Index: /trunk/ICRC_01/mccontrib.tex
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--- /trunk/ICRC_01/mccontrib.tex	(revision 810)
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 The threshold of the MAGIC telesope is defined as the peak 
 in the $dN/dE$ distribution. For all different trigger settings
-this value is determined. 
+this value is determined. The energy threshold could 
+depend among other variables on the Background simulated conditions, 
+the threshold of the trigger discriminator and the zenith angle. We 
+check the influence of the three above-mentioned variables.
+
+\begin{figure}[h]
+ \vspace*{2.0mm} % just in case for shifting the figure slightly down
+ \includegraphics[width=8.3cm]{enerthres.eps} % .eps for Latex,
+                                            % pdfLatex allows .pdf, .jpg, .png and .tif
+ \caption{Caption text}
+ \label{fig_enerthres}
+\end{figure}
+
+For both, gammas and protons, some different background conditions 
+have been simulated (without any background light, diffuse light, 
+and light from Crab Nebula field of view). The results pointed out 
+that there is not any variation of the energy threshold inside our 
+error in determining the maximum that is few GeV for gammas, It is 
+worth to remember that this is based only in first level trigger. 
+Most likely there will be some effects when one enters the second 
+level trigger and the shower reconstruction.
+
+Magic will do observations in a large range of zenith angles, 
+therefore is worth to studie the energy threshold as function of 
+the zenith angle. In figure three it is shown for 0, 5 and 10 degrees.
+
+If one lowers the threshold of the trigger discriminator, then less 
+photons in the camera plane are needed to trigger the Telescope. 
+And it helps the low energy showers to fulfil the required trigger 
+conditions. In figure 3 one can see that the threshold energy decreases 
+while lowering the discriminator. It is 25 GeV for 3 mV and 105 GeV 
+for 7 mV. Since one of the aims of the Telescope is lowering as much 
+as possible the energy threshold, a low discriminator value is 
+preferred. But for 3 mV the expected rate due to protons increases a 
+lot (see section 3.1.3), while it keeps under control at 4 mV. 
+Therefore, the threshold of the discriminator would be keep above 
+4 mV, which yields a energy threshold of 45 GeV.
 
 \subsubsection{Expected rates}