The Beam Delivery System (BDS) transports the e$^+$/e$^-$
beams from the linacs to the IP, see~\ref{BDS}.
The BDS uses the dispersion generated by horizontal bending dipoles 
both to collimate low energy particles and to correct the
chromaticity with the sextupoles in the Final Focus.
Therefore, by design, the BDS contains two sources of
emittances dilution: synchrotron radiation and 
the higher order transport aberrations.

Incoherent synchrotron radiation is responsible of a 20\% loss
of luminosity. The bending dipoles and the final doublet
are equally responsible of this luminosity loss. The CLIC
IP vertical beta function 
is designed to operate slightly below the theoretical optimum
value given by the Oide effect~\cite{Oide}.
Coherent synchrotron radiation has negligible effects on emittance
dilution.

Higher order aberrations have been carefully minimized by adding
multipolar corrector magnets to the lattice~\cite{Tomas}. 
The residual higher order aberrations increase the vertical beam size
by 15\%. Assuming an ideal transport without aberrations
and neglecting synchrotron radiation luminosity would increase
by about 40\%. Therefore design aberrations and synchrotron radiation
approximately share the luminosity loss in equal parts. 




\begin{thebibliography}{99}
\bibitem{Oide} K.~Oide, Phys. Rev. Lett. {\bf 61}, 1713 - 1715 (1988).
\bibitem{Tomas} R.~Tom\'as,  Phys. Rev. ST Accel. Beams {\bf 9}, 081001 (2006).
\end{thebibliography}
