Production of particle unstable light nuclei in 11.5 A GeV/c Au+Pt heavy-ion collisions

We report measurements from experiment E864 at the BNL-AGS of the yields of particle unstable light nuclei in central collisions of ${}^{197}\mathrm{Au}$ with beam momentum of $11.5A$ $\mathrm{GeV}/c$ on ${}^{197}\mathrm{Pt}.$ Yields are reported as a function of rapidity for the nuclei ${}^{4}\mathrm{H},$ ${}^{4}\mathrm{Li},$ ${}^{5}\mathrm{He},$ and ${}^{5}\mathrm{Li}$ in the rapidity range from ${y}_{\mathrm{c}.\mathrm{m}.}$ to ${y}_{\mathrm{c}.\mathrm{m}.}+0.8$ and in the transverse momentum range of approximately $0.1l~{p}_{T}/Al~0.4\mathrm{GeV}/c.$ The yields are compared to previously reported yields and trends for the production of stable light nuclei. The nonobservation of two excited states ${}^{5}{\mathrm{He}}_{16.75\mathrm{MeV}}^{*}$ and ${}^{5}{\mathrm{Li}}_{16.66\mathrm{MeV}}^{*}$ is used to set an upper limit on the yields of these states.