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1. Design and construction of a novel energy-loss optical scintillation system (ELOSS) for heavy‐ion particle identification

   https://doi.org/10.1063/5.0124846  

   Cortesi, M.; Dziubinski, S.; Gade, A.; Zegers, R.; Pereira, J.; Asciutto, J.; Lidia, S.; Bazin, D. (December 2022, Review of Scientific Instruments)

   We present the development of a novel heavy-ion particle-identification (PID) device based on an energy-loss measurement to be implemented in the focal plane of the S800 spectrograph of the Facility for Rare Isotope Beams (FRIB). The new instrument consists of a multi-segmented optical detector [energy-loss optical scintillation system (ELOSS)] that is filled with xenon at pressures ranging from 400 to 800 Torr. The gas volume is surrounded by arrays of photomultiplier tubes and placed along the direction of the beam for recording the prompt scintillation light. The number of detected photons, which is proportional to the energy deposited by the beam particle along its track in the detector volume, allows one to identify the corresponding atomic number (Z). The ELOSS technology is expected to provide high-resolution ΔE measurements (≤0.6% σ) at a high counting rate (>50 kHz). In addition, it has the capability of providing timing information with around 150 ps resolution (σ) compared to the lack of useable timing information of the conventional ionization chamber relying on drifting charges. The development of fast, accurate ΔE measurement techniques for present and future nuclear science facilities will have a high impact on the design and implementation of rare-isotope beam experiments at FRIB and their scientific outcome. As such, ELOSS also represents a prototype for the development of PID detector systems of other planned and future spectrometers, such as the high rigidity spectrometer at FRIB. 

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2. Exploding stars and the synthesis of heavy elements: Introducing the facility for rare isotope beams

   https://doi.org/10.1063/5.0175775  

   Spyrou, Artemis (January 2023, AIP Conference Proceedings)

   Since its birth roughly 60 years ago, the field of nuclear astrophysics has strived to provide a comprehensive description of element synthesis in the Universe. While some of the astrophysical processes responsible for stellar nucleosynthesis are well understood, others remained elusive for decades. One of the major open questions in the field centered on the production of elements heavier than iron. An important breakthrough happened in 2017 when gravitational wave and electromagnetic observatories around the world and in space detected for the first time the merging of two neutron stars and the subsequent production of heavy elements. The puzzle, however, is far from solved. Interpreting the observations requires understanding the nuclear processes that drive these events. My work focuses on the measurement of critical nuclear properties needed to explain neutron-star mergers and other astrophysical observations. In this article, I discuss recent experiments performed at the National Superconducting Cyclotron Laboratory at Michigan State University, as well as new initiatives and plans to undertake work at the next-generation rare isotope facility, the Facility for Rare Isotope Beams. 

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3. Optical potentials for the rare-isotope beam era

   https://doi.org/10.1088/1361-6471/acc348  

   Hebborn, C.; Nunes, F. M.; Potel, G.; Dickhoff, W. H.; Holt, J. W.; Atkinson, M. C.; Baker, R. B.; Barbieri, C.; Blanchon, G.; Burrows, M.; et al (April 2023, Journal of Physics G: Nuclear and Particle Physics)

   Abstract We review recent progress and motivate the need for further developments in nuclear optical potentials that are widely used in the theoretical analysis of nucleon elastic scattering and reaction cross sections. In regions of the nuclear chart away from stability, which represent a frontier in nuclear science over the coming decade and which will be probed at new rare-isotope beam facilities worldwide, there is a targeted need to quantify and reduce theoretical reaction model uncertainties, especially with respect to nuclear optical potentials. We first describe the primary physics motivations for an improved description of nuclear reactions involving short-lived isotopes, focusing on its benefits for fundamental science discoveries and applications to medicine, energy, and security. We then outline the various methods in use today to build optical potentials starting from phenomenological, microscopic, andab initiomethods, highlighting in particular, the strengths and weaknesses of each approach. We then discuss publicly-available tools and resources facilitating the propagation of recent progresses in the field to practitioners. Finally, we provide a set of open challenges and recommendations for the field to advance the fundamental science goals of nuclear reaction studies in the rare-isotope beam era. This paper is the outcome of the Facility for Rare Isotope Beams Theory Alliance (FRIB-TA) topical program ‘Optical Potentials in Nuclear Physics’ held in March 2022 at FRIB. Its content is non-exhaustive, was chosen by the participants and reflects their efforts related to optical potentials. 

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4. Lead isotopes and rare earth elements geochemistry of global phosphate rocks: Insights into depositional conditions and environmental tracing

   https://doi.org/10.1016/j.chemgeo.2023.121715  

   Wang, Zhen; Hill, Robert; Williams, Gordon; Dwyer, Gary S; Hu, Jun; Schnug, Ewald; Bol, Roland; Sun, Yajie; Coleman, Drew S; Liu, Xiao-Ming; et al (November 2023, Chemical Geology)

   Phosphate rock bears both geologically and environmentally significant information. Rare earth elements and yttrium (i.e., REY) characteristics have been commonly used for reconstructing the redox conditions of depositional environments of and the effects of post-depositional diagenetic alteration on phosphate rock. In addition, phosphate rock is typically enriched in a range of trace elements such as uranium (U) and cadium (Cd) that can be dispersed as contaminants into the environment with phosphate mining and phosphate fertilizer application. Here we report the lead (Pb) isotope compositions combined with Pb and REY concentrations of both global sedimentary and igneous phosphate rocks, aiming to evalute the geological origin of phosphate rocks over time and the potential of using them for environmental tracing. Phopshate rocks samples analyzed in this study were sourced from major economic phosphate deposits in the world, including China, Southern Tethys (e.g., Morocco, Tunisia, Israel), the U.S., India, South Africa and Russia. Our results show a wide range of 208Pb/204Pb (35.70 to 60.58), 207Pb/204Pb (15.20 to 18.25), and 206Pb/204Pb (16.369 to 71.806) ratios in phosphate rocks, with sedimentary phosphate rocks being significantly more radiogenic than igneous rocks. The majority of the sedimentray phosphate rocks show a notable isotopic overprinting by non-radiogenic terrestrial Pb, except for those from Israel and Morocco that have the most radiogenic Pb isotope compositions. Correspondingly, phosphate rocks with more radiogenic Pb isotope ratios show relatively pristine seawater REY features, likely suggesting their preservation of the original oxic seawater conditions and/or minimal diagenetic alteration. In contrast, phosphate rocks with less radiogenic Pb isotope compositions show REY indications for more anoxic seawater redox conditions and/or greater diagenetic alteration. We further evaluate the potential utility of Pb isotopes for tracing the associated contamination with phosphate rock mining and fertilizer application in the environment. In most cases, the radiogenic Pb isotope composition of phosphate rocks and corresponding P-fertilizers is distinctive from both natural crustal Pb and major anthropogenic Pb sources (e.g., Pb ore deposits and pesticides), which provides a great advantage for applying Pb isotopes as environmental tracers for metal(loid) contamination from phosphate sources. The combination of Pb isotope ratios and REY proxies could further constrain the Pb source discrimination. Overall, this study provides new Pb isotopic and REY geochemical data on global phosphate rocks and fertilizers, which lays the groundwork for future regional and local studies on both their geological and environmental implications. 

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5. Seasonal aboveground plant biomass estimates at 15 net primary production (NPP) study sites at Jornada Basin LTER from 1989-ongoing

   https://doi.org/10.6073/pasta/5507ade25993c2123e1886a545b509c8  

   Peters, Debra C; Huenneke, Laura F (January 2023, Environmental Data Initiative)

   This data package contains aboveground vegetation cover, volume, and calculated biomass values at the 15 Net Primary Production (NPP) study sites on Jornada Experimental Range (JER) and Chihuahuan Desert Rangeland Research Center (CDRRC) lands. Sites were selected to represent the 5 major ecosystem types in the Chihuahuan Desert (upland grasslands, playa grasslands, mesquite-dominated shrublands, creosotebush-dominated shrublands, tarbush-dominated shrublands). For each ecosystem type, three sites were selected to represent the range in variability in production and plant diversity; thus the locations are not replicates. All sites are excluded from domestic grazing. Eleven sites are in non-grazed pastures, and at the other four sites 1 hectare areas around the observational plots were fenced in 1988. At all sites a grid of 49 (48 at one playa location) 1m x 1m replicate quadrats was laid out when sampling began in 1989. For each quadrat, aboveground biomass has been calculated from two data sources: 1) non-destructive horizontal cover and vertical height measurements of individual plants, or plant parts, within each quadrat, and 2) linear regression coefficients for each plant species derived from off-quadrat cover, height, and harvested biomass measurements. Non-destructive measurements (1) are taken during winter, spring, and fall measurement campaigns, then aggregated by species for each quadrat, and resulting dimensions are used to calculate species biomass (grams) by quadrat and season using using the species-specific regression coefficients derived from dataset 2. This is the most detailed biomass dataset available and can be used to derive values of net primary production between seasons or annually. Each dataset record contains calculated biomass (and related variables) by species, quadrat, season, and site. Data collection is ongoing with new observations in spring, fall, and winter of each year, but this data package may be updated less frequently. Attention: 1) For most species, these data are not appropriate for estimates of percentage cover or volume because of the way the data are collected. 2) Calculated values in this data package have changed over time as the methodology for estimating biomass has changed. If you are updating or adding to an earlier analysis of these data we recommend consulting with the dataset authors or a Jornada data manager. 3) Relating long-term NPP derived from this package with long-term precipitation is problematic given the importance of wet and dry periods and their effect on production in these ecosystems. 4) Data from 2013 and later are currently in provisional status and subject to change as we review the allometric equations used for estimating biomass. See Notes in the methods element for further details. 

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