\section{Contents of a \dir{mc} Directory}\label{sect:mcdir}

This directory contains information generated by the \moc{MC:} multigroup Monte Carlo
module.

\subsection{State vector content for the \dir{mc} data structure}\label{sect:mcstate}

The dimensioning parameters for the \dir{mc} data structure, which are stored in
the state vector $\mathcal{S}^{mc}$, represent:

\begin{itemize}
\item Nominal number of source histories $M$ per $K_{\rm eff}$ cycle $N_{\rm nsrck}=\mathcal{S}^{mc}_{1}$
\item Number of source cycles $I_{\rm c}$ to skip before $K_{\rm eff}$ accumulation $N_{\rm ikz}=\mathcal{S}^{mc}_{2}$
\item Total number of cycles $N$ in the problem $N_{\rm kct}=\mathcal{S}^{mc}_{3}$
\item Initial seed for the random number generator $S=\mathcal{S}^{mc}_{4}$
\item N2N processing flag $F=\mathcal{S}^{mc}_{5}$
\begin{displaymath}
F = \left\{
\begin{array}{ll}
0 & \textrm{do not use information in the {\tt 'N2N} and {\tt 'N3N} records} \\
1 & \textrm{use information in the {\tt 'N2N} and {\tt 'N3N} records to perform
the random walk}
\end{array} \right.
\end{displaymath}
\item Type of tallies $T=\mathcal{S}^{mc}_{6}$
\begin{displaymath}
T = \left\{
\begin{array}{ll}
0 & \textrm{no tallies} \\
1 & \textrm{effective multiplication factor tally} \\
2 & \textrm{effective multiplication factor {\sl and} macrolib tallies}
\end{array} \right.
\end{displaymath}
\item The number of homogenized mixtures in the macrolib tally ${M_{\rm out}}=\mathcal{S}^{mc}_{7}$ 
\item The number of condensed energy groups in the macrolib tally ${G_{\rm out}}=\mathcal{S}^{mc}_{8}$ 
\item The number of regions in the initial geometry ${N_{\rm in}}=\mathcal{S}^{mc}_{9}$ 
\end{itemize}

\subsection{The main \dir{mc} directory}\label{sect:mcdirmain}

The following records and sub-directories will be found on the first level of a \dir{mc}
directory:

\begin{DescriptionEnregistrement}{Main records and sub-directories in \dir{mc}}{8.0cm}
\CharEnr
  {SIGNATURE\blank{3}}{$*12$}
  {Signature of the \dir{mc} data structure ($\mathsf{SIGNA}=${\tt L\_MC\blank{8}}).}
\IntEnr
  {STATE-VECTOR}{$40$}
  {Vector describing the various parameters associated with this data structure
  $\mathcal{S}^{mc}_{i}$, as defined in \Sect{mcstate}.}
\RealEnr
  {K-EFFECTIVE\blank{1}}{$1$}{}
  {Effective multiplication factor $K_{\mathrm{eff}}$}
\RealEnr
  {K-EFFECTI-SD}{$1$}{}
  {Standard deviation of the effective multiplication factor $\Delta K_{\mathrm{eff}}$}
\OptIntEnr
  {REF:IMERGE\blank{2}}{$N_{\rm in}$}{$T =2$}
  {Merged region number associated with each of the original region number in the macrolib tally $M_{r}$}
\OptIntEnr
  {REF:IGCOND\blank{2}}{$G_{\rm out}$}{$T =2$}
  {Reference group limits associated with the condensed groups in the macrolib tally $C_{g}$}
\OptDirEnr
  {MACROLIB\blank{4}}{$T =2$}
  {Directory containing the \dir{macrolib} structure associated with the
  macrolib tally, following the specification presented in \Sect{macrolibdirmain}.}
\end{DescriptionEnregistrement}