\begin{table}%t1
\caption{Beam particle densities for beams with power-law energy spectra for
different sets of initial energy flux and spectral indices.}\label{tab1}
%\centering
\par
\begin{tabular}{cccc}
\hline\hline
{\small Flux, erg cm}$^{-2}${\small \ s}$^{-1}$ & {10$^8$} & {10$^{10}$} & {%
10$^{12}$} \\ \hline
$\gamma $ & \multicolumn{3}{c}{{\small Particle density, cm}$^{-3}$} \\ 
\hline
3 & $2.2 \times 10^5$ & $2.2 \times 10^7$ & $2.2 \times 10^9$ \\ 
5 & $3.4 \times 10^5$ & $3.4 \times 10^7$ & $3.4 \times 10^9$ \\ 
7 & $4.8 \times 10^5$ & $4.8 \times 10^7$ & $4.8 \times 10^9$ \\ 
\hline
\end{tabular}
\end{table}