Deuterium/hydrogen in a new Lyman limit absorption system at z= 3.256 towards PKS1937−1009

We have identified a new Lyman limit absorption system towards PKS1937-1009, with logN(H i) = 18.25 ± 0.02 at z = 3.256 that is suitable for measuring D/H. We find a 68.3% confidence range for D/H of 1.6 +0.25 0.30 × 10 5 , and a 95.4% range of 1.6 +0.5 0.4 × 10 5 . The metallicity of the cloud where D/H was measured is low, [Si/H] = 2.0±0.5. At these metallicities we expect that D/H will be close to the primordial value. Our D/H is lower than the D/H value predicted using the b calculated from the cosmic background radiation measured by WMAP, 2.60 +0.19 0.17 × 10 5 . Our result