The ORNL analysis technique for extracting β-delayed multi-neutron branching ratios with BRIKEN

Many choices are available in order to evaluate large radioactive decay networks. There are many parameters that influence the calculated β-decay delayed single and multi-neutron emission branching fractions. We describe assumptions about the decay model, background, and other parameters and their influence on β-decay delayed multi-neutron emission analysis. An analysis technique, the ORNL BRIKEN analysis procedure, for determining β-delayed multi-neutron branching ratios in β-neutron precursors produced by means of heavy-ion fragmentation is presented. The technique is based on estimating the initial activities of zero, one, and two neutrons occurring in coincidence with an ion-implant and β trigger. The technique allows one to extract β-delayed multi-neutron decay branching ratios measured with the 3He BRIKEN neutron counter. As an example, two analyses of the β-neutron emitter 77Cu based on different a priori assumptions are presented along with comparisons to literature values.