GENIE Object-Oriented Neutrino Generator

Get started with the GENIE/Generator

This page includes a basic descriptions of the steps required to obtain the GENIE/Generator source code (and the required 3rd party software packages), configure it, build it, and run a few simple post-installation tests. For more details, please see the GENIE Physics & User manual. Please report any problems to the authors.

Obtaining the GENIE/Generator source code

You can obtain the GENIE/Generator source code from its official repository in the GENIE GitHub organization. Detailed instructions are provided in the GENIE GitHub page. For example, to obtain the GENIE trunk (master) version, type:

shell% git clone https://github.com/GENIE-MC/Generator.git

Third-party software packages

This section contains information for building 3rd party (external) software used by GENIE. If you encounter problems building the 3rd party software please contact the package authors or your local system administrators.

For a typical GENIE installation you need:

ROOT
GNU Scientific Library (GSL)
PYTHIA6
LHAPDF5 or LHAPDF6 [Both of which are optional in GENIE v3.0.0 and above]
log4cpp
libxml2

Installation of external packages in UNIX (incl. LINUX, MAC OS X)

log4cpp

Description: Message/Error logging library for C++
Recommended version:
Web-site: http://sourceforge.net/projects/log4cpp

Installing development version from source:
Get the source code from the sourceforge.net CVS repository:

shell$ cd /your/software/area/
shell$ cvs -d :pserver:anonymous@log4cpp.cvs.sourceforge.net:/cvsroot/log4cpp login
(passwd: just press enter)
shell$ cvs -d :pserver:anonymous@log4cpp.cvs.sourceforge.net:/cvsroot/log4cpp -z3 co log4cpp
shell$ cd log4cpp
shell$ ./autogen.sh
shell$ ./configure --prefix=[location]
shell$ gmake
shell$ gmake install

Notes:
- log4cpp may already exist in your system (look for a liblog4cpp library)
- Precompiled binaries are also readily available on LINUX (eg using yum: `yum install log4cpp') and MAC OS X (eg. using DarwinPorts: `sudo port install log4cpp').

libxml2

Description: XML parser.
Recommended version: any reasonably new
Web-site: http://www.xmlsoft.org

Installing development version from source:

shell$ cd /your/software/area/
shell$ svn co https://svn.gnome.org/svn/libxml2/trunk libxml2
shell$ cd libxml2
shell$ ./autogen.sh --prefix=[location]
shell$ gmake
shell$ gmake install

Notes:
- libxml2 is most likely already installed at your system (look for a libxml2 library)
- Precompiled binaries are also readily available on LINUX (eg using yum: `yum install libxml2') and MAC OS X (eg. using DarwinPorts: `sudo port install libxml2').

LHAPDF

Description: The Les Houches Accord PDF Interface
Recommended version: Optional in v3.0.0 and above
Web-site: http://projects.hepforge.org/lhapdf/

Installing version x.y.z from source:

shell$ cd /your/software/area/
shell$ wget http://www.hepforge.org/archive/lhapdf/lhapdf-x.y.z.tar.gz
shell$ tar xzvf lhapdf-x.y.z.tar.gz
shell$ cd lhapdf
shell$ ./configure --prefix=[location]
shell$ gmake
shell$ gmake install

PYTHIA6 and ROOT/PYTHIA thin wrapper library

Description: LUND Monte Carlo (used by GENIE for hadronizing the high-W fraction of neutrino events)
Recommended version: Do not use the precompiled PYTHIA version that comes with CERNLIB.
Web-site: http://www.thep.lu.se/~torbjorn/Pythia.html

Installing from source:
There is a number of steps in order to build PYTHIA for GENIE. Downloading, tweaking and building PYTHIA is automated using Robert Hatcher's build_pythia6.sh script. Please read the script documentation. It would download all the required source files, modify them as needed and build them. So you only need to do:

shell$ cd /your/software/area/
shell$ source build_pythia6.sh

Notes:
- build_pythia6.shneeds to access the internet to download the source code. If you access the internet through a proxy server and not directly then remember to set the http_proxy environmental variable.
- build_pythia6.sh accepts a PYTHIA6 version as an argument. For example, in order to build v6.4.12 then type: `source build_pythia6.sh 6412'. Read the script documentation for details.
- If you are using a recent version of ROOT and have problems with undefined pytune_ symbols, then move to a recent version of PYTHIA6.

ROOT Class Libraries

Recommended version: Please get a recent ROOT6 version. ROOT5 should still work but is no longer supported by GENIE.
Web-site: http://root.cern.ch

Detailed installation instructions are given in http://root.cern.ch/root/Install.html

For a standard GENIE installation the only extra ROOT configuration options you need are the ones required for enabling GSL (via MathMore) and the ROOT/PYTHIA interface. When configuring ROOT, add: `--enable-pythia6', `--enable-mathmore' and `--with-pythia6-libdir=/path/to/pythia/lib'

Configuring and building GENIE

If all external dependencies are installed, then in order to configure and build GENIE you just need to:

shell% configure [options]
shell% gmake
shell% gmake install (*optional*, see below)

FLAG	DESCRIPTION	DEFAULT
--prefix	installation location (for 'gmake install')	/usr/local

enable/disable options with either --enable- or --disable- (eg --enable-lhapdf --disable-flux-drivers)

profiler	GENIE code profiling using Google perftools	default: disabled
doxygen-doc	Generate doxygen documentation at build time	default: disabled
dylibversion	Adds version number in dynamic lib names	default: enabled (recommended)
lowlevel-mesg	Disable (rather than filter out at run time) some prolific debug/info level messages known to slow GENIE down	default: disabled
debug	Adds -g in the compiler options to request debug info	default: disabled
lhapdf	Use the LHAPDF parton density function library, requires libLHAPDF	default: enabled
cernlib	Use the PDFLIB parton density function library, requires CERNLIB	default: disabled (LHAPDF is preferred)
flux-drivers	Built-in flux drivers	default: enabled
geom-drivers	Built-in detector geometry drivers	default: enabled
mueloss	Muon energy loss modeling (for atm. upgoing muon sim.)	default: enabled
vle-extension	GENIE very low energy (1 MeV - 100 MeV) extension	default: disabled (experimental)
validation-tools	GENIE physics model validation tools	default: disabled
test	Test programs	default: disabled
t2k	Enables T2K-specific generation app	default: disabled
fnal	Enables FNAL experiment-specific event generation app	default: disabled
atmo	Atmospheric neutrino event generation app	default: disabled
nucleon-decay	Nucleon decay event generation app	default: disabled
masterclass	GENIE neutrino masterclass app	default: disabled (in devel)

with options for 3rd party software, prefix with --with- (eg --with-lhapdf-lib=/some/path/)
optimiz-level	Compiler optimization level (O,O2,O3,OO,Os)	default: O2
profiler-lib	Path to profiler library	needed if you --enable-profiler
doxygen-path	Doxygen binary path	needed if you --enable-doxygen
pythia6-lib	PYTHIA6 library path	always needed / auto-detected afterchecking for $PYTHIA6 env.var.
cern-lib	CERN libraries path	needed if you --enable-cern / auto-detected after checking for $CERNLIB env.var.
lhapdf-inc	Path to LHAPDF includes	needed if you --enable-lhapdf / auto-detected after checking for $LHAPDF_INC env.var.
lhapdf-lib	Path to LHAPDF libraries	needed if you --enable-lhapdf / auto-detected after checking for $LHAPDF_LIB env.var.
libxml2-inc	Path to libxml2 includes	always needed / auto-detected
libxml2-lib	Path to libxml2 library	always needed / auto-detected
log4cpp-inc	Path to log4cpp includes	always needed / auto-detected
log4cpp-lib	Path to log4cpp library	always needed / auto-detected

Below, is an example of how I typically build the GENIE/Generator:

shell% cd $GENIE
shell% ./configure
             --prefix=/some/installation/path
             --disable-profiler
             --disable-validation-tools
             --disable-cernlib
             --enable-lhapdf
             --enable-flux-drivers
             --enable-geom-drivers
             --disable-doxygen
             --enable-test
             --enable-mueloss
             --enable-dylibversion
             --enable-t2k
             --enable-fnal
             --enable-atmo
             --enable-nucleon-decay
             --disable-masterclass
             --disable-debug
             --with-optimiz-level=O2
             --with-pythia6-lib=/full/path/to/my/libPythia6/
             --with-lhapdf-inc=/full/path/to/my/lhapdf/includes/
             --with-lhapdf-lib=/full/path/to/my/lhapdf/library/
             --with-libxml2-inc=/full/path/to/my/libml2/includes/
             --with-libxml2-lib=/full/path/to/my/libxml2/library/
             --with-log4cpp-inc=/full/path/to/my/log4cpp/includes/
             --with-log4cpp-lib=/full/path/to/my/log4cpp/library/
shell% gmake

Further notes:

The configure script has defaults for all the enable/disable options and auto-detection capabilities for figuring out the paths. It is likely that a simple './configure' (no arguments) would work in your system. However, we recommend you staying in control of the build configuration and supply all the required inputs.
You can run 'gmake install' to to copy binaries, libraries and headers under $DIR/bin, $DIR/lib and $DIR/include respectivelly, where $DIR is the installation location specified with --prefix at the GENIE configuration step. I usually skip that and just pick the GENIE binaries, libraries and headers from $GENIE/bin, $GENIE/lib and $GENIE/src respectivelly.
Before following the installation instructions given above and and/or before running GENIE, make sure that:
- You have defined $GENIE to point at your top level GENIE directory
- You have defined $ROOTSYS to point at your ROOT installation
- All your library paths ($ROOTSYS/lib, $GENIE/lib, /path/to/pyhia6, /path/to/libxml2/lib, /path/to/log4cpp/lib, ...) are listed in $LD_LIBRARY_PATH (of $DYLD_LIBRARY_PATH on Mac OS X)
- All your binary paths ($ROOTSYS/bin, $GENIE/bin) are listed in $PATH
When using old versions of gcc (< 4) don't use optimizations above the O2 level as it generates a seekoff overload problem. See this email at the gnu-gcc mailing list.

What to do next - Testing your installation

If the installation was successfull you should find a bunch of libraries in $GENIE/lib and some applications in $GENIE/bin. Here is a set of instructions, for running a few simple apps, and making sure there is no major issue with your GENIE installation.

First, download pre-computed cross-sections, from nu_mu+O^16 interactions, from here . Download datafiles corresponding to the version of GENIE and the physics tune you plan on using. If you want to generate these cross-sections by yourself, see the GENIE User and Physics manual.

Generate a 100k event sample of nu_mu+O^16 interactions between 0 and 10 GeV using a simple analytical (x*exp(-x)) numu flux description (Note: pdg_code(nu_mu)=14, pdg_code(O^16)=1000080160):

shell& gevgen -n 100000 -p 14 -t 1000080160 -e 0,10 -f 'x*exp(-x)' --run 1000 --seed 1721827 --cross-sections /path/to/downladed/cross_sections.xml --tune tune_name

Print-out the first 50 events from the GHEP (GENIE's native event format) event file generated during the previous step (there should be a file named `gntp.1000.ghep.root'):

shell& gevdump -n 50 -f gntp.1000.ghep.root

Generate a 10k event sample of pi^{+}+16O interactions for pi^{+}'s of 200 MeV kinetic energy:

shell& gevgen_hadron -n 10000 -p 211 -t 1000080160 -k 0.2 --seed 65431

If everything seems to work then the GENIE is really out of the bottle. Read the Physics and User manual for further instructions and information on GENIE tools. Have fun...