Nuclear charge radius of 26m^{26m}Al and its implication for Vud_{ud} in the quark-mixing matrix

Collinear laser spectroscopy was performed on the isomer of the aluminium isotope $^{26m}$Al. The measured isotope shift to $^{27}$Al in the 3s^{2}3p\;^{2}\!P^\circ_{3/2} \rightarrow 3s^{2}4s\;^{2}\!S_{1/2} atomic transition enabled the first experimental determination of the nuclear charge radius of $^{26m}$Al, resulting in $R_c$=\qty{3.130\pm.015}{\femto\meter}. This differs by 4.5 standard deviations from the extrapolated value used to calculate the isospin-symmetry breaking corrections in the superallowed $\beta$ decay of $^{26m}$Al. Its corrected $\mathcal{F}t$ value, important for the estimation of $V_{ud}$ in the CKM matrix, is thus shifted by one standard deviation to \qty{3071.4\pm1.0}{\second}.Comment: 5 pages, 2 figures, submitted to Phys. Rev. Let

Probing the single-particle behavior above Sn-132 via electromagnetic moments of Sb-133,Sb-134 and N=82 isotones

International audienceMagnetic and quadrupole moments of the $7/2^+$ ground state in $^{133}$Sb and the ($7^-$) isomer in $^{134}$Sb have been measured by collinear laser spectroscopy to investigate the single-particle behavior above the doubly magic nucleus $^{132}$Sn. The comparison of experimental data of the $7/2^+$ states in $^{133}$Sb and neighboring $N = 82$ isotones to shell-model calculations reveals the sensitivity of magnetic moments to the splitting of the spin-orbit partners $\pi 0g_{9/2}$ and $\pi 0g_{7/2}$ across the proton shell closure at $Z = 50$. In contrast, quadrupole moments of the N = 82 isotones are insensitive to cross-shell excitations, but require the full proton model space from $Z = 50$ to 82 for their accurate description. In fact, the linear trend of the quadrupole moment follows approximately the expectation of the seniority scheme when filling the $\pi 0g_{7/2}$ orbital. As far as the isomer in $^{134}$Sb is concerned, its electromagnetic moments can be perfectly described by the additivity rule employing the moments of $^{133}$Sb and $^{133}$Sn, respectively. These findings agree with shell-model calculations and thus confirm the weak coupling between the valence proton and neutron in $^{134}$Sb

Electromagnetic moments of the antimony isotopes 112−133^{112−133}Sb

International audienceNuclear moments of the antimony isotopes 113−133Sb are measured by collinear laser spectroscopy and used to benchmark phenomenological shell-model and ab initio calculations in the valence-space in-medium similarity renormalization group (VS-IMSRG). The shell-model calculations reproduce the electromagnetic moments over all Sb isotopes when suitable effective g-factors and charges are employed. Good agreement is achieved by VS-IMSRG for magnetic moments on the neutron-deficient side for both odd-even and odd-odd Sb isotopes while its results deviate from experiment on the neutron-rich side. When the same effective g-factors are used, VS-IMSRG agrees with experiment nearly as well as the shell model. Hence, the wave functions are very similar in both approaches and missing contributions to the M1 operator are identified as the cause of the discrepancy of VS-IMSRG with experiment. Electric quadrupole moments remain more challenging for VS-IMSRG

Measurements of binding energies and electromagnetic moments of silver isotopes – A complementary benchmark of density functional theory

International audienceWe report on a set of high-precision measurements of nuclear binding and excitation energies, as well as nuclear spins, magnetic dipole and electric quadrupole moments of neutron-rich silver isotopes, 113−123Ag. The measurements were performed using the JYFLTRAP mass spectrometer and the collinear laser spectroscopy beamline at the Ion Guide Isotope Separator On-Line (IGISOL) facility. For the first time, we can firmly establish the ordering of the long-lived Iπ=1/2−,7/2+ states in these isotopes, and pin down the inversion of these two levels at either A=121(N=74) or A=123(N=76). We compare these findings to calculations performed with density functional theory (DFT), from which we establish the crucial role that the spin-orbit strength and time-odd mean fields play in the simultaneous description of electromagnetic moments and nuclear binding