\subsection{The {\tt {\tt SALT:}} tracking module}\label{sect:SALTData1}

The \moc{{\tt SALT:}} module can process general 2--D 
geometries. It is used to compute the tracking information requested in
the method of collision probabilities or in the method of characteristics.

\vskip 0.2cm

The calling specification for this module is:
\begin{DataStructure}{Structure \dstr{SALT:}}
\dusa{TRKNAM} \dusa{TRKFIL}
\moc{:=} \moc{SALT:}~\dusa{SURFIL} $[$ \dusa{TRKNAM} $]~[$ \dusa{GEONAM} $]$ \moc{::} \dstr{descsalt}
\end{DataStructure}

\noindent  where
\begin{ListeDeDescription}{mmmmmmm}

\item[\dusa{TRKNAM}] \texttt{character*12} name of the SALT \dds{tracking} data
structure that will contain region volume and surface area vectors in
addition to region identification pointers and other tracking information.
If \dusa{TRKNAM} also appears on the RHS, the merging and gigogne indexing
information calculated by {\tt G2S:} (see \Sect{G2SData}) will
be recovered and completed (in-place) by {\tt {\tt SALT:}}.

\item[\dusa{TRKFIL}] \texttt{character*12} name of the sequential binary tracking
file used to store the tracks lengths.

\item[\dusa{SURFIL}] \texttt{character*12} name of the sequential {\sc ascii}
file used to store the surfacic elements of the geometry. This file may be build
using the operator {\tt G2S:} (see \Sect{G2SData}) or recovered from SALOME.

\item[\dusa{GEONAM}] {\tt character*12} name of the \dds{geometry} data
structure containing the double heterogeneity (Bihet) data.

\end{ListeDeDescription}

\vskip 0.2cm

All information for the modelization used can be found in \citen{salt}.
The \moc{{\tt SALT:}} specific tracking data in \dstr{descsalt} is defined as :

\begin{DataStructure}{Structure \dstr{descsalt}}
$[$ \moc{EDIT} \dusa{iprint} $]$ \\
$ $    \moc{QUAD} \dusa{ioption} $ $ \\
$[~\{$ \moc{NSN} \dusa{nsn} $|$ \moc{AN2D} \dusa{nphi} \moc{AN3D} \dusa{npsix} $\} ~]$ \\
$ $  \moc{DELM}  \dusa{xdelm} $ $\\
$[$ \moc{NDIV} \dusa{nsn} $]$ \\
$[$ \moc{NGAU} \dusa{ngau} $]$ \\
$[$ \moc{NMAX} \dusa{nmax} $]$ \\
$[$ \moc{MPHI} \dusa{mphi} $]$ \\
$[$ \moc{MTETA} \dusa{mteta} $]$ \\
$ $ \moc{DELR}  \dusa{xdelr} $ $ \\
$\{$ \moc{DP00} $|$ \moc{DP01} $|$ \moc{SPEC} $\}$ \\
$[$ \moc{QUAB} \dusa{iquab} $]$ \\
{\tt ;}
\end{DataStructure}

\noindent with

\begin{ListeDeDescription}{mmmmmm}

\item[\moc{EDIT}] keyword used to modify the print level \dusa{iprint}.

\item[\dusa{iprint}] index used to control the printing in this operator.
It must be equal to  1 if printing on the output file is required. Default value is 0.

\item[\moc{QUAD}] keyword used for the quadrature type  \dusa{ioption}.

\item[\dusa{ioption}] index used to control the quadrature type used for tracking and transport
computation. The different value allowed are :
\begin{enumerate}
\item $3$ for SN equiweight quadratures,
\item $4$ for SN Level Symetric quadratures without $\mu_0$ optimization,
\item $5$ for SN Level Symetric quadratures with $\mu_0$ optimization,
\item $6$ for non symetric SN quadratures,
\item $7$ for product quadratures (recommended for PIJ calculation)
\item $8$ for cyclic quadratures,
\item $9$ for quadratures used to deal with rotations,
\item $10$ for quadratures used to deal with axial symetries.
\end{enumerate}
For \dusa{ioption} value bigger than (or equal to)  $7$,  (\moc{AN2D} , \dusa{mphi}) and 
 (\moc{AN3D} , \dusa{mpsi}) must be defined, otherwise  ($\moc{NSN}$, \dusa{nsn}) must be defined.
 No default value.

\item[\moc{NSN}] keyword used to define degree of the $S_n$ angular discretization  \dusa{nsn},

\item[\dusa{ioption}] index used to control the $S_n$ angular discretization. Must be even and defined if
$ioption$ lesser than 7.\\
No default value.

\item[\moc{AN2D}] keyword used to specify the number \dusa{mphi} of horizontal discretization levels used for product 
angular quadratures.

\item[\dusa{mphi}] number of horizontal levels of discretization  used with a product quadrature.
The number must be set if \dusa{ioption} of the \moc{QUAD} keyword is $\ge 7$.

\item[\moc{AN3D}] keyword used to specify the number \dusa{mpsi} of vertical discretization levels we use for product quadratures.

\item[\dusa{mphi}] number of horizontal angles of discretization used with a product quadrature.
The number must be set if \dusa{ioption} of the \moc{QUAD} keyword is $\ge 7$.

\item[\moc{NDIV}] keyword used to specify the number of spatial divisions for computing the distance between the
tracking trajectories.

\item[\dusa{ndiv}] number associated to \moc{NDIV}. If $ndiv >0$, the distance $delr$  between the tracks is evaluated by :
\[
delr=max(sqrt(v)/ndiv,delmin),
\]
where $v$ is the minimum volume of the 2D nodes defined in the geometry.

\item[\moc{NGAU}] keyword used to specify the type of radial and axial quadrature in space.
\item[\dusa{ngau}]  value associated to \moc{NGAU}.\\
If $ \dusa{ngau} >0 $, use FLURIG scheme ($del0= 1e-3 delr$, $del1= delr$, $del2= 2 delr$).\\
 Otherwise use normal gaussian integration($del0= 1e-3 delr$, $del1= 2 delr$, $del2= 4 delr$).
\begin{itemize}
\item  $ = 0 =>  $  constant quadrature with step delr, 
\item   $ \ne 0 => $ project all discontinuities. If 
\begin{itemize}
\item
                      0 points       for piece $< del0$,
\item
                      1 point        for piece $< del1$,
\item
                      2 Gauss points for piece $< del2$,
\item
                      for piece $ > del2$ use a minimum step of 
                      $deln=ngau*delr$ with $ngau$ points per subsegment.
\end{itemize}
\end{itemize}

\item[\moc{NMAX}] keyword used to specify the size of the buffer tracking.

\item[\dusa{nmax}]  value associated to \moc{NMAX} : the size of the buffer is \moc{NMAX}*1000 for writing
trajectories.

\item[\moc{MPHI}] keyword used to specify the method used to calculate angular formular for
product quadratures. Must be used if $QUAD \ge 7$.

\item[\dusa{mphi}] value associated to \moc{MPHI}.
\begin{itemize}
\item For $QUAD = 8$ :
\begin{itemize}
\item $= 1$ : compute the shortest track,
\item $= 2$ : compute nearly equidistant angles,
\item $= 3$ : $M_n$ quadrature Mn (option TSPC MEDI in EXCELT:),
\item $= 4$ : $T_n$ quadrature (option TSPC in EXCELT:).
\end{itemize}
\item For $QUAD = 7, 9,10$ :
\begin{itemize}
\item $= 1$ : compute Gauss Legendre quadrature,
\item $= 2$ : compute double Gauss Legendre quadrature,
\item $= 3$ : compute equiweight quadrature.
\end{itemize}
\end{itemize}

\item[\moc{MTETA}] keyword used to specify the circular type quadrature for product quadrature. Must be used if
$QUAD \ge 7$.

\item[\dusa{mteta}] value associated to \moc{MTETA}. 
\begin{itemize}
\item $= 1$ : compute Gauss Legendre quadrature,
\item $= 2$ : compute double Gauss Legendre quadrature,
\item $= 3$ : compute equiweight quadrature.
\end{itemize}

\item[\moc{DELR}] keyword used to specify the default value for the distance between trajectories. Must be defined.

\item[\dusa{xdelr}] value associated to \moc{DELR}. Used if $ndiv=0$.

\item[\moc{DELM}] keyword used to specify the minimum value for $delr$. Used if $ndiv .ne. 0$. Must be defined.

\item[\dusa{xdelm}] value associated to \moc{DELM}

\item[\moc{DP00}] keyword used to specify isotropic (i.e., double $P_0$) reflexion on \moc{ALBE}--type
boundary conditions. Set a numerotation compatible with the method of $P_{ij}$. By default, the
numerotation is compatible with the method of characteristics.

\item[\moc{DP01}] keyword used to specify linearly anisotropic (i.e., double $P_1$) reflexion on \moc{ALBE}--type
boundary conditions. Set a numerotation compatible with the method of $P_{ij}$. By default, the
numerotation is compatible with the method of characteristics.

\item[\moc{SPEC}] keyword used to specify specular reflexion on \moc{ALBE}--type
boundary conditions. Set a numerotation compatible with the method of $P_{ij}$. By default, the
numerotation is compatible with the method of characteristics.

\item[\moc{QUAB}] keyword to specify the number of basis point for the
numerical integration of each micro-structure in cases involving double
heterogeneity (Bihet).

\item[\dusa{iquab}] the number of basis point for the numerical integration of
the collision probabilities in the micro-volumes using the  Gauss-Jacobi
formula. The values permitted are: 1 to 20, 24, 28, 32 or  64. The default value
is \dusa{iquab}=5.

\end{ListeDeDescription}
\clearpage
