Speaker
Description
Exciting new opportunities for beta-decay experiments have emerged at the ISOLDE facility with the recently developed spectroscopy station called DeVITO [1]. The novelty of the new setup lies in its integration with the VITO beamline [2] for laser-polarisation of radioactive beams, enabling spectroscopy measurements with spin-oriented nuclei that emit radiation anisotropically. The ability to exploit the directional distribution of radiation represents a significant advance over conventional beta-decay experiments, which greatly benefit from the high angular-momentum selectivity of the process but constantly struggle to unambiguously infer nuclear spins and parities from observed beta-decay feeding intensities [3]. These quantum numbers, essential for discussing complex phenomena observed in nuclei, can be inferred from experimental beta-decay asymmetries measured in coincidence with delayed radiation [4, 5]. This novel approach to beta-decay measurements utilising laser-polarised nuclei was pioneered by a group from the University of Osaka, which successfully applied it to studies of allowed beta transitions [5-7]. It has been shown that the key ingredient for unambiguous spin-parity assignments is the high degree of polarisation in parent nuclei. The VITO beamline, where spin orientation in atoms or ions is induced via optical pumping with laser light, has proven to be an excellent place for implementing this technique and further developing its extension.
The initial configuration of the DeVITO station and the initiated research programme [8] are targeted at studies of very neutron-rich nuclei to gain insight into the mechanism of beta-delayed neutron emission, which is the primary decay mode of exotic nuclei involved in one of the astrophysical processes responsible for the formation of about half of the chemical elements heavier than iron. This contribution highlights key features of the DeVITO station and presents preliminary results from a proof-of-concept run conducted at ISOLDE in April 2024 with laser-polarised beams of neutron-rich potassium isotopes.
References
[1] BeLaPEx project, Marie Skłodowska-Curie Individual Fellowship (H2020-MSCA-IF-2020); Grant agreement 101032999.
[2] M. Kowalska et al., Phys. G: Nucl. Part. Phys. 44, 084005 (2017).
[3] S. Turkat et al., At. Data Nucl. Data Tables 152, 101584 (2023).
[4] K. S. Krane, In: H. Postma, N. J. Stone, Low Temp. Nucl. Orient., North Holland, 1986.
[5] H. Miyatake et al., Phys. Rev. C 67, 014306 (2003).
[6] Y. Hirayama et al., Phys. Lett. B 611, 239 (2005).
[7] H. Nishibata et al., Phys. Rev. C 99, 024322 (2019).
[8] M. Piersa-Siłkowska, M. Madurga, M. Kowalska, N. Azaryan et al., Tech. rep. CERN-INTC-2023-026, Geneva (2023).
This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie grant agreement No. 101032999 (BeLaPEx) and the European Union’s Horizon Europe Framework research and innovation programme under grant agreement No. 101057511 (EURO-LABS).
