter value in the fortran variable format. You can set all the input parameters
separated by commas, however, the important ones are listed below.
{\bf parameter\_1:} must be one of the following variable names, an error message is returned if the specified variable is not in the input parameter list.
{\bf value\_1:} is the input parameter's value.\\
JO Example:\\
The following command generates 10 events for Pb+Pb collisions at 5.02 TeV center-of-mass energy along with important input parameters for process 59 i.e $\gamma\gamma\rightarrow\gamma\gamma$. \\
You can change the input.DAT file to change the C.O.M collision energy for the particular process, process no., numberof events etc. Above commands will produce output stored under the directory {\bf 'evrecs' }.
