Valence nucleon populations in the Ni isotopes

Measurements of neutron-adding, neutron-removing, and proton-adding reactions were carried out for the four stable even Ni isotopes. Particular attention was paid to obtaining precise values of the cross sections at the peaks of the angular distributions. Tests with sum rules for the neutron data indicate that the results are self-consistent at the level of a few tenths of a nucleon. Data on proton-adding reactions were also obtained and analyzed with a slightly different method—while these data are also consistent, the ambiguities are larger. The occupancies of the neutron orbits derived from the data, the proton vacancies, and the energy centroids of the neutron, neutron-hole, and proton single-particle excitations are obtained. The data also provide some estimate about the closure of the 0f7/2 shell. The results are compared to shell-model calculations and may serve as a reference point for future exploration

Evolution of single-particle structure near the N=20 island of inversion

7 pags., 5 figs., 2 tabs.The single-particle properties of Mg29 have been investigated via a measurement of the Mg28(d,p)Mg29 reaction, in inverse kinematics, using the ISOLDE Solenoidal Spectrometer. The negative-parity intruder states from the fp shell have been identified and used to benchmark modern shell-model calculations. The systematic data on the single-particle centroids along the N=17 isotones show good agreement with shell-model predictions in describing the observed trends from stability toward O25. However, there is also evidence that the effect of the finite geometry of the nuclear potential is playing a role on the behavior of the p orbitals near the particle-emission threshold.This work wassupported by the U.K. Science and Technology Facilities Council [Grants No. ST/P004598/1, No. ST/N002563/1, No. ST/M00161X/1 (Liverpool), No. ST/P004423/1 (Manchester), No. ST/P005314/1 (Surrey), the ISOL-SRS Grant (Daresbury), No. ST/R004056/1 (Ernest Rutherford Fellowship - Gaffney), and No. ST/T004797/1 (Ernest Rutherford Fellowship - Sharp)], the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Contracts No. DE-AC02-06CH11357 (ANL) and No. DE-SC-0014552 (UConn), the European Union’s Horizon 2020 Framework research and innovation program under Grant Agreement No. 654002 (ENSAR2), the Marie Skłodowska-Curie Grant Agreement No. 665779, the Research Foundation Flanders (FWO, Belgium), the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013)/ERC Grant Agreement No. 617156, and the Spanish Ministry of Science and Innovation under Grants No. PGC2018-095640- B-I00“ELEGANT” and No. PID2019-104390GB-I00. This research used targets provided by the Center for Accelerator Target Science at Argonne National Laboratory. The FSU shell-model calculations were performed using the computational facility of the nuclear physics theory group, Florida State University, supported by grants from the U.S. Department of Energy, Office of Science (DE-SC-0009883 (FSU)

Evolution of the nuclear spin-orbit splitting explored via the ³²Si<i>(d,p)</i>³³Si reaction using SOLARIS

The spin-orbit splitting between neutron 1p orbitals at 33Si has been deduced using the single-neutron-adding (d,p) reaction in inverse kinematics with a beam of 32Si, a long-lived radioisotope. Reaction products were analyzed by the newly implemented SOLARIS spectrometer at the reaccelerated-beam facility at the National Superconducting Cyclotron Laboratory. The measurements show reasonable agreement with shell-model calculations that incorporate modern cross-shell interactions, but they contradict the prediction of proton density depletion based on relativistic mean-field theory. The evolution of the neutron 1p-shell orbitals is systematically studied using the present and existing data in the isotonic chains of = 17, 19, and 21. In each case, a smooth decrease in the separation of the - orbitals is seen as the respective p-orbitals approach zero binding, suggesting that the finite nuclear potential strongly influences the evolution of nuclear structure in this region

Structure of Fe 70: Single-particle and collective degrees of freedom

Excited states in the neutron-rich Fe70 nucleus were populated in a one-proton removal reaction from Co71 projectiles at 87 MeV/nucleon. A new transition was observed with the γ-ray tracking array GRETINA and shown to feed the previously assigned 41+ state. In comparison to reaction theory calculations with shell-model spectroscopic factors, it is argued that the new γ ray possibly originates from the 61+ state. It is further shown that the Doppler-reconstructed γ-ray spectra are sensitive to the very different lifetimes of the 2+ and 4+ states, enabling their approximate measurement. The emerging structure of Fe70 is discussed in comparison to LNPS-new large-scale shell-model calculations

Intermediate-energy Coulomb excitation of 58,60,62Cr: The onset of collectivity toward N=40

Intermediate-energy Coulomb excitation measurements were performed on the neutron-rich isotopes 58,60,62Cr. The electric quadrupole excitation strengths, B(E2; 01+→21+), of 60,62Cr are determined for the first time. The results quantify the trend of increasing quadrupole collectivity in the Cr isotopes approaching neutron number N=40. The results are confronted with large-scale shell-model calculations in the fpgd shell using the state-of-the-art LNPS effective interaction. Different sets of effective charges are discussed that provide an improved and robust description of the B(E2) values of the neutron-rich Fe and Cr isotopes in this region of rapid shell evolution. The ratio of the neutron and proton transition matrix elements, |Mn/Mp|, is proposed as an effective tool to discriminate between the various choices of effective charges

Search for jet extinction in the inclusive jet-pT spectrum from proton-proton collisions at s=8 TeV

Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published articles title, journal citation, and DOI.The first search at the LHC for the extinction of QCD jet production is presented, using data collected with the CMS detector corresponding to an integrated luminosity of 10.7  fb−1 of proton-proton collisions at a center-of-mass energy of 8 TeV. The extinction model studied in this analysis is motivated by the search for signatures of strong gravity at the TeV scale (terascale gravity) and assumes the existence of string couplings in the strong-coupling limit. In this limit, the string model predicts the suppression of all high-transverse-momentum standard model processes, including jet production, beyond a certain energy scale. To test this prediction, the measured transverse-momentum spectrum is compared to the theoretical prediction of the standard model. No significant deficit of events is found at high transverse momentum. A 95% confidence level lower limit of 3.3 TeV is set on the extinction mass scale

GOTO065054+593624: An 8.5 mag amplitude dwarf nova identified in real time via Kilonova Seekers

Dwarf novae are astrophysical laboratories for probing the nature of accretion, binary mass transfer, and binary evolution, but their diverse observational characteristics continue to challenge our theoretical understanding. We here present the discovery of and subsequent observing campaign on GOTO065054+593624 (hereafter GOTO0650), a dwarf nova of the WZ Sge type that was discovered in real-time by citizen scientists via the Kilonova Seekers citizen science project. The nova has an outburst amplitude of 8.5 mag. An extensive dataset charts the photometric and spectroscopic evolution of this object, and it covers the 2024 superoutburst. GOTO0650 shows an absence of visible emission lines during the high state, strong H and barely detected He II emission, and high-amplitude echo outbursts on a rapidly decreasing timescale. The comprehensive dataset we present marks GOTO0650 as a candidate period bouncer, and it highlights the important contribution made by citizen scientists to the study of Galactic transients

Relevant aspects of golden retriever muscular dystrophy for the study of Duchenne muscular dystrophy in humans

ABSTRACT: Golden Retriever muscular dystrophy (GRMD) is the most representative model for studying Duchenne muscular dystrophy (DMD) in humans, owing its phenotypic expression. DMD is a recessive disorder linked to the X chromosome in which the loss of dystrophin induces progressive weakness and degeneration of the skeletal and cardiac muscles, which lead to replacement by connective and adipose tissues. Onset of clinical signs occurs between 2 and 5 years of age, and many patients die from heart or respiratory failure. The main studies concerning dystrophic Golden Retrievers (DGR) sought to elucidate the pathophysiology of the disease and its clinical implications to develop therapies and alternative treatments to improve the quality of life and increase longevity of DMD patients. This review presents an overview of relevant contributions of the DGR model for elucidating DMD in humans

Follow up of GW170817 and its electromagnetic counterpart by Australian-led observing programmes

The discovery of the first electromagnetic counterpart to a gravitational wave signal has generated follow-up observations by over 50 facilities world-wide, ushering in the new era of multi-messenger astronomy. In this paper, we present follow-up observations of the gravitational wave event GW170817 and its electromagnetic counterpart SSS17a/DLT17ck (IAU label AT2017gfo) by 14 Australian telescopes and partner observatories as part of Australian-based and Australian-led research programs. We report early- to late-time multi-wavelength observations, including optical imaging and spectroscopy, mid-infrared imaging, radio imaging, and searches for fast radio bursts. Our optical spectra reveal that the transient source emission cooled from approximately 6 400 K to 2 100 K over a 7-d period and produced no significant optical emission lines. The spectral profiles, cooling rate, and photometric light curves are consistent with the expected outburst and subsequent processes of a binary neutron star merger. Star formation in the host galaxy probably ceased at least a Gyr ago, although there is evidence for a galaxy merger. Binary pulsars with short (100 Myr) decay times are therefore unlikely progenitors, but pulsars like PSR B1534+12 with its 2.7 Gyr coalescence time could produce such a merger. The displacement (~2.2 kpc) of the binary star system from the centre of the main galaxy is not unusual for stars in the host galaxy or stars originating in the merging galaxy, and therefore any constraints on the kick velocity imparted to the progenitor are poor