Speaker
Description
Experimental β-decay studies contribute significantly to improving our understanding of exciting nuclear phenomena emerging far from stability, such as β-delayed multiple-particle emission [1–3], evolution of the shell structure [4], and the appearance of so-called “islands of inversion” [5]. The great success of β-decay experiments in probing ground- and excited-state properties is due to the high angular-momentum selectivity of the β decay that populates states with particular "allowed" configurations in the daughter nuclei.
β-decay spectroscopy becomes even more powerful when spin-polarised nuclei are utilised, i.e. when the nuclear spin of the β-decay emitter has a directional orientation with respect to the axis of an applied magnetic field. In this way, one can benefit from the parity non-conserving nature of the weak interaction and exploit the anisotropy of the β-particle emission from spin-oriented nuclei to unambiguously assign spins and parities of states populated in daughter nuclei via allowed transitions [6, 7].
This novel approach to β-decay measurements, pioneered by a group from the University of Osaka [8-11], has recently been adopted at the VITO beamline [12], which is a permanent setup at the ISOLDE facility devoted to versatile studies with laser-polarised radioactive beams. In this contribution, a new experimental station that accommodates β-particle, γ-ray, and neutron detection following the β decay of laser-polarised nuclei will be presented. The research program focused on strong β-delayed neutron (βn) emitters will be discussed. β-decay studies with spin-polarised beams can provide a robust experimental dataset to test βn emission models and answer critical questions about the mechanism of βn decay, being a prevalent decay branch of exotic nuclides, with great relevance to the r-process nucleosynthesis. Preliminary results from the commissioning experiment with laser-polarised beams of neutron-rich potassium isotopes will be presented [13].
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[10] Y. Hirayama et al., Phys. Rev. C 91, 024328 (2015).
[11] H. Nishibata et al., Phys. Rev. C 99, 024322 (2019).
[12] M. Kowalska et al., Phys. G: Nucl. Part. Phys. 44, 084005 (2017).
[13] M. Piersa-Siłkowska, M. Madurga, M. Kowalska et al., CERN-INTC-2023-026; INTC-P-662 (2023).
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 101032999 (BeLaPEx).
