==== - Installation ====
-
AtRIS has been tested under arch-linux. It should work equally well with other *nix systems. Windows functionality has not been tested. 

=== - Building and installing Geant4 ===

5 years ago, the compilation and installation of Geant4 was rather complicated. Mostly due to the fact that a large number of libraries was necessary. The recent geant4 versions are shipping with most of the required libraries. Here, we describe how you can deploy geant4 so that you can compile and use AtRIS. Consider: 
  * Commands starting with HOSTNAME# have to be performed with super-user privileges
  * Commands starting with HOSTNAME$ should be performed as a regular user
  * //pacman// is a package manager for archlinux and mandjaro, find out what your distribution requires (debian base: apt-get, slackware sbopkg, ...)
  * We are building geant4 in //single threaded mode//. 
  * from optional build options, we will only turn the following on:
    * **GEANT4_USE_GDML**, since AtRIS makes extensive use of the //GDML// format for the planetary specification.
    * **GEANT4_INSTALL_DATA**, to obtain the relevant interaction data.
    * Additional information about building possibilites can be found here [(links:>http://geant4.web.cern.ch/geant4/UserDocumentation/UsersGuides/InstallationGuide/html/index.html)] and here [(links:>http://geant4.web.cern.ch/geant4/UserDocumentation/UsersGuides/InstallationGuide/html/installguide.html#geant4buildoptions)]
  * To enable use of geometry reading/writing from GDML XML files, the Xerces-C++ headers and library >=3 must be installed, compiled against the C++11 Standard.
  * The following is only a suggestion, please modify as necessary. <code bash | building and installing geant4>
HOSTNAME$ su -                        #become root
HOSTNAME# pacman -S xerces-c          #install xerces-c
HOSTNAME# mkdir /geant4 & cd /geant4  #make /geant4 folder and change in to it. 
HOSTNAME# chown -R user /geant4       #make user the owner of the /geant4 directory
HOSTNAME# exit                        #return to normal user
HOSTNAME$ cd /geant4                  #change in to the new directory
# download the geant4 source code
HOSTNAME$ wget http://geant4.web.cern.ch/geant4/support/source/geant4.10.04.tar.gz #check if there are newer versions!
HOSTNAME$ tar -xf geant               #extract the source code
HOSTNAME$ ln -s geant4.10.04 source   #make a symbolic link from geant4.10.04 to source
HOSTNAME$ mkdir build install         #make build and install directories
HOSTNAME$ cd build                    #change in to the build director
# configure the build process:
HOSTNAME$ cmake -DCMAKE_INSTALL_PREFIX=/geant4/install -DGEANT4_USE_GDML=ON -DGEANT4_INSTALL_DATA=ON /geant4/source/
HOSTNAME$ make -j4                   #build geant4 with 4 threads
HOSTNAME$ make install               #install geant4
HOSTNAME$ source /geant4/install/bin/geant4.sh
</code>
  * The last command is necessary to set up the environment variables so that we can compile and use AtRIS. It must be executed before each use in a new terminal. Alternatively, configure this via your //.bashrc// file. 

== Distribution specific notes ==
  * The above instructions were made using the current branch of slackware 14.2
  * On manjaro and arch, you need to install cmake and xerces-c. Both come with an AUR script for geant4 compilation. Make sure to enable **gdml** if you are using this script. 

=== - Obtaining anaconda python 2 ===

AtRIS evaluation notebooks have been tested against an anaconda python2 distribution, which can be obtained here [(links:>https://anaconda.org/anaconda/python)]. The user is free to choose whichever **python2** distribution he wants, but the following packages have to be installed:
  * numpy
  * matplotlib

== Possible problems ==
  * **Missing module** - if a script requires a python module which is not present please install either with //pip// or with //conda install module_name//. 
  * During compilation of AtRIS, if anaconda is added to PATH, it might happen that the cmake points the compilation against anaconda qt library files. This can lead to build errors. A solution is to build AtRIS before adding anaconda to PATH. 

=== - Obtaining and building AtRIS ===

Steps involved:
  * Obtain an account on gitlab.physik.uni-kiel.de
  * Ask Sasha for access
  * Clone the repository: 
<code bash | cloning and building AtRIS>
HOSTNAME$ mkdir clonetarget       # choose your own name!
HOSTNAME$ cd clonetarget
HOSTNAME$ git clone https://gitlab.physik.uni-kiel.de/banjac/atris
HOSTNAME$ cd AtRIS
HOSTNAME$ mkdir build             # create a folder for the build. Choose your own name.
HOSTNAME$ cd build
HOSTNAME$ source /geant4/install/bin/geant4.sh  # tell your terminal where to find geant4 files
HOSTNAME$ cmake ..                # configure the build with the make files from the AtRIS folder
HOSTNAME$ make -j8                # where 8 is the number of threads to use
HOSTNAME$ ./AtRIS FTFP_BERT_HP example -1 # start the example simulation
</code>