Production cross sections of neutron-rich projectile fragments have been measured for the reaction 213 MeV/nucleon ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$+Be. The neutron-rich nuclides ${}_{}{}^{20}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{27}{}_{}{}^{}\mathrm{F}$ have been observed for the first time. A method to strengthen our evidence for the possible particle stability of ${}_{}{}^{21}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{23}{}_{}{}^{}\mathrm{N}$, and ${}_{}{}^{25}{}_{}{}^{}\mathrm{O}$ is presented.

RADIOACTIVITY First observation of ${}_{}{}^{20}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{27}{}_{}{}^{}\mathrm{F}$ produced in fragmentation of 213 MeV/nucleon ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$.

• Received 5 March 1981

DOI:https://doi.org/10.1103/PhysRevC.24.2102