PROJECTILE COULOMB-EXCITATION WITH FAST RADIOACTIVE BEAMS

We report a search for gamma rays emanating from Coulomb excitation of fast (30-46 MeV/u) radioactive projectiles He-8, Be-11,Be-12,Be-14 in teracting with a lead target. These are clearly identified by their Do ppler shift. The 320 keV 1/2(-) --> 1/2(+)gamma transition from Be-11 was observed with a cross-section of 191 +/- 26 mb which is noticeably less than expected from the known lifetime and in the perturbation li mit of pure Coulomb excitation. In the other nuclei rather stringent u pper limits of 0.01 to 0.2 Weisskopf units, are placed on the hypothet ical transition to 1(-) states.