Speaker
Description
Rich nuclear structure phenomena, such as shape coexistence and shell evolution, have been observed in the neutron rich region up to N = 50 around $^{78}$Ni [1-4]. Moving to more neutron-rich nuclei, theoretical calculation shows that the shell evolution and deformation will also appear in the ground states of isotopes beyond N = 50 [4-6]. Nuclear spins, electromagnetic moments and charge radii of the ground states of these neutron-rich nuclei, which are accessed by laser spectroscopy techniques, would provide important information on theoretically-predicted exotic structure. However, due to the low production yield of neutron-rich isotopes in the northeast of $^{78}$Ni, as well as the accompanying large isobaric contamination, measurement of ground-state properties in this region using laser spectroscopy has been limited till now.
Recently, thanks to the strong rubidium suppression by using a quartz transfer line in the ISOLDE target, and the high sensitivity and selectivity of the Collinear Laser Spectroscopy (CRIS) technique [7,8], measurements of $^{81,82}$Zn (N = 51,52) close to the $^{78}$Ni have been performed successfully. This leads to the first determination of the nuclear spin and electromagnetic moments of $^{81}$Zn and the charge radii of $^{81,82}$Zn. In this talk, the details of the CRIS experiment as well as the extracted nuclear properties of the $^{81,82}$Zn isotopes will be presented. The experimental results will be further discussed based on the on-going shell model and ab-initio calculations.
References:
[1] X. F. Yang et al. Isomer shift and magnetic moment of the long-lived 1/2$^+$ isomer in
49: signature of shape coexistence near $^{78}$Ni. Physical Review Letters, 116:182502, 2016.
[2] F. Nowacki, A. Poves, E. Caurier, and B. Bounthong. Shape coexistence in $^{78}$Ni as the portal to the fifth island of inversion. Physical Review Letters, 117:272501, 2016.
[3] S. Padgett et al. β decay of 81Zn and migrations of states observed near the N = 50 closed shell. Physical Review C, 82:064314, 2010.
[4] R. Taniuchi, C. Santamaria, P. Doornenbal, et al. $^{78}$Ni revealed as a doubly magic stronghold against nuclear deformation, Nature 569: 53, 2019.
[5] G. Hagen, G. R. Jansen, and T. Papenbrock. Structure of $^{78}$Ni from first-principles
computations. Physical Review Letters, 117:172501, 2016.
[6] K. Maurya, P. C. Srivastava, and I. Mehrotra. Shell model description of N = 51
isotones. IOSR Journal of Applied Physics, 3:52, 2013.
[7]R. P. De Groote, J. Billowes, C. L. Binnersley, et al. Measurement and microscopic description of odd–even staggering of charge radii of exotic copper isotopes. Nature Physics, 16:620-624, 2020.
[8]M. Athanasakis-Kaklamanakis, J. R. Reilly, Á. Koszorús, et al. Voltage scanning and technical upgrades at the Collinear Resonance Ionization Spectroscopy experiment. Nucl. Instrum. Methods Phys. Res. A, 541:86-89, 2023.
