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I have this weird problem with a latex poster where I want to colour the background but there is always a white strip at the top of the poster that wont colour.

    \documentclass[final,20pt]{beamer}
\usepackage[utf8]{inputenc}
\usepackage{tikz}
\usepackage{tcolorbox}
%\definecolor{background}{rgb}{0.1, 0.1, 0.1}

\setlength{\paperwidth}{46.8in}

\setlength{\paperheight}{33.1in}

\usepackage{geometry}
\geometry{paperwidth=46.8in,paperheight=33.1in,margin=2cm}

\setbeamertemplate{navigation symbols}{}
\setbeamertemplate{headline}{}


\begin{document}

\setbeamercolor{background canvas}{bg=blue}

\font\titlefont=cmr12 at 70pt
\font\authorfont=cmr12 at 50pt
\font\intitutefont=cmr12 at 50pt

\title{\titlefont The Bubble Chamber} % Poster title
\author{\authorfont CT} % Author(s)

\date{}

\begin{frame}
% Title section

     \begin{columns}


     \vspace{5cm}
  \begin{column}{0.3\linewidth}
  \end{column}
   \begin{column}{0.3\linewidth}
   \maketitle
    \vskip1cm
    \centering
    \vskip1cm
   \end{column}
   \begin{column}{0.3\linewidth}

   \end{column}

    \end{columns}

    \hrule 

    \vspace{3cm}

    % Page is split into 1-2-1 arrangement for first half 

    \begin{columns}[t,totalwidth=\linewidth]

    \begin{column}{0.24\linewidth}
    \vspace{0.7cm}

     \begin{tcolorbox}[colback=white,colframe=blue,boxrule=5pt,title=\centering \Huge Production Process ]


    The bubble chamber was exposed to a beam of $K^-$ mesons which are slowed by ionising the gas in the chamber, creating bubbles until they are close to stationary at which point the $K^-$ will interact with a neighbouring proton.

    This process occurs through the strong interaction wherein the proton and kaon exchange a quark and some gluons:





\end{tcolorbox}

     \begin{tcolorbox}[colback=white,colframe=blue,boxrule=5pt,title=\centering \Huge $\Sigma$ Identification]

      Visually this is presented in the bubble chamber as a kaon track stopping and two other tracks emerging from it with a $180^{\circ}$ angle between them as shown in Fig 1. 

      Events where the angle between the tracks $\neq 180^{\circ}$ indicates that the particles are not stationary in the lab frame when the interaction, violating one of the requirements for the use of the mass formula.



\end{tcolorbox}

    \end{column}

\begin{column}{0.49\linewidth}

    \begin{columns}[t,totalwidth=0.49\linewidth]

    \begin{column}{0.49\linewidth}

     \begin{tcolorbox}[colback=white,colframe=blue,boxrule=5pt,title=\centering \Huge Decay Process ]

    The decay of the hyperon then occurs via the weak interaction, a W boson is produced by the Hyperon which pair produces a quark antiquark pair:




However there is the possibility of a semileptonic decay mode, replacing the $q\bar{q}$ pair with a lepton and neutrino:

\begin{align}
\Lambda \to p + e^- + \bar{\nu}_e    
\end{align}

Which could be seen in the bubble chamber as an single electron line and proton line emerging instead of a pair of lines corresponding to a proton and pion.

However this process is \textbf{forbidden} by isospin/hypercharge baryon model, thus study of it allows us to test that description of these particles.

    \end{tcolorbox}

    \end{column}

     \begin{column}{0.49\linewidth}



    \end{column}   

   \end{columns}

   \vspace{1cm}

 \begin{tcolorbox}[colback=white,colframe=red,boxrule=5pt,title=\centering \Huge $\Sigma$ Mass Formula ]
 The mass of the sigma baryon is calculated through the application of energy and momentum conservation:
 \begin{gather}
p_{\pi} = p_{\Sigma} \hspace{1cm} \textrm{Momentum Conservation} \\
m_0 c^2 = \sqrt{m_{\Sigma}^2 c^4 + p_{\Sigma}^2 c^2} + \sqrt{m_{\pi}^2 c^4 + p_{\pi}^2 c^2} \hspace{1cm} \textrm{Energy Conservation}
 \end{gather}

 When these two are combined a singe formula for the mass of the Sigma baryon is obtained:

 \begin{equation}
m_{\Sigma} = \frac{1}{c^2} \left[\left( m_0c^2 - \sqrt{m_{\pi}^2c^4+p_{\pi}^2c^2} \right)^2 - p_{\pi}^2c^2  \right]^{1/2}   \hspace{0.7cm}  m_0 = m_p + m_K
\end{equation}

\end{tcolorbox}

\end{column}

  \begin{column}{0.24\linewidth}

    \begin{tcolorbox}[colback=blue,coltext=white]
    \centering
    \Huge Production Process
    \end{tcolorbox}

    Some text here.



    \end{column}

    \end{columns}


\end{frame}
\end{document}

Here is a screenshot so you can see what the problem is:

enter image description here

I have tried doing things like putting a vspace under everything to force content to the top of the page but the white box persists.

Any help would be appreciated. I haven't seen anyone experiencing this problem anywhere so I don't really know what to do at this point.

1 Answer 1

3

The problem is caused by your setting of margin=2cm in the geometry options. This not only sets the horizontal margins, but also the margin at top and bottom which interferes with beamers own settings of the top margin.

The easiest solution would be to only set the horizontal margins in the geometry settings and let beamer do its own thing with the top margin:

\documentclass{beamer}


\usepackage{geometry}
\geometry{paperwidth=46.8in,paperheight=33.1in,hmargin=2cm}

\setbeamertemplate{navigation symbols}{}
\setbeamertemplate{headline}{}

\setbeamercolor{background canvas}{bg=blue}


\begin{document}

\begin{frame}
test
\end{frame}
\end{document}
0

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