Gas and dust in the Cloverleaf quasar at redshift 2.5

We observed the upper fine structure line of neutral carbon, CI ..., ( ...GHz), the ..., line ( ....GHz) and the 1.2 mm continuum emission from H1413+117 (Cloverleaf quasar, z=2.5) using the IRAM interferometer. Together with the detection of the lower fine structure line (Barvainis et al. 1997), the Cloverleaf quasar is now only the second extragalactic system, besides M 82, where both carbon lines have convincingly been detected. Our analysis shows that the carbon lines are optically thin and have an excitation temperature of T ex, ~~10K. CO is subthermally excited and the observed line luminosity ratios are consistent with n(H2),~~10^3-4 cm^-3 at T kin,= 30-50 K. Using three independent methods (CI, dust, CO) we derive a total molecular gas mass (corrected for magnification) of M(H2)~~1.2 +-0.3 *10^10 M(annual). Our observations suggest that the molecular disk extends beyond the region seen in CO(7-6) to a zone of more moderately excited molecular gas that dominates the global emission in CI, and the low J CO lines.