\subsection{The Fast Simulation}
The Fast Simulation (FastSim) is designed to allow studies on the major detector concepts, particle generators and the development of the analysis tools. The concept behind is to have a detector emulation, based on estimates and experience, which runs significantly faster than the fill simulation chain. Therefore even the processing of the initial particles with the transport code is omitted. 

The FastSim is a FairTask which reads the list of generated particles and returns particle candidates which are digestible for the analysis software. Between in- and output the particles parameters (like momentum, starting vertex and energy) are smeared with a given resolution.

Two concepts of setting the resolution are available: A subdetector based ansatz and a combined one.

\begin{itemize}
\item In the \emph{subdetector based} concept the resolutions are constructed from sets of resolutions. Each set represents a subdetector, like the MVD or EMC. Due to the different natures of the system they will often only contribute to some resolution parameters, not all. However this modular concept lacks a description for the track finding and fitting.
\item With the \emph{combined ansatz} the whole resolution is taken from the full simulation and parametrized. This takes the tracking into account as well as the improvements of combining many detector systems. As a drawback these parameterization is not very flexible, since each change under study at the setup would require the full simulation before.
\end{itemize}


\codetable{FairPrimaryGenerator* primGen = new FairPrimaryGenerator();\\
primGen->DoTracking(kFALSE);\\
\alert{PndFastSim}* fastSim = new PndFastSim();\\
fastSim->AddDetector("\alert{CmpDet}");\\
fastSim->EnablePropagation(propagation);\\
fastSim->SetSeed(seed);\\
fRun->AddTask(fastSim);\\
}


\subsection{The Detector Simulation Packages}
The detector simulation packages contain the description of physical processes to generate the signals as well as digitization code, electronics emulation and the subsystems reconstruction codes. 
\subsubsection{Mvd}
\subsubsection{Stt}
\subsubsection{Tpc}
\subsubsection{Emc}
\subsubsection{Drc}
\subsubsection{Gem}
\subsubsection{...}
\subsubsection{etc}

\subsection{Reconstruction}
\subsubsection{LheTrack}
\subsubsection{Genfit}
\subsubsection{Pid}
\subsubsection{RhoAnalysis}