Measurement of the t Production Cross Section and Top Quark Mass at DO

I report on preliminary measurements of the t production cross section, and a measurement of the top quark mass, performed by the DO Collaboration. The cross section is measured using candidates for dilepton, single-lepton, and all-hadronic t decays collected at DO during RunII of the Tevatron. The results for the various modes are:tt-bar{expression} = 14.3-4.3+5.1{expression} (stat.) -1.9+2.6{expression} (syst.) +/- 0.9 (lumi.) pb (dilepton)tt-bar{expression} = 7.2-2.4+2.6{expression} (stat.) -1.7+1.6{expression} (syst.) +/- 0.5 (lumi.) pb (lepton+jets)tt-bar{expression} = 7.7-3.3+3.4{expression} (stat.) -3.7+4.7{expression} (syst.) +/- 0.5 (lumi.) pb 6(all-hadronic).The mass measurement uses an improved method to re-analyze lepton+jets events collected during RunI of the Tevatron, and obtains mt = 180.1 +/- 3.6 (stat.) +/- 4.0 (syst.) GeV/c2.