Toth, Derrick2015-08-192015-08-192014-05https://hdl.handle.net/11299/173943University of Minnesota Ph.D. dissertation. May 2014. Major: Physics. Advisor: Ron Poling. 1 computer file (PDF) xv, 138 pages.We measure the branching ratio for psi(3770) to non-DDBar final states at a center-of-mass energy of 3.773 GeV to be (9.54 +- 0.31(stat) +-; 2.64(sys))% using 2.92 fb annihilation data collected with the BESIII detector at the BEPCII collider at 3.773 GeV, as well as 44.5 pb taken at 3.65 GeV and a total of 18.7 pb-1 taken at five points between 3.5 GeV and 3.671 GeV. The cross sections of psi(3770) to D0D0 Bar and psi(3770) to D+D at 3.773 GeV center-of-mass energy are also measured as (3.641 ± 0.010(stat) ; 0.047(sys)) nb and (2.844 ± 0.011(stat) ; 0.036(sys)) nb, respectively.enThesis or Dissertation