The $\beta$ decay of ${}^9\mathrm{C}$ ${(T}_{1/2}=126.5\mathrm{}\hspace{0.5em}\mathrm{ms})$ has been studied in two experiments observing about $15\times {10}^7$ and $8\times {10}^7$ 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 ${}^9\mathrm{B}.$ In the experiments single spectra, and double and triple coincidence spectra, were recorded. Several states in ${}^9\mathrm{B}$ were observed; $\beta$-branching ratios to these states, and particle decay channels from these states, are reported. In particular, secondary decays into the ${}^5\mathrm{Li}$ and ${}^8\mathrm{Be}$ ground states were observed. With the inclusion of a considerable continuum and additional states, fair agreement with the reported ${}^9\mathrm{Li}\log \mathrm{ft}$ 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.

• Received 3 June 1999

DOI:https://doi.org/10.1103/PhysRevC.61.064310