I.D. Moore

NUCLEAR REACTIONS 3 He (32 S, α) 31 S, E= 128 MeV; measured reaction products, Eγ, Iγ; deduced γ-ray energies, levels, T 1/2, resonances. Comparison with the shell-model code NuShellX calculations. Modern Markov chain Monte Carlo-based Bayesian statistical techniques. The Doppler Shift Lifetimes (DSL2) facility at the TRIUMF Isotope Separator and Accelerator (ISAC-II) facility.

Isomers close to the doubly magic nucleus Ni (, ) provide essential information on the shell evolution and shape coexistence far from stability. The existence of a long-lived isomeric state in Cu has been debated for a long time. We have performed high-precision mass measurements of Cu with the JYFLTRAP double Penning trap mass spectrometer at the Ion Guide Isotope Separator On-Line facility and confirm the existence of such a isomeric state with an excitation energy keV. Based on the ratio of detected ground- and isomeric-state ions as a function of time, we show that the isomer is the shorter-living state previously considered as the ground state of Cu. The result can potentially change the conclusions made in previous works related to the spin-parity and charge radius of the Cu ground state. Additionally, the new Cu reaction -value has an impact on the astrophysical rapid neutron-capture process.

The multinucleon transfer (MNT) reaction approach was successfully employed for the first time to measure the isomeric ratios (IRs) of 211Po isomer (25/2+) and its ground state (9/2+) at the IGISOL facility using a 945 MeV 136Xe beam impinged on 209Bi and natPb targets. The dominant production of isomers compared to the corresponding ground states was consistently revealed in the α-decay spectra. Deduced IR of 211Po populated through the 136Xe+natPb reaction was found to have an enhancement of ≈1.8-times than that observed for the 136Xe+209Bi. State-of-the-art Langevin-type model calculations have been utilized to estimate the spin distribution of an MNT residue. The computations qualitatively corroborate with the considerable increase in the IRs of 211Po produced from 136Xe+natPb compared to 136Xe+209Bi. Theoretical investigations indicate a weak dependence of target spin on the IRs …

We report on new precision mass measurements of neutron-rich Sb and I isotopes from the JYFLTRAP double Penning trap mass spectrometer. We confirm the value from the previous Penning-trap measurement of Sb at the Canadian Penning Trap and therefore rule out the conflicting result from the Experimental Storage Ring. The ground state and isomer in I were resolved and measured directly for the first time. The isomer excitation energy, keV, agrees with the literature but is three times more precise. The measurements have improved the precision of the mass values and confirmed previous results in the majority of cases. However, for I the results differ by 17(6) keV and 23(12) keV, respectively. This could be explained by an unresolved contamination or different ratio of unresolved isomeric states in the case of I.

The absolute mass of Sr was determined using the phase-imaging ion-cyclotron-resonance technique with the JYFLTRAP double Penning trap mass spectrometer. A more precise value for the mass of Sr is essential for providing potential indications of physics beyond the Standard Model through high-precision isotope shift measurements of Sr atomic transition frequencies. The mass excess of Sr was refined to be -80649.229(37) keV/c from high-precision cyclotron-frequency-ratio measurements with a relative precision of 4.810. The obtained mass-excess value is in agreement with the adopted value in the Atomic Mass Evaluation 2020, but is 30 times more precise. With this new value, we confirm the previously observed nonlinearity in the study of the isotope shift of strontium. Moreover, the double-beta () decay value of Sr was directly determined to be 1790.115(37) keV, and the precision was improved by a factor of 30.

The masses of Br, Mo, Pd, Ag, In, Sb and their respective isomeric states have been measured with the JYFLTRAP Penning trap mass spectrometer using the phase-imaging ion-cyclotron-resonance technique. The excitation energies of the isomeric states in Sb and Pd were experimentally determined for the first time, while for Br, Pd and In, the precision of the mass values was substantially improved. In Mo and Pd there were no signs of a long-lived isomeric state. The ground-state measurements of Pd and Ag indicated that both are significantly more bound than the literature values. For Ag, there was no indication of a proposed third long-lived state. The results for the nucleus Br and isomers close to doubly magic Sn have been compared to the shell-model, proton-neutron quasi-particle random-phase approximation (pnQRPA) and the microscopic quasiparticle-phonon model (MQPM) calculations.

High-precision mass measurements of exotic Ag isotopes close to the line have been conducted with the JYFLTRAP double Penning trap mass spectrometer, with the silver ions produced using the recently commissioned inductively-heated hot cavity catcher laser ion source at the Ion Guide Isotope Separator On-Line facility. The atomic mass of Ag was directly determined for the first time. In addition, the atomic masses of -decaying 2 and 8 states in Ag have been identified and measured for the first time, and the precision of the Ag mass has been improved. The newly measured masses, with a precision of 1 keV/c , have been used to investigate the 50 neutron shell closure confirming it to be robust. Precise empirical shell-gap and pairing energies determined with the new ground-state mass data are used to benchmark state-of-the-art\textit {ab initio} calculations with various chiral effective field theory Hamiltonians. In addition, density functional theory (DFT) calculations and configuration-interaction shell-model (CISM) calculations are compared with the experimental results. All theoretical approaches face challenges to reproduce the trend of nuclear ground-state properties in the silver isotopic chain across the 50 neutron shell and toward the proton drip-line. Furthermore, the precise determination of the isomeric excitation energy of Ag serves as a benchmark for\textit {ab initio} predictions of nuclear properties beyond the ground state, specifically for odd-odd nuclei situated in proximity to the proton dripline below Sn.

High-precision mass measurements of exotic Ag isotopes close to the line have been conducted with the JYFLTRAP double Penning trap mass spectrometer, with the silver ions produced using the recently commissioned inductively-heated hot cavity catcher laser ion source at the Ion Guide Isotope Separator On-Line facility. The atomic mass of Ag was directly determined for the first time. In addition, the atomic masses of -decaying 2 and 8 states in Ag have been identified and measured for the first time, and the precision of the Ag mass has been improved. The newly measured masses, with a precision of 1 keV/c, have been used to investigate the 50 neutron shell closure confirming it to be robust. Precise empirical shell-gap and pairing energies determined with the new ground-state mass data are used to benchmark state-of-the-art \textit{ab initio} calculations with various chiral effective field theory Hamiltonians. In addition, density functional theory (DFT) calculations and configuration-interaction shell-model (CISM) calculations are compared with the experimental results. All theoretical approaches face challenges to reproduce the trend of nuclear ground-state properties in the silver isotopic chain across the 50 neutron shell and toward the proton drip-line. Furthermore, the precise determination of the isomeric excitation energy of Ag serves as a benchmark for \textit{ab initio} predictions of nuclear properties beyond the ground state, specifically for odd-odd nuclei situated in proximity to the proton dripline below Sn.

High-resolution laser spectroscopy can be used to precisely measure atomic hyperfine structures and shifts in spectral lines. These nuclear perturbations of the atomic structure provide insight into the bulk properties of nuclei as well as the intricate details of the nucleon–nucleon interactions inside the atomic nucleus. Collinear laser spectroscopy in particular allows for the extraction of nuclear moments and changes in the mean-square charge radii with high precision. We provide an overview of the manner in which collinear laser spectroscopy is currently implemented at radioactive ion beam facilities. Through examples, we illustrate how this method gives access to direct and nuclear model-independent evidence for changes in nuclear spins, electromagnetic moments and nuclear radii caused by structural changes in atomic nuclei.

The first direct determination of the ground-state-to-ground-state -decay -value of As to Se was performed by measuring their atomic mass difference utilizing the double Penning trap mass spectrometer, JYFLTRAP. The resulting -value is 684.463(70) keV, representing a remarkable 24-fold improvement in precision compared to the value reported in the most recent Atomic Mass Evaluation (AME2020). With the significant reduction of the uncertainty of the ground-state-to-ground-state -value and knowledge of the excitation energies in Se from -ray spectroscopy, the ground-state-to-excited-state -value of the transition As (3/2, ground state) Se (5/2, 680.1035(17) keV) was refined to be 4.360(70) keV. We confirm that this potential low -value -decay transition for neutrino mass determination is energetically allowed at a confidence level of about 60. Nuclear shell-model calculations with two well-established effective Hamiltonians were used to estimate the partial half-life for the low -value transition. The half-life was found to be of the order of 10 years, which makes this candidate a potential source for rare-event experiments searching for the electron antineutrino mass.

We 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− 123 Ag. 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 I π= 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.

Collinear laser spectroscopy was performed on the isomer of the aluminium isotope Al 26 m. The measured isotope shift to Al 27 in the 3 s 2 3 p P 3/2○ 2→ 3 s 2 4 s S 1/2 2 atomic transition enabled the first experimental determination of the nuclear charge radius of Al 26 m, resulting in R c= 3.130 (15) fm. This differs by 4.5 standard deviations from the extrapolated value used to calculate the isospin-symmetry breaking corrections in the superallowed β decay of Al 26 m. Its corrected F t value, important for the estimation of V u d in the Cabibbo-Kobayashi-Maskawa matrix, is thus shifted by 1 standard deviation to 3071.4 (1.0) s.

A Low Energy Branch for the MARA separator, MARA-LEB, is under construction at the University of Jyväskylä, Finland. It will be used to purify and study exotic beams initially via nuclear decay and laser spectroscopy. Two experiments have been performed using the MARA separator to determine the acceptance of the gas cell and to assess the feasibility of future experiments at the new facility. Products of different reaction mechanisms have been produced and their transmission from the focal plane of MARA into the LEB gas cell has been estimated. In one experiment, medium-mass nuclei have been produced in fusion–evaporation reactions. In a second experiment, with the primary goal of studying the non-fusion reaction dynamics, heavy target-like fragments from multi-nucleon transfer reactions have been produced. Production cross sections have been measured and are presented in this work.

In this paper we present the first high-resolution laser spectroscopy results obtained at the GISELE laser laboratory of the GANIL-SPIRAL2 facility, in preparation for the first experiments with the S 3-Low Energy Branch. Studies of neutron-deficient radioactive isotopes of erbium and tin represent the first physics cases to be studied at S 3. The measured isotope-shift and hyperfine structure data are presented for stable isotopes of these elements. The erbium isotopes were studied using the 4 f 12 6 s 2 3 H 6→ 4 f 12 (3 H) 6 s 6 p J= 5 atomic transition (415 nm) and the tin isotopes were studied by the 5 s 2 5 p 2 (3 P 0)→ 5 s 2 5 p 6 s (3 P 1) atomic transition (286.4 nm), and are used as a benchmark of the laser setup. Additionally, the tin isotopes were studied by the 5 s 2 5 p 6 s (3 P 1)→ 5 s 2 5 p 6 p (3 P 2) atomic transition (811.6 nm), for which new isotope-shift data was obtained and the corresponding field-shift F …

Pa 225 and Ac 221 were produced at the IGISOL facility through proton-induced fusion-evaporation reactions and have been studied using α-particle spectroscopy, as well as α− γ and α-electron coincidence spectroscopy. The level scheme of Ac 221, daughter of Pa 225, and of Fr 217, daughter of Ac 221 were reconstructed. An interpretation of Ac 221 levels as K= 5/2±and K= 3/2±parity-doublet bands is proposed. Such bands appear in reflection-asymmetric models and would be an indication of a static reflection asymmetric shape for Ac 221.

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, molecular, nuclear, astrophysical, and chemical advances which provide the foundation for their study, describe the facilities where these species are and will be produced, and provide an outlook for the future of this nascent field.

We report on the precise mass measurement of the Hf isotope performed at the Ion Guide Isotope Separator On-Line facility using the JYFLTRAP double Penning trap mass spectrometer. The new mass-excess value,  keV, is in agreement with the literature while being nine times more precise. The newly determined Hf electron-capture Q value,  keV, allows us to firmly reject the population of an excited state at 1578 keV in Lu and 11 transitions tentatively assigned to the decay of Hf. Our refined mass value of Hf reduces mass-related uncertainties in the reaction rate of HfHf. Thus, the rate for the main photodisintegration destruction channel of the p nuclide Hf in the relevant temperature region for the process is better constrained.

We report on precision mass measurements of Ru 113, 115, 117 performed with the JYFLTRAP double Penning trap mass spectrometer at the Accelerator Laboratory of University of Jyväskylä. The phase-imaging ion-cyclotron-resonance technique was used to resolve the ground and isomeric states in Ru 113, 115 and enabled for the first time a measurement of the isomer excitation energies, E x (Ru m 113)= 100.5 (8) keV and E x (Ru m 115)= 129 (5) keV. The ground state of Ru 117 was measured using the time-of-flight ion-cyclotron-resonance technique. The new mass-excess value for Ru 117 is around 36 keV lower and seven times more precise than the previous literature value. With the more precise ground-state mass values, the evolution of the two-neutron separation energies is further constrained and a similar trend as predicted by the BSkG1 model is obtained up to the neutron number N= 71.

The β decays of more than twenty fission fragments were measured in the first experiments with radioactive-ion beams employing the Decay Total Absorption γ-ray Spectrometer. In this work, we summarize the main results obtained so far from this experimental campaign carried out at the Ion Guide Isotope Separator On-Line facility. The advances introduced for these studies represent the state-of-the-art of our analysis methodology for segmented spectrometers.

Phys. Rev. C 107, 029901 (2023) - Erratum: High-resolution, accurate multiple-reflection time-of-flight mass spectrometry for short-lived, exotic nuclei of a few events in their ground and low-lying isomeric states [Phys. Rev. C 99, 064313 (2019)] Skip to Main Content APS Logo Journals Physical Review Letters Physical Review X PRX Energy PRX Life PRX Quantum Reviews of Modern Physics Physical Review A Physical Review B Physical Review C Physical Review D Physical Review E Physical Review Research Physical Review Accelerators and Beams Physical Review Applied Physical Review Fluids Physical Review Materials Physical Review Physics Education Research Physical Review Physical Review (Series I) Physics Physique Fizika Physics Magazine Help/Feedback Search/Article Lookup Log in Physical Review C covering nuclear physics Highlights Recent Accepted Collections Authors Referees …