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Park, J.

Publications and source records attributed to Park, J..

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Precise measurement of nuclear interaction cross sections towards neutron-skin determination with R 3 B

The R 3 B (Reactions with Relativistic Radioactive Beams) experiment as a major instrument of the NUSTAR collaboration for the research facility FAIR in Darmstadt is designed for kinematically complete studies of reactions with high-energy radioactive beams. Part of the broad physics program of R 3 B is to constrain the asymmetry term in the nuclear equation-of-state and hence improve the description of highly asymmetric nuclear matter (e.g., in neutron stars). For a precise determination of the neutron-skin thickness – an observable which is directly correlated with the symmetry energy in theoretical calculations – by measuring absolute fragmentation cross sections, it is essential to quantify the uncertainty and challenge the reaction model under stable conditions. During the successful FAIR Phase-0 campaign of R 3 B, we precisely measured the energy dependence of total interaction cross sections in 12 C + 12 C collisions, for a direct comparison with calculations based on the eikonal reaction theory.

Ponnath, L. (ORCID:0000000286742624)↗
DOE OSTI2024

Enhanced plasma performance in C-2W advanced beam-driven field-reversed configuration experiments

TAE Technologies’ fifth-generation fusion device, C-2W (also called ‘Norman’), is the world’s largest compact-toroid device and has made significant progress in field-reversed configuration (FRC) plasma performance. C-2W produces record breaking, macroscopically stable, high-temperature advanced beam-driven FRC plasmas, dominated by injected fast particles and sustained in steady state, which is primarily limited by neutral-beam (NB) pulse duration. The NB power supply system has recently been upgraded to extend the pulse length from 30 ms to 40 ms, which allows for a longer plasma lifetime and thus better characterization and further enhancement of FRC performance. An active plasma control system is routinely used in C-2W to produce consistent FRC performance as well as for reliable machine operations using magnet coils, edge-biasing electrodes, gas injection and tunable-energy NBs. Google’s machine learning framework for experimental optimization has also been routinely used to enhance plasma performance. D

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Measurement of nuclear interaction cross sections towards neutron-skin thickness determination

The accuracy of reaction theories used to extract properties of exotic nuclei from scattering experiments is often unknown or not quantified, but of utmost importance when, e.g., constraining the equation of state of asymmetric nuclear matter from observables as the neutron-skin thickness. In order to test the Glauber multiple-scattering model, the total interaction cross section of 12 C on carbon targets was measured at initial beam energies of 400, 550, 650, 800, and 1000 MeV/nucleon. The measurements were performed during the first experiment of the newly constructed R 3 B (Reaction with Relativistic Radioactive Beams) experiment after the start of FAIR Phase-0 at the GSI/FAIR facility with beam energies of 400, 550, 650, 800, and 1000 MeV/nucleon. The combination of the large-acceptance dipole magnet GLAD and a newly designed and highly efficient Time-of-Flight detector enabled a precise transmission measurement with several target thicknesses for each initial beam energy with an experimental uncertainty of ±0.4%. A comparison with the Glauber model revealed a discrepancy of around 3.1% at higher beam energies, which will serve as a crucial baseline for the model-dependent uncertainty in future fragmentation experiments.

Astronomy & Astrophysics↗
NASA NTRS2019

Genetic Relationship Between Martian Chassignites and Nakhlites Revealed from Noble Gases

A group called as Martian meteorites is composed of shergottites, nakhlites, chassignites, and orthopyroxenite, and they are thought to be derived from Mars. Among the Martian meteorites nakhlites and chassignites show similar cosmic-ray exposure (CRE) ages of 11-12 million years, although petrologic characteristics are very different between them. Both nakhlites and chassignites indicate similar cooling rates, and would have cooled in identical scale of igneous bodies. However, the relationship between nakhlites and chassignites is still unclear, although they might have ejected at the same time, i.e., by accidentally coincidental impact events which occurred at different places on Mars or by a single impact which excavated both nakhlites and chassignites residing in a relatively small area. Here we propose that the chassignites show a genetically close relationship with nakhlites, i.e., both groups could be located within a relatively narrow area from where a single impact could have launched those meteorites, based on noble gas data obtained in our laboratory. If chassignites were really ejected with nakhlites by a single impact, both types of meteorites will provide us with geological/petrological profile in the area where both pyroxene-rich lava (nakhlites) and dunite-rich rocks (chassignites) are located close to the Martian surface. [i.e. discusses NWA 2737, etc. (Martian meteorites that fell in Northwest Africa)]

Nagao, K.↗
NASA NTRS2017

Ne-20/Ne-22 in the Martian Atmosphere: New Evidence from Martian Meteorites

Analyses of Ne trapped in "pods" of impact melt in the Elephant Moraine 79001 (EET 79001) Martian meteorite led to suggest (Ne-20/Ne-22) approx.10 in the Martian atmosphere (MA). In contrast, obtained trapped (Ne-20/Ne-22)Tr approx.7 from an impact melt vein in Yamato 793605 (Y-793605) and concluded that the isotopic composition of Martian Ne remained poorly defined. A "pyroxene-rich" separate from Dhofar 378 (Dho 378) analyzed gave a comparatively high trapped Ne concentration and (Ne-20/Ne-22) = 7.3+/-0.2 in agreement with the Y-793605 value. We explore the hypothesis that Martian Ne was trapped in the Dho 378 meteorite in a manner similar to entrapment of terrestrial Ne in tektites strengthening the "Martian atmosphere" interpretation. We also report new data for Northwest Africa 7034 (NWA 7034) that are consistent with the Ne data for Dho 378.

Park, J.↗
NASA NTRS2016

Feldspathic Meteorites MIL 090034 and 090070: Late Additions to the Lunar Crust

Our studies of the Miller Range lunar meteorites MIL 090034, 090036, and 090070 show them to be a diverse suite of rocks from the lunar highlands hereafter referred to as MIL 34, MIL 36, and MIL 70, resp. MIL34 and MIL70, the focus of this work, are crystalline melt breccias. Plagioclase compositions in both peak sharply around An96-97. Mg numbers of olivine vary from 58-65 with a few higher values. MIL36 is a regolith breccia. MIL 34 and MIL 70 have some of the highest Al2O3 abundances of lunar highland meteorites, indicating that they have among the largest modal abundances of plagioclase for lunar meteorites. They have lower Sc and Cr abundances than nearly all lunar highland meteorites except Dho 081, Dho 489 and Dho 733. MIL34 and MIL70 also have similar cosmic ray exposure (CRE) ages of approximately 1-2 Ma indicating they are launch paired. (MIL36 has a larger CRE age approximately greater than 70 Ma). Park et al. found a variation in Ar-Ar ages among subsamples of MIL 34 and MIL70, but preferred ages of 3500+/-110 Ma for the "Dark" phase of MIL 34 anorthite and 3520+/-30 Ma for the "Light" phase of MIL70. Bouvier et al. reported a Pb-Pb age of 3894+/-39 Ma for a feldspathic clast of MIL 34 and a similar age for a melt lithology. Here we reexamine the Rb-Sr and Sm-Nd isotopic data, which show complexities qualitatively consistent with those of the Ar-Ar and Pb-Pb data. The Sm-Nd data in particular suggest that the feldspathic compositions of MIL 34 and MIL 70 formed during initial lunar geochemical differentiation, and REE modeling suggests a relatively late-stage formation.

Nyquist, L. E.↗
NASA NTRS2016

40Ar/39Ar Ages of Carbonaceous Xenoliths in 2 HED Meteorites

The generally young K/Ar and 40Ar/39Ar ages of CM chondrites made us wonder whether carbonaceous xenoliths (CMX) entombed in Howardite–Eucrite–Diogenite (HED) meteorites might retain more radiogenic 40Ar than do ‘free-range’ CM-chondrites. To find out, we selected two HED breccias with carbonaceous inclusions in order to compare the 40Ar/39Ar release patterns and ages of the inclusions with those of nearby HED material. Carbonaceous inclusions (CMXs) in two HED meteorites lost a greater fraction of radiogenic 40Ar than did surrounding host material, but a smaller fraction of it than did free-range CM-chondrites such as Murchison or more heavily altered ones. Importantly, however, the siting of the CMXs in HED matrix did not prevent the 40Ar loss of about 40 percent of the radiogenic 40Ar, even from phases that degas at high laboratory temperatures. We infer that carbonaceous asteroids with perihelia of 1 astronomical unit probably experience losses of at least this size. The usefulness of 40Ar/39Ar dating for samples returned from C-type asteroids may hinge, therefore, on identifying and analyzing separately small quantities of the most retentive phases of carbonaceous chondrites.

Turrin, B.↗
NASA NTRS2015

Mineralogy, Petrology, Chronology, and Exposure History of the Chelyabinsk Meteorite and Parent Body

The Chelyabinsk meteorite fall on February 15, 2013 attracted much more attention worldwide than do most falls. A consortium led by JSC received 3 masses of Chelyabinsk (Chel-101, -102, -103) that were collected shortly after the fall and handled with care to minimize contamination. Initial studies were reported in 2013; we have studied these samples with a wide range of analytical techniques to better understand the mineralogy, petrology, chronology and exposure history of the Chelyabinsk parent body.

Righter, K.↗
NASA NTRS2014

Sm-Nd and Rb-Sr Isotopic Systematics of a Heavily Shocked Martian Meteorite Tissint and Petrogenesis of Depleted Shergottites

Tissint is a very fresh Martian meteorite that fell near the town of Tissint in Morocco on July 18, 2011. It contains abundant olivine megacrysts (~23%) in a fine-grained matrix of pyroxene (~55%), maskelynitized plagioclase (~15%), opaques (~4%) and melt pockets (~3%) and is petrographically similar to lithologies A and C of picritic shergottite EETA 79001 [1,2]. The presence of 2 types of shock-induced glasses and all 7 high-pressure mineral phases that were ever found in melt pockets of Martian meteorites suggests it underwent an intensive shock metamorphism of ~25 GPa and ~2000 C localized in melt pockets [2]. Mineral textures suggest that olivines, pyroxenes and plagioclases probably did not experience such hightemperature. Earlier determinations of its age yielded 596+/-23 Ma [3] and 616+/-67 Ma [4], respectively, for the Sm-Nd system and 583+/-86 Ma for the Lu-Hf system [4], in agreement with the 575+/-18 Ma age of the oldest olivine-phyric depleted shergottite Dho 019 [5]. However, the exposure ages of Tissint (~1 Ma [1, 6, 7]) and Dho 019 (~20 Ma [8]) are very different requiring two separate ejection events. These previously determined Sm-Nd and Lu-Hf ages are older than the Ar-Ar maskelynite plateau age of 524+/-15 Ma [9], reversing the pattern usually observed for Martian meteorites. In order to clarify these age issues and place models for Tissint's petrogenesis on a firm basis, we present new Rb-Sr and Sm- Nd isotopic results for Tissint, and discuss (a) the shock effects on them and the Ar-Ar chronometer, (b) correlation of the determined ages with those of other depleted shergottites, and (c) the petrogenesis of depleted shergottites. Since the meteorite is a recent fall, terrestrial contamination is expected to be minimal, but, the strong shock metamorphism might be expected to compromise the equilibrium of the isotopic systems.

Shih, C.-Y.↗
NASA NTRS2014

A Comparison of Anorthositic Lunar Lithologies: Variation on the FAN Theme

Certain anorthositic rocks that are rare in the returned lunar samples have been identified among lunar meteorites. The variety of anorthosites in the Apollo collection also is more varied than is widely recognized. James eta. identified three lithologies in a composite clast o ferroan anorthosite (FAN)-suite rocks in lunar breccia 64435. They further divided all FANs into four subgroups: anorthositic ferroan (AF), mafic magnesian (MM), mafic ferroan (MF), and anorthositic sodic (AS, absent in the 64435 clast). Here we report Sm-Nd isotopic studies of the lithologies present in the 64435 composite clast and compare the new data to our previous data for lunar anorthosites incuding lunar anorthositic meteorites. Mineralogy-petrography, in situ trace element studies, Sr-isotope studies, and Ar-Ar chronology are included, but only the Nd-isotopic studies are currently complete.

Nyquist, L. E.↗
NASA NTRS2014

Ar-40/Ar-39 Studies of Martian Meteorite RBT 04262 and Terrestrial Standards

Park et al. recently presented an Ar-40/Ar-39 dating study of maskelynite separated from the Martian meteorite RBT 04262. Here we report an additional study of Ar-40/Ar-39 patterns for smaller samples, each consisting of only a few maskelynite grains. Considered as a material for Ar-40/Ar-39 dating, the shock-produced glass maskelynite has both an important strength (relatively high K concentration compared to other mineral phases) and some potentially problematic weaknesses. At Rutgers, we have been analyzing small grains consisting of a single phase to explore local effects that might be averaged and remain hidden in larger samples. Thus, to assess the homogeneity of the RBT maskelynite and for comparison with the results of, we analyzed six approx. 30 microgram samples of the same maskelynite separate they studied. Furthermore, because most Ar-40/Ar-39 are calculated relative to the age of a standard, we present new Ar-40/Ar-39 age data for six standards. Among the most widely used standards are sanidine from Fish Canyon (FCs) and various hornblendes (hb3gr, MMhb-1, NL- 25), which are taken as primary standards because their ages have been determined by independent, direct measurements of K and A-40.

Park, J.↗
NASA NTRS2013

Are Soft Short Tests Good Indicators of Internal Li-ion Cell Defects?

The self discharge test at full state of charge, may not be a good one to detect subtle defects since the li-ion chemistry has the highest self discharge at full state of charge. One should characterize self discharge versus storage time for each cell manufacturer/design to differentiate between normal self discharge and that due to a subtle manufacturing defect. The various soft short test methods indicate that if this test is carried out at full discharge (0% SOC) with all capacity removed (by lowering the current load in a stepwise manner to the same end of discharge voltage), then the cells need to be placed in storage for more than 72 hours to get a good analysis on the presence of subtle defects since it takes more than 72 hours to achieve voltage stabilization. If the cells are to be charged up even to a small percentage (ex. 1%), 72 hours are sufficient to determine issues. However, the pass/fail criteria should be based on a valid OCV decline. Less than 10 mV voltage decline is not a good method to detect subtle defects. As mentioned in the first bullet, self discharge is a competing reaction when a charge is introduced and hence a characterization of the self discharge versus storage time is required to fully correlate voltage decline to a failure due to a subtle defect. Soft short test method cannot be relied on for defect detection because cells with and without voltage decline seemed to have similar defects and characteristics. Screening methods such as internal resistance and capacity as well as a 3-sigma range for OCV, mass and dimensions should be used to screen out outliers. A very critical aspect in the understanding of subtle defects is to carry out destructive analysis of cells from every lot to confirm the quality of production and screen all cells and batteries in a stringent manner to have a high quality set of flight cells. Self Discharge Test: Fully charged cells shall be placed in Open circuit stand for 72 hours (OCV measurement twice a day); continue for total of 14 days with 1 reading per day 2. Soft Short Test 1: Fully charge; cells discharged to manufacturer's end of disch. Voltage (EODV) cutoff at C/5 rate; stand for 30 minutes; discharge with C/500 to the same EODV. stand for another 30 minutes; discharge the cells again using C/1000 current to the same EODV. OCV measurements twice a day for 72 hours and then for total of 14 days (data collection same as in 1.) 3. Soft Short Test 2: Fully charge; cells discharged to the manuf. EODV with a C/13 constant current; provide a 10 hour rest, discharge again to the same EODV with a current of C/250, provide a 10 hour rest, discharge again using a C/250 rate, provide a 24 hour rest, charge using C/250 to 3.15 V (for ~12 hours). OCV measurements twice a day for at 72 hours. (data collection same as in 1.) 4. Soft Short Test 3: Fully charge; cells shall be discharged using C/10 current to manuf. EODV. Allow the cell to remain at Open circuit for 10 seconds. Discharge the cell at C/20 rate to the same EODV, hold open circuit for 24 hours. Discharge the cells at C/200 rate to the same end of voltage cutoff and hold open circuit for 24 hours. Discharge the cells one more time at C/200 rate to the same EODV and hold open circuit for 36 hours. Charge at C/200 rate to 3.15 V and hold for 3 days. Record OCV during the open circuit stand periods every 12 hours and at the beginning and end of the 3 day hold (include the 12 hour OCV recording during this time also). Capacity Cycling: Cells with declining voltages - one cell from each manufacturer chosen for cycling Destructive Physical Analysis (DPA): Cells with and without decline chosen from each lot for DPA.

Jeevarajan, J.↗
NASA NTRS2013

Mineralogical, Chemical, and Isotopic Heterogeneity in Zagami: Evidence for a Complex Petrogenesis

Textural variations in the shergottite Zagami were initially interpreted as evidence that it formed in a heterogeneous lava flow. Variations in initial Sr-87/Sr-86 ratios between a Coarse Grained (CG) and a Fine Grained (FG) lithology and evidence for more extensive fractionation of the Rb/Sr ratio in a Dark Mottled Lithology (DML) are consistent with such an interpretation. More recently, Niihara et al. and Misawa et al. have reported the mineralogy and Sr-isotopic systematics of an Olivine Rich Lithology (ORL) found in association with the coarse-grained DML lithology in the Kanagawa Zagami specimen [6,7]. Here we call this lithology DML(Ka) to maintain a distinction with DML(USNM) as studied. An Ar-Ar study by Park et al. of a late stage K-rich melt enriched in K2O to approx 7% and intruded into ORL yielded an Ar-Ar age of 202+/0 7 Ma. The present work extends the study of Kanagawa Zagami to Nd-isotopes.

Nyquist, L. E.↗
NASA NTRS2013

Ar-Ar and Rb-Sr Ages of the Tissint Olivine-phyric Martian Shergottite

The fifth martian meteorite fall, Tissint, is an olivine-phyric shergottite that contains olivine macrocrysts (approximately 1.5 mm) [1]. [2] reported the Sm-Nd age of Tissint as 596 plus or minus 23 Ma along with Rb-Sr data that defined no isochron. [3] reported Lu-Hf and Sm-Nd ages of 583 plus or minus 86 Ma and 616 plus or minus 67 Ma, respectively. The cosmic-ray exposure ages of Tissint are 1.10 plus or minus 0.15 Ma based on 10Be [4], and 1.0-1.1 Ma, based on 3He, 21Ne, and 38Ar [5,6].We report Ar-Ar ages and Rb-Sr data.

Park, J.↗
NASA NTRS2013

Consortium Study of the Chelyabinsk Meteorite

On February 15, 2013 approximately 17 m asteroid hit Earth, causing shock waves and air blasts over a portion of Russia. A significant amount of material has been recovered from this meteorite fall, officially named Chelyabinsk.

Righter, K.↗
NASA NTRS2013

Ar-40/Ar-39 Ages for Maskelynites and K-Rich Melt from Olivine-Rich Lithology in (Kanagawa) Zagami

We report Ar/Ar release patterns for small maskelynite grains and samples of a K-rich phase separated from the basaltic shergottite Zagami. The purpose of the work is to investigate the well-known discrepancy between published Ar/Ar ages of Zagami, >200 Ma, and its age of approx. 170 Ma as determined by other methods [1-6]. Niihara et al. [7] divide less abundant darker material present in Zagami into an olivine-rich lithology (ORL), from which most of our samples came, and a pyroxene-rich one (Dark Mottled-Lithology: DML) [8, 9]. ORL consists of vermicular fayalitic olivine, coarse-grained pyroxene, maskelynite, and a glassy phase exceptionally rich in K (up to 8.5 wt%), Al, and Si, but poor in Fe and Mg. The elemental composition suggests a late-stage melt, i.e., residual material that solidified late in a fractional crystallization sequence. Below we refer to it as "K-rich melt." The K-rich melt contains laths of captured olivine, Ca-rich pyroxene, plagioclase, and opaques. It seemed to offer an especially promising target for Ar-40/Ar-39 dating.

Park, J.↗
NASA NTRS2013

Ar-40/Ar-39 Ages of Maskelynite Grains from ALHA 77005

We present Ar-40/Ar-39 measurements for twelve small (20-60 micro-g) maskelynite samples from the heavily shocked martian meteorite ALHA 77005. The reported modal composition for ALHA 77005 is 50-60% olivine (Fa28), 30-40% pyroxene (Wo5Fs23En72), approx.8% maskelynite (An53), and approx.2% opaques by volume [1]). The meteorite is usually classified as a lherzolite. Previous Studies - Ar-40/Ar-39 results from previous work display disturbed release spectra [2,3]. In study [2], Ar-40/Ar-39 measurements on a 52-mg whole-rock sample produced an extremely disturbed release spec-trum, with all calculated apparent ages > 1 Ga, (Fig. 1). In a subsequent study [3], a light and a dark phase were analyzed. A 2.3-mg sample of the light, relatively low-K phase produced a disturbed release spectrum. For the first 20% of the Ar-39(sub K), most of the apparent ages exceeded >1 Ga; the remaining 80% yielded ages between 0.3-0.5 Ga. The integrated age for this phase is 0.9 Ga.

Turrin, B.↗