Towards measurement of charge radii of neutron-deficient ^52,53Ni

Chains of charge radius of Ca and Ni isotopes show a similar trend across the neutron magic number N = 28, though ⁴⁸Ca is known to be a robust doubly-magic nucleus, whereas ⁵⁶Ni is soft as a doubly-magic nucleus [1]. The charge radius measurements will be extended to very neutron-deficient ^52,53Ni isotopes to investigate if the surprising similarity persists and for better understanding of structure around the soft ⁵⁶Ni. The experiment will be performed at the BECOLA/RISE facility at FRIB. Currently, test experiments are performed to establish an efficient, low-background multi-step laser resonant ionization scheme using a Rydberg state as a final state to be ionized via field ionization. Details of the development as well as the science background will be discussed.

[1] F. Sommer et al., Phys. Rev. Lett. 129, 132501 (2022).