Compiling with Pythia 8.1 (HEP event generator) o n local Linux servers

1. Compiling with Pythia 8.1 (HEP event generator) on local Linux servers http://home.thep.lu.se/~torbjorn/Pythia.html http://www3.gantep.edu.tr/pythia/ http://www4.gantep.edu.tr/pythia/

2. Introduction PYTHIA is a program for the generation of high-energy physics events, i.e. collisonse+ e- or p p etc at high energy. It contains theory and models for a number of physics aspects, including hard and soft interactions, parton distributions, initial- and final-state parton showers, multiple interactions, fragmentation and decay. In ATLAS, Pythia is used within the Athena framework at the first step of the Monte-Carlo chain for event generation, i.e. all the physics that occurs at the p-p interaction point and subsequent decays before interacting with the material of the detector.

3. Pythia 8.1 With the release of PYTHIA 8.100, this new C++ version series takes over from the older Fortran 77-based PYTHIA 6.4 one as the current standard. 8.1 does not yet offer a complete replacement of 6.4 and is not yet tested and tuned enough to be recommended for major production runs. However PYTHIA 8 has already reached a certain level of maturity.. The current release is focussed towards LHC and Tevatron applications

4. Running Pythia is standalone mode Instead of running Pythia in Athena we can run it in “stand alone” mode and so do not depend on ATLAS/CERN software or CERN infrastructure. This presentation describes how to set up your Linux account on either gul3 or gul4 to compile your C++ programs with Pythia. Very basic information is given - enough for a successful compile – further information can be found in the documentation (and possibly in future talks). If you are familiar with installing Pythia for a single user; basically what I have done is taken pythia8135.tgz, which is setup to install in a single user’s account, and copied the relevant files and libraries so that they are available system wide for all users. Also I replaced the make utility with a simple compile script and modified the runmains script to work accordingly. The details are archived in the appendix for future reference (or correction!). The current version is 8.135; I intend to keep the installations up to date.

5. Setting your account to run the Pythia examples Login to your gul3 or gul4 account and perform the following operations: $ mkdir pythia8135 $ cd pythia8135 $ cp -a /usr/local/lib/pythia8135/examples . $ cd examples $ export PYTHIA8DATA=/usr/local/lib/pythia8135/xmldoc then either compile and run individual examples $ compile main01 (assumes the file main01.ccexists) $ main01.exe or compile and run all examples $ runmains The compile script can be copied to any directory you use for developing Pythia programs. External (CERN) HepMC, LHAPDF, or FastJet libraries are not included.

6. Directories and Documentation /usr/local/lib/pythia8135/Pythia libraries /usr/local/lib/pythia8135/include/Pythia headers /usr/local/lib/pythia8135/xmldoc/Pythia configurations You can recreate the xmldoc directory in your <own file space> and $ export PYTHIA8DATA=<own file space>/pythia8135/xmldoc Local documentation can be found on the server where Pythia is installed: http://www3.gantep.edu.tr/pythia/pythia8135/phpdoc/Welcome.php http://www4.gantep.edu.tr/pythia/pythia8135/phpdoc/Welcome.php Look out for pythia8100.pdf for a brief overview. And of course from the home page which contains more links: http://home.thep.lu.se/~torbjorn/Pythia.html

7. Appendix Pythia installation http://home.thep.lu.se/~torbjorn/Pythia.html http://home.thep.lu.se/~torbjorn/pythia8/pythia8135.tgz Documentation Study A Brief Introduction to PYTHIA 8.1, available in pythia8135/htmldoc/pythia8100.pdf, for an overview. pythia8135/htmldoc/Welcome.html pythia8135/phpdoc/Welcome.php requires phpdoc/files/ to be write access Tutorials/talks are linked from http://home.thep.lu.se/~torbjorn/Pythia.html Installation (single user) This assumes we are NOT going to use the HepMC, LHAPDF, or FastJet libraries. Do *not* "./configure" because this will set you up for external HepMC, LHAPDF, or FastJet libraries on /afs # tar xvfz pythia8135.tgz. # cd pythia8135/ # make then go to examples/ Do *not* "./conifig.sh" because this will set you up for external HepMC, LHAPDF, or FastJet libraries on /afs # make mainNN [replace NN with the example number.] # ./mainNN.exe or "runmains" to compile and run all examples.

8. Installation (system wide users) "make" does this: g++ -O2 -ansi -pedantic -W -Wall -Wshadow -I../include main04.cc -o ../bin/main04.exe \ -L../lib/archive -lpythia8 -llhapdfdummy So we need to create system wide: "/usr/local/lib/pythia8135/include" from "pythia8135/include" "/usr/local/lib/pythia8135" from "pythia8135/lib/archive" "/usr/local/lib/pythia8135/xmldoc" from "pythia8135/xmldoc" and "/usr/local/lib/pythia8135/examples from "pythia8135/examples" with *.cc, *.cmnd, *.lhe, *.spc and the "compile" and "runmains" scripts where "compile" replaces "make". You also need this (maybe in .login): export PYTHIA8DATA=/usr/local/lib/pythia8135/xmldoc and the compile becomes: g++ $src -o $exe -O2 -ansi -pedantic -W -Wall -Wshadow \ -I/usr/local/lib/pythia8135/include \ -L/usr/local/lib/pythia8135 -lpythia8 -llhapdfdummy You should now be able to compile and run all the example programs.