Speaker
Description
Beta-delayed neutron (βn) emission is a dominant decay channel for neutron-rich nuclei far from stability. The current theoretical paradigm treats βn emission in two steps independently: first, β decay, and then neutron emission. Due to its complicated nature, the neutron-emission part is modeled using Bohr’s hypothesis of the compound nucleus [1]. It assumes neutron emission only depends on the spins, parities, and excitation energies of the initial and final states, and is independent of the formation process [2]. Recent experimental work suggested evidence of non-statistical βn emission near doubly magic 132Sn [3].
To address the problem in a broader range of nuclei, we have studied βn decay of many neutron-rich isotopes in various mass regions. In this talk, I will present our recent experimental efforts validating the statistical nature of βn decay around 54Ca. It includes two experiments performed at the ISOLDE Decay Station and the FRIB Decay Station initiator, respectively. In those experiments, we performed coincidence measurements on βs, neutrons, and γs, allowing us to extract the exclusive neutron-emission branching ratios from the unbound states of β-decay daughters to the low-lying states in the neutron-emission residues. The comparisons between the experimental data and the Hauser-Feshbach statistical model show surprising results, constituting a strong challenge to the existing theories of the decay process.
References
[1] N. Bohr, Nature 137, 344 (1936).
[2] T. Kawano et al., Phys. Rev. C 78, 054601 (2008).
[3] J. Heideman et al., Phys. Rev. C 108, 024311 (2023).
| Contribution category | Experiment |
|---|---|
| Presenter status | Postdoc |