Further Evidence for Shape Coexistence in

Isomers close to doubly magic _{28}^{78}Ni_{50} provide essential information on the shell evolution and shape coexistence near the Z=28 and N=50 double shell closure. We report the excitation energy measurement of the 1/2^{+} isomer in _{30}^{79}Zn_{49} through independent high-precision mass measurements with the JYFLTRAP double Penning trap and with the ISOLTRAP multi-reflection time-of-flight mass spectrometer. We unambiguously place the 1/2^{+} isomer at 942(10) keV, slightly below the 5/2^{+} state at 983(3) keV. With the use of state-of-the-art shell-model diagonalizations, complemented with discrete nonorthogonal shell-model calculations which are used here for the first time to interpret shape coexistence, we find low-lying deformed intruder states, similar to other N=49 isotones. The 1/2^{+} isomer is interpreted as the bandhead of a low-lying deformed structure akin to a predicted low-lying deformed band in ^{80}Zn, and points to shape coexistence in ^{79,80}Zn similar to the one observed in ^{78}Ni. The results make a strong case for confirming the claim of shape coexistence in this key region of the nuclear chart.

Impact of Nuclear Deformation and Pairing on the Charge Radii of Palladium Isotopes.

The impact of nuclear deformation can been seen in the systematics of nuclear charge radii, with radii generally expanding with increasing deformation. In this Letter, we present a detailed analysis of the precise relationship between nuclear quadrupole deformation and the nuclear size. Our approach combines the first measurements of the changes in the mean-square charge radii of well-deformed palladium isotopes between A=98 and A=118 with nuclear density functional calculations using Fayans functionals, specifically Fy(std) and Fy(Δr,HFB), and the UNEDF2 functional. The changes in mean-square charge radii are extracted from collinear laser spectroscopy measurements on the 4d^{9}5s ^{3}D_{3}→4d^{9}5p ^{3}P_{2} atomic transition. The analysis of the Fayans functional calculations reveals a clear link between a good reproduction of the charge radii for the neutron-rich Pd isotopes and the overestimated odd-even staggering: Both aspects can be attributed to the strength of the pairing correlations in the particular functional which we employ.

Solving the Puzzles of the Decay of the Heaviest Known Proton-Emitting Nucleus

Two long-standing puzzles in the decay of ^{185}Bi, the heaviest known proton-emitting nucleus are revisited. These are the nonobservation of the 9/2^{-} state, which is the ground state of all heavier odd-A Bi isotopes, and the hindered nature of proton and α decays of its presumed 60-µs 1/2^{+} ground state. The ^{185}Bi nucleus has now been studied with the ^{95}Mo(^{93}Nb,3n) reaction in complementary experiments using the Fragment Mass Analyzer and Argonne Gas-Filled Analyzer at Argonne National Laboratory's ATLAS facility. The experiments have established the existence of two states in ^{185}Bi; the short-lived T_{1/2}=2.8_{-1.0}^{+2.3} µs, proton- and α-decaying ground state, and a 58(2)-µs γ-decaying isomer, the half-life of which was previously attributed to the ground state. The reassignment of the ground-state lifetime results in a proton-decay spectroscopic factor close to unity and represents the only known example of a ground-state proton decay to a daughter nucleus (^{184}Pb) with a major shell closure. The data also demonstrate that the ordering of low- and high-spin states in ^{185}Bi is reversed relative to the heavier odd-A Bi isotopes, with the intruder-based 1/2^{+} configuration becoming the ground, similar to the lightest At nuclides.

High-Precision Q-Value Measurement Confirms the Potential of

The ground-state-to-ground-state ß-decay Q value of ^{135}Cs(7/2^{+})→^{135}Ba(3/2^{+}) has been directly measured for the first time. The measurement was done utilizing both the phase-imaging ion-cyclotron resonance technique and the time-of-flight ion-cyclotron resonance technique at the JYFLTRAP Penning-trap setup and yielded a mass difference of 268.66(30) keV between ^{135}Cs(7/2^{+}) and ^{135}Ba(3/2^{+}). With this very small uncertainty, this measurement is a factor of 3 more precise than the currently adopted Q value in the Atomic Mass Evaluation 2016. The measurement confirms that the first-forbidden unique ß^{-}-decay transition ^{135}Cs(7/2^{+})→^{135}Ba(11/2^{-}) is a candidate for antineutrino mass measurements with an ultralow Q value of 0.44(31) keV. This Q value is almost an order of magnitude smaller than those of nuclides presently used in running or planned direct (anti)neutrino mass experiment.

Erratum: Precision Mass Measurements on Neutron-Rich Rare-Earth Isotopes at JYFLTRAP: Reduced Neutron Pairing and Implications for r-Process Calculations [Phys. Rev. Lett. 120, 262701 (2018)].

This corrects the article DOI: 10.1103/PhysRevLett.120.262701.

Precision Mass Measurements on Neutron-Rich Rare-Earth Isotopes at JYFLTRAP: Reduced Neutron Pairing and Implications for r-Process Calculations.

The rare-earth peak in the r-process abundance pattern depends sensitively on both the astrophysical conditions and subtle changes in nuclear structure in the region. This work takes an important step towards elucidating the nuclear structure and reducing the uncertainties in r-process calculations via precise atomic mass measurements at the JYFLTRAP double Penning trap. ^{158}Nd, ^{160}Pm, ^{162}Sm, and ^{164-166}Gd have been measured for the first time, and the precisions for ^{156}Nd, ^{158}Pm, ^{162,163}Eu, ^{163}Gd, and ^{164}Tb have been improved considerably. Nuclear structure has been probed via two-neutron separation energies S_{2n} and neutron pairing energy metrics D_{n}. The data do not support the existence of a subshell closure at N=100. Neutron pairing has been found to be weaker than predicted by theoretical mass models. The impact on the calculated r-process abundances has been studied. Substantial changes resulting in a smoother abundance distribution and a better agreement with the solar r-process abundances are observed.

Single and Double Beta-Decay Q Values among the Triplet

The atomic mass relations among the mass triplet ^{96}Zr, ^{96}Nb, and ^{96}Mo have been determined by means of high-precision mass measurements using the JYFLTRAP mass spectrometer at the IGISOL facility of the University of Jyväskylä. We report Q values for the ^{96}Zr single and double ß decays to ^{96}Nb and ^{96}Mo, as well as the Q value for the ^{96}Nb single ß decay to ^{96}Mo, which are Q_{ß}(^{96}Zr)=163.96(13), Q_{ßß}(^{96}Zr)=3356.097(86), and Q_{ß}(^{96}Nb)=3192.05(16) keV. Of special importance is the ^{96}Zr single ß-decay Q value, which has never been determined directly. The single ß decay, whose main branch is fourfold unique forbidden, is an alternative decay path to the ^{96}Zr ßß decay, and its observation can provide one of the most direct tests of the neutrinoless ßß-decay nuclear-matrix-element calculations, as these can be simultaneously performed for both decay paths with no further assumptions. The theoretical single ß-decay rate has been re-evaluated using a shell-model approach, which indicates a ^{96}Zr single ß-decay lifetime within reach of an experimental verification. The uniqueness of the decay also makes such an experiment interesting for an investigation into the origin of the quenching of the axial-vector coupling constant g_{A}.

Selection of patients for percutaneous closure in nonlacunar cryptogenic stroke associated with patent foramen ovale. Data from the NORDICTUS cooperative registry.

INTRODUCTION: There is an extending use of percutaneous closure of patent foramen ovale (PFO) as therapy for PFO-associated cryptogenic strokes. The aim of our study was to investigate the clinical practice of percutaneous closure of PFO and to analyse the variables for decision-making on the selection of patients for this procedure. METHOD: A prospective observational multicentric survey was conducted using all the cases of cryptogenic stroke/transient ischaemic attack associated with PFO recorded in the NORDICTUS hospital registry during the period 2018-2021. Clinical data, radiological patterns, echocardiogram data and factors related to PFO-associated stroke (thromboembolic disease and paradoxical embolism criteria) were recorded. The indication for closure was analysed according to age (≤/> 60 years) and the characteristics of the PFO. RESULTS: In the group ≤ 60 years (n = 488), 143 patients (29.3%) underwent PFO closure. The most influential variables for this therapy were detection of a high-risk PFO (OR 4.11; IC 2.6-6.5, P < .001), criteria for paradoxical embolism (OR 2.61; IC 1.28-5.28; P = .008) and previous use of antithrombotics (OR 2.67; IC 1.38-5.18; P = .009). In the > 60 years group (n = 124), 24 patients had PFO closure (19%). The variables related to this option were history of pulmonary thromboembolism, predisposition to thromboembolic disease, paradoxical embolism criteria, and high-risk PFO. CONCLUSIONS: The detection of a high-risk PFO (large shunt, shunt with associated aneurysm) is the main criterion for a percutaneous closure-based therapy. Other conditions to consider in the eligibility of patients are the history of thromboembolic disease, paradoxical embolism criteria or the previous use of antithrombotics.

Evidence of a sudden increase in the nuclear size of proton-rich silver-96.

Understanding the evolution of the nuclear charge radius is one of the long-standing challenges for nuclear theory. Recently, density functional theory calculations utilizing Fayans functionals have successfully reproduced the charge radii of a variety of exotic isotopes. However, difficulties in the isotope production have hindered testing these models in the immediate region of the nuclear chart below the heaviest self-conjugate doubly-magic nucleus 100Sn, where the near-equal number of protons (Z) and neutrons (N) lead to enhanced neutron-proton pairing. Here, we present an optical excursion into this region by crossing the N = 50 magic neutron number in the silver isotopic chain with the measurement of the charge radius of 96Ag (N = 49). The results provide a challenge for nuclear theory: calculations are unable to reproduce the pronounced discontinuity in the charge radii as one moves below N = 50. The technical advancements in this work open the N = Z region below 100Sn for further optical studies, which will lead to more comprehensive input for nuclear theory development.

The Advanced LIGO photon calibrators.

The two interferometers of the Laser Interferometry Gravitational-wave Observatory (LIGO) recently detected gravitational waves from the mergers of binary black hole systems. Accurate calibration of the output of these detectors was crucial for the observation of these events and the extraction of parameters of the sources. The principal tools used to calibrate the responses of the second-generation (Advanced) LIGO detectors to gravitational waves are systems based on radiation pressure and referred to as photon calibrators. These systems, which were completely redesigned for Advanced LIGO, include several significant upgrades that enable them to meet the calibration requirements of second-generation gravitational wave detectors in the new era of gravitational-wave astronomy. We report on the design, implementation, and operation of these Advanced LIGO photon calibrators that are currently providing fiducial displacements on the order of 10-18m/Hz with accuracy and precision of better than 1%.