Charm photoproduction at 20 GeV

Sixty-two charm events have been observed in an exposure of the SLAC Hybrid Facility to a backward scattered laser beam. Based on 22 neutral and 21 charged decays we have measured the charmed-meson lifetimes to be tau/sub D//sup 0/ = (6.8/sub -1.8//sup +2.3/)= x 10/sup -13/ sec, tau/sub D//sup + -/ = (7.4/sub -2.0//sup +2.3/) x 10/sup -13/ sec and their ratio tau/sub D//sup + -//tau0 = 1.1/sub -0.3/ /sup +0.6/. The inclusive charm cross section at a photon energy of 20 GeV has been measured to be 56/sub -/23/sup +24/ nb. Evidence is presented for a non-DD-bar component to charm production, consistent with (35 +- 20)% ..lambda../sub c//sup +/ production and some D/sup asteriskplus-or-minus/ production. We have found no unambiguous F decays.