New search for 26O

An attempt was made to find the very neutron-rich isotope ²⁶O among the fragmentation products of a 90 MeV/nucleon ⁴⁰Ar beam. This isotope has been predicted to be bound but was not observed in a previous experiment by Guillemaud-Mueller et al. As part of the search, the momentum distributions of all the oxygen isotopes in the range from ¹⁷O to ²⁴O were carefully determined so that the optimum separator setting for ²⁶O could be used. From an extrapolation of the counting rates of the lighter oxygen isotopes, we expected to observe several hundred events of ²⁶O during the measurement. However, no events could be attributed to ²⁶O, thus indicating the particle instability of this isotope. The results for the production cross sections of 72 neutron-rich isotopes, ranging from ³⁸P to ¹¹B, are presented and compared to predictions.

Duke Scholars

Author John H Kelley Physics