High-precision lifetime measurements in 28Mg were performed to study neutron shell evolution in Mg isotopes and the onset of the =20 island of inversion. Using both the recoil distance and Doppler shift attenuation methods, five lifetimes were measured in addition to six upper limits. The observation of two long-lived, negative-parity states demonstrate the importance of studying Mg isotopes for the contribution of intruder configurations to -shell nuclei. Lifetimes of the 2+1 and 4+1 states of 1.81(5) ps and 172(+11-10)stat.(4)stop.(8)feed.(4)targ.fs, respectively, demonstrate a loss of collectivity with increasing spin in the yrast band, permitting for distinguishing between current theoretical models. These measurements also highlight the progression of yrast structure across the Mg isotopic chain from rotational at =12 to large shape mixing at =16 and back to collective behavior at =20 but with dominating intruder configurations.

The cross-shell excited states of 34Si have been investigated via beta decays of the 4- ground state and the 1+ isomeric state of 34Al. Since the valence protons and valence neutrons occupy different major shells in the ground state as well as the intruder 1+ isomeric state of 34Al, intruder levels of 34Si are populated via allowed beta decays. Spin assignments to such intruder levels of 34Si were established through gamma -gamma angular correlation analysis for the negative-parity states with dominant configurations (nu d3/2)-1 (R) (nu f7/2)1 as well as the positive-parity states with dominant configurations (nu sd )-2 (R) (nu f7/2p3/2)2. The configurations of such intruder states play crucial roles in our understanding of the N = 20 shell gap evolution. A configuration interaction model derived from the FSU Hamiltonian was utilized in order to interpret the intruder states in 34Si. Shell model interaction derived from a more fundamental theory with the valence space in medium similarity renormalization group method was also employed to interpret the structure of 34Si.

The excited states of N=44 ^{74}Zn were investigated via γ-ray spectroscopy following ^{74}Cu β decay. By exploiting γ-γ angular correlation analysis, the 2_{2}^{+}, 3_{1}^{+}, 0_{2}^{+}, and 2_{3}^{+} states in ^{74}Zn were firmly established. The γ-ray branching and E2/M1 mixing ratios for transitions deexciting the 2_{2}^{+}, 3_{1}^{+}, and 2_{3}^{+} states were measured, allowing for the extraction of relative B(E2) values. In particular, the 2_{3}^{+}→0_{2}^{+} and 2_{3}^{+}→4_{1}^{+} transitions were observed for the first time. The results show excellent agreement with new microscopic large-scale shell-model calculations, and are discussed in terms of underlying shapes, as well as the role of neutron excitations across the N=40 gap. Enhanced axial shape asymmetry (triaxiality) is suggested to characterize ^{74}Zn in its ground state. Furthermore, an excited K=0 band with a significantly larger softness in its shape is identified. A shore of the N=40 "island of inversion" appears to manifest above Z=26, previously thought as its northern limit in the chart of the nuclides.

We have measured the cross section of the $^{83}$Rb(p,$\gamma)^{84}$Sr radiative capture reaction in inverse kinematics using a radioactive beam of $^{83}$Rb at incident energies of 2.4 and $2.7 A$ MeV. Prior to the radioactive beam measurement, the $^{84}$Kr(p,$\gamma)^{85}$Rb radiative capture reaction was measured in inverse kinematics using a stable beam of $^{84}$Kr at an incident energy of $2.7 A$ MeV. The effective relative kinetic energies of these measurements lie within the relevant energy window for the $\gamma$ process in supernovae. The central values of the measured partial cross sections of both reactions were found to be $0.17-0.42$ times the predictions of statistical model calculations. Assuming the predicted cross section at other energies is reduced by the same factor leads to a slightly higher calculated abundance of the $p$ nucleus $^{84}$Sr, caused by the reduced rate of the $^{84}$Sr($\gamma$,p)$^{83}$Rb reaction derived from the present measurement.

Background: Detailed spectroscopy of neutron-rich, heavy, deformed nuclei is of broad interest for nuclear astrophysics and nuclear structure. Nuclei in the r-process path and following freeze-out region impact the resulting r-process abundance distribution, and the structure of nuclei midshell in both proton and neutron number helps to understand the evolution of subshell gaps and large deformation in these nuclei. Purpose: We aim to improve the understanding of the nuclear structure of 160Gd, specifically the K & pi; = 4+ bands, as well as study the & beta; decay of 160Eu into 160Gd. Methods: High-statistics decay spectroscopy of 160Gd resulting from the & beta;-decay of 160Eu was collected using the GRIFFIN spectrometer at the TRIUMF-ISAC facility. Results: Two new excited states and ten new transitions were observed in 160Gd. The & beta;-decaying half-lives of the low-and high-spin isomers in 160Eu were determined, and the low-spin state's half-life was measured to be t1/2 = 26.0(8) s, & AP;16% shorter than previous measurements. Lifetimes of the two K & pi; = 4+ bandheads in 160Gd were measured for the first time, as well as & gamma; -& gamma; angular correlations and mixing ratios of intense transitions out of those bandheads. Conclusions: Lifetimes and mixing ratios suggest that the hexadecapole phonon model of the K & pi; = 4+ bandheads in 160Gd is preferred over a simple two-state strong mixing scenario, although further theoretical calculations are needed to fully understand these states. Additionally, the 1999.0-keV state in 160Gd heavily populated in & beta; decay is shown to have positive parity, which raises questions regarding the structure of the high-spin & beta;-decaying state in 160Eu.

Background: Detailed spectroscopy of neutron-rich, heavy, deformed nuclei is of broad interest for nuclear astrophysics and nuclear structure. Nuclei in the $r$-process path and following freeze-out region impact the resulting $r$-process abundance distribution, and the structure of nuclei midshell in both proton and neutron number helps to understand the evolution of subshell gaps and large deformation in these nuclei.Purpose: We aim to improve the understanding of the nuclear structure of $^{160}\mathrm{Gd}$, specifically the ${K}^{\ensuremath{\pi}}={4}^{+}$ bands, as well as study the $\ensuremath{\beta}$ decay of $^{160}\mathrm{Eu}$ into $^{160}\mathrm{Gd}$.Methods: High-statistics decay spectroscopy of $^{160}\mathrm{Gd}$ resulting from the $\ensuremath{\beta}$-decay of $^{160}\mathrm{Eu}$ was collected using the GRIFFIN spectrometer at the TRIUMF-ISAC facility.Results: Two new excited states and ten new transitions were observed in $^{160}\mathrm{Gd}$. The $\ensuremath{\beta}$-decaying half-lives of the low- and high-spin isomers in $^{160}\mathrm{Eu}$ were determined, and the low-spin state's half-life was measured to be ${t}_{1/2}=26.0(8)$ s, $\ensuremath{\approx}16%$ shorter than previous measurements. Lifetimes of the two ${K}^{\ensuremath{\pi}}={4}^{+}$ bandheads in $^{160}\mathrm{Gd}$ were measured for the first time, as well as $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ angular correlations and mixing ratios of intense transitions out of those bandheads.Conclusions: Lifetimes and mixing ratios suggest that the hexadecapole phonon model of the ${K}^{\ensuremath{\pi}}={4}^{+}$ bandheads in $^{160}\mathrm{Gd}$ is preferred over a simple two-state strong mixing scenario, although further theoretical calculations are needed to fully understand these states. Additionally, the 1999.0-keV state in $^{160}\mathrm{Gd}$ heavily populated in $\ensuremath{\beta}$ decay is shown to have positive parity, which raises questions regarding the structure of the high-spin $\ensuremath{\beta}$-decaying state in $^{160}\mathrm{Eu}$.

We have measured the cross section of the $^{83}$Rb(p,$\gamma)^{84}$Sr radiative capture reaction in inverse kinematics using a radioactive beam of $^{83}$Rb at incident energies of 2.4 and $2.7 A$ MeV. Prior to the radioactive beam measurement, the $^{84}$Kr(p,$\gamma)^{85}$Rb radiative capture reaction was measured in inverse kinematics using a stable beam of $^{84}$Kr at an incident energy of $2.7 A$ MeV. The effective relative kinetic energies of these measurements lie within the relevant energy window for the $\gamma$ process in supernovae. The central values of the measured partial cross sections of both reactions were found to be $0.17-0.42$ times the predictions of statistical model calculations. Assuming the predicted cross section at other energies is reduced by the same factor leads to a slightly higher calculated abundance of the $p$ nucleus $^{84}$Sr, caused by the reduced rate of the $^{84}$Sr($\gamma$,p)$^{83}$Rb reaction derived from the present measurement.

The properties of a nanosecond isomer in $^{32}$Si, disputed in previous studies, depend on the evolution of proton and neutron shell gaps near the `island of inversion'. We have placed the isomer at 5505.2(2) keV with $J^{\pi} = 5^-$, decaying primarily via an $E3$ transition to the $2^+_1$ state. The $E3$ strength of 0.0841(10) W.u. is unusually small and suggests that this isomer is dominated by the $(\nu d_{3/2})^{-1} \otimes (\nu f_{7/2})^{1}$ configuration, which is sensitive to the $N=20$ shell gap. A newly observed $4^+_1$ state is placed at 5881.4(13) keV; its energy is enhanced by the $Z=14$ subshell closure. This indicates that the isomer is located in a `yrast trap', a feature rarely seen at low mass numbers.

We have measured the cross section of the( 83)Rb(p, ? ) Sr-84 radiative capture reaction in inverse kinematics using a radioactive beam of Rb-83 at incident energies of 2.4 and 2.7A MeV. Prior to the radioactive beam measurement, the Kr-84(p, ? ) Rb-85 radiative capture reaction was measured in inverse kinematics using a stable beam of Kr-84 at an incident energy of 2.7A MeV. The effective relative kinetic energies of these measurements lie within the relevant energy window for the ? process in supernovae. The central values of the measured partial cross sections of both reactions were found to be 0.17-0.42 times the predictions of statistical model calculations. Assuming the predicted cross section at other energies is reduced by the same factor leads to a slightly higher calculated abundance of the p nucleus Sr-84, caused by the reduced rate of the Sr-84(? , p) Rb-83 reaction derived from the present measurement.

To analyze the cause of the destruction of thin, carbon-backed lithium fluoride targets during a measurement of the fusion of 7Li and 17O, we estimate theoretically the lifetimes of carbon and LiF films due to sputtering, thermal evaporation, and lattice damage and compare them with the lifetime observed in the experiment. Sputtering yields and thermal evaporation rates in carbon and LiF films are too low to play significant roles in the destruction of the targets. We estimate the lifetime of the target due to lattice damage of the carbon backing and the LiF film using a previously reported model. In the experiment, elastically scattered target and beam ions were detected by surface silicon barrier (SSB) detectors so that the product of the beam flux and the target density could be monitored during the experiment. The areas of the targets exposed to different beam intensities and fluences were degraded and then perforated, forming holes with a diameter around the beam spot size. Overall, the target thickness tends to decrease linearly as a function of the beam fluence. However, the thickness also exhibits an increasing interval after SSB counts per beam ion decreases linearly, extending the target lifetime. The lifetime of thin LiF film as determined by lattice damage is calculated for the first time using a lattice damage model, and the calculated lifetime agrees well with the observed target lifetime during the experiment. In experiments using a thin LiF target to induce nuclear reactions, this study suggests methods to predict the lifetime of the LiF film and arrange the experimental plan for maximum efficiency.

This paper presents the Mechanical Ventilator Milano (MVM), a novel intensive therapy mechanical ventilator designed for rapid, large-scale, low-cost production for the COVID-19 pandemic. Free of moving mechanical parts and requiring only a source of compressed oxygen and medical air to operate, the MVM is designed to support the long-term invasive ventilation often required for COVID-19 patients and operates in pressure-regulated ventilation modes, which minimize the risk of furthering lung trauma. The MVM was extensively tested against ISO standards in the laboratory using a breathing simulator, with good agreement between input and measured breathing parameters and performing correctly in response to fault conditions and stability tests. The MVM has obtained Emergency Use Authorization by U.S. Food and Drug Administration (FDA) for use in healthcare settings during the COVID-19 pandemic and Health Canada Medical Device Authorization for Importation or Sale, under Interim Order for Use in Relation to COVID-19. Following these certifications, mass production is ongoing and distribution is under way in several countries. The MVM was designed, tested, prepared for certification, and mass produced in the space of a few months by a unique collaboration of respiratory healthcare professionals and experimental physicists, working with industrial partners, and is an excellent ventilator candidate for this pandemic anywhere in the world.

We have performed the first direct measurement of the ^{83}Rb(p,γ) radiative capture reaction cross section in inverse kinematics using a radioactive beam of ^{83}Rb at incident energies of 2.4 and 2.7A  MeV. The measured cross section at an effective relative kinetic energy of E_{cm}=2.393  MeV, which lies within the relevant energy window for core collapse supernovae, is smaller than the prediction of statistical model calculations. This leads to the abundance of ^{84}Sr produced in the astrophysical p process being higher than previously calculated. Moreover, the discrepancy of the present data with theoretical predictions indicates that further experimental investigation of p-process reactions involving unstable projectiles is clearly warranted.

A high-precision branching ratio measurement for the superallowed Fermi beta(+) emitter Ga-62 was performed with the Gamma-Ray Infrastructure for Fundamental Investigations of Nuclei (GRIFFIN) spectrometer at the Isotope Separator and Accelerator (ISAC) radioactive ion beam facility at TRIUMF. The high efficiency of the GRIFFIN spectrometer allowed 63 gamma -ray transitions, with intensities down to approximate to 1 part per million (ppm) per Ga-62 beta(+) decay, to be placed in the level scheme of the daughter nucleus Zn-62, establishing the superallowed beta branching ratio for Ga-62 decay to be 99.8577(-0.0029)(+0.0023)%, a factor of 4 more precise than the previous world average. For several cascades, gamma-gamma angular correlation measurements were performed to assign spins and/or determine the mixing ratios of transitions. In particular, the spin of the 2.342 MeV excited state in the daughter nucleus Zn-62 was definitively assigned as J = 0. This assignment resolves a discrepancy between previous measurements and has important implications for the isospin symmetry breaking correction, delta(C1), in Ga-62 superallowed Fermi beta decay.

The ^{80}Ge structure was investigated in a high-statistics β-decay experiment of ^{80}Ga using the GRIFFIN spectrometer at TRIUMF-ISAC through γ, β-e, e-γ, and γ-γ spectroscopy. No evidence was found for the recently reported 0_{2}^{+} 639-keV level suggested as evidence for low-energy shape coexistence in ^{80}Ge. Large-scale shell model calculations performed in ^{78,80,82}Ge place the 0_{2}^{+} level in ^{80}Ge at 2 MeV. The new experimental evidence combined with shell model predictions indicate that low-energy shape coexistence is not present in ^{80}Ge.

This corrects the article DOI: 10.1103/PhysRevLett.123.082501.

The TRIUMF Fast Ion Counter (TRIFIC) is a tilted-grid gas counter detector for identifying the impurities in radioactive ion beams (RIBs). Placed at zero degrees downstream of a primary reaction target at the TRIUMF ISAC-II facility, TRIFIC provides accurate Z identification of beam species on an event-by-event basis at a rate of up to 5×105 particles per second and functions as a beam composition monitor at rates up to 5×107 particles per second. With this additional level of diagnostics, RIB experiments at TRIUMF are able to reach levels of sensitivity not previously possible. Details regarding the construction and instrumentation of TRIFIC as well as results from the commissioning of the detector are presented.

The elusive β^{-}p^{+} decay was observed in ^{11}Be by directly measuring the emitted protons and their energy distribution for the first time with the prototype Active Target Time Projection Chamber in an experiment performed at ISAC-TRIUMF. The measured β^{-}p^{+} branching ratio is orders of magnitude larger than any previous theoretical model predicted. This can be explained by the presence of a narrow resonance in ^{11}B above the proton separation energy.