add constant function fits to 80C vs 50C plot

Author: sixie

doc/paper/LGAD_May2017/LGAD_May2017_FNALTB.tex

@@ -904,8 +904,8 @@ \subsection{Comparison of uniformity of HPK 50 $\mu$m with 80 $\mu$m}
 
 \begin{figure}[htbp] 
 \centering
-\includegraphics[width=0.7\textwidth]{figs/FNAL_TimeResolution_vs_X_HPK50CVs80C.pdf} 
-\caption{Comparison of the uniformity of the measured time resolution of the HPK 80C-PIX versus 50C-PIX sensors. The 80~$\mu$m sensor is mounted on the FNAL board, and is biased at -610~V, and the 50~$\mu$m sensor is mounted on the KU board and is biased at -400~V.} 
+\includegraphics[width=0.7\textwidth]{figs/FNAL_TimeResolution_vs_X_HPK50CVs80C_WithFits.pdf} 
+\caption{Comparison of the uniformity of the measured time resolution of the HPK 80C-PIX versus 50C-PIX sensors. The 80~$\mu$m sensor is mounted on the FNAL board, and is biased at -610~V, and the 50~$\mu$m sensor is mounted on the KU board and is biased at -400~V. The lines show fits of the data to constant functions.} 
 \label{fig:HPK50CVs80C} 
 \end{figure}