\usepackage[a4paper,margin=2cm]{geometry}
\usepackage[latin1]{inputenc}
\usepackage[distiller]{pstricks}
+\usepackage{pst-slpe}
\usepackage{pstricks-add,pst-eqdf,pst-func,pst-solides3d}
\usepackage{array,amsmath}
\begin{document}
\section{La d\'{e}couverte de la diffusion des particules $\alpha$ par le noyau d'or}
+
\subsection{L'exp\'{e}rience d'Ernest Rutherford en 1909}
Rutherford bombarde avec des particules $\alpha$ (noyau d'h\'{e}lium : 2 neutrons et 2 protons) une mince feuille d'or.
+\begin{center}
+\begin{pspicture}(-1,-1)(1,1)
+\def\Kernradius{7.5pt}
+\def\KernabstandHe{7.5pt}
+\def\ColorProton{red}
+\def\ColorNeutron{gray!20}
+
+\newpsstyle{proton}{linecolor={[rgb]{0.72 0 0}},slopebegin=red!50,sloperadius=0.15,linewidth=0.1pt,slopecenter=0.65 0.6,linestyle=solid}
+\newpsstyle{neutron}{linecolor=gray!50,slopebegin=white,sloperadius=0.11,linewidth=0.1pt,slopecenter=0.65 0.6,linestyle=solid}
+
+\def\Proton{\psBall[style=proton](0,0){\ColorProton}{\Kernradius}}
+\def\Neutron{\psBall[style=neutron](0,0){\ColorNeutron}{\Kernradius}}
+
+\def\AtomKernHe{%
+\multido{\iAngle=40+180}{2}{%
+\rput(\KernabstandHe;\iAngle){\Proton}%
+}%
+\multido{\iAngle=130+180}{2}{%
+\rput(\KernabstandHe;\iAngle){\Neutron}%
+}%
+}%
+\rput(0,0){\AtomKernHe}
+\rput(1.5,0){$^{4}_{2}$He$^{2+}$}
+\end{pspicture}
+\end{center}
+
+\subsection{Montage exp\'{e}rimental}
+
\begin{center}
\begin{pspicture}(-6,-4)(6,5)
\psset{lightsrc=10 -20 50,viewpoint=10 -10 10,Decran=20}
\psdot(0,0)
\uput[135](0,0){$F$}
\psdot(-1,0)
-\uput[135](-1,0){$A$}
+\uput[135](-1,0){$C$}
\psline(-2,-3)(-2,3)
\uput[90](-2,3){Directrice $d$}
\psline[linestyle=dashed,linecolor=lightgray](0,0)(0,-3)