Konturintegraldiagramm

Question

Ich habe jetzt den untenstehenden Code (danke an @AndréC), aber ich wollte auch einen zusätzlichen Halbkreis einfügen, der im handgezeichneten Bild zu sehen ist. Es tut mir leid, ich bin noch nicht so gut mit Tikz. Danke! Hier ist der Code:

\documentclass[border=5mm]{standalone}
\usepackage{tikz}
\usetikzlibrary{calc,decorations.markings,positioning}
\begin{document}
        \begin{tikzpicture}
        %configurable parameters
        \def\gap{0.4}
        \def\bigradius{4}
        \def\littleradius{1}
        %axes
        \draw[line width=2pt,->](-1.5*\bigradius,0) -- (1.5*\bigradius,0)
        (0,-1.5*\bigradius) -- (0,1.5*\bigradius);
        \draw[line width=2pt,->] (0,0)--(45:\littleradius);
        \draw[line width=2pt,->](0,0) -- (135:\bigradius); \node[above
        right] at (45:\littleradius/1.5) {\large\bf{$\varepsilon$}};
        \draw[line width=1pt,decoration={markings,
            mark=at position 0.07 with{\arrow[line width =2pt]{>}},%{latex}},
            mark=at position 0.17 with{\arrow[line width =2pt]{>}},
            mark=at position 0.27 with{\arrow[line width =2pt]{>}},
            mark=at position 0.35 with {\arrow[line width =2pt]{>}},%{latex}},
            mark=at position 0.47 with{\arrow[line width =2pt]{>}},
            mark=at position 0.53 with{\arrow[line width =2pt]{>}},%{latex}},
            mark=at position 0.6 with {\arrow[line width =2pt]{>}},%{latex}},
            mark=at position 0.65 with {\arrow[line width =2pt]{>}},%{latex}},
            mark=at position 0.7 with{\arrow[line width =2pt]{>}},
            mark=at position 0.8 with{\arrow[line width =2pt]{>}},
            mark=at position 0.85 with{\arrow[line width =2pt]{>}},
            mark=at position 0.955 with{\arrow[line width =2pt]{>}}},%{latex}}},
        postaction={decorate}]
        let
        \n1={asin(\gap/2/\bigradius)},
        \n2={asin(\gap/2/\littleradius)}
        in (180-\n1:\bigradius) -- (-180-\n2:\littleradius)
        arc(180-\n2:-180+\n2:\littleradius)--(-180+\n1:\bigradius)
        arc(-180+\n1:-45:\bigradius)--(45:\bigradius)arc(45:(180-\n1):\bigradius);
        \coordinate (T) at (135:2);
         \node[above] at (T){$T$}; 
        \coordinate (H) at (1.5*\bigradius,0);
         \node[below] at (H){\Large\bf {x}};
        \coordinate (J) at (0,1.5*\bigradius);
         \node[left] at (J){$\Large\bf y$}; 
        \coordinate (C) at (\littleradius,0);
         \node[below right] at (C) {\Large\bf {C}};
        \coordinate (D) at ({180-asin(\gap/2/\littleradius)}:1);            \node[above left] at (D) {$ \Large\bf B$}; 
        \coordinate (E) at ({-180+asin(\gap/2/\littleradius)}:1);           \node[below left] at (E) {$\Large\bf D$}; 
        \coordinate (F) at ({180-asin(\gap/2/\bigradius)}:\bigradius); 
        \node[above left] at (F) {$\Large\bf A$}; 
        \coordinate (G) at ({-180+asin(\gap/2/\bigradius)}:\bigradius); 
        \node[below left] at (G) {$\Large\bf  E$}; 
        \coordinate (P) at (0,-4);
        
         \node[below right] at (P) {$\Large\bf F$};
         \coordinate(Q) at (3,-4);
        \node[right] at (Q) {$\Large\bf G(\gamma-iT)$}; 
        \coordinate (R) at (3,4); 
        \node[right] at (R) {$\Large\bf H(\gamma+iT)$}; 
        \coordinate (S) at (0,4);
        \node[above right] at (S) {$\Large\bf K$};
        \end{tikzpicture}
\end{document}

und hoffte, dass links neben dem kleineren Kreis in der Mitte ein zusätzlicher Halbkreis zu sehen ist:

BEARBEITEN:Mir ist es gelungen, das Folgende hinzuzufügen, was zu meiner leicht bearbeiteten Grafik passt:

        \draw[thick, line width=   0.63pt] (-.9,.25) +(180:.3) arc (0:180:.3);
        \draw[thick, line width=   0.63pt] (-.9,-.25) +(-180:.3) arc (0:-180:.3);

Aber wie werde ich die Linien unter den kleinen Kreisen los? Ich möchte einen Halbkreis ohne Boden, wie den auf dem handgezeichneten Bild. Gibt es eine Möglichkeit, das mit diesem Code zu machen?

Answer 1

\documentclass[border=5mm]{standalone}
\usepackage{tikz}
\usetikzlibrary{calc,decorations.markings,positioning}
\begin{document}
        \begin{tikzpicture}
        %configurable parameters
        \def\gap{0.4}
        \def\bigradius{4}
        \def\littleradius{1}
        \def\tinyradius{.5}%<-- new radius for the new semi-circle
        %axes
        \draw[line width=2pt,->](-1.5*\bigradius,0) -- (1.5*\bigradius,0)
        (0,-1.5*\bigradius) -- (0,1.5*\bigradius);
        \draw[line width=2pt,->] (0,0)--(45:\littleradius);
        \draw[line width=2pt,->](0,0) -- (135:\bigradius); \node[above
        right] at (45:\littleradius/1.5) {\large\bf{$\varepsilon$}};
        \draw[line width=1pt,decoration={markings,
            mark=at position 0.065 with{\arrow[line width =2pt]{>}},%{latex}},
            mark=at position 0.17 with{\arrow[line width =2pt]{>}},
            mark=at position 0.29 with{\arrow[line width =2pt]{>}},
            mark=at position 0.35 with {\arrow[line width =2pt]{>}},%{latex}},
            mark=at position 0.47 with{\arrow[line width =2pt]{>}},
            mark=at position 0.53 with{\arrow[line width =2pt]{>}},%{latex}},
            mark=at position 0.6 with {\arrow[line width =2pt]{>}},%{latex}},
            mark=at position 0.65 with {\arrow[line width =2pt]{>}},%{latex}},
            mark=at position 0.7 with{\arrow[line width =2pt]{>}},
            mark=at position 0.8 with{\arrow[line width =2pt]{>}},
            mark=at position 0.85 with{\arrow[line width =2pt]{>}},
            mark=at position 0.955 with{\arrow[line width =2pt]{>}}},%{latex}}},
        postaction={decorate}]
        let
        \n1={asin(\gap/2/\bigradius)},
        \n2={asin(\gap/2/\littleradius)}
        in (180-\n1:\bigradius) --($(180-\n1:\bigradius)!.5! (-180-\n2:\littleradius)$)arc(180:0:\tinyradius)-- (-180-\n2:\littleradius)
        arc(180-\n2:-180+\n2:\littleradius)--($(-180+\n2:\littleradius)!.5!(-180+\n1:\bigradius)!2*\tinyradius cm!(-180+\n2:\littleradius)$)arc(0:-180:\tinyradius)--(-180+\n1:\bigradius)
        arc(-180+\n1:-45:\bigradius)--(45:\bigradius)arc(45:(180-\n1):\bigradius);
        \coordinate (T) at (135:2);
         \node[above] at (T){$T$}; 
        \coordinate (H) at (1.5*\bigradius,0);
         \node[below] at (H){\Large\bf {x}};
        \coordinate (J) at (0,1.5*\bigradius);
         \node[left] at (J){$\Large\bf y$}; 
        \coordinate (C) at (\littleradius,0);
         \node[below right] at (C) {\Large\bf {C}};
        \coordinate (D) at ({180-asin(\gap/2/\littleradius)}:1);            \node[above left] at (D) {$ \Large\bf B$}; 
        \coordinate (E) at ({-180+asin(\gap/2/\littleradius)}:1);           \node[below left] at (E) {$\Large\bf D$}; 
        \coordinate (F) at ({180-asin(\gap/2/\bigradius)}:\bigradius); 
        \node[above left] at (F) {$\Large\bf A$}; 
        \coordinate (G) at ({-180+asin(\gap/2/\bigradius)}:\bigradius); 
        \node[below left] at (G) {$\Large\bf  E$}; 
        \coordinate (P) at (0,-4);
        
         \node[below right] at (P) {$\Large\bf F$};
         \coordinate(Q) at (3,-4);
        \node[right] at (Q) {$\Large\bf G(\gamma-iT)$}; 
        \coordinate (R) at (3,4); 
        \node[right] at (R) {$\Large\bf H(\gamma+iT)$}; 
        \coordinate (S) at (0,4);
        \node[above right] at (S) {$\Large\bf K$};
        \end{tikzpicture}
\end{document}