Spectroscopy of the proton drip-line nucleus Fr-203
Résumé
The nucleus Fr-203 has been studied through gamma-ray and electron spectroscopy, using the recoil-decay tagging technique. A 13/2(+) state, with a half-life of 0.37(5) mu s, has been observed in Fr-203. Both the alpha-decay branch and the internal de-excitation of the 1/2(+) isomer in Fr-203 have been studied. Furthermore, the corresponding 1/2(+) state, with a half-life of 0.31(8) s, has been found in At-199. In addition, transitions feeding the 9/2(-) ground state of Fr-203 have been identified. The observed level pattern suggests that the ground state is still spherical.