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\begin{document}

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\begin{titlepage}

\noindent


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%% 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-08-042} Submitted to & & &
 \epsfig{file=/h1/iww/ipublications/H1PublicationTemplates/H1logo_bw_small.epsi
 ,width=1.5cm} \\[.2em] \hline
 \multicolumn{4}{l}{{\bf
                XVI International Workshop on Deep-Inelastic Scattering, DIS2008},
                 April 7-11,~2008,~London} \\
%                  Abstract:        & {\bf }    & & \\
                  Parallel Session & {\bf Structure Functions}   & & \\ \hline
   \multicolumn{4}{l}{\footnotesize {\it Electronic Access:https://www-h1.desy.de/publications/H1preliminary.short\_list.html
     %www-h1.desy.de/h1/www/publications/conf/conf\_list.html
     }} \\[.2em]
 \end{tabular}
 \end{small}
 \end{center}



\vspace*{2cm}
%%%%%%%%%%%%%%%%%%%
\begin{center}
  \Large
  {\bf 
   A Measurement of the Longitudinal Proton Structure Function $F_{L}(x,Q^{2})$ at high $Q^{2}$ at HERA}

  \vspace*{1cm}
    {\Large H1 Collaboration} 
\end{center}

\begin{abstract}

\noindent
A measurement of the longitudinal proton structure function $F_{L}(x,Q^{2})$ derived 
from inclusive deep inelastic $ep$ scattering cross section measurements at high $Q^{2}$ 
with the H1 detector at HERA is presented. The data were taken in the year 2007 at 
a positron beam energy of $E_{e}=27.5$~GeV and proton beam energies $E_{p}$ of 920~GeV, 
575~GeV and 460~GeV. The measurements of the NC cross sections from this analysis
combined with the reported earlier NC cross section measurements for the same data 
periods at medium $Q^{2}$ allowed to measure $F_{L}(x,Q^{2})$  
in a range of high four-momentum transfer squared $12 \leq Q^2 \leq 800~$GeV$^2$ and 
correspondingly Bjorken-$x$ between $0.00028\leq x \leq 0.0353$. The measured longitudinal 
structure function is found to be consistent with the NLO QCD expectations.
\noindent
\end{abstract}


\end{titlepage}

\pagestyle{plain}


%\newpage
%\begin{thebibliography}{99}

%\bibitem {klein}
%\cite{Klein:vs}
%M.~Klein and T.~Riemann,
%``Electroweak Interactions Probing The Nucleon Structure,''
%Z.\ Phys.\ C {\bf 24} (1984) 151.
%%CITATION = ZEPYA,C24,151;%%

%\bibitem{h1hiq2}
%C.~Adloff {\it et al.}  [H1 Collaboration],
%``Measurement and QCD Analysis of Neutral and Charged Current Cross Sections 
% at HERA''
%Eur.\ Phys.\ J.\ C {\bf 30} (2003) 1-32
%[hep-ex/0304003].
%%CITATION = HEP-EX 0304003;%%
%\vspace{-2mm}

%\bibitem{h1det}
% H1 Collaboration, I.~Abt {\it et al.}, Nucl.\ Instr.\ Meth.\ A386 (1997)
% 310 and 348.  -> No, 310 & 397
%I.~Abt {\it et al.}  [H1 Collaboration],
%``The H1 detector at HERA,''
%Nucl.\ Instrum.\ Meth.\ A {\bf 386} (1997) 310 and 348; \\
%%CITATION = NUIMA,A386,310;%%
%
%R.~D.~Appuhn {\it et al.}  [H1 SPACAL Group Collaboration],
%``The H1 lead/scintillating-fibre calorimeter,''
%Nucl.\ Instrum.\ Meth.\ A {\bf 386} (1997) 397.
%%CITATION = NUIMA,A386,397;%%

%\bibitem{spin}
% A.A.~Sokolov and I.M.~Ternov, Sov.\ Phys.\ Dokl.\ {\bf 8} No. 12 (1964) 1203.;
 
%\bibitem{tpol}
% D.B.~Barber {\it et al.}, Nucl.\ Instrum.\ Meth.\ A {\bf 329} (1993) 79.;
 
%\bibitem{lpol}
% M.~Beckmann {\it et al.}, Nucl.\ Instrum.\ Meth.\ A {\bf 479} (2002) 334.;

%\bibitem{jb}
%A.~Blondel and F.~Jacquet, Proceedings of the Study of an $ep$ Facility for 
%Europe, ed.\ U.~Amaldi, DESY 79/48 (1979) 391.
%\end{thebibliography}

\newpage

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%\begin{figure}[htb]
%%%\begin{center}
%%%\begin{picture}(90,160)(0,0)
%%%\setlength{\unitlength}{1 mm}
%%%\put(-32, 0){\epsfig{file=H1prelim-08-042.fig1.eps,width=15cm}}
%%%\end{picture}
%%%\end{center}
%%%\caption{
%%%Example trigger efficiencies for the LAr, Spacal, Jet Trigger - FTT 
%%%subtriggers as a function of the scattered electron energy,
%%%shown for electrons pointing to the transition BBE-CB region
%%%of the LAr calorimeter for the low proton beam 
%%%energy (460~GeV). Combined trigger efficiency is shown 
%%%in the bottom right plot.
%%%}
%%%\label{cp460trigEff}
%%%\end{figure}
%%%
%%%\newpage

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,60)(0,0)
\setlength{\unitlength}{1 mm}
\put(-35,  -10){\epsfig{file=H1prelim-08-042.fig2.eps,width=16cm}}
\end{picture}
\end{center}
%>>> skip figure 1
\vspace*{-10.8cm}
\caption{}
\vspace*{10cm}
%>>> skip figure 1
\caption{
Comparison of the correct electron charge data (points) with a sum 
of background determined from the wrong ``electron'' charge data 
(green histogram) and DIS MC (open histogram)
for the low proton beam energy (460~GeV)
in the region of the electron energy below 6~GeV
without applying addition electron identification cuts.
The distributions from left to right are 
the distance between extrapolated track and the center of gravity
of the cluster in LAr  ($D_{CJC\_LAr}$), tranverse size of the
electron cluster in LAr (Ecra) and ratio of transverse
momenta as measured in the tracker and in the LAr 
calorimeter ($Pt_{track}/Et_{cluster}$). The cut values
on the two latter quantities applied in the analysis 
are indicated by vertical lines.
} 
\label{cp460elID}
\end{figure}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,60)(0,0)
\setlength{\unitlength}{1 mm}
\put(-35,  -10){\epsfig{file=H1prelim-08-042.fig3.eps,width=16cm}}
\end{picture}
\end{center}
\caption{
Comparison of the correct electron charge data (points) with a sum 
of background determined from the wrong ``electron'' charge data 
(green histogram) and DIS MC (open histogram)
for the medium proton beam energy (575~GeV)
in the region of the electron energy below 6~GeV
without applying addition electron identification cuts.
The distributions from left to right are 
the distance between extrapolated track and the center of gravity
of the cluster in LAr  ($D_{CJC\_LAr}$), tranverse size of the
electron cluster in LAr (Ecra) and ratio of transverse
momenta as measured in the tracker and in the LAr 
calorimeter ($Pt_{track}/Et_{cluster}$). The cut values
on the two latter quantities applied in the analysis 
are indicated by vertical lines.
} 
\label{cp575elID}
\end{figure}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,60)(0,0)
\setlength{\unitlength}{1 mm}
\put(-5,  -10){\epsfig{file=H1prelim-08-042.fig4.eps,width=9cm}}
\end{picture}
\end{center}
\caption{Comparison of the correct electron charge data (points) with a 
sum of background determined from the wrong ``electron'' charge data 
(green histogram) and DIS MC (open histogram) for the low proton beam 
energy (460~GeV) in the high $y$ range $0.7<y<0.9$. The distributions 
from left to right and from top to bottom are the scattered 
electron energy, the scattered electron polar angle $\Theta_{elec}$, 
the z-position of the event vertex $Z_{vtx}$ and the sum $E-p_{z}$ of 
all final state particles. The vertical line in $E-p_{z}$ distribution
indicates the cut value.}
\label{cp460} 
\end{figure}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,80)(0,0)
\setlength{\unitlength}{1 mm}
\put(-5,  -10){\epsfig{file=H1prelim-08-042.fig5.eps,width=9cm}}
\end{picture}
\end{center}
\caption{Comparison of signal distributions (background subtracted with 
corresponding asymmetry factor) for the low proton beam energy (460~GeV)
in the high $y$ range $0.7<y<0.9$.
The distributions from left to right and from top to bottom 
are the scattered electron energy, the scattered electron polar angle 
$\Theta_{elec}$, the z-position of the event vertex $Z_{vtx}$ and the sum 
$E-p_{z}$ of all final state particles. The vertical line in $E-p_{z}$ 
distribution indicates the cut value.}
\label{cp460nobg}
\end{figure}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,60)(0,0)
\setlength{\unitlength}{1 mm}
\put(-5,  -10){\epsfig{file=H1prelim-08-042.fig6.eps,width=9cm}}
\end{picture}
\end{center}
\caption{Comparison of the correct electron charge data (points) with a 
sum of background determined from the wrong ``electron'' charge data 
(green histogram) and DIS MC (open histogram) for the medium proton beam 
energy (575~GeV) in the high $y$ range $0.7<y<0.9$. The distributions from 
left to right and from top to bottom are the scattered electron 
energy, the scattered electron polar angle $\Theta_{elec}$, the z-position of the 
event vertex $Z_{vtx}$ and the sum $E-p_{z}$ of all final state particles. 
The vertical line in $E-p_{z}$ distribution indicates the cut value.}
\label{cp575}
\end{figure}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,80)(0,0)
\setlength{\unitlength}{1 mm}
\put(-5,  -10){\epsfig{file=H1prelim-08-042.fig7.eps,width=9cm}}
\end{picture}
\end{center}
\caption{Comparison of signal distributions (background subtracted with 
corresponding asymmetry factor) for the medium proton beam energy (575~GeV)
 in the high $y$ range $0.7<y<0.9$.
The distributions from left to right and from top to bottom 
are the scattered electron energy, the scattered electron polar angle 
$\Theta_{elec}$, the z-position of the event vertex $Z_{vtx}$ and the sum 
$E-p_{z}$ of all final state particles. The vertical line in $E-p_{z}$ 
distribution indicates the cut value.}
\label{cp575nobg}
\end{figure}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,50)(0,0)
\setlength{\unitlength}{1 mm}
\put(-35,  -5){\epsfig{file=H1prelim-08-042.fig8.eps,width=16cm}}
\end{picture}
\end{center}
\caption{Comparison of the correct electron charge data (points) with a sum 
of background determined from the wrong ``electron'' charge data 
(green histogram) and DIS MC (open histogram) for the low proton beam 
energy (460~GeV) in the high $y$ range $0.7<y<0.9$.
The distributions from left to right are the inelasticity $y$, 
the four-momentum transfer squared $Q^{2}$ and Bjorken $x$.}
\label{cp460kin}
\end{figure}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,30)(0,0)
\setlength{\unitlength}{1 mm}
\put(-35,  -5){\epsfig{file=H1prelim-08-042.fig9.eps,width=16cm}}
\end{picture}
\end{center}
\caption{Comparison of signal distributions (background subtracted 
with corresponding asymmetry factor) for the low proton beam energy (460~GeV)
in the high $y$ range $0.7<y<0.9$.
The distributions from left to right are the inelasticity $y$, 
the four-momentum transfer squared $Q^{2}$ and Bjorken $x$.}
\label{cp460kinnobg}
\end{figure}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\begin{figure}[htb]
\begin{center}
\begin{picture}(90,50)(0,0)
\setlength{\unitlength}{1 mm}
\put(-35,  -5){\epsfig{file=H1prelim-08-042.fig10.eps,width=16cm}}
\end{picture}
\end{center}
\caption{Comparison of the correct electron charge data (points) with a sum 
of background determined from the wrong ``electron'' charge data 
(green histogram) and DIS MC (open histogram) for the medium proton beam 
energy (575~GeV) in the high $y$ range $0.7<y<0.9$.
The distributions from left to right are the inelasticity $y$, 
the four-momentum transfer squared $Q^{2}$ and Bjorken $x$.}
\label{cp575kin}
\end{figure}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,30)(0,0)
\setlength{\unitlength}{1 mm}
\put(-35,  -5){\epsfig{file=H1prelim-08-042.fig11.eps,width=16cm}}
\end{picture}
\end{center}
\caption{Comparison of signal distributions (background subtracted 
with corresponding asymmetry factor) for the medium proton beam energy 
(575~GeV) in the high $y$ range $0.7<y<0.9$.
The distributions from left to right are the inelasticity $y$, 
the four-momentum transfer squared $Q^{2}$ and Bjorken $x$.}
\label{cp575kinnobg}
\label{pol}
\end{figure}


\clearpage
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,160)(0,0)
\setlength{\unitlength}{1 mm}
\put(-25,  -10){\epsfig{file=H1prelim-08-042.fig12.eps,width=13cm}}
\end{picture}
\end{center}
\caption{Comparison of the correct electron charge data (points) with a 
sum of background determined from the wrong ``electron'' charge data 
(green histogram) and DIS MC (open histogram) for the low proton beam 
energy (460~GeV) in the complete analysis range in $y$. The distributions 
from left to right and from top to bottom are the scattered 
electron energy, the scattered electron polar angle $\Theta_{elec}$, 
the sum $E-p_{z}$ of all final state particles,
momentum balance $P_{t}^{had}/P_{t}^{elec}$,
the four-momentum transfer squared $Q^{2}$ and Bjorken $x$.}
\label{cp460all}
\end{figure}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,160)(0,0)
\setlength{\unitlength}{1 mm}
\put(-25,  -10){\epsfig{file=H1prelim-08-042.fig13.eps,width=13cm}}
\end{picture}
\end{center}
\caption{Comparison of signal distributions (background subtracted 
with corresponding asymmetry factor) for the low proton beam 
energy (460~GeV) in the complete analysis range in $y$. The distributions 
from left to right and from top to bottom are the scattered 
electron energy, the scattered electron polar angle $\Theta_{elec}$, 
the sum $E-p_{z}$ of all final state particles,
momentum balance $P_{t}^{had}/P_{t}^{elec}$,
the four-momentum transfer squared $Q^{2}$ and Bjorken $x$.}
\label{cp460allsubtr}
\end{figure}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,160)(0,0)
\setlength{\unitlength}{1 mm}
\put(-25,  -10){\epsfig{file=H1prelim-08-042.fig14.eps,width=13cm}}
\end{picture}
\end{center}
\caption{Comparison of the correct electron charge data (points) with a 
sum of background determined from the wrong ``electron'' charge data 
(green histogram) and DIS MC (open histogram) for the medium proton beam 
energy (575~GeV) in the complete analysis range in $y$. The distributions 
from left to right and from top to bottom are the scattered 
electron energy, the scattered electron polar angle $\Theta_{elec}$, 
the sum $E-p_{z}$ of all final state particles,
momentum balance $P_{t}^{had}/P_{t}^{elec}$,
the four-momentum transfer squared $Q^{2}$ and Bjorken $x$.}
\label{cp575all}
\end{figure}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,160)(0,0)
\setlength{\unitlength}{1 mm}
\put(-25,  -10){\epsfig{file=H1prelim-08-042.fig15.eps,width=13cm}}
\end{picture}
\end{center}
\caption{Comparison of signal distributions (background subtracted 
with corresponding asymmetry factor) for the medium proton beam 
energy (575~GeV) in the complete analysis range in $y$. The distributions 
from left to right and from top to bottom are the scattered 
electron energy, the scattered electron polar angle $\Theta_{elec}$, 
the sum $E-p_{z}$ of all final state particles,
momentum balance $P_{t}^{had}/P_{t}^{elec}$,
the four-momentum transfer squared $Q^{2}$ and Bjorken $x$.}
\label{cp575allsubtr}
\end{figure}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,160)(0,0)
\setlength{\unitlength}{1 mm}
\put(-25,  -10){\epsfig{file=H1prelim-08-042.fig16.eps,width=13cm}}
\end{picture}
\end{center}
\caption{Comparison of the data (points) with a sum of background 
determined from photoproduction MC 
(green histogram) and DIS MC (open histogram) 
for the nominal proton beam 
energy (920~GeV) in the complete analysis range in $y$. The distributions 
from left to right and from top to bottom are the scattered 
electron energy, the scattered electron polar angle $\Theta_{elec}$, 
the sum $E-p_{z}$ of all final state particles,
momentum balance $P_{t}^{had}/P_{t}^{elec}$,
the four-momentum transfer squared $Q^{2}$ and Bjorken $x$.}
\label{cp920all}
\end{figure}

\clearpage
\newpage
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,160)(0,0)
\setlength{\unitlength}{1 mm}
\put(-43,  -15){\epsfig{file=H1prelim-08-042.fig17.eps,width=18cm}}
\end{picture}
\end{center}
\caption{Reduced cross section measured at high $Q^{2}$ as a function 
of $x$ using data taken at different proton beam energies of 920~GeV 
(full boxes), 575~GeV (stars) and 460~GeV (full points). The inner
(outer) error bars represent statistical (total, with
statistical and systematical errors added in quadrature) errors. 
Theoretical predictions of reduced cross section are shown as the solid 
lines for 920~GeV (blue), 575~GeV (black) and 460~GeV (red) line. 
The dashed line represents the QCD expectation of $F_{2}$.
Theoretical expectations are derived from the H1 PDF 2000 fit.}
\label{sigmared-lar}
\end{figure}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,160)(0,0)
\setlength{\unitlength}{1 mm}
\put(-32,120){\epsfig{file=H1prelim-08-042.fig18.eps,angle=270.,width=15.5cm}}
\end{picture}
\end{center}
\caption{The reduced cross section $\sigma_{r}(x,Q^{2},y)$ measured 
at $Q^{2}=150~GeV^{2}$ and fixed values of $x$ as a function of 
$f(y)=\frac{y^{2}}{1+(1-y)^{2}}$. The full boxes represent the nominal 
energy data (920~GeV), stars the medium energy data (575~GeV) and full 
circles the low energy data (460~GeV). The inner error bars are the 
statistical errors and the full error bars represent the statistical 
and systematic errors, added in quadrature. The lines show the linear 
fits used to determine $F_{L}$.}
\label{rosenbluth-lar}
\end{figure}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,160)(0,0)
\setlength{\unitlength}{1 mm}
\put(-42,  -10){\epsfig{file=H1prelim-08-042.fig19.eps,width=16.5cm}}
\end{picture}
\end{center}
\caption{The longitudinal structure function $F_{L}$ measured as 
a function of $x$ at fixed values of $Q^{2}$ obtained 
from the LAr cross section measurements using 
data taken at different proton beam energies of 460~GeV, 575~GeV 
and 920~GeV. The inner error bars are the statistical errors and the 
full error bars represent the statistical and systematic errors, 
added in quadrature. The line represents a QCD prediction 
based on H1 PDF 2000 fit.}
\label{fl-lar}
\end{figure}


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,160)(0,0)
\setlength{\unitlength}{1 mm}
\put(-40,  -5){\epsfig{file=H1prelim-08-042.fig20.eps,width=16.5cm}}
\end{picture}
\end{center}
\caption{The longitudinal structure function $F_{L}$ averaged 
in $x$ at given value of $Q^{2}$ 
in the range of high $Q^{2}$ using 
data taken at different proton beam energies of 460~GeV, 575~GeV 
and 920~GeV. The resulting x values of the averaged $F_{L}$
measurements are given in the figure for each point in $Q^{2}$.
The inner error bars are the statistical errors and the 
full error bars represent the statistical and systematic errors, 
added in quadrature. 
The correlated systematic error between 
the averaged  $F_{L}$ measurements
is estimated to vary between 0.05 
and 0.10 in the measured kinematics range.
The solid red line represents a QCD prediction 
based on H1 PDF 2000 fit.}
\label{flav-lar}
\end{figure}

\clearpage
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,160)(0,0)
\setlength{\unitlength}{1 mm}
\put(-43,  -15){\epsfig{file=H1prelim-08-042.fig21.eps,width=18cm}}
\end{picture}
\end{center}
\caption{Reduced cross section measured in the full range 
of medium and high $Q^{2}$ as a function 
of $x$ using data taken at different proton beam energies of 920~GeV 
(full boxes), 575~GeV (stars) and 460~GeV (full points). The inner
(outer) error bars represent statistical (total, with
statistical and systematical errors added in quadrature) errors. 
Theoretical predictions of reduced cross section are shown as the solid 
lines for 920~GeV (blue), 575~GeV (black) and 460~GeV (red) line. 
The dashed line represents the QCD expectation of $F_{2}$.
Theoretical expectations are derived from the H1 PDF 2000 fit.}
\label{sigmared}
\end{figure}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,160)(0,0)
\setlength{\unitlength}{1 mm}
\put(-35,0){\epsfig{file=H1prelim-08-042.fig22.eps,width=16.5cm}}
\end{picture}
\end{center}
\caption{The reduced cross section $\sigma_{r}(x,Q^{2},y)$ measured 
at fixed values of $x$ and $Q^{2}$ as a function of 
$f(y)=\frac{y^{2}}{1+(1-y)^{2}}$. Only $x$ and $Q^{2}$ values are
shown which include cross section measurements from both
LAr and Spacal analyses.
The full boxes represent the nominal 
energy data (920~GeV), stars the medium energy data (575~GeV) and full 
circles the low energy data (460~GeV). The inner error bars are the 
statistical errors and the full error bars represent the statistical 
and systematic errors, added in quadrature. The lines show the linear 
fits used to determine $F_{L}$.}
\label{rosenbluth-lar-spac}
\end{figure}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,160)(0,0)
\setlength{\unitlength}{1 mm}
\put(-45,  -10){\epsfig{file=H1prelim-08-042.fig23.eps,width=17cm}}
\end{picture}
\end{center}
\caption{The longitudinal structure function $F_{L}$ measured as 
a function of $x$ at fixed values of $Q^{2}$ in the full range
of medium and high $Q^{2}$ using 
data taken at different proton beam energies of 460~GeV, 575~GeV 
and 920~GeV. The inner error bars are the statistical errors and the 
full error bars represent the statistical and systematic errors, 
added in quadrature. The line represents a QCD prediction 
based on H1 PDF 2000 fit.}
\label{fl}
\end{figure}


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,160)(0,0)
\setlength{\unitlength}{1 mm}
\put(-40,  -5){\epsfig{file=H1prelim-08-042.fig24.eps,width=16.5cm}}
\end{picture}
\end{center}
\caption{The longitudinal structure function $F_{L}$ averaged 
in $x$ at given value of $Q^{2}$ 
in the full range of medium and high $Q^{2}$ using 
data taken at different proton beam energies of 460~GeV, 575~GeV 
and 920~GeV. The resulting x values of the averaged $F_{L}$
measurements are given in the figure for each point in $Q^{2}$.
The inner error bars are the statistical errors and the 
full error bars represent the statistical and systematic errors, 
added in quadrature. 
The correlated systematic error between 
the averaged  $F_{L}$ measurements
is estimated to vary between 0.05 
and 0.10 in the measured kinematics range.
The solid red line represents a QCD prediction 
based on H1 PDF 2000 fit.
}
%%%and the dashed blue line a QCD prediction based on MSTW PDF.}
\label{flav}
\end{figure}


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,160)(0,0)
\setlength{\unitlength}{1 mm}
\put(-40,  -5){\epsfig{file=H1prelim-08-042.fig25.eps,width=16.5cm}}
\end{picture}
\end{center}
\caption{The longitudinal structure function $F_{L}$ averaged 
in $x$ at given value of $Q^{2}$ 
in the full range of medium and high $Q^{2}$ using 
data taken at different proton beam energies of 460~GeV, 575~GeV 
and 920~GeV. The resulting x values of the averaged $F_{L}$
measurements are given in the figure for each point in $Q^{2}$.
The inner error bars are the statistical errors and the 
full error bars represent the statistical and systematic errors, 
added in quadrature. 
The correlated systematic error between 
the averaged  $F_{L}$ measurements
is estimated to vary between 0.05 
and 0.10 in the measured kinematics range.
The solid red line represents a QCD prediction 
based on H1 PDF 2000 fit. The dashed lines represents the MSTW 
and the dashed-dotted line the CTEQ6.6 predictions (private communications).
}
%%%and the dashed blue line a QCD prediction based on MSTW PDF.}
\label{flav}
\end{figure}
\clearpage
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%



%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[htb]
\begin{center}
\begin{picture}(90,160)(0,0)
\setlength{\unitlength}{1 mm}
\put(-40,  -5){\epsfig{file=H1prelim-08-042.fig26.eps,width=16.5cm}}
\end{picture}
\end{center}
\caption{The longitudinal structure function $F_{L}$ averaged
in $x$ at given value of $Q^{2}$
in the full range of medium and high $Q^{2}$ using
data taken at different proton beam energies of 460~GeV, 575~GeV
and 920~GeV. The resulting x values of the averaged $F_{L}$
measurements are given in the figure for each point in $Q^{2}$.
The inner error bars are the statistical errors and the
full error bars represent the statistical and systematic errors,
added in quadrature.
The correlated systematic error between
the averaged  $F_{L}$ measurements
is estimated to vary between 0.05
and 0.10 in the measured kinematics range.
The solid red line represents a QCD prediction
based on H1 PDF 2000 fit. The dashed brown line represents FL calculations based on the NNLO QCD fit by S. Alekhin (Phys.Rev.D74:054033,2006)
and the green dashed-dotted line
corresponds to
0.27 times F2 from the H1 PDF 2000
fit, motivated by the recent publication of
M. Kuroda and D. Schildknecht (arXiv:0806:0202). 
}
%%%and the dashed blue line a QCD prediction based on MSTW PDF.}
\label{flav}
\end{figure}
\clearpage
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%





\end{document}

width=\textwidth}}