@Article{Yokoyama_etal2019,
author="Yokoyama, R. et al
and Tain, J. L.
and Algora, A.
and Agramunt, J.
and Domingo-Pardo, C.
and Morales, A. I.
and Rubio, B.
and Tolosa-Delgado, A.",
title="Strong one-neutron emission from two-neutron unbound states in beta decays of the r-process nuclei Ga-86,Ga-87",
journal="Physical Review C",
year="2019",
publisher="Amer Physical Soc",
volume="100",
number="3",
pages="031302--6pp",
abstract="beta-delayed one-neutron and two-neutron branching ratios (P-1n and P-2n) have been measured in the decay of A = 84 to 87 Ga isotopes at the Radioactive-Isotope Beam Factory (RIBF) at the RIKEN Nishina Center using a high-efficiency array of He-3 neutron counters (BRIKEN). Two-neutron emission was observed in the decay of Ga-84,Ga-85,Ga-87 for the first time and the branching ratios were measured to be P-2n = 1.6(2){\%}, 1.3(2){\%}, and 10.2(28)(stat)(5)(sys){\%}, respectively. One-neutron branching ratio of Ga-87 (P-1n = 81(9)(stat)(8)(sys){\%}) and half-life of 29(4) ms were measured for the first time. The branching ratios of Ga-86 were also measured to be P-1n = 74(2)(stat)(8)(sys){\%} and 16.2(9)(stat)(6)(sys){\%} with better precision than a previous study. The observation that P-1n > P-2n for both Ga-86,Ga-87 was unexpected and is interpreted as a signature of dominating one-neutron emission from the two-neutron unbound excited states in Ge-86,Ge-87. In order to interpret the experimental results, shell-model and Hauser-Feshbach statistical model calculations of delayed particle and gamma-ray emission probabilities were performed. This model framework reproduces the experimental results. The shell model alone predicts P-2n significantly larger than P-1n for the Ga-87 decay, and it is necessary to invoke a statistical description to successfully explain the observation that P-1n > P-2n. Our new results demonstrate the relevance and importance of a statistical description of neutron emission for the prediction of the decay properties of multineutron emitters and that it must be included in the r-process modeling.",
optnote="WOS:000486641000001",
optnote="exported from refbase (https://references.ific.uv.es/refbase/show.php?record=4145), last updated on Fri, 12 Nov 2021 13:41:24 +0000",
issn="2469-9985",
doi="10.1103/PhysRevC.100.031302",
opturl="https://doi.org/10.1103/PhysRevC.100.031302",
language="English"
}