Investigations on a Q0 Doublet Optics for the LHC Luminosity Upgrade

The Q0 scheme of the LHC insertion region is based on the introduction of a doublet of quadrupoles at 13 m from the IP. We present here the doublet optics and the magnets layout such as gradients, lengths, positions and apertures. In this scheme we show the gain in luminosity and chromaticity, with respect to a nominal layout with $\beta^{*}$ = 0.25 m (i.e. LHC phase 1 upgrade) and $\beta^{*} = 0.15 m, due to a smaller beta-max. We show the alignment tolerance and the energy deposition issues, in Q0A-Q0B. We also consider shielding the magnets with liners. The capability of Q0 optics to limit the b function could be exploited after the LHC Phase 1 upgrade in order to reduce the $\beta^{*}$ below 0.25 m, leaving the upgraded triplet unchanged