Ne Isotopes Research Articles

Shape coexistence in Ne isotopes and hyperon impurity effect on low-lying states

Shape coexistence in Ne isotopes and hyperon impurity effect on low-lying states

Water can trigger nuclear reaction to produce energy and isotope gases

This paper reports the discovery that water can trigger a peculiar nuclear reaction and produce energy. Cavitation may induce unusual reactions through implosion of water vapor bubbles. Many of this research has been published formally or informally. We have conducted experiments using two reactor types made from multiple-pipe heat exchanger and found that the heat exchange process of water produces peculiar excess heat and abnormally high pressure leading to rupture of the reactor. Recently, we have tested another eight reactors. Interestingly, these reactors produce non-condensable gas. We suspected that they include 22Ne and CO2. We used a mass spectrometer (MS) to analyze 14 gas samples collected from 8 reactors, including ten samples showing a coefficient of performance COPx > 1.05 (with excess heat) and four having COPx < 1.05 (without excess heat). Several methods were adopted to identify the gas content. For CO2 identification, two methods are employed. For 22Ne identification, three methods are employed. All the results confirm that isotope 22Ne and regular CO2 really exist in the output gas from reactors determined to have excess heat. We conjecture a possible mechanism to produce 22Ne and CO2 and find out that 12C and isotope 17O are the intermediate. They finally form isotope gases containing 17O, including H2O-17 (heavy-oxygen water), isotope O2 (16O–17O), and isotope CO2 (12C–16O–17O). In the excess heat producing reactors, all these gasses were detected by MS in the absence of 20Ne and 21Ne. The observed isotope gases produced from reactors having excess heat verifies that water can trigger a peculiar nuclear reaction and produce energy.

Study of the 20Ne(p,γ)21Na reaction at LUNA

The NeNa-MgAl cycles are involved in the synthesis of Ne, Na, Mg, and Al isotopes. The 20Ne(p,γ)21Na (Q = 2431.68 keV) reaction is the first and slowest reaction of the NeNa cycle and it controls the speed at which the entire cycle proceeds. At the state of the art, the uncertainty on the 20Ne(p,γ)21Na reaction rate affects the production of the elements in the NeNa cycle. In particular, in the temperature range from 0.1 GK to 1 GK, the rate is dominated by the 366 keV resonance corresponding to the excited state of EX = 2797.5 keV and by the direct capture component. The present study focus on the study of the 366 keV resonance and the direct capture below 400 keV. At LUNA (Laboratory for Underground Nuclear Astrophysics) the 20Ne(p,γ)21Na reaction has been measured using the intense proton beam delivered by the LUNA 400 kV accelerator and a windowless differential-pumping gas target. The products of the reaction are detected with two high-purity germanium detectors. The experimental details and preliminary results on the 366 keV resonance and on the direct capture component at very low energies will be shown, together with their possible impact on the 20Ne(p,γ)21Na reaction rate.

Intensity coupling characteristics of dual-longitudinal mode ring lasers with Ne dual-isotope.

The intensity coupling characteristics of Ne dual-isotope inflation and dual-longitudinal-mode operation ring lasers were investigated based on the Lamb theory. Considering the contribution of the Ne isotope system to the polarization of the gain medium and gain saturation effects, the frequency coupling effects were analyzed. Combined with the plasma dispersion function, the optical cavity length is 0.47 m, Ne20: Ne22= 0.53:0.47; the frequency spacing of the adjacent longitudinal mode is 640 MHz, and the intensity tuning curve of the ring laser is simulated. The alterations in the gain self-saturation and mutual saturation coefficients between the four frequencies generated via dual-longitudinal mode splitting are comprehensively discussed. Finally, a detection experiment for the intensity-tuning curve is designed to verify the theoretical analysis.

Shape evolution of nuclei in the region of (A≈30) using covariant density functional theory

Shape evolution of even–even isotopes of Ne, Mg, Si, S, Ar and Ca in the vicinity of [Formula: see text] mass region of the nuclear chart is studied using covariant density functional theory. It will be studied based on finite range NN-interaction force represented by NL3∗ and DD-ME2 and zero finite range NN-interaction force represented by DD-PC1. Both [Formula: see text]Mg and [Formula: see text]Si exhibit shape coexistence and the ground state shape which is found to be both oblate and prolate. The spherical shape is obtained for the Ca isotopes, and for nuclei that have magic neutron numbers [Formula: see text] and 20. The rest of the isotopic chain has only one minimum and alternates between prolate and oblate shapes. Physical properties are calculated at the location of ground state deformation with neutron number ([Formula: see text]) and proton number ([Formula: see text]), such as the binding energy, two-neutron separation energies, proton, neutron and charge radii. In general, a smooth change in these properties is found, except near [Formula: see text] and 20 one can see a sharp change, which reflects the sudden change in the ground state deformation in the neighboring nuclei. A very good agreement is found with the available experimental data, HF and FRDM models

Electroexcitation Form Factors and Deformation of 20,22Ne Isotopes Based on the Shell Model and Hartree-Fock plus BCS Calculations

Nuclear structure of 20,22Ne isotopes has been studied via the shell model with Skyrme-Hartree-Fock calculations. In particular, the transitions to the low-lying positive and negative parity excited states have been investigated within three shell model spaces; sd for positive parity states, spsdpf large-basis (no-core), and zbme model spaces for negative parity states. Excitation energies, reduced transition probabilities, and elastic and inelastic form factors were estimated and compared to the available experimental data. Skyrme interaction was used to generate a one-body potential in the Hartree-Fock calculations for each selected excited states, which is then used to calculate the single-particle matrix elements. Skyrme interaction was used to calculate the radial wave functions of the single-particle matrix elements, from which a one-body potential in Hartree-Fock theory with SLy4 parametrization can be generated. Furthermore, we have explored the interplays among neutron and proton density profiles in two dimensions, along with the deformations of 20,22Ne using Hartree-Fock plus BCS calculations.

Nuclear physics with TriSol at Notre Dame’s Nuclear Science Laboratory

The detailed study of radioactive nuclei has resulted in opportunities for addressing many open questions in low-energy nuclear physics. For over three decades, the TwinSol separator at the University of Notre Dame has produced high-quality in-flight radioactive beams at low-energy for light isotopes that have been used in experiments aimed at nuclear structure, astrophysics, and fundamental symmetries studies. We have recently upgraded the TwinSol separator by adding additional elements: a dipole magnet, and a third solenoid. This new TriSol separator will improve the quality and purity of future radioactive beams. This improvement will enable the use of heavier beams and address beam contamination that has hindered past experiments. The current status of TriSol and its science program will be presented along with the role the TriSol program plays in the current landscape of nuclear physics user facilities. The TriSol program includes plans for studies of 11C(p, p)11C reaction for investigating the nature of the first stars, 14O(α, p)17F and its influence on reaction networks in X-ray bursts, the measurement of fusion reactions on Ne isotopes important for pycnonuclear reactions, precision half-life measurements for fundamental symmetries studies, and the use of TriSol as a magnetic spectrometer.

Conceptual Hydrodynamic Model with Hydrochemical and Isotopic Signatures of the Triassic and Silurian-Devonian Groundwater Systems in Northwestern Saudi Arabia

Groundwaters from an Upper Silurian-Lower Devonian sandstone-siltstone aquifer and an Upper Triassic calcareous unit in the northwestern part of Saudi Arabia were geochemically assessed to define their provenances, lateral migration pathways, secondary alteration processes, and potential connectivity between both aquifers. The water samples were analysed for their hydrochemical properties (n = 74), 87Sr/86Sr ratios (n = 14), 14C activities and noble gases (n = 5). The Devonian aquifer is of NaCl and Na-Cl-HCO3 water type, while the Triassic aquifer is of NaCl and Ca-Cl-SO4 type. A general increase in water salinity from 189 mg/L toward maximum concentrations of 5546 mg/L in the NW confirms potential recharge from Devonian outcrop areas with a lateral fluid migration from SE to NW. Principal component analysis (PCA) with nine variables (Na+, Ca2+, Mg2+, K+, Cl−, and SO42−, alkalinity, TDS, pH) revealed variations in TDS reflecting the observed lateral groundwater migration. A positive correlation between SO42− and Ca2+ loadings on PC2 illustrates the presence of gypsiferous water. An inverse correlation between Ca2+ and Na+ loadings on PC2 indicates cation exchange processes for both aquifers. The sandstone/siltstone-composed Silurian-Devonian aquifer groundwater was found to be dominantly undersaturated in terms of aragonite, calcite, and dolomite. Overlapping Ca/HCO3 and Na/Cl ratios for some Devonian and Triassic samples indicates mixing between both aquifers along the Hercynian Unconformity in the northwestern part of the study area. A depth-related increase in 87Sr/86Sr ratios (from 0.708611 to 0.711577) suggests the presence of water-rock exchange processes between the infiltrating groundwater and 87Sr/86Sr-enriched underlying units, likely by vertical segregating fluids. The general lack of measured 14C activities suggest the occurrence of recharge prior to Late Pleistocene Pluvial period or, more likely, a complete 14C decay during groundwater flow from recharge to the present discharge area. Elevated 4He/20Ne and depleted R/Ra ratios (0.01 to 0.05) of the groundwater indicate crustal radiogenic influence from the interaction with crustal fluids. 4He is produced in-situ with negligible contribution from the mantle. Evidence of noble gas isotopic fractionation was reflected in one water sample, indicating a preferential loss of some of the lighter isotopes of Ne and Ar.

Modification of exogenous CO2 on the pathway of microbial degradation coal to CH4: From the view of stable isotope

The sources of CO2 in coalbed gas (CBG), and their geological significance have been widely discussed. However, the influence of exogenous CO2 on the pathway of microbial degradation of coal to CH4 has not been identified and carefully discussed. To investigate the modification of exogenous CO2 on microbial degradation coal to CH4 pathways, 22 CBG and coproduced water samples from the Miquan and Fukang areas of the southern Junggar Basin were sampled in this study and tested for stable isotopes. The results show that there are significant differences in CBG composition and genesis between Miquan and Fukang areas. The CBG in the Fukang area is mainly CH4, and the thermogenic gas and biogenic gas account for 32.8% − 34.1% and 65.9% − 67.2%, respectively. Almost all the biogenic gas is produced by the CO2 reduction pathway. Unlike the Fukang area, the CBG in the Miquan area has a high CO2 concentration (2.0% to 36.9%). He and Ne isotopes indicate that CO2 in the Miquan area are mainly of crustal origin and have undergone at least 72.5% loss and dilution. Almost all CBG in Miquan area is of biological origin (92.3% to 92.9%). However, the production pathway of biogas is very different from that of Fukang. The CO2 reduction pathway and acetic acid/methyl fermentation pathway account for 65.2% − 79.3% and 20.7% − 34.8%, respectively. The thermogenic gas and biogenic gas in the two areas are from Early Cretaceous and Pleistocene, respectively. The only difference is that CBG in Miquan area was intruded by crustal-derived CO2 during middle to late Miocene. Crust-derived CO2 was utilized by microorganisms to produce enough CH3COOH, which provided sufficient substrate for microorganisms to produce CH4 using CH3COOH. Disturbance by exogenous CO2 explains differences in microbial methanogenic pathways in two areas. This study not only clarifies the fate of CO2 in the Miquan area, but also raises the principle of modification of microbial methanogenic pathways by exogenous CO2.

The study of the 20Ne(p,γ)21Na reaction at LUNA

The NeNa and MgAl cycles have been the subject of much experimental activity during the last decade because of their relevance to the synthesis of Ne, Na, and Mg isotopes during the H burning in several astrophysical scenarios. Key reactions in these cycles are also believed to be the main agents of the observed anti-correlations in O-Na and Al-Mg abundances exhibited by the stars of Galactic globular clusters. The 20Ne(p,γ)21Na is the first reaction and the bottleneck of the NeNa cycle: having the slowest reaction rate, it controls the speed of the entire cycle. In order to better constrain the overall astrophysical reaction rate of this important reaction, the LUNA collaboration has started a new experimental effort to study the 366 keV resonance and to improve the knowledge of the cross section at proton energies below 400 keV. This contribution describes the experimental setup and preliminary results.

Mantellic degassing of helium in an extensional active tectonic setting at the front of a magmatic arc (central Mexico)

Abstract The physicochemical and isotopic characteristics of groundwater and dissolved gas of central Mexico provide valuable information about the geologic and tectonic context of the area. Low–high-enthalpy manifestations (up to 98 °C in springs and more than 100 °C in geothermal wells) are distributed within the San Juan del Río, Querétaro, and Celaya hydrologic basins, located at the boundary between the current Mexican magmatic arc and an extensional continental area with intraplate volcanism called Mesa Central Province. Groundwaters in the study area represent a mixture between the cold water end-member with a Ca2+-Mg2+-HCO3-composition and a hydrothermal end-member enriched in Na+, K+, SO42−, and Cl-. Cold and hot groundwaters δ2H and δ18O plot along the same evaporation lines and do not exhibit a magmatic input. Dissolved and free gas do not show a typical volcanic composition signature. He and Ne isotope composition provide evidence of an important contribution of non-atmospheric noble gases. Although helium composition mainly has a crustal origin (21–83%), the mantellic contribution (1–39%) is higher than expected for an area lacking recent volcanism. A volatilerich magma aging at depth was discarded as the source of this mantellic helium signature but points out a recent mantellic contribution. Thus, we propose that mantellic helium comes from the sublithospheric mantle into the shallow crust through the highly permeable tectonic boundaries between the geologic provinces, namely the N−S Taxco−San Miguel de Allende and Chapala-Tula fault systems. Mantellic helium flow rates through these fault systems were estimated to have values ranging from 0.1 m/yr to 2.9 m/yr. This He flux range implies that aside from subduction, mantle volatile degassing enhanced by crustal fault systems is the main degassing process in the region studied.

Discovery of ^{39}Na.

The new isotope ^{39}Na, the most neutron-rich sodium nucleus observed so far, was discovered at the RIKEN Nishina Center Radioactive Isotope Beam Factory using the projectile fragmentation of an intense ^{48}Ca beam at 345 MeV/nucleon on a beryllium target. Projectile fragments were separated and identified in flight with the large-acceptance two-stage separator BigRIPS. Nine ^{39}Na events have been unambiguously observed in this work and clearly establish the particle stability of ^{39}Na. Furthermore, the lack of observation of ^{35,36}Ne isotopes in this experiment significantly improves the overall confidence that ^{34}Ne is the neutron dripline nucleus of neon. These results provide new key information to understand nuclear binding and nuclear structure under extremely neutron-rich conditions. The newly established stability of ^{39}Na has a significant impact on nuclear models and theories predicting the neutron dripline and also provides a key to understanding the nuclear shell property of ^{39}Na at the neutron number N=28, which is normally a magic number.

A study of shape transition and bubbleness in Ne isotopes

We have studied shape transition and development of quadrupole deformation in even-even 18-36Ne isotopes by employing covariant density functional theory (CDFT) with density-dependent meson exchange (DD-ME2) and density-dependent point coupling (DD-PC1) parameter sets. A sudden shape transition is observed in the Ne isotopic chain and can be related to the evolution of shell structure of single-particle orbitals. The correlations between shape transition and discontinuity in the other physical observables are also examined. Our results for ground-state properties are in good agreement with the available experimental data and the result of various theoretical models. The present calculations infer the neutron drip line at 34Ne. In addition to shape transition, the bubble structure is also studied for magic nuclei in this chain.

The heterogeneity of the Mexican lithospheric mantle: Clues from noble gas and CO2 isotopes in fluid inclusions

The abundance of mantle-derived rocks and lavas, in combination with its tectonic evolution, render Mexico a perfect laboratory to investigate the chemical and the isotopic heterogeneity of the lithospheric mantle. New data on the composition of noble gases and CO2in Mexican mantle xenoliths and lavas is reported. Our samples consist of six ultramafic nodules from the Durango Volcanic Field (DVF) and the San Quintin Volcanic Field (SQVF), monogenetic complexes belonging to the Mexican Basin and Range province; and four lavas from the Sierra Chichinautzin (SCN), a Quaternary monogenetic volcanic field located in the Mexican volcanic arc. Ne and Ar isotopes in fluid inclusions reveal mixing between atmospheric and MORB-like fluids (e.g.,40Ar/36Ar &amp;lt; 1,200). DVF and SQVF nodules record low40Ar/36Ar and4He/20Ne that confirm the existence of recycled atmospheric-derived noble gases in the local mantle. The averages of the Rc/Ra ratios (3He/4He corrected for atmospheric contamination) measured in Mexican localities are within the MORB-like range: DVF= 8.39 ± 0.24 Ra, SQVF = 7.43 ± 0.19 Ra and SCN lavas = 7.15 ± 0.33 Ra (1σ). With the aim of assessing the isotopic variability of the Mexican lithospheric mantle, the above results were compared with similar data previously obtained from ultramafic nodules found in the Ventura Espiritu Santo Volcanic Field (VESVF), another Quaternary monogenetic volcanic complex belonging the Basin and Range. The higher3He/4He ratios in DVF relative to those reported for the VESVF and the SQVF are explained as reflecting different ages of mantle refertilization, triggered by the retreating of the Farallon slab (∼40 Ma ago) and associated delamination slab processes. We propose that the DVF mantle was refertilized more recently (&amp;lt;10 Ma ago) than the mantle beneath the SQVF and VESVF (∼40–20 Ma ago). On the other hand, He-Ne-Ar compositions of SCN olivines share similarities with VESVF xenoliths, suggesting a relatively homogeneous lithospheric mantle in central Mexico. Finally, DVF and the SCN samples exhibit δ13C values within the MORB range (comparable to other values previously reported in fluid inclusions and fumaroles from Popocatépetl, Colima—Ceboruco volcanoes). While we explain the MORB-like carbon signatures of the DVF samples as the result of the above-mentioned refertilization process, the SCN signatures likely reflect either (i) trapping of isotopically fractionated CO2derived from magmatic degassing or (ii) a mantle source unaffected by subduction-related crustal carbon recycling.

Study of the Steady-State Operation of a Dual-Longitudinal-Mode and Self-Biasing Laser Gyroscope.

In order to stabilize the self-biasing state of a laser gyroscope, a dual-longitudinal-mode asymmetric frequency stabilization technique was studied. The special frequency stabilization is based on the accurate control of the intensity tuning curve in the prism ring laser. In this study, the effects of the ratio of the Ne isotopes, the inflation pressure, and the frequencies coupling on the intensity tuning curve in a laser gyro were examined. The profiles of the intensity tuning curve were simulated under the mixing ratios of Ne20 and Ne22 of 1:1 and 7:3, and the inflation pressures were 350 Pa, 400 Pa, and 450 Pa. The mixing ratio of Ne20 and Ne27 was dealt with similarly. The method for precisely adjusting the profiles of the intensity tuning curve was analyzed. The profiles were verified by experiments under different isotope ratios and pressures. Finally, based on a prism ring laser with an optical length of 0.47 m, the proposed frequency stabilization method was preliminarily verified.

Low-pressure THGEM-based operation with Ne＋ H2 Penning mixtures

The operation of Thick Gas Electron Multipliers (THGEMs) in Time Projection Chambers (TPCs) using various gas mixtures has applications in various nuclear and particle physics experiments. Of particular interest in low-energy nuclear physics is study of nuclear reactions involving Ne isotopes. These reactions can be studied using Ne-based gas mixtures at low pressures in TPCs used as active targets for radioactive beams. We report on the low-pressure operation of THGEMs in Ne + H2 gas mixtures. We show that, since the Ne+H2 forms a Penning pair, higher gains with THGEMs are achievable compared to pure neon gas. Moreover, H2 acts as a quench gas allowing for higher THGEMs voltages while producing minimal background in reactions such as fusion compared to carbon-based neon gas mixtures. Detailed electron transport and amplification simulations have been performed and they qualitatively agree with the increased gain H2 provides in the Ne:H2 mixture. The higher THGEM gains that are achieved with a Ne:H2 mixture will enhance the study of Ne-based reactions in active-target detectors that have high-granularity pad planes, leading to higher spatial-resolution heavy-ion track data.

A dry ancient plume mantle from noble gas isotopes

Primordial volatiles were delivered to terrestrial reservoirs during Earth's accretion, and the mantle plume source is thought to have retained a greater proportion of primordial volatiles compared with the upper mantle. This study shows that mantle He, Ne, and Xe isotopes require that the plume mantle had low concentrations of volatiles like Xe and H2O at the end of accretion compared with the upper mantle. A lower extent of mantle processing alone is not sufficient to explain plume noble gas signatures. Ratios of primordial isotopes are used to determine proportions of solar, chondritic, and regassed atmospheric volatiles in the plume mantle and upper mantle. The regassed Ne flux exceeds the regassed Xe flux but has a small impact on the mantle Ne budget. Pairing primordial isotopes with radiogenic systems gives an absolute concentration of 130Xe in the plume source of ∼1.5 × 107 atoms 130Xe/g at the end of accretion, ∼4 times less than that determined for the ancient upper mantle. A record of limited accretion of volatile-rich solids thus survives in the He-Ne-Xe signatures of mantle rocks today. A primordial viscosity contrast originating from a factor of ∼4 to ∼250 times lower H2O concentration in the plume mantle compared with the upper mantle may explain (a) why giant impacts that triggered whole mantle magma oceans did not homogenize the growing planet, (b) why the plume mantle has experienced less processing by partial melting over Earth's history, and (c) how early-formed isotopic heterogeneities may have survived ∼4.5 Gy of solid-state mantle convection.

Noble gas isotope systematics in the Canary Islands and implications for refractory mantle components

Noble gas isotope systematics of ocean island basalts (OIB) provide evidence for relatively undegassed and primitive mantle sources. These OIB sources partly derive from the deep mantle by virtue of their distinctiveness from mid-ocean ridge basalts (MORB), which dominantly sample upper mantle. New helium, neon and argon isotope data are presented for Canary Islands lavas, carbonatites and cumulate and mantle xenoliths confirming 3He/4He ratios that are the same or lower than MORB, but that are heterogeneous (∼3–9.5RA) within and between islands in the archipelago. Neon and Ar isotope systematics for lavas are mostly within the range of air compositions. Harzburgite xenoliths from Lanzarote, which are interpreted to represent ancient refractory mantle residues, have distinct He-Ne-Ar isotope systematics from lavas or cumulate xenoliths. The harzburgites are characterized by forsteritic olivine (>Fo91) with uniformly low-3He/4He (6.6 ± 0.2RA), high 40Ar/36Ar (630–4900), and have Ne isotope compositions that range between air values or that are similar or more nucleogenic than depleted MORB mantle (DMM). Similar refractory mantle peridotites have been discovered as xenoliths at other OIB localities and are likely to be distinct from continental lithospheric mantle. Refractory mantle (RM), which by virtue of its high melting temperature is difficult to partially melt, may be a significant component in the convecting mantle and has potential to impart a cryptic noble gas signature to partial melts in intraplate, divergent and convergent margin settings. In this sense, RM may represent a ‘sixth mantle component’ after DMM, high-µ (high 238U/204Pb; HIMU), enriched mantle endmembers (EMI, EMII) and the ‘focus zone’ (FOZO). An RM-type component may be presented in the older eastern Canary Islands and possibly in recent rejuvenated volcanism from Teide (Tenerife). Canary Island intraplate volcanism samples multiple mantle components, confirming that the most gas-rich mantle sources involved in magmatism dominate OIB noble gas compositions.

Possible shape coexistence in odd-A Ne isotopes and the impurity effects of Λ hyperons * *Supported by the National Natural Science Foundation of China (U2032141), the Natural Science Foundation of Henan Province (202300410479), the Foundation of Fundamental Research for Young Teachers of Zhengzhou University (JC202041041), and the Physics Research and Development Program of Zhengzhou University (32410217)

In this study, shape evolution and possible shape coexistence are explored in odd-A Ne isotopes in the framework of the multidimensionally constrained relativistic-mean-field (MDC-RMF) model. By introducing and hyperons, the impurity effects on the nuclear shape, energy, size, and density distribution are investigated. For the interaction, the PK1 parameter set is adopted, and for the interaction, the PK1-Y1 parameter set is used. The nuclear ground state and low-lying excited states are determined by blocking the unpaired odd neutron in different orbitals around the Fermi surface. Moreover, the potential energy curves (PECs), quadrupole deformations, nuclear r.m.s. radii, binding energies, and density distributions for the core nuclei as well as the corresponding hypernuclei are analyzed. By examining the PECs, possibilities for shape coexistence in Ne and a triple shape coexistence in 31Ne are found. In terms of the impurity effects of Λ hyperons, as noted for even-even Ne hypernuclear isotopes, the hyperon exhibits a clear shrinkage effect, which reduces the nuclear size and results in a more spherical nuclear shape. The hyperon occupying the orbital is prolate, which causes the nuclear shape to be more prolate, and the hyperon occupying the orbital displays an oblate shape, which drives the nuclei to be more oblate.

Space history of the High Possil and Strathmore meteorites from Ne and Ar isotopes

The High Possil and Strathmore L6 chondrites fell in Scotland in 1804 and 1917 respectively. Unravelling their cosmic-ray exposure (CRE) ages provides crucial information about when they were ejected from the parent body, how they were delivered to Earth and is ultimately important for understanding the dynamics of small bodies in the solar system. Here we use new measurements of the Ne and Ar isotopic composition to determine CRE ages of both meteorites. Duplicated cosmogenic 21 Ne and 38 Ar concentrations yield CRE ages of 44.6 ± 4.6 Ma for High Possil and 15.4 ± 1.3 Ma for Strathmore. These coincide with well-established peaks in the ejection record for the L6 chondrites. They yield 40 Ar gas retention ages in excess of 3.15 Ga, which is consistent with both meteorites originating at depth within the parent body at the time of asteroidal break-up. Thematic collection: This article is part of the Early Career Research collection available at: https://www.lyellcollection.org/cc/SJG-early-career-research