Direct Measurement of the W Production Charge Asymmetry in p anti-p Collisions at s**(1/2) = 1.96-TeV

We present the first direct measurement of the W production charge asymmetry as a function of the W boson rapidity y{sub W} in p{bar p} collisions at {radical}s = 1.96 TeV. We use a sample of W {yields} e{nu} events in data from 1 fb{sup -1} of integrated luminosity collected using the CDF II detector. In the region |y{sub W}| < 3.0, this measurement is capable of constraining the ratio of up and down quark momentum distributions in the proton more directly than in previous measurements of the asymmetry that are a function of the charged-lepton pseudorapidity.