Masses and charge radii of 17-22Ne and the two-proton-halo candidate 17Ne

Measurement of the scalar curvature of high-power lasers

High-power lasers develop high energy per unit time, and as energy curves space, we expect atomic energy levels to change. The fluorescence spectrum is a good measurement of the matrix elements involved in the Rabi oscillation and consequently allows us to determine the scalar curvature. At high Z, electrons oppose ionization even for strong intensities. Because high-power lasers address relativistic atoms, the wave functions involved must be solutions of the Dirac equation in a curved space-time. The paper can be seen as a way to check whether the Einstein's gravitational theory is valid in the dimension of laboratory.

Simple Nuclear Structure in (111-129)Cd from Atomic Isomer Shifts

Isomer shifts have been determined in ^{111-129}Cd by high-resolution laser spectroscopy at CERN-ISOLDE. The corresponding mean square charge-radii changes, from the 1/2^{+} and the 3/2^{+} ground states to the 11/2^{-} isomers, have been found to follow a distinct parabolic dependence as a function of the atomic mass number. Since the isomers have been previously associated with simplicity due to the linear mass dependence of their quadrupole moments, the regularity of the isomer shifts suggests a higher order of symmetry affecting the ground states in addition. A comprehensive description assuming nuclear deformation is found to accurately reproduce the radii differences in conjunction with the known quadrupole moments. This intuitive interpretation is supported by covariant density functional theory.

Breakdown of the isobaric multiplet mass equation for the A = 20 and 21 multiplets

Using the Penning trap mass spectrometer TITAN, we performed the first direct mass measurements of (20,21)Mg, isotopes that are the most proton-rich members of the A = 20 and A = 21 isospin multiplets. These measurements were possible through the use of a unique ion-guide laser ion source, a development that suppressed isobaric contamination by 6 orders of magnitude. Compared to the latest atomic mass evaluation, we find that the mass of (21)Mg is in good agreement but that the mass of (20)Mg deviates by 3 σ. These measurements reduce the uncertainties in the masses of (20,21)Mg by 15 and 22 times, respectively, resulting in a significant departure from the expected behavior of the isobaric multiplet mass equation in both the A = 20 and A = 21 multiplets. This presents a challenge to shell model calculations using either the isospin nonconserving universal sd USDA and USDB Hamiltonians or isospin nonconserving interactions based on chiral two- and three-nucleon forces.

High-precision measurement of the 19Ne half-life and implications for right-handed weak currents

We report a precise determination of the (19)Ne half-life to be T(1/2)=17.262±0.007 s. This result disagrees with the most recent precision measurements and is important for placing bounds on predicted right-handed interactions that are absent in the current standard model. We are able to identify and disentangle two competing systematic effects that influence the accuracy of such measurements. Our findings prompt a reassessment of results from previous high-precision lifetime measurements that used similar equipment and methods.

Nuclear charge radius of 12Be

The nuclear charge radius of (12)Be was precisely determined using the technique of collinear laser spectroscopy on the 2s(1/2)→2p(1/2,3/2) transition in the Be(+) ion. The mean square charge radius increases from (10)Be to (12)Be by δ<r(c)(2)>(10,12)=0.69(5) fm(2) compared to δ<r(c)(2)>(10,11)=0.49(5) fm(2) for the one-neutron halo isotope ^{11}Be. Calculations in the fermionic molecular dynamics approach show a strong sensitivity of the charge radius to the structure of ^{12}Be. The experimental charge radius is consistent with a breakdown of the N=8 shell closure.

Nuclear charge radii of (21-32)Mg

Charge radii of all magnesium isotopes in the sd shell have been measured, revealing evolution of the nuclear shape throughout two prominent regions of assumed deformation centered on (24)Mg and (32)Mg. A striking correspondence is found between the nuclear charge radius and the neutron shell structure. The importance of cluster configurations towards N=8 and collectivity near N=20 is discussed in the framework of the fermionic molecular dynamics model. These essential results have been made possible by the first application of laser-induced nuclear orientation for isotope shift measurements.

Microscopic calculation of the 3He(α,γ)7Be and 3H(α,γ)7Li capture cross sections using realistic interactions

The radiative capture cross sections for the 3He(α,γ)7Be and 3H(α,γ)7Li reactions are calculated in the fully microscopic fermionic molecular dynamics approach using a realistic effective interaction that reproduces the nucleon-nucleon scattering data. At large distances bound and scattering states are described by antisymmetrized products of 4He and 3He/3H ground states. At short distances the many-body Hilbert space is extended with additional many-body wave functions needed to represent polarized clusters and shell-model-like configurations. Properties of the bound states are described well, as are the scattering phase shifts. The calculated S factor for the 3He(α,γ)7Be reaction agrees very well with recent experimental data in both absolute normalization and energy dependence. In the case of the 3H(α,γ)7Li reaction the calculated S factor is larger than available experimental data by about 15%.

High-precision metrology of highly charged ions via relativistic resonance fluorescence

Resonance fluorescence of laser-driven highly charged ions is investigated with regard to precisely measuring atomic properties. For this purpose an ab initio approach based on the Dirac equation is employed that allows for studying relativistic ions. These systems provide a sensitive means to test correlated relativistic dynamics, quantum electrodynamic phenomena and nuclear effects by applying x-ray lasers. We show how the narrowing of sidebands in the x-ray fluorescence spectrum by interference due to an additional optical driving can be exploited to determine atomic dipole or multipole moments to unprecedented accuracy.

Test of the conserved vector current hypothesis in T=1/2 mirror transitions and new determination of |V ud|

The V{ud} element of the Cabibbo-Kobayashi-Maskawa quark mixing matrix has traditionally been determined from the analysis of data in nuclear superallowed 0;{+}-->0;{+} transitions, neutron decay, and pion beta decay. After providing a new test of the conserved vector current hypothesis, we present here a new independent determination of |V{ud}| from a set of five T=1/2 nuclear mirror transitions. The extracted value, |V{ud}|=0.9719+/-0.0017, is at 1.2 combined standard deviations from the value obtained from superallowed 0;{+}-->0;{+} transitions and has a precision comparable to the value obtained from neutron decay experiments.