We have searched for particle-bound ${}^{26}\mathrm{O}$ and ${}^{28}\mathrm{F}$ isotopes in the reaction products of secondary ${}^{27}\mathrm{F}$ and ${}^{29}\mathrm{Ne}$ beams, respectively. No events have been observed. Upper limits of 3.3 mb and 1.2 mb for the respective production cross sections of ${}^{26}\mathrm{O}$ and ${}^{28}\mathrm{F}$ by one p-stripping reactions are established. Since in the case of ${}^{28}\mathrm{F}$, this upper limit is sufficiently small compared to common estimates, we conclude that ${}^{28}\mathrm{F}$ is most likely unbound. For the case of ${}^{26}\mathrm{O}$, our result is not statistically significant, thus, the question cannot be answered whether ${}^{26}\mathrm{O}$ is a particle-unbound nucleus or not.

• Received 5 April 2005

DOI:https://doi.org/10.1103/PhysRevC.72.037601