Mass measurement of short-lived halo nuclides

. A direct mass measurement of the very-short-lived halo nuclide 11 Li ( T 1/2 = 8.7ms) has been performed with the transmission mass spectrometer MISTRAL. The preliminary result for the two-neutron separation energy is S 2n = 376±5keV, improving the precision seven times with an increase of 20% compared to the previous value. In order to confirm this value, the mass excess of 11 Be has also been measured, ME = 20171±4keV, in good agreement with the previous value.