β-delayed particle decay of ⁹C and the A=9, T=1/2 nuclear system: Experiment, data, and phenomenological analysis

The β decay of ⁹C (T_1/2=126.5 ms) has been studied in two experiments observing about 15×10⁷ and 8×10⁷ decays, respectively, at the TISOL facility at TRIUMF; different detector configurations were employed in the two experiments. In this first of two papers, the two experimental setups are described, as well as data analysis and a phenomenological approach to deducing branching ratios to and from states in ⁹B. In the experiments single spectra, and double and triple coincidence spectra, were recorded. Several states in ⁹B were observed; β-branching ratios to these states, and particle decay channels from these states, are reported. In particular, secondary decays into the ⁵Li and ⁸Be ground states were observed. With the inclusion of a considerable continuum and additional states, fair agreement with the reported ⁹Lilogft values is found with a phenomenological approach for deducing the branching ratios. To extend the discussion, in a second, forthcoming paper, a multichannel, multistate R-matrix analysis of these data will be described.