Halo neutrons and the β-decay of 11Li

Abstract

The β-decay of 11Li has been studied at ISAC/TRIUMF using the 8pi spectrometer, an array of 20 Compton-suppressed high-purity germanium detectors. Most of the 11Li β-decay strength is observed to proceed through unbound states in 11Be, which subsequently decay by one-neutron emission to 10Be. This results in the observation of a γ-spectrum dominated by the decay of the excited states in 10Be. These transitions exhibit characteristic Doppler broadened lineshapes, due to the the recoiling effect induced by the neutron emission. A Monte-Carlo simulation was developed to analyze the complex shape of these γ-lines. Both the half-lives of states in 10Be and the energies of the β-delayed neutrons feeding those states were obtained. It was also possible to determine the excitation energies of the parent states in 11Be. The present contribution was the subject of a publication in a scientific journal (F. Sarazin et al., Phys. Rev. C 70, 031302(R)(2004) )shortly before the conference. It was judged not appropriate to submit for peerreviewing a contribution with nearly the same content. The reader is therefore invited to read the original publication.