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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Na5Bi2As(CO4)4 by Materials Project

Na5Bi2As(CO4)4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are twenty inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with five NaO6 octahedra, edges with two BiO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–85°. There are a spread of Na–O bond distances ranging from 2.37–2.70 Å. In the second Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.29–2.70 Å. In the third Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with four NaO6 octahedra, edges with two BiO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 82–88°. There are a spread of Na–O bond distances ranging from 2.29–2.70 Å. In the fourth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with seven NaO6 octahedra, edges with two BiO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–88°. There are a spread of Na–O bond distances ranging from 2.37–2.66 Å. In the fifth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with seven NaO6 octahedra, edges with two BiO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–88°. There are a spread of Na–O bond distances ranging from 2.37–2.68 Å. In the sixth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six NaO6 octahedra, edges with two BiO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 60–88°. There are a spread of Na–O bond distances ranging from 2.38–2.74 Å. In the seventh Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with five NaO6 octahedra, edges with two BiO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 60–86°. There are a spread of Na–O bond distances ranging from 2.38–2.68 Å. In the eighth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six NaO6 octahedra, edges with two BiO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–86°. There are a spread of Na–O bond distances ranging from 2.37–2.71 Å. In the ninth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with five NaO6 octahedra, edges with two BiO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–84°. There are a spread of Na–O bond distances ranging from 2.37–2.69 Å. In the tenth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six NaO6 octahedra, edges with two BiO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 55–86°. There are a spread of Na–O bond distances ranging from 2.29–2.69 Å. In the eleventh Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with five NaO6 octahedra, edges with two BiO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–85°. There are a spread of Na–O bond distances ranging from 2.36–2.70 Å. In the twelfth Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.29–2.75 Å. In the thirteenth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with five NaO6 octahedra, edges with two BiO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–87°. There are a spread of Na–O bond distances ranging from 2.28–2.75 Å. In the fourteenth Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.28–2.75 Å. In the fifteenth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with five NaO6 octahedra, edges with two BiO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 55–88°. There are a spread of Na–O bond distances ranging from 2.28–2.75 Å. In the sixteenth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with four NaO6 octahedra, edges with two BiO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–62°. There are a spread of Na–O bond distances ranging from 2.36–2.65 Å. In the seventeenth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six NaO6 octahedra, edges with two BiO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–86°. There are a spread of Na–O bond distances ranging from 2.36–2.69 Å. In the eighteenth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six NaO6 octahedra, edges with two BiO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–89°. There are a spread of Na–O bond distances ranging from 2.37–2.72 Å. In the nineteenth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six NaO6 octahedra, edges with two BiO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–86°. There are a spread of Na–O bond distances ranging from 2.37–2.63 Å. In the twentieth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with four NaO6 octahedra, edges with two BiO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 84–89°. There are a spread of Na–O bond distances ranging from 2.29–2.69 Å. There are sixteen inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.29–1.31 Å. In the second C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.29 Å) and two longer (1.31 Å) C–O bond length. In the third C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.30 Å) and one longer (1.31 Å) C–O bond length. In the fourth C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. All C–O bond lengths are 1.30 Å. In the fifth C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.30 Å) and one longer (1.31 Å) C–O bond length. In the sixth C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.30 Å) and one longer (1.31 Å) C–O bond length. In the seventh C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.30 Å) and one longer (1.31 Å) C–O bond length. In the eighth C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.30 Å) and one longer (1.31 Å) C–O bond length. In the ninth C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.29–1.31 Å. In the tenth C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. All C–O bond lengths are 1.30 Å. In the eleventh C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. All C–O bond lengths are 1.30 Å. In the twelfth C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.29–1.31 Å. In the thirteenth C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.29–1.31 Å. In the fourteenth C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.29–1.31 Å. In the fifteenth C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.29–1.31 Å. In the sixteenth C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.29 Å) and two longer (1.31 Å) C–O bond length. There are eight inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded to six O2- atoms to form BiO6 octahedra that share edges with four NaO6 octahedra. There are a spread of Bi–O bond distances ranging from 2.33–2.44 Å. In the second Bi3+ site, Bi3+ is bonded to six O2- atoms to form BiO6 octahedra that share edges with four NaO6 octahedra. There are a spread of Bi–O bond distances ranging from 2.34–2.43 Å. In the third Bi3+ site, Bi3+ is bonded to six O2- atoms to form BiO6 octahedra that share edges with four NaO6 octahedra. There are a spread of Bi–O bond distances ranging from 2.34–2.45 Å. In the fourth Bi3+ site, Bi3+ is bonded to six O2- atoms to form BiO6 octahedra that share edges with five NaO6 octahedra. There are a spread of Bi–O bond distances ranging from 2.34–2.43 Å. In the fifth Bi3+ site, Bi3+ is bonded to six O2- atoms to form BiO6 octahedra that share edges with three NaO6 octahedra. There are a spread of Bi–O bond distances ranging from 2.35–2.43 Å. In the sixth Bi3+ site, Bi3+ is bonded to six O2- atoms to form BiO6 octahedra that share edges with five NaO6 octahedra. There are a spread of Bi–O bond distances ranging from 2.36–2.40 Å. In the seventh Bi3+ site, Bi3+ is bonded to six O2- atoms to form BiO6 octahedra that share edges with five NaO6 octahedra. There are a spread of Bi–O bond distances ranging from 2.37–2.40 Å. In the eighth Bi3+ site, Bi3+ is bonded to six O2- atoms to form BiO6 octahedra that share edges with four NaO6 octahedra. There are a spread of Bi–O bond distances ranging from 2.35–2.43 Å. There are four inequivalent As5+ sites. In the first As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share edges with three NaO6 octahedra. All As–O bond lengths are 1.74 Å. In the second As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share edges with six NaO6 octahedra. All As–O bond lengths are 1.73 Å. In the third As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share edges with two NaO6 octahedra. All As–O bond lengths are 1.74 Å. In the fourth As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share edges with six NaO6 octahedra. All As–O bond lengths are 1.73 Å. There are sixty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Na1+, one C4+, and one Bi3+ atom. In the second O2- site, O2- is bonded in a distorted T-shaped geometry to two Na1+ and one As5+ atom. In the third O2- site, O2- is bonded in a distorted T-shaped geometry to two Na1+ and one As5+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one C4+, and one Bi3+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to two Na1+, one C4+, and one Bi3+ atom. In the sixth O2- site, O2- is bonded in a distorted T-shaped geometry to two Na1+ and one As5+ atom. In the seventh O2- site, O2- is bonded in a distorted T-shaped geometry to two Na1+ and one As5+ atom. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one C4+, and one Bi3+ atom. In the ninth O2- site, O2- is bonded in a 1-coor

36 MATERIALS SCIENCE↗
DOE OSTI2025

Nuclear Waste Tank Emission Contributions to Particle Size Distribution

Pollutants from anthropogenic activities including industrial processes are ubiquitous to the environment. To understand the impact from industrial aerosol on climate and human health, industrial aerosol needs to be better characterized. Here, in this study, particle number concentrations were used as a proxy for atmospheric pollutants, which include both particles and gases. Particle concentration and size distribution were measured using a scanning mobility particle sizer (SMPS) approximately 4.5 km from primary industrial areas at the Savannah River Site in Aiken, SC. Industrial areas include numerous nuclear waste storage and processing tanks. The SMPS data were divided into two groups depending on the wind direction measured onsite to categorize transport from the industrial area or from elsewhere. Industrial contributions were found to have a higher concentration of particles with sizes less than 200 nm, 859 ± 564 cm -3 , in comparison to non-industrial attributed particles, 733 ± 495 cm -3 on average from March-July 2021. For sizes larger than 200 nm, industrial and non-industrial particles have a similar concentration, 89 ± 59 cm -3 and 99 ± 61 cm -3 , with non-industrial concentrations being slightly larger. To confirm that industrial particles could travel to the sampling location, air dispersion modeling was completed for specific case studies during the sampling period. The atmospheric dispersion modeling results confirmed that particles released at the industrial areas reached the sampling location when the wind direction was favorable for transport from the industrial areas. The greater concentration of smaller-sized particles in industrial emissions has implications for typical particulate measurements (PM2.5), heath impacts, and climatological influences.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1982

Rolling resistance of electric vehicle tires from track tests

Special low-rolling-resistance tires were made for DOE's ETV-1 electric vehicle. Tests were conducted on these tires and on a set of standard commercial automotive tires to determine the rolling resistance as a function of time during both constant-speed tires and SAE J227a driving cycle tests. The tests were conducted on a test track at ambient temperatures that ranged from 15 to 32 C (59 to 89 F) and with tire pressures of 207 to 276 kPa (30 to 40 psi). At a contained-air temperature of 38 C (100 F) and a pressure of 207 kPa (30 psi) the rolling resistances of the electric vehicle tires and the standard commercial tires, respectively, were 0.0102 and 0.0088 kilogram per kilogram of vehicle weight. At a contained-air temperature of 38 C (100 F) and a pressure of 276 kPa (40 psi) the rolling resistances were 0.009 and 0.0074 kilogram per kilogram of vehicle weight, respectively.

Dustin, M. O.↗
NASA NTRS2018

Long-Term Solar Activity Studies Using Microwave Imaging Observations and Prediction for Cycle 25

We use microwave imaging observations from the Nobeyama Radioheliograph at 17 GHz for long-term studies of solar activity. In particular, we use the polar and low-latitude brightness temperatures as proxies to the polar magnetic field and the active-regions, respectively. We also use the location of prominence eruptions as a proxy to the filament locations as a function of time. We show that the polar microwave brightness temperature is highly correlated with the polar magnetic field strength and the fast solar wind speed. We also show that the polar microwave brightness at one cycle is correlated with the low latitude brightness with a lag of about half a solar cycle. We use this correlation to predict the strength of the solar cycle: the smoothed sunspot numbers in the southern and northern hemispheres can be predicted as 89 and 59, respectively. These values indicate that cycle 25 will not be too different from cycle 24 in its strength. We also combined the rush to the pole data from Nobeyama prominences with historical data going back to 1860 to study the north-south asymmetry of sign reversal at solar poles. We find that the reversal asymmetry has a quasi-periodicity of 3-5 cycles.

N. Gopalswamy↗
NASA NTRS2018

A Decade of MWC 758 Disk Images: Where are the Spiral-Arm-Driving Planets?

Large-scale spiral arms have been revealed in scattered light images of a few protoplanetary disks. Theoretical models suggest that such arms may be driven by and corotate with giant planets, which has called for remarkable observational efforts to look for them. By examining the rotation of the spiral arms for the MWC 758 system over a 10 year timescale, we are able to provide dynamical constraints on the locations of their perturbers. We present reprocessed Hubble Space Telescope (HST)/NICMOS F110W observations of the target in 2005, and the new Keck/NIRC2 L'-band observations in 2017. MWC 758's two well-known spiral arms are revealed in the NICMOS archive at the earliest observational epoch. With additional Very Large Telescope (VLT)/SPHERE data, our joint analysis leads to a pattern speed of 0.°6(sup +3.°3, sub -0.°6)/yr at 3σ for the two major spiral arms. If the two arms are induced by a perturber on a near-circular orbit, its best-fit orbit is at 89 au (0."59), with a 3σ lower limit of 30 au (0."20). This finding is consistent with the simulation prediction of the location of an arm-driving planet for the two major arms in the system.

MWC 758↗
DOE OSTI2020

Materials Data on Na5Mn2As(CO4)4 by Materials Project

Na5Mn2As(CO4)4 crystallizes in the orthorhombic F222 space group. The structure is three-dimensional. there are five inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six NaO6 octahedra, edges with two equivalent MnO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–86°. There are a spread of Na–O bond distances ranging from 2.44–2.53 Å. In the second Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six NaO6 octahedra, edges with two equivalent MnO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 55–89°. There are a spread of Na–O bond distances ranging from 2.42–2.52 Å. In the third Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six NaO6 octahedra, edges with two equivalent MnO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 55–86°. There are a spread of Na–O bond distances ranging from 2.38–2.53 Å. In the fourth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six NaO6 octahedra, edges with two equivalent MnO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–86°. There are a spread of Na–O bond distances ranging from 2.46–2.54 Å. In the fifth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with eight NaO6 octahedra, edges with two equivalent MnO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–89°. There are a spread of Na–O bond distances ranging from 2.43–2.55 Å. Mn3+ is bonded to six O2- atoms to form MnO6 octahedra that share edges with five NaO6 octahedra. There are a spread of Mn–O bond distances ranging from 2.06–2.24 Å. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.29 Å) and one longer (1.31 Å) C–O bond length. In the second C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.29 Å) and one longer (1.31 Å) C–O bond length. There are two inequivalent As5+ sites. In the first As5+ site, As5+ is bonded to four equivalent O2- atoms to form AsO4 tetrahedra that share edges with six NaO6 octahedra. All As–O bond lengths are 1.72 Å. In the second As5+ site, As5+ is bonded to four equivalent O2- atoms to form AsO4 tetrahedra that share edges with four NaO6 octahedra. All As–O bond lengths are 1.72 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one Mn3+, and one C4+ atom. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Na1+, one Mn3+, and one C4+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Mn3+, and one C4+ atom. In the fourth O2- site, O2- is bonded to three Na1+ and one As5+ atom to form distorted edge-sharing ONa3As trigonal pyramids. In the fifth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Na1+, one Mn3+, and one C4+ atom. In the sixth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Na1+, one Mn3+, and one C4+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one As5+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Mn3+, and one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Uncertainty-quantified phenomenological optical potentials for single-nucleon scattering

Optical-model potentials (OMPs) continue to play a key role in nuclear reaction calculations. However, the uncertainty of phenomenological OMPs in widespread use—inherent to any parametric model trained on data—has not been fully characterized, and its impact on downstream users of OMPs remains unclear. Here we assign well-calibrated uncertainties for two representative global OMPs, those of Koning-Delaroche and Chapel Hill '89, using Markov-chain Monte Carlo for parameter inference. By comparing the canonical versions of these OMPs against the experimental data originally used to constrain them, we show how a lack of outlier rejection and a systematic underestimation of experimental uncertainties contributes to bias of, and overconfidence in, best-fit parameter values. Our updated, uncertainty-quantified versions of these OMPs address these issues and yield complete covariance information for potential parameters. Scattering predictions generated from our ensembles show improved performance both against the original training corpora of experimental data and against a new “test” corpus comprising many of the experimental single-nucleon scattering data collected over the last twenty years. Finally, we apply our uncertainty-quantified OMPs to two case studies of application-relevant cross sections. We conclude that, for many common applications of OMPs, including OMP uncertainty should become standard practice. Furthermore, to facilitate their immediate use, digital versions of our updated OMPs and related tools for forward uncertainty propagation are included as Supplemental Material.

150 ≤ A ≤ 189↗
DOE OSTI2025

Bayesian analysis of the 86 Sr ⁢(𝛼,𝛼) reaction to constrain the 86 Sr ⁢(𝛼,𝑛) cross section at astrophysical energies

The alpha optical model potential (𝛼-OMP ) is a phenomenological approach used to describe elastic scattering where multiple reaction channels are open. It is one of the most critical inputs for the calculation of thermonuclear reaction rates in explosive stellar environments, but uncertainties within the 𝛼-OMP lead to imprecise predictions hindering comparisons between calculations and observations. In order to improve the precision of the 𝛼-OMP, additional nuclear physics data are required. In this paper, a measurement of the 86 Sr (𝛼, 𝛼) elastic scattering cross section at multiple energies is reported. Here, a local optical potential is constructed via a fully Bayesian analysis of the elastic scattering data. The resulting uncertainties on the low-energy cross sections relevant to nuclear astrophysics are then calculated and shown to be on the order of 50%.

59 ≤ A ≤ 89↗
DOE OSTI2025

Discovery of new isotopes in the fragmentation of 82 Se and insights into their production

The production cross sections of neutron-rich nuclei for elements just above 60 Ca were measured at the Facility for Rare Isotope Beams (FRIB). Four previously unobserved isotopes ( 63 Sc, 65,66 Ti, and 68 V) were produced, separated, and identified for the first time using the Advanced Rare Isotope Separator (ARIS). One event was found to be consistent with 61 Ca . The new isotopes were created through the interaction of an 82 Se beam with a carbon target at an energy of 228 MeV/𝑢 and a primary beam current of 1.07 p⁢µ⁢A. The event-by-event particle identification of the mass number (𝐴), atomic number (𝑍), and ionic charge state (𝑞) for the reaction products was achieved by combining measurements of energy loss, time of flight, magnetic rigidity, and total kinetic energy. This successful search for new isotopes, conducted at the beginning of FRIB's third year of operation, highlights the facility's discovery potential, which will continue to grow as the beam current increases. The production cross sections were analyzed in the context of the newly developed Δ⁢𝐵⁢𝐸 systematics that provides trends in neutron-rich regions and increased sensitivity to nuclear binding, an important nuclear structure observable. Furthermore, the new systematics addresses gaps in 𝑄 𝑔 -based methods commonly used to interpret the production cross sections of light neutron-rich elements, and provides an efficient empirical approach to describe cross-section trends across isotopic chains. Good agreement with the measured data was obtained when the Δ⁢𝐵⁢𝐸 systematics and abrasion-ablation calculations were performed using the Hartree-Fock-Bogoliubov (HFB-22) mass table.

59 ≤ A ≤ 89↗
DOE OSTI2025

Emerging tension between isospin symmetry and nuclear deformation at 𝐴 = 78

Since the nuclear interaction is, to first order, isospin independent, simple relationships can be derived for 𝐸⁢2 strengths across isobaric analog states within an isobaric triplet. At the same time, there is a well-known relationship between the 2 + excitation energy and the 𝐵(𝐸⁢2;2 + → 0 + ) transition strength in deformed even-even nuclei. Here, we highlight a tension between these two trends in the 𝐴 = 78 isobaric triplet. Recent level-energy determinations indicate that the proton-rich member of the triplet, 78 Zr, is strongly deformed while recent lifetime measurements in 78 Sr and 78 Y, as extrapolated into 78 Zr, would imply that 78 Zr is weakly deformed. Furthermore, we explore the implications of this apparent contradiction and explore potential solutions.

59 ≤ A ≤ 89↗
DOE OSTI2025

Triaxiality and shape dynamics in 70 Ge

The electromagnetic properties of low-lying states in 70 Ge were investigated via multi-step Coulomb excitation of a 70 Ge beam impinging on a 208 Pb target at the ATLAS facility of the Argonne National Laboratory. A total of 27 transitional elements and six diagonal matrix elements coupling 11 low-lying states, were extracted from the measured cross sections. These were used to calculate reduced transition probabilities, spectroscopic quadrupole moments, and rotational invariant shape parameters, providing enhanced precision and expanding on previous studies. The experimental data were compared within several theoretical frameworks, including the generalized triaxial rotor model, configuration interaction shell-model calculations, and computations within the combined frameworks of relativistic density functional theory and the five-dimensional collective Hamiltonian. The results demonstrate a good agreement with the experimental data and, in conjunction with calculations using a two-state mixing model, support significant triaxiality and strong mixing between the 0$^{+}_{1}$ and 0$^{+}_{2}$ states. This results in the magnitudes of their respective quadrupole deformations [β rms (0$^{+}_{1}$) = 0.228 (3), β rms (0$^{+}_{2}$) = 0.273 (1)] being more similar than previously observed. Furthermore, the implications of these results for understanding the complex shape coexistence phenomena, the role of triaxiality, and shape evolution along the Ge isotopic chain are discussed.

59 ≤ A ≤ 89↗
DOE OSTI2025

Constraining the Synthesis of the Lightest 𝑝 Nucleus 74 Se

We provide the first experimental cross section of the 73 As(p, γ) 74 Se reaction to constrain one of the main destruction mechanisms of the p nucleus 74 Se in explosive stellar environments. The measurement was done using a radioactive 73 As beam at incident energies of 3.1 and 3.7 MeV/nucleon. Along with the total cross section measurement, statistical properties of the 74 Se compound nucleus were extracted, constraining the reaction cross section across the entire Gamow window of the γ process. The impact of the experimentally constrained reaction rate on 74 Se production in Type II supernovae is investigated through Monte Carlo one-zone network simulations. The results indicate that the overproduction of 74 Se by Type II supernova models cannot be resolved by nuclear physics and point towards the description of the astrophysical conditions of the γ process.

59 ≤ A ≤ 89↗
DOE OSTI2025

Evidence for triaxial shape coexistence in 74 Ge

The deformation properties of the low-lying states in 74 Ge have been investigated using multistep Coulomb excitation. The measurements were carried out with the advanced 𝛾-ray tracking array, GRETINA, and the CHICO2 particle detector. A comprehensive set of 𝐸⁢2 transition and diagonal matrix elements was deduced following an analysis with the semiclassical coupled-channels code GOSIA. The data were compared with results of calculations carried out within the framework of the generalized triaxial rotor model as well as with the configuration interaction shell model and the symmetric rotor model. Results from calculations with covariant density functional theory were used to construct a five-dimensional collective Hamiltonian for further comparisons with the data. Collectively, the calculations provide an accurate reproduction of the experimental matrix elements and further support an understanding in terms of the coexistence of two axially asymmetric shapes. In conclusion, this leads to an overall interpretation of the underlying structure of 74 Ge requiring triaxiality, as is also the case in the neighboring even-mass Ge isotopes.

59 ≤ A ≤ 89↗
DOE OSTI2025

Measurements of Gamow-Teller transitions from 59 Co via the 59 Co ⁢(𝑡, 3 He +𝛾) charge-exchange reaction and its application to the stellar electron-capture rates

Electron-capture reactions on iron-group nuclei play a crucial role in the late stages of massive star evolution. Since stellar evolution simulations depend on accurate electron-capture rates—which are highly sensitive to the detailed Gamow-Teller (GT) strength distributions—reliable theoretical models are essential. However, experimental data on GT strength distributions are scarce. High-resolution measurements are therefore vital for benchmarking and improving these theoretical calculations. To provide high-resolution data on Gamow-Teller strength distributions of iron-group nuclei and to compare these results with theoretical calculations within this mass region. Differential cross sections for the 59 Co ⁢(𝑡, 3 He)⁢ 59 Fe charge-exchange reaction at 115 MeV/u were measured using the S800 spectrometer. Furthermore, to resolve individual levels that are not distinguishable in the S800 particle singles data, coincident 𝛾 rays from the 59 Fe residual nucleus were detected by using the Gamma-Ray Energy Tracking In-beam Nuclear Array 𝛾-ray tracking array. Here, the Gamow-Teller transition strength distribution from the ground state of 59 Co to 59 Fe was extracted up to an excitation energy of 10 MeV. Additionally, transition strengths for several low-lying states were determined from coincident 𝛾-ray measurements. Electron-capture rates calculated using the present data indicate that these low-lying states contribute significantly to the overall rates in relevant stellar environments. The experimental results show reasonable agreement with theoretical predictions based on both shell-model and projected shell-model calculations. High-resolution data on Gamow-Teller strength distributions—particularly for individual low-lying states—are essential for accurately determining electron-capture rates in iron-group nuclei. Coincident 𝛾-ray measurements provide a powerful tool for obtaining such detailed information. While the present work demonstrates that shell-model calculations successfully reproduce the experimental results, such comparisons are scarce and more experimental data are desirable.

59 ≤ A ≤ 89↗
DOE OSTI2020

Mass measurements of neutron-rich gallium isotopes refine production of nuclei of the first r -process abundance peak in neutron-star merger calculations

We report mass measurements of neutron-rich Ga isotopes 80–85 Ga with TRIUMF's Ion Trap for Atomic and Nuclear science. The measurements determine the masses of 80–83 Ga in good agreement with previous measurements. Here, the masses of 84 Ga and 85 Ga were measured for the first time. Uncertainties between 25 and 48 keV were reached. The new mass values reduce the nuclear uncertainties associated with the production of A ≈ 84 isotopes by the r-process for astrophysical conditions that might be consistent with a binary neutron star (BNS) merger producing a blue kilonova. Our nucleosynthesis simulations confirm that BNS merger may contribute to the first abundance peak under moderate neutron-rich conditions with electron fractions Y e = 0.35–0.38.

59 ≤ A ≤ 89↗
DOE OSTI2020

Examination of the inversion of isobaric analogue states in mirror nuclei

A recent study by Hoff and collaborators [Nature (London) 580, 52 (2020)] presented evidence that the ground-state spin of [Math Processing Error] is different from that of its mirror, [Math Processing Error], likely due to an inversion of the ground- and first-excited states. Here, we assess the likelihood of such an inversion arising from normal isospin-symmetry breaking and, more broadly, whether such phenomena challenge our understanding of charge-symmetry-breaking forces in atomic nuclei. By placing the result within the context of previous experimental and theoretical work we demonstrate that this inversion lies entirely within the bounds of normal isospin-symmetry-breaking behavior. We further note that, in the context of isospin, neither level inversions nor the nuclear ground state hold any special significance.

59 ≤ A ≤ 89↗
DOE OSTI2020

State-of-the-art γ-ray assay of 86 Y for medical imaging

An emerging direction in nuclear medicine is the coupling of a therapeutic isotope with an imaging isotope to form a so-called theranostic pair, which allows one to quantitatively track and image the delivery of the therapeutic isotope. 90 Y is used in several therapy applications and a convenient candidate imaging partner is the positron emitter 86 Y. A 27.6 MBq source of 86 Y was produced at the University of Wisconsin and assayed with the Gammasphere array at Argonne National Laboratory. Over 200 γ-ray transitions were identified, more than double that which was previously known. In conclusion, the positron emission probability inferred from the present level scheme leads to 27.9(12)%, an important (≈14%) reduction with respect to the previously recommended value.

59 ≤ A ≤ 89↗
DOE OSTI2021

In-beam γ-ray spectroscopy of 62,64 Cr

The region of neutron-rich Cr isotopes has garnered much attention in recent years due to a rapid onset of collectivity near neutron number N = 40. We report here on the first γ-ray spectroscopy beyond the ($4$ $^{+}_{1}$) state in 62,64 Cr, using nucleon removal reactions from several projectiles within a rare-isotope beam cocktail. A candidate for the 6 + state in 64 Cr is presented as well as one for, possibly, the second excited 0 + state in 62 Cr. The results are discussed in comparison to the LNPS shell-model predictions that allow for neutron excitations across the N = 40 harmonic oscillator gap into the g 9/2 and d 5/2 orbitals. Here, the calculated level schemes for 62,64 Cr reveal intriguing collective structures. From the predicted neutron particle-hole character of the low-lying states in these Cr isotopes, 62 Cr emerges as a transitional system on the path to the center of the N = 40 island of inversion.

59 ≤ A ≤ 89↗