\section{Underground sites}
\label{sec:Phys-Sites}
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%\REDBLA{Created by JEC 3/5/06}
%\REDBLA{updated by JEC+Mosca 5/5/06}
%\REDBLA{updated by JEC 9/5/06}
%\REDBLA{updated by A. Bueno 19/5/06}
%\REDBLA{updated by JEC 21/6/06}
%\REDBLA{updated by JEC 18/10/06}
%\REDBLA{updated by Mosca 23/10/06}
%\REDBLA{updated by Campagne 19/12/06}
%\REDBLA{updated by Campagne 21/12/06}
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The proposed large detectors require underground laboratories of adequate size and depth, naturally protected against cosmic rays, which represent a potential source of background events mainly for non-accelerator experiments.
Additional characteristics of these sites contributing to qualify them as best candidates for the proposed projects of experiments are: the type and quality of the rock allowing the feasibility of such a large caverns at reasonable cost and time, the distance from existing or future accelerators and nuclear reactors, the type and quality of the access, the geographical position, the quality of the environment, etc.

%JEC 21/12/06 START introduce the Gran Sasso in the list
The presently pre-selected candidate sites in the world are essentially located in 3 regions : North-America, Asia (Japan/Korea, \dots) and Europe. In this paper we consider the European region, where, at this stage, the following sites are assumed as candidates: Gran Sasso (Italy), Fréjus (France/Italy), Pyhäsalmi (Finland), Boulby (UK), Canfranc (Spain) and Sieroszewice (Poland). The basic characteristics of these sites are presented on \refTab{tab:Phys-site-parameters}. For the Gran Sasso case, possible new sites are envisaged to be located at 10km from the present underground laboratory outside the National Park.
The possibility of under-water solutions, as for instance Pylos for the LENA project, is not taken into account here.
%JEC 21/12/06 END

The identification and measurement of the different background components in the candidate sites (muons, fast neutrons from muon interactions, slow neutrons from nuclear reactions in the rock, gammas, electrons/positrons and alphas from radioactive decays,\dots) is underway mainly in the context of the ILIAS European (JRA) Network. The collection of the presently known values of these background components are reported on \refTab{tab:Phys-site-parameters}.

%JEC 21/12/06 START add the sentence
None of the existing sites have yet a cavity to accommodate the foreseen detectors.
%JEC 21/12/06 END
For two of the candidate sites (Fréjus and Pyhäsalmi), a preliminary feasibility study for large excavation at a deep depth has been already performed. For the Fréjus site the main conclusion from the simulations (in 2005) constrained by a series of rock parameters measurements made during the Fréjus road tunnel excavation, is that the "shaft shape" is strongly preferred compared to the "tunnel shape" for large cavities. Several (up to 5) such shafts cavities with a diameter of about 65~m (a volume of 250~000~m${}^3$) each, seem feasible in the region around the middle of the Fréjus tunnel, at a depth of 4800~m.w.e, where by chance the quality of the rock is the best.
For the Pyhäsalmi site the preliminary study has been performed (in 2002) for two main cavities with tunnel-shape and dimensions   $(20 \times 20 \times 120)$~m${}^3$ and $(20 \times 20 \times 50)$~m${}^3$ respectively, and one shaft-shaped cavity with 25~m in diameter and 25~m in height, all at a depth of about 1430~m of rock (4000~m.w.e). 
%\begin{figure}
%%\centerline{\epsfig{figure=./figures/muonflux.eps,width=8cm,}}
%\caption{\it Muon flux as a function of overburden. 
%The Frejus site is indicated by "LSM". \REDBLA{TO BEšPROVIDED}}
%\label{muonflux}
%\end{figure}
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\begin{turnpage}
\begin{table*}
\caption{\label{tab:Phys-site-parameters}
Summary of relevant characteristics of some sites foreseen for the proposed detectors. The Rn content depends on the ventilation of the cavity. The "*" means that the parameter is not yet available. \REDBLA{To be completed and cross-checked and unit uniformized as possible}.}
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\begin{tabular}{lcccccc}
\hline\hline\noalign{\smallskip}
Site & Gran Sasso ext.	 &  Fréjus                     & Pyh\"asalmi  &  Boulby     & Canfranc & Sieroszowice\\
\hline\noalign{\smallskip}
Location       & Italy & Italy-France border        & Finland      & UK          &  Spain   & Poland \\
Distance from CERN (km)& 730 & 130                  & 2300         &  1050       & 630      &     950 \\ 
Type of access          & ? & Fréjus tunnel               &  Mine        & Potash Mine & Somport tunnel & Mine\\
Vertical Depth (m.w.e)  & ? & 4800               & 4000         & 3300       & 2500    & 2200 \\
%Equiv. Depth   (km.w.e)  & 4.2               &  ?           & 2.8         & ?    &  ? \\
Type of rock  & hard rock & hard rock                     & hard rock   & salt        & hard rock        & salt \& rock \\
Type/size of cavity  & ? & \parbox[b]{3cm}{\center{shafts\\$\Phi = 65~\mathrm{m}, H=80~\mathrm{m}$}}
                     & \parbox[b]{3cm}{\center{tunnel\\ $20~\mathrm{m}\times 20~\mathrm{m}\times 120~\mathrm{m}$}}
                     & ?
                     & *
                     & \parbox[b]{3cm}{\center{tunnel\\ $15~\mathrm{m}\times 15~\mathrm{m}\times 100~\mathrm{m}$}} \\
$\mu$ Flux ($10^{-9}$~cm$^{-2}$s$^{-1}$) & ? & 4.8         &   ?          & 41.7         & 200.0      & ? \\[-3mm]
n Flux ($10^{-6}$~cm$^{-2}$s$^{-1}$)  & ? &  \parbox{3cm}{\center{1.6 (0-0.63~eV)\\ 4.0 (2-6~MeV)}}
																		 & ?
																		 &  \parbox{3cm}{\center{2.8 (>100~keV)\\ 1.3 (>1~MeV)}}
																		 & 3.82 (integral) & * \\
$\gamma$ Flux (cm$^{-2}$s$^{-1}$)    & ? & 7.0 (>4~MeV)  & * & * & $2\ 10^{-2}$ (energy?)  & *\\
$^{238}$U (ppm) Rock/Cavern  & ? & 0.84/1.90   & 28-44 Bq/m$^3$   & 0.07      & 30 Bq/kg & $0.017 \pm 0.003$ Bq/kg\\
$^{232}$Th (ppm) Rock/Cavern  & ? & 2.45/1.40   & 4-19 Bq/m$^3$   & 0.12      & 76 Bq/kg & $0.008 \pm 0.001$ Bq/kg\\
K (Bq/kg)          Rock/Cavern  & ? & 213/77     & 267-625 Bq/m$^3$   & 1130      & 680 & $4.0 \pm 0.9$ Bq/kg\\
Rn (Bq/m$^3$) Cavern (Vent. ON/OFF) &?  & 15-150    &  10-148     &  *  & 50-100 Bq/kg & $10-50$\\ 
\hline\hline
\end{tabular}
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\end{table*}
\end{turnpage}
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