β-delayed deuteron emission from 11Li: Decay of the halo

The deuteron-emission channel in the β decay of the halo nucleus 11Li was measured at the Isotope Separator and Accelerator facility at TRIUMF by implanting postaccelerated 11Li ions into a segmented silicon detector. The events of interest were identified by correlating the decays of 11Li with those of the daughter nuclei. This method allowed the energy spectrum of the emitted deuterons to be extracted, free from contributions from other channels, and a precise value for the branching ratio Bd=1.30(13)×10−4 to be deduced for Ec.m.>200 keV. The results provide the first unambiguous experimental evidence that the decay takes place essentially in the halo of 11Li and that it proceeds mainly to the 9Li+d continuum, opening up a new means to study the halo wave function of 11Li