Mass measurements of the exotic nuclides 11Li and 11,12Be performed with the MISTRAL spectrometer

The mass of the halo nuclide Li-11 has been measured with unprecedented precision with the MISTRAL mass spectrometer at CERN's ISOLDE facility. Its resulting two-neutron separation energy, S-2n = 378 +/- 5 keV, is 25% higher than the previously accepted value and about an order of magnitude more precise than any of the previous measurements. We also report measurement of the masses of Be-11 and Be-12. The detailed analysis of these results and their evaluation are presented, along with a discussion concerning mass models. (C) 2009 Elsevier B.V. All rights reserved.