0000000000650467
AUTHOR
Jason D. Holt
Measurement and microscopic description of odd-even staggering of charge radii of exotic copper isotopes
Isotopes with an odd number of neutrons are usually slightly smaller in size than their even-neutron neighbours. In charge radii of short-lived copper isotopes, a reduction of this effect is observed when the neutron number approaches fifty. The mesoscopic nature of the atomic nucleus gives rise to a wide array of macroscopic and microscopic phenomena. The size of the nucleus is a window into this duality: while the charge radii globally scale as $A^{1/3}$, their evolution across isotopic chains reveals unanticipated structural phenomena [1-3]. The most ubiquitous of these is perhaps the Odd-Even Staggering (OES) [4]: isotopes with an odd number of neutrons are usually smaller in size than …
Nuclear moments put a new spin on the structure of 131In
Abstract In spite of the high-density and strongly correlated nature of the atomic nucleus, experimental and theoretical evidence suggests that around particular 'magic' numbers of nucleons, nuclear properties are governed by a single unpaired nucleon1,2. A microscopic understanding of the extent of this behaviour and its evolution in neutron-rich nuclei remains an open question in nuclear physics 3-5. A textbook example is the electromagnetic moments of indium (Z = 49) 6, which are dominated by a hole with respect to the proton magic number Z = 50 nucleus. They exhibit a remarkably constant behaviour over a large range of odd-mass isotopes, previously interpreted as pure "single-particle b…
Precision Mass Measurements of Cr58–63 : Nuclear Collectivity Towards the N=40 Island of Inversion
The neutron-rich isotopes $^{58-63}$Cr were produced for the first time at the ISOLDE facility and their masses were measured with the ISOLTRAP spectrometer. The new values are up to 300 times more precise than those in the literature and indicate significantly different nuclear structure from the new mass-surface trend. A gradual onset of deformation is found in this proton and neutron mid-shell region, which is a gateway to the second island of inversion around \emph{N}=40. In addition to comparisons with density-functional theory and large-scale shell-model calculations, we present predictions from the valence-space formulation of the \emph{ab initio} in-medium similarity renormalization…
Examining the N=28 shell closure through high-precision mass measurements of Ar46–48
The strength of the $N=28$ magic number in neutron-rich argon isotopes is examined through high-precision mass measurements of $^{46\text{--}48}\mathrm{Ar}$, performed with the ISOLTRAP mass spectrometer at ISOLDE/CERN. The new mass values are up to 90 times more precise than previous measurements. While they suggest the persistence of the $N=28$ shell closure for argon, we show that this conclusion has to be nuanced in light of the wealth of spectroscopic data and theoretical investigations performed with the SDPF-U phenomenological shell model interaction. Our results are also compared with ab initio calculations using the valence space in-medium similarity renormalization group and the s…
Shell evolution of $N=40$ isotones towards $^{60}$Ca: First spectroscopy of $^{62}$Ti
7 pags., 4 figs., 1 tab.
First Glimpse of the N=82 Shell Closure below Z=50 from Masses of Neutron-Rich Cadmium Isotopes and Isomers
We probe the $N=82$ nuclear shell closure by mass measurements of neutron-rich cadmium isotopes with the ISOLTRAP spectrometer at ISOLDE-CERN. The new mass of $^{132}\mathrm{Cd}$ offers the first value of the $N=82$, two-neutron shell gap below $Z=50$ and confirms the phenomenon of mutually enhanced magicity at $^{132}\mathrm{Sn}$. Using the recently implemented phase-imaging ion-cyclotron-resonance method, the ordering of the low-lying isomers in $^{129}\mathrm{Cd}$ and their energies are determined. The new experimental findings are used to test large-scale shell-model, mean-field, and beyond-mean-field calculations, as well as the ab initio valence-space in-medium similarity renormalizat…
Opportunities for Fundamental Physics Research with Radioactive Molecules
Molecules containing short-lived, radioactive nuclei are uniquely positioned to enable a wide range of scientific discoveries in the areas of fundamental symmetries, astrophysics, nuclear structure, and chemistry. Recent advances in the ability to create, cool, and control complex molecules down to the quantum level, along with recent and upcoming advances in radioactive species production at several facilities around the world, create a compelling opportunity to coordinate and combine these efforts to bring precision measurement and control to molecules containing extreme nuclei. In this manuscript, we review the scientific case for studying radioactive molecules, discuss recent atomic, mo…
Dawning of the N=32 shell closure seen through precision mass measurements of neutron-rich titanium isotopes
A precision mass investigation of the neutron-rich titanium isotopes 51 − 55 Ti was performed at TRIUMF’s Ion Trap for Atomic and Nuclear science (TITAN). The range of the measurements covers the N = 32 shell closure, and the overall uncertainties of the 52 − 55 Ti mass values were significantly reduced. Our results conclusively establish the existence of the weak shell effect at N = 32 , narrowing down the abrupt onset of this shell closure. Our data were compared with state-of-the-art ab initio shell model calculations which, despite very successfully describing where the N = 32 shell gap is strong, overpredict its strength and extent in titanium and heavier isotones. These measurements a…
Ground-state electromagnetic moments of calcium isotopes
Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAM
Testing microscopically derived descriptions of nuclear collectivity: Coulomb excitation of Mg-22
Many-body nuclear theory utilizing microscopic or chiral potentials has developed to the point that collectivity might be dealt with in an {\it ab initio} framework without the use of effective charges; for example with the proper evolution of operators, or alternatively, through the use of an appropriate and manageable subset of particle-hole excitations. We present a precise determination of $E2$ strength in $^{22}$Mg and its mirror $^{22}$Ne by Coulomb excitation, allowing for rigorous comparisons with theory. No-core symplectic shell-model calculations were performed and agree with the new $B(E2)$ values while in-medium similarity-renormalization-group calculations consistently underpre…
New determination of double-β-decay properties in48Ca: High-precisionQββ-value measurement and improved nuclear matrix element calculations
We report a direct measurement of the Q-value of the neutrinoless double-beta-decay candidate 48Ca at the TITAN Penning-trap mass spectrometer, with the result that Q = 4267.98(32) keV. We measured the masses of both the mother and daughter nuclides, and in the latter case found a 1 keV deviation from the literature value. In addition to the Q-value, we also present results of a new calculation of the neutrinoless double-beta-decay nuclear matrix element of 48Ca. Using diagrammatic many-body perturbation theory to second order to account for physics outside the valence space, we constructed an effective shell-model double-beta-decay operator, which increased the nuclear matrix element by ab…
$^{78}$Ni revealed as a doubly magic stronghold against nuclear deformation
Nuclear magic numbers, which emerge from the strong nuclear force based on quantum chromodynamics, correspond to fully occupied energy shells of protons, or neutrons inside atomic nuclei. Doubly magic nuclei, with magic numbers for both protons and neutrons, are spherical and extremely rare across the nuclear landscape. While the sequence of magic numbers is well established for stable nuclei, evidence reveals modifications for nuclei with a large proton-to-neutron asymmetry. Here, we provide the first spectroscopic study of the doubly magic nucleus $^{78}$Ni, fourteen neutrons beyond the last stable nickel isotope. We provide direct evidence for its doubly magic nature, which is also predi…
Unexpectedly large charge radii of neutron-rich calcium isotopes
Despite being a complex many-body system, the atomic nucleus exhibits simple structures for certain "magic" numbers of protons and neutrons. The calcium chain in particular is both unique and puzzling: evidence of doubly-magic features are known in 40,48Ca, and recently suggested in two radioactive isotopes, 52,54Ca. Although many properties of experimentally known Ca isotopes have been successfully described by nuclear theory, it is still a challenge to predict their charge radii evolution. Here we present the first measurements of the charge radii of 49,51,52Ca, obtained from laser spectroscopy experiments at ISOLDE, CERN. The experimental results are complemented by state-of-the-art theo…