First evidence of multiple β-delayed neutron emission for isotopes with a > 100

Abstract

The β-delayed neutron emission probability, Pn, of very neutron-rich nuclei allows us to achieve a better understanding of the nuclear structure above the neutron separation energy, Sn. The emission of neutrons can become the dominant decay process in neutron-rich astrophysical phenomena such as the rapid neutron capture process (r-process). There are around 600 accessible isotopes for which β-delayed one-neutron emission (β1n) is energetically allowed, but the branching ratio has only been determined for about one third of them. β1n decays have been experimentally measured up to the mass A ∼ 150, plus a single measurement of 210Tl. Concerning two-neutron emitters (β2n), ∼ 300 isotopes are accessible and only 24 have been measured so far up to the mass A = 100. In this contribution, we report recent experiments which allowed the measurement of β1n emitters for masses beyond A > 200 and N > 126 and identified the heaviest β2n emitter measured so far, 136Sb.