The ALICE HMPID detector ready for collisions at the LHC

ALICE has been specifically optimized to study heavy-ion collisions at the LHC, up to a charged particle density of 8000 per unit of rapidity in central heavy-ion collisions at $\sqrt{s_{NN}}$ = 5.5 TeV. The High Momentum Particle Identification Detector (HMPID) has a proximity focusing geometry with a liquid $\rm C_{6}F_{14}$ Cherenkov radiator coupled to Multi-Wire Pad Chambers (MWPC) equipped with CsI photocathodes, over a total active area of 11 $\rm m^2$. It has been designed to identify charged pions and kaons in the range 1 $\leq p \leq$ 3 \GeV/$c$ and protons in the range 2 $\leq p \leq$ 5 \GeV/$c$. The as-built detector and all relevant subsystems (gas, liquid $\rm C_{6}F_{14}$, cooling and control) are described. Installation issues and first commissioning results are also presented.