The production of D mesons in e e" annihilation for the center-ofmass energy range 3.7 to 7.0 KeV has been studied with the HARK I magnatlc detector at the Stanford Positron Electron Accelerating Rinss facility. We observed a resonance in the total cross-section for hadron production In e e annihilation at an energy just above the threshold Cor charm production. This resonance, which we name i>'\ has a mass of 3772 ± 6 MeV/c , a total width of 28 + 5 MeV/c 2 , a partial width to electron pairs

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... f 345 ± 85 oV/c , and decays almost exclusively Into DD pairs. The i|/" provides a rich source of background-free and kinematical ly well defined D mesons for study. From the study of D mesons produced in the decay of the IJJ" we have determined the masses of the D and D mesons to be 1863.3 + 0.9 MeV/c 2 and 1868.3 ± 0.9 MeV/c 2 respectively. We also determined the branching fractions for D° decay to K~n + , K°n n~ and K~i> iT-ir to be (2.2 t 0.6)1, (4.0 t 1.3)Z, and (3.2 t 1.1)7. and the branching fractions for D + decay to K°n + and K'TIV" to be (1.5 t 0.6)2 and (3.9 1 1.0)%. The average number of kaons per D decay was found to be 0.52 + 0,14 K°'s and 0.42 + 0.12 K +, s. The rate for inclusive production of D mesons at center-of-mass energies above the i|>" has been measured; we find that it can account lor most, if not all, of the observed increase in the total hadronic crosssection for center-of-mass energies above 4 CeV. The inclusive momentum and energy spectra for D's have been measured at the highest available center-of-mass energy (7 GeV), The energy spectra are rapidly decreasing functions of energy with a slope similar to the slope of the charged [lion spectrum at the same center-of-tnass energy. This behaviour suggests that the fragmentation function if the charmed quark into charmed mesons is a decreasing function of the scaling variable z = 2F. /E . ip-.ni.nrJ hy ilir t'mifj Ruin i.,..(. imit-J Sum nor (lit IMntJ Sin imrnl ScilMMlir i Ofpiftmcnl «' ( [n«g>. n«» in> of ihnr r(npln>« ^'Z^'Z tny njiuril), t\fir%i m minlifd. ,.r juuinr. J(H lff;j! iiitnniit pnvaifly inin<J nghu. JIJIul.C'lJ".! '" ~"1 ACKNOWLEDGMENTS Current research in high-energy physics is dominated! by large collaborations of tens of physicists working in unison, trying to unravel the mysteries of nature. This work, therefore, owes its existence, to a great extent, to the diligent efforts of the members of the collaborations for experiments SP-17 and SP-26 at SPEAR. The members of these collaborations were: