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\begin{document}  
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\begin{titlepage}

\noindent
%DESY xx-xxx \hspace*{105mm} ISSN xxxx-xxxx\\
% hep-ex/0412xxx \\
%\today 

\noindent
%Date:        \today                   \\ 
%Version:     0.01                     \\
% Editors:     P. Laycock, P. Newman, D. Salek       \\
% Referees:    C. Niebuhr, A. Valkarova        \\
%%%%%%%%%%%% For conference papers  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%
%%%%%%%%%%%% coment the header and fill the right conference
%%%%% {\it {\large version of \today}} \\[.3em]
\begin{center} %%% you may want to use this line for working versions
 \begin{small}
 \begin{tabular}{llrr}
 {\bf H1prelim-09-011} Submitted to & & &
 \epsfig{file=H1logo_bw_small.epsi
 ,width=1.5cm} \\[.2em] \hline
 \multicolumn{4}{l}{{\bf
                  XVII International Workshop on Deep Inelastic Scattering,
                  DIS2009},
                  April 26-30,~2009,~Madrid} \\
%                  Abstract:        & {\bf xx-xxx}    & & \\
                  Parallel Session & {\bf Diffraction and Vector Mesons}   & & \\ \hline
   \multicolumn{4}{l}{\footnotesize {\it Electronic Access:
  www-h1.desy.de/publications/H1preliminary.short\_list.html}} \\[.2em]
 \end{tabular}
 \end{small}
 \end{center}

\vspace{2cm}

\vspace*{2cm}

\begin{center}
\begin{Large}
{\boldmath \bf      
First measurement of the longitudinal diffractive structure function $F_L^D$ at HERA
}

\vspace{2cm}
H1 Collaboration

\end{Large}
\end{center}

\vspace{2cm}

\begin{abstract}
\noindent

A first measurement of the longitudinal diffractive structure function 
$F_L^D$ using the H1 detector at HERA is presented.  The structure 
function is extracted from first measurements of the diffractive cross 
section at centre of mass energies $\sqrt{s}$ of 225 and 252 GeV,
together with a new measurement at $\sqrt{s}$ of 319 GeV, using data
taken in 2007 at high values of inelasticity $y$. The measured $F_L^D$
is compared to predictions from NLO QCD fits to previous measurements
of the inclusive diffractive DIS cross section.

\end{abstract}

\end{titlepage}


\newpage

\begin{figure}
\begin{center}
\includegraphics[width=0.5\columnwidth]{H1prelim-09-011.fig1.eps}
\caption{The electron energy distribution for $y_e > 0.38$ in the
  $E_p=460\; {\rm GeV}$ data.  The positively-charged data events
  (points) are compared with the sum of negatively charged data events
  (green filled histogram) and diffractive DIS Monte Carlo which does
  not include $F_L^D$ (red histogram).}
\end{center}
\end{figure}

\newpage

\begin{figure}
\begin{center}
\includegraphics[width=1.0\columnwidth]{H1prelim-09-011.fig2.eps}
\caption{The electron energy, $log(Q^2)$, $y_e$, the summed $E-p_z$ of
  all final state particles, $\beta$ and $\xpom$ distributions for the
  $E_p=460\;{\rm GeV}$ data, shown for $y>0.38$.  The positively-charged
  data events (points) are compared with the sum of negatively charged
  data events (green filled histogram) and diffractive DIS Monte Carlo
  which does not include $F_L^D$ (red histogram).}
\end{center}
\end{figure}

\newpage

\begin{figure}
\begin{center}
\includegraphics[width=1.0\columnwidth]{H1prelim-09-011.fig3.eps}
\caption{The electron energy, $log(Q^2)$, $y_e$, the summed $E-p_z$ of
  all final state particles, $\beta$ and $\xpom$ distributions for the
  $E_p=575\; {\rm GeV}$ data, shown for $y>0.38$.  The positively-charged
  data events (points) are compared with the sum of negatively charged
  data events (green filled histogram) and diffractive DIS Monte Carlo
  which does not include $F_L^D$ (red histogram).}
\end{center}
\end{figure}

\newpage

\begin{figure}
\begin{center}
\includegraphics[width=1.0\columnwidth]{H1prelim-09-011.fig4.eps}
\caption{The electron energy, $log(Q^2)$, $y_e$, the summed $E-p_z$ of
  all final state particles, $\beta$ and $\xpom$ distributions for the
  $E_p=460\; {\rm GeV}$ data, shown for all $y$.  The positively-charged
  data events after subtraction of negatively charged events are shown
  as points, compared with diffractive DIS Monte Carlo which does not
  include $F_L^D$ (red histogram).}
\end{center}
\end{figure}

\newpage

\begin{figure}
\begin{center}
\includegraphics[width=1.0\columnwidth]{H1prelim-09-011.fig5.eps}
\caption{The electron energy, $log(Q^2)$, $y_e$, the summed $E-p_z$ of
  all final state particles, $\beta$ and $\xpom$ distributions for the
  $E_p=575\; {\rm GeV}$ data, shown for all $y$.  The positively-charged
  data events after subtraction of negatively charged events are shown
  as points, compared with diffractive DIS Monte Carlo which does not
  include $F_L^D$ (red histogram).}
\end{center}
\end{figure}

\newpage

\begin{figure}
\begin{center}
\includegraphics[width=1.0\columnwidth]{H1prelim-09-011.fig6.eps}
\caption{The electron energy, $log(Q^2)$, $y_e$, the summed $E-p_z$ of
  all final state particles, $\beta$ and $\xpom$ distributions for the
  $E_p=920\; {\rm GeV}$ data, shown for all $y$.  The positively-charged
  data events after subtraction of negatively charged events are shown
  as points, compared with diffractive DIS Monte Carlo which does not
  include $F_L^D$ (red histogram).}
\end{center}
\end{figure}

\newpage

\begin{figure}
\begin{center}
\includegraphics[width=0.6\columnwidth]{H1prelim-09-011.fig7.eps}
\caption{Measurement of the reduced cross section at $E_p=460\; {\rm
    GeV}$.  The data are compared to an NLO QCD fit to previous H1
  data, H1 2006 DPDF Fit B.  Also shown is the prediction for $F_2^D$
  from the same fit.  The inner error bars are statistical, outer
  error bars show the statistical and systematic errors added in
  quadrature.}
\end{center}
\end{figure}

\newpage

\begin{figure}
\begin{center}
\includegraphics[width=0.6\columnwidth]{H1prelim-09-011.fig8.eps}
\caption{Measurement of the reduced cross section at $E_p=575\; {\rm
    GeV}$.  The data are compared to an NLO QCD fit to previous H1
  data, H1 2006 DPDF Fit B.  Also shown is the prediction for $F_2^D$
  from the same fit.  The inner error bars are statistical, outer
  error bars show the statistical and systematic errors added in
  quadrature.}
\end{center}
\end{figure}

\newpage

\begin{figure}
\begin{center}
\includegraphics[width=0.6\columnwidth]{H1prelim-09-011.fig9.eps}
\caption{Measurement of the reduced cross section at $E_p=920\; {\rm
    GeV}$.  The data are compared to an NLO QCD fit to previous H1
  data, H1 2006 DPDF Fit B.  Also shown is the prediction for $F_2^D$
  from the same fit.  The inner error bars are statistical, outer
  error bars show the statistical and systematic errors added in
  quadrature.}
\end{center}
\end{figure}

\newpage

\begin{figure}
\begin{center}
\includegraphics[width=0.6\columnwidth]{H1prelim-09-011.fig10.eps}
\caption{Measurement of the reduced cross section at $E_p=460, 575$
  and $920\; {\rm GeV}$.  The data are compared to an NLO QCD fit to
  previous H1 data, H1 2006 DPDF Fit B.  Also shown is the prediction
  for $F_2^D$ from the same fit.  The inner error bars are
  statistical, outer error bars show the statistical and systematic
  errors added in quadrature.}
\end{center}
\end{figure}

\newpage

\begin{figure}
\begin{center}
\includegraphics[width=1.0\columnwidth]{H1prelim-09-011.fig11.eps}
\caption{The reduced cross section measured at $Q^2=13.5\; GeV^2$ and
  different bins of $\beta$ as a function of $y^2 / [(1+(1-y)^2)]$ for
  $E_p=460$ (red squares), $E_p=575$ (blue triangles) and $E_p=920$
  (black circles) GeV.  The inner error bars are statistical, outer
  error bars show the statistical and systematic errors added in
  quadrature.  The straight lines show the linear fits used to
  determine $F_L^D$.}
\end{center}
\end{figure}

\newpage

\begin{figure}
\begin{center}
\includegraphics[width=0.6\columnwidth]{H1prelim-09-011.fig12.eps}
\caption{The diffractive longitudinal structure function $F_L^D$
  multiplied by $\xpom$.  The data are compared to predictions from
  two NLO QCD fits to previous H1 data, H1 2006 DPDF Fit A (blue line)
  and Fit B (red line).  The data are consistent with both
  predictions.  Also shown is the value of $F_2^D$ as a dashed red
  line.}
\end{center}
\end{figure}


\end{document}
