\begin{table}%t8
\caption{\label{tab:DSA}Predictions from the shock acceleration model.}
\small%\centerline
 {
\begin{tabular}{c c c c c c c} 
\hline\hline
Relic        &$\alpha$ & $M$ &  $R$    & $P_2/P_1$    &  $T_2/T_1$ & $(B_2/B_1)_{{\rm iso}P}$\\
\hline     
Abell 2345-1 &1.5 $\pm$ 0.1 &2.8 $\pm$ 0.1&2.5 $\pm$ 0.2&6 $\pm$ 1  & 2.4 $\pm$ 0.4  &2.4 $\pm$ 0.2\\
Abell 2345-2 &1.3 $\pm$ 0.1 &2.2 $\pm$ 0.1&2.9 $\pm$ 0.2&9 $\pm$ 3  & 3 $\pm$ 1      &3.0 $\pm$ 0.5\\
Abell 1240-1 &1.2 $\pm$ 0.1 &3.3 $\pm$ 0.2&3.1 $\pm$ 0.3&14 $\pm$ 6 & 4 $\pm$ 2      &3.7 $\pm$ 0.8\\
Abell 1240-2 &1.3 $\pm$ 0.2 &2.8 $\pm$ 0.3&2.9 $\pm$ 0.4&9 $\pm$ 3  & 3 $\pm$ 2      &3.0 $\pm$ 0.5\\
\hline
\end{tabular}}
\medskip
Column~1: source name; Col~2: spectral index value; Col.~3:  mach number; Col.~4: shock compression ratio estimated  from the radio spectral index;  Cols.~5,~6: pressure and temperature jump across the shock; Col.~7: magnetic field  strength in the pre and post shock regions required to
support the relic against the thermal pressure.
\end{table}