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Since the discovery of large shape staggering in neutron-deficient mercury isotopes Z = 80 [1], the region around Z = 82 and N = 104 has been extensively studied using in-source laser spectroscopy, due to its intriguing nuclear structure phenomena [2-3]. Recent experiments have revealed substantial shape staggering in neighbouring bismuth isotopes Z = 83 starting at neutron number N = 105 [4], which contrasts sharply with lead isotopes Z = 82 that remain predominantly spherical [5]. For gold isotopes Z = 79, earlier studies indicated an onset of strong deformation starting from neutron number N = 107 and persisting down to N = 101 [6-7].
We report recent high-resolution collinear resonance ionization spectroscopy measurements of neutron-deficient gold isotopes performed at the CRIS experiment, ISOLDE/CERN. Our experimental campaign includes high-resolution studies of the isotopes 181−197Au (N = 102 − 118), enabling spin measurements and determination of spectroscopic quadrupole moments. These results will shed light on our understanding of nuclear shapes and deformation phenomena near the closed-shell nucleus lead Z = 82.
[1]. Bonn, J et al.. "Sudden change in the nuclear charge distribution of very light mercury isotopes", Physics Letters B, Volume 38, Issue 5,1972, Pages 308-311, ISSN 0370-2693.
[2]. B. A. Marsh, T. Day Goodacre, S. Sels, et al. "Characterization of the shape-staggering effect in mercury nuclei". Nature Physics, 14:1163 1167, Dec 2018.
[3]. S. Sels, T. Day Goodacre, B. A. Marsh, et al. "Shape staggering of midshell mercury isotopes from in-source laser spectroscopy compared with density-functional-theory and monte carlo shell-model calculations". Phys. Rev. C, 99:044306, Apr 2019.
[4]. A. Barzakh, A. N. Andreyev, C. Raison, et al.. "Large shape staggering in neutron-deficient Bi isotopes". Phys. Rev. Lett., 127:192501, Nov 2021.
[5]. H. De Witte, A. N. Andreyev, N. Barre, et al. "Nuclear charge radii of neutron deficient lead isotopes beyond N = 104 midshell investigated by in-source laser spectroscopy". Phys. Rev. Lett., 98:112502, Mar 2007.
[6]. K. Wallmeroth, G. Bollen, A. Dohn, et al. "Nuclear shape transition in light gold Isotopes". Nuclear Physics A, 493(2):224 252, 1989.
[7]. J.G. Cubiss et al. "Deformation versus Sphericity in the Ground States of the Lightest Gold Isotopes". Phys. Rev. Lett. 131, 202501 Published 14 November 2023.
