Investigating the large deformation of the 5/2+ isomeric state in Zn73 : An indicator for triaxiality

Abstract

Recently reported nuclear spins and moments of neutron-rich Zn isotopes measured at ISOLDE-CERN [C. Wraith et al., Phys. Lett. B 771, 385 (2017)] show an uncommon behavior of the isomeric state in 73 Zn. Additional details relating to the measurement and analysis of the 73m Zn hyperfine structure are addressed here to further support its spin-parity assignment 5/2 + and to estimate its half-life. A systematic investigation of this 5/2 + isomer indicates that significant collectivity appears due to proton/neutron E2 excitations across the proton Z = 28 and neutron N = 50 shell gaps. This is confirmed by the good agreement of the observed quadrupole moments with large scale Monte Carlo shell model calculations. In addition, potential energy surface calculations in combination with T plots reveal a triaxial shape for this isomeric state.

Emergence of simple patterns in many-body systems: from macroscopic objects to the atomic nucleus

“…scaled inverse of the excitation energy of the first 2 + state, 1/E 2 + Z; and v. normalized transition probability to the first 2 + excited state, B(E2)/Z 2 R 2 . Experimental data were taken from [38,101,113,[131][132][133][134][135][136][137][138][139][140].…”

Multiconfiguration calculations of electronic isotope-shift factors in Zn i

“…None of the computed FS factors, whose average value is F = 346(3) MHz/fm 2 , agrees with the number from Refs. [6] and [61], although the three models provide values very close to each other. Turning to the total MS factor, an average of K MS = −14(7) GHz u can be deduced from the three computed values.…”

“…Yang et al [6] measured ISs between the same stable isotopes for the 4s4p 3 P o 2 → 4s5s 3 S 1 transition (481.2 nm). To calibrate the FS factor, a King plot was made using their set of ISs against the measured ISs from Ref.…”

“…Neglecting terms of higher order than δ r 2 in the Seltzer moment (or nuclear factor) [43], (6) the line frequency shift in the transition k arising from the difference in nuclear charge distributions between two isotopes, A and A , can be written as [31,44,45] …”

“…Specific mass shifts (SMSs) were extracted, and a large value has been assigned to the ground state, emphasizing the substantial 3d core-valence polarization. Recently, Yang et al [6] investigated the 4s4p 3 P o 2 → 4s5s 3 S 1 transition (481.2 nm) in a bunched-beam collinear laser spectroscopy experiment to determine nuclear properties of the 79 Zn isotope. The isomer shift between the nuclear ground state and the long-lived 1/2 + isomeric state was measured, and the change of the mean-square charge radii of 79,79m Zn has been extracted via the MS and FS electronic factors.…”