Symbole de la radioactivité et illustration de la loi de décroissance

Symbole de la radioactivité et illustration de la loi de décroissance, avec PSTricks, par Thomas Söll et Gilg Jürgen :

Le listing :

\documentclass[dvipsnames]{article}
\usepackage[a4paper]{geometry}
\usepackage{pst-plot}
\SpecialCoor
\begin{document}
\begin{center}
\begin{pspicture}(-2,-2)(2,2)
\pspolygon[fillstyle=solid,fillcolor=yellow,linewidth=5\pslinewidth](2.875;-30)(2.875;90)(2.875;210)
\pswedge*(0,0){1.25}{0}{60}
\pswedge*(0,0){1.25}{120}{180}
\pswedge*(0,0){1.25}{240}{300}
\pscircle*[linecolor=yellow](0,0){0.375}
\pscircle*(0,0){0.25}
%%Radienverh\"{a}ltnis 1 : 1,5 : 5
\end{pspicture}

\begin{pspicture}(-2,-2)(2,2)
\psframe[fillstyle=solid,fillcolor=yellow,linecolor=gray](-2,-2)(2,2)
\pswedge*(0,0){1.75}{0}{60}
\pswedge*(0,0){1.75}{120}{180}
\pswedge*(0,0){1.75}{240}{300}
\pscircle*[linecolor=yellow](0,0){0.5}
\pscircle*(0,0){0.35}
\end{pspicture}
\end{center}

\begin{center}
\begin{pspicture}(-2,-1)(12,11)
\def\radioakt{%
\pscircle[fillstyle=solid,fillcolor=yellow,linestyle=none](0,0){0.125}
\pswedge*(0,0){0.125}{0}{60}
\pswedge*(0,0){0.125}{120}{180}
\pswedge*(0,0){0.125}{240}{300}
\pscircle*[linecolor=yellow](0,0){0.0375}
\pscircle*(0,0){0.025}
}
\def\nichtradioakt{%
\pscircle*[linecolor=SeaGreen](0,0){0.125}
}
\multido{\rA=0.25+0.5}{4}{%
\multido{\rB=0.27+0.635}{16}{%
\rput(\rA,\rB){\radioakt}
}}
\multido{\rA=2.25+0.5}{4}{%
\multido{\rB=0.27+0.635}{8}{%
\rput(\rA,\rB){\radioakt}
}}
\multido{\rA=2.25+0.5}{4}{%
\multido{\rB=5.35+0.635}{8}{%
\rput(\rA,\rB){\nichtradioakt}
}}
\multido{\rA=4.25+0.5}{4}{%
\multido{\rB=0.27+0.635}{4}{%
\rput(\rA,\rB){\radioakt}
}}
\multido{\rA=4.25+0.5}{4}{%
\multido{\rB=2.825+0.635}{12}{%
\rput(\rA,\rB){\nichtradioakt}
}}
\multido{\rA=6.25+0.5}{4}{%
\multido{\rB=0.27+0.635}{2}{%
\rput(\rA,\rB){\radioakt}
}}
\multido{\rA=6.25+0.5}{4}{%
\multido{\rB=1.55+0.635}{14}{%
\rput(\rA,\rB){\nichtradioakt}
}}
\psline(0,10)(2,10)(2,5)(4,5)(4,2.5)(6,2.5)(6,1.25)(8,1.25)(8,0)
\psaxes[ticks=none,labels=none]{->}(0,0)(-0.5,-0.5)(10,11)
\psplot[linecolor=red,algebraic,linewidth=1.5pt]{0}{10}{10*0.5^(0.5*x)}
\uput[0](10,0){$t$}
\psxTick(2){T_{1/2}}
\psxTick(4){2T_{1/2}}
\psxTick(6){3T_{1/2}}
\psxTick(8){4T_{1/2}}
\psyTick(10){100\,\%}
\psyTick(5){50\,\%}
\psyTick(2.5){25\,\%}
\psyTick(1.25){12,5\,\%}
\end{pspicture}
\end{center}
\end{document}