Study of the reactions ψ' → γγψ [Thesis]

A large solid angle array (the Crystal Ball detector) of NaI(Tl) crystals, together with spark and multiwire proportional chambers for charged particle tracking, is used to study the decays of the psi' meson. Cascade reactions of the form psi' ..-->.. ..gamma..chi, chi ..-->.. ..gamma..psi, psi ..-->.. (e/sup +/e/sup -/ or ..mu../sup +/..mu../sup -/) are used in this experiment to observe the intermediate chi states and to measure their spin by analyzing the angular correlations among the final-state particles. In addition, the multipole coefficients describing the individual radiative transitions are measured using the angular correlations. Values of J = 2 and J = 1 are obtained for the chi states with masses of 3.55 and 3.51 GeV, respectively. Radiative transitions to and from the chi states are found to be dominantly E1 in nature. The well-established J = 0 chi(3.41) state is observed in a cascade reaction, with a branching ratio BR(psi' ..-->.. ..gamma..chi ..-->.. ..gamma gamma..psi) = (0.06 +- 0.02 +- 0.01)%; the first error describes uncertainties arising from statistics and acceptance corrections, while the second error is systematic. Branching ratios of (1.26 +- 0.08 +- 0.20)% for chi(3.55) and (2.38 +- 0.12 +- 0.38)% for chi(3.51) are consistent with those obtained in previous experiments. Natural line-widths of (4 +- 1) MeV for chi(3.55) and a full width consistent with the resolution of the apparatus for chi(3.51) are obtained.

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