\chapter{Introduction}

%000000000000000000000000000000000000000000000000000000000000000
\section{Motivation}%concealed Uranium and Plutonium.
%\section{The Cargo Container Problem}%concealed Uranium and Plutonium.
\indent


\section{Emittance}
\indent

In July 2010y, Emittance measurement of HRRL was conducted at Beam Lab, at Physics Department of ISU. We installed a YAG crystal on the HRRL beam line to see electron beam. A quadrupole magnet was installed between HRRL gun and the YAG screen. We changed current on the quadrupole to control magnetic field strength of the quadrupole magnet, thus we changed electron beam shape on the YAG screen. 

\subsection{Experimental Setup}
We did quadrupole scan to measure emittance of the electron beam in HRRL. In quadrupole method, the strength of the quadrupole magnet was changed by changing the current go through quadrupole coils. The electron beam were coming out of the gun went through quadrupole first, then beam would enter a 3-way cross. 2 end of the 3-way cross was installed on the beam line. The third end of the 3-way cross was placed upward and there was a actuator installed to it.  The YAG crystal was mounted in the actuator, which can put the YAG in the beam line or take it out of the beam line. 

 and the beam will change under the magnetic field of the 


\section{Positron Target}
\indent

\section{Positron Yield}
\indent

\section{Conclusion}
\indent









%~\cite{Sommerfeld1931}
%${\bf P_i}$
%${\bf {\theta}_f}$


%\begin{figure}[htbp] 
%\centering
%\includegraphics[scale=0.6]{1_brem_emission}
%\caption{Bremsstrahlung process and plane of emission in bremsstrahlung }
%\label{fig:brem_emission} 
%\end{figure}

%\begin{equation}
%\theta_c = \frac {m_ec^2}{E_0}  \label{eq:char-ang}
%\end{equation}

%\noindent  





%\begin{table}[ht]
%\caption{Angular distribution coefficients.}  
%\centering
%\begin{tabular}{|c|c|c|c|c|c|} % ccc means 3 columns, all centered; alternatives are l, r

%\hline % draws a line under the column headers
%         J & K &    a   		  &     b   &      c        &      d     \\ 
%\hline 1 & 0 &  $ -$ 	  &   3/4  &     $ - $       &      3/4  \\  
%\hline 1 & 1 & 3/4 		 &  $-$3/8  &     $ -  $      &     $-$3/8  \\ 
%\hline 2 & 0 &  $ -  $	 &          &  +15/16  &     15/4  \\ 
%\hline 2 & 1 & 5/4 		& $ -$5/8  &   $ -$5/8     &   $ -$15/8  \\ 
%\hline 2 & 2 &     		 &  +5/8  &  +5/32   &              \\ 
%\hline

%\end{tabular}      
%\label{tb:ang-dis-cof-abc}
%\end{table}


% \begin{center}                
 %                   $f_{2}(L,L)$=$\frac{1}{2} $ \\
  %                  $f_{2}(L,L)$=$\frac{1}{2} $  \\
  %                  $f_{4}(L,L)$=-$\frac{1}{2} $   \\
           
 %\end{center}


%\begin{sidewaysfigure}[htbp] 
%\centering
%  \includegraphics[scale=0.7]{1_Setup_abc}
%\caption{Experimental setup for photodisintegration experiment with HRRL whole view}
%\label{fig:1_Setup_abc} 
%\end{sidewaysfigure}


%Fig.~\ref{fig:1_Setup_abc} is the view of whole setup. 

