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%\title[GEANT4/EGS5]{GEANT4/EGS5}

\title{Geant4/EGS5}

\author{Sho Uemura}
%\institute[MIT]{MIT --- Department of Physics\\}
\date[August 31, 2010]

\begin{document}

%\begin{frame}
%  \titlepage
%\end{frame}

\begin{frame}{Geant4 multiple scattering}
	\begin{itemize}
		\item Smaller step sizes $\to$ more scattering
		\item Single Coulomb scattering model: less scattering
	\end{itemize}
	\begin{center}
		\includegraphics[width=.45\textwidth]{g4_step_025_occup1}
		\includegraphics[width=.45\textwidth]{g4_025_occup1}
	\end{center}
\end{frame}

\begin{frame}{Bremsstrahlung production}
	\begin{columns}
		\column{.5\textwidth}
		\begin{itemize}
			\item 0.25\% $X_0$ target, $10^9$ beam electrons --- save all photons with energy above 20 MeV
			\item Total counts: $1.67\times10^7$ for EGS5, $1.70\times10^7$ for Geant4
			\item Energy distributions are similar
		\end{itemize}
		\column{.5\textwidth}
		\includegraphics[width=\textwidth]{photon_en}
	\end{columns}
\end{frame}

\begin{frame}{Bremsstrahlung angular distribution}
	\begin{itemize}
		\item Geant4 produces much fewer photons than EGS5 at large angles
		\item Geant4 produces more electrons than EGS5, so difference in bremsstrahlung processes must be responsible
		\item Geant3 (similar angle formula to Geant4) with small steps gives same electron distribution as EGS5, but few photons at large angles
	\end{itemize}
	\begin{center}
		\includegraphics[width=.45\textwidth]{photon_u_wide}
		\includegraphics[width=.45\textwidth]{photon_u_narrow}
	\end{center}
\end{frame}


\end{document}