Using a predefined shape circular sector

Question

I'm trying to use the shape "circular sector" pgfman301a, p.706.

1. I find no way to change length of axes (should be variable dependent of circle dimension).
2. to position "apex" on 0,0
3. why "minimum size" doesn't work?

The code:

\documentclass[]{scrartcl}
\usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage{lmodern}
\usepackage[ngerman]{babel} \usepackage[margin=0cm,a4paper]{geometry}
\usepackage[a4,frame,center]{crop}
\usepackage{tikz}
\usetikzlibrary{mindmap,%to get annotations
          decorations.fractals,
          decorations.pathmorphing,
          decorations.text,
          positioning,
          fadings,lindenmayersystems,shadings,calendar,spy,math,calc,
          shapes.geometric,
          intersections,
          shadows,
          fadings,backgrounds}
\begin{document}  
\begin{tikzpicture} 
   \coordinate (circleorig) at (0cm,0cm); 
   \newdimen\circledim
 \tikzmath{ \circledim=8 cm; }%end tikzmath
 \tikzset{shape circlesec/.style={bottom color=black!30,
                                  top color=red,
                                  draw,
                                  fill=yellow!30,
                                  line width=0.1pt,
                                  inner xsep=0pt,
                                  inner ysep=0pt,
                                 } 
          }%end tikzset
%help lines
%\draw [help lines,step=0.5cm] (0,5) grid (8,-8);
\foreach \x in {-8,-7.5,...,8}
  \draw [yshift=0 cm](\x,1pt) -- (\x,-1pt) node[anchor=north]{\tiny $\x$};
\foreach \y in {-8,-7.5,...,8}
  \draw [yshift=0 cm](1pt,\y) -- (-1pt,\y) node[anchor=east]{\tiny $\y$};
\node [name=j,
      shape=circular sector, 
            style=shape circlesec,
            inner sep=0cm,
            circular sector angle=30,
            shape border uses incircle,
            shape border rotate=-105,
            %minimum size = 10cm,%has no effect?
     ] 
     %at (sector center) 
     {\fbox{\begin{minipage}{3.5cm}
               Januar: Bildung\\
               der ersten silikaten\\
               Erdrinde bald nach \\
               dem prim\"aren,\\
               dissonanten Akt.
            \end{minipage}}
     }; 
    %\draw[shift=(j.south)] plot[mark=x] coordinates{(0,0)}  
    %   node[right] {j.south};
\end{tikzpicture} 
\end{document}

Answer 1

Kpym has already told you what I was going to tell you about minimum size. Other than that you need to use an appropriate anchor and only know how big the node will be after you have drawn it, so you can draw the grid below it afterwards on the background layer.

\documentclass[tikz,border=3.14mm]{standalone}
\usetikzlibrary{math,calc,shapes.geometric,backgrounds}
\begin{document}  
\begin{tikzpicture}[scale=0.5,transform shape] 
   \coordinate (circleorig) at (0cm,0cm); 
   \newdimen\circledim
 \tikzmath{ \circledim=8 cm; }%end tikzmath
 \tikzset{shape circlesec/.style={bottom color=black!30,
                                  top color=red,
                                  draw,
                                  fill=yellow!30,
                                  line width=0.1pt,
                                  inner xsep=0pt,
                                  inner ysep=0pt,
                                 } 
          }%end tikzset
\node [name=j,
      shape=circular sector, 
            style=shape circlesec,
            inner sep=0cm,
            circular sector angle=30,
            shape border uses incircle,
            shape border rotate=-105,
            anchor=sector center,inner sep=-2mm,
            %minimum size = 20cm,%has an effect if the original size was smaller
     ] 
     (cs) at (0,0) 
     {\fbox{\begin{minipage}{3.5cm}
               Januar: Bildung\\
               der ersten silikaten\\
               Erdrinde bald nach \\
               dem prim\"aren,\\
               dissonanten Akt.
            \end{minipage}}
     }; 
\begin{scope}[on background layer]
%help lines
%\draw [help lines,step=0.5cm] (0,5) grid (8,-8);
\draw let \p1=($(cs.north)-(cs.sector center)$),\n1={int(1+\y1*1pt/1cm)}
in
\pgfextra{\pgfmathtruncatemacro{\xmax}{\n1}\pgfmathtruncatemacro{\nextx}{\xmax-1}\typeout{\n1}}
foreach \x in {-\xmax,-\nextx,...,\xmax}
  {(\x,1pt) -- (\x,-1pt) node[anchor=north,font=\tiny]{ $\x$} } 
foreach \y in {-\xmax,-\nextx,...,\xmax}
{(1pt,\y) -- (-1pt,\y) node[anchor=east,font=\tiny]{$\y$}};

\end{scope}

    %\draw[shift=(j.south)] plot[mark=x] coordinates{(0,0)}  
    %   node[right] {j.south};
\end{tikzpicture} 
\end{document}