\begin{table}%T2
%\centering
\par
\caption{This table indicates the radius inside which a given fraction
     $f(r_{\rm lim})$ of secondary cosmic rays reaching the center were
     emitted from, for several
     $L$ and in the case of a disk of radius $R=20$ kpc.
     The last line shows that for small $L$, the effect of the side
     boundary is completely negligible.}
     \label{table_origine_sec}
     \begin{tabular}{ccccccc}   \hline\hline
	& \multicolumn{2}{c}{$f(r_{\rm lim}) = 50$\%}  &
	\multicolumn{2}{c}{$f(r_{\rm lim}) = 90$\%}
	& \multicolumn{2}{c}{$f(r_{\rm lim}) = 99$\%}\\
	\hfill
	& $R=\infty$  & $R=20$~kpc & $R=\infty$ & $R=20$~kpc& $R=\infty$
	&$R=20$~kpc\\
	\hline
	$L = \infty$ & -- & 8.6 kpc& -- & 15.3 kpc& -- & 18.5 kpc\\
	$L = 5$ kpc &   5.5 kpc&  5.3 kpc &  12.5 kpc& 12 kpc& 25 kpc&
	17.2 kpc\\
	$L = 1$ kpc &  1.1 kpc& 1.1 kpc&  2.5 kpc& 2.5 kpc& 4.4 kpc& 4.4 kpc\\
	\hline
     \end{tabular}
     \end{table}