Abstract
A primary beam of Ni at 600 MeV/nucleon from the SIS synchrotron at GSI was used to produce proton-rich isotopes in the titanium-to-nickel region by projectile fragmention on a beryllium target. The fragments were separated by a projectile-fragement separator and unambiguously identified. We report here the first observation of the nuclei Fe and Ni, the most proton-rich nuclei ever synthesized with an excess of seven protons. In addition, the new isotope Cr was identified. According to commonly used mass predictions, these isotopes are all unbound with respect to two-proton emission from their ground states. From the nonobservation of Ti in this experiment, an upper limit of 120 ns is deduced for the half-life of this isotope.
- Received 25 July 1996
DOI:https://doi.org/10.1103/PhysRevLett.77.2893
©1996 American Physical Society