0000000001071418
AUTHOR
W. Nörtershäuser
Isomer shift and magnetic moment of the long-lived 1/2$^{+}$ isomer in $^{79}_{30}$Zn$_{49}$: signature of shape coexistence near $^{78}$Ni
Collinear laser spectroscopy has been performed on the $^{79}_{30}$Zn$_{49}$ isotope at ISOLDE-CERN. The existence of a long-lived isomer with a few hundred milliseconds half-life was confirmed, and the nuclear spins and moments of the ground and isomeric states in $^{79}$Zn as well as the isomer shift were measured. From the observed hyperfine structures, spins $I = 9/2$ and $I = 1/2$ are firmly assigned to the ground and isomeric states. The magnetic moment $\mu$ ($^{79}$Zn) = $-$1.1866(10) $\mu_{\rm{N}}$, confirms the spin-parity $9/2^{+}$ with a $\nu g_{9/2}^{-1}$ shell-model configuration, in excellent agreement with the prediction from large scale shell-model theories. The magnetic mo…
Charge Radii of ^{55,56}Ni Reveal a Surprisingly Similar Behavior at N=28 in Ca and Ni Isotopes.
Nuclear charge radii of $^{55,56}$Ni were measured by collinear laserspectroscopy. The obtained information completes the behavior of the chargeradii at the shell closure of the doubly magic nucleus $^{56}$Ni. The trend ofcharge radii across the shell closures in calcium and nickel is surprisinglysimilar despite the fact that the $^{56}$Ni core is supposed to be much softerthan the $^{48}$Ca core. The very low magnetic moment$\mu(^{55}\mathrm{Ni})=-1.108(20)\,\mu_N$ indicates the impact of M1excitations between spin-orbit partners across the $N,Z=28$ shell gaps. Ourcharge-radii results are compared to \textit{ab initio} and nuclear densityfunctional theory calculations, showing good agreeme…
Spins and magnetic moments of 58;60;62;64Mn ground states and isomers
The odd-odd 54;56;58;60;62;64Mn isotopes (Z = 25) were studied using bunched-beam collinear laser spectroscopy at ISOLDE, CERN. From the measured hyperfine spectra the spins and magnetic moments of Mn isotopes up to N = 39 were extracted. The previous tentative ground state spin assignments of 58;60;62;64Mn are now firmly determined to be I = 1 along with an I = 4 assignment for the isomeric states in 58;60;62Mn. The I = 1 magnetic moments show a decreasing trend with increasing neutron number while the I = 4 moments remain quite constant between N = 33 and N = 37. The results are compared to large-scale shell-model calculations using the GXPF1A and LNPS effective interactions. The excellen…
Spins and Magnetic Moments of $^{49}$K and $^{51}$K: establishing the 1/2$^+$ and 3/2$^+$ level ordering beyond $N$ = 28
The ground-state spins and magnetic moments of $^{49,51}$K have been measured using bunched-beam high-resolution collinear laser spectroscopy at ISOLDE-CERN. For $^{49}$K a ground-state spin $I = 1/2$ was firmly established. The observed hyperfine structure of $^{51}$K requires a spin $I > 1/2$ and from its magnetic moment $\mu(^{51}\text{K})= +0.5129(22)\, \mu_N$ a spin/parity $I^\pi=3/2^+$ with a dominant $\pi 1d_{3/2}^{-1}$ hole configuration was deduced. This establishes for the first time the re-inversion of the single-particle levels and illustrates the prominent role of the residual monopole interaction for single-particle levels and shell evolution.
On the performance of wavelength meters : Part 1 : consequences for medium-to-high-resolution laser spectroscopy
Present-day laser-spectroscopy experiments increasingly rely on modern commercial devices to monitor, stabilize, and scan the wavelength of their probe laser. Recently, new techniques are capable of achieving unprecedented levels of precision on atomic and nuclear observables, pushing these devices to their performance limits. Considering the fact that these observables themselves are deduced from the frequency difference between specific atomic resonances, in the order of MHz–GHz, the uncertainty on the output of the device measuring the wavelength is often directly related to the final systematic uncertainty on the experimental results. Owing to its importance, the performance of several …
Electromagnetic moments of scandium isotopes and $N=28$ isotones in the distinctive $0f_{7/2}$ orbit
The electric quadrupole moment of $^{49}$Sc was measured by collinear laser spectroscopy at CERN-ISOLDE to be $Q_{\rm s}=-0.159(8)$ $e$b, and a nearly tenfold improvement in precision was reached for the electromagnetic moments of $^{47,49}$Sc. The single-particle behavior and nucleon-nucleon correlations are investigated with the electromagnetic moments of $Z=21$ isotopes and $N=28$ isotones as valence neutrons and protons fill the distinctive $0f_{7/2}$ orbit, respectively, located between magic numbers, 20 and 28. The experimental data are interpreted with shell-model calculations using an effective interaction, and ab-initio valence-space in-medium similarity renormalization group calcu…
Nuclear mean-square charge radii of $^{63,64,66,68−82}$Ga nuclei: No anomalous behavior at N=32
Collinear laser spectroscopy was performed on the 63,64,66,68−82Ga isotopes with neutron numbers from N = 32 to N = 51. These measurements were carried out at the ISOLDE radioactive ion beam facility at CERN. Here we present the nuclear mean-square charge radii extracted from the isotope shifts and, for the lighter isotopes, new spin and moment values. New ground-state nuclear spin and moments were extracted from the hyperfine spectra of 63,70Ga, measured on an atomic transition in the neutral atom. The ground-state spin of 63Ga is determined to be I = 3/2. Analysis of the trend in the change in mean-square charge radii of the gallium isotopes demonstrates that there is no evidence of anoma…
Investigating the large deformation of the 5/2(+) isomeric state in Zn-73: An indicator for triaxiality
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)PYLBAJ0370-269310.1016/j.physletb.2017.05.085] show an uncommon behavior of the isomeric state in Zn73. Additional details relating to the measurement and analysis of the Zn73m 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 mo…
Modern Ives-Stilwell Experiments At Storage Rings: Large Boosts Meet High Precision
We give a brief overview of time dilation tests using high-resolution laser spectroscopy at heavy-ion storage rings. We reflect on the various methods used to eliminate the first-order Doppler effect and on the pitfalls encountered, and comment on possible extensions at future facilities providing relativistic heavy ion beams at $\gamma \gg 1$.