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We established a new laboratory for noble gas mass spectrometry that is dedicated to the development and application to cosmogenic nuclides at the University of Cologne (Germany). At the core of the laboratory are a state-of-the-art high-mass-resolution multicollector Helix MC Plus (Thermo Fisher Scientific) noble gas mass spectrometer and a novel custom-designed automated extraction line. The mass spectrometer is equipped with five combined Faraday multiplier collectors, with 1012 and 1013 Ω pre-amplifiers for faraday collectors. We describe the extraction line and the automated procedure for cosmogenic neon and the current performance of the experimental set-up. Performance tests were conducted using gas of atmospheric isotopic composition (our primary standard gas), as well as CREU-1 intercomparison material, containing a mixture of neon of atmospheric and cosmogenic composition. We use the results from repeated analysis of CREU-1 to assess the performance of the current experimental set-up at Cologne. The precision in determining the abundance of cosmogenic 21Ne is equal to or better than those reported for other laboratories. The absolute value we obtain for the concentration of cosmogenic 21Ne in CREU is indistinguishable from the published value.

Cosmogenic Ne isotopes are used for constraining the timing and rate of cosmological and Earth surface processes. We combined an automated gas extraction (laser) and purification system with a Thermo Fisher ARGUS VI mass spectrometer for high through-put, high precision Ne isotope analysis. For extra-terrestrial material with high cosmogenic Ne concentrations, we used multi-collection on Faraday detectors. Multiple measurements (n = 26) of 1.67 × 10−8 cm3 air-derived 20Ne yielded an uncertainty of 0.32%, and 21Ne/20Ne = 0.17% and 22Ne/20Ne = 0.09%. We reproduced the isotope composition of cosmogenic Ne in the Bruderheim chondrite and Imilac pallasite in a sub-ten mg sample. For lower Ne amounts that are typical of terrestrial samples, an electron multiplier detector was used in peak jumping mode. Repeated analysis of 3.2 × 10−11 cm3 STP 20Ne from air reproduced 21Ne/20Ne and 22Ne/20Ne with 1.1% and 0.58%, respectively, and 20Ne intensity with 1.7% (n = 103) over a 4-month period. Multiple (n = 8) analysis of cosmogenic Ne in CREU-1 quartz yielded 3.25 ± 0.24 × 108 atoms/g (2 s), which overlaps with the global mean value. The repeatability is comparable to the best data reported in the international experiments performed so far on samples that are 2–5× smaller. The ability to make precise Ne isotope determinations in terrestrial and extra-terrestrial samples that are significantly smaller than previously analysed suggests that the new system holds great promise for studies with limited material.

Absorption of probe laser radiation by a mixture of even isotopes of neon in a gas discharge plasma is investigated by the method of magnetic scanning of 3s2–2p4 transition. The contours of absorption lines of isotopes are resolved by means of numerical modeling. It is discovered that, upon decrease in relative concentration of one of the isotopes, its contribution to absorption is replaced by gain. The effect is found to be caused by radiative transfer of excitation energy between atoms of different kinds in the absence of a difference in level energies (the process known as optical pumping). The effect of this mechanism turned out to be substantial for the upper level transitions from which to the ground state are allowed while being absent for the lower level of the transition from which such transitions are forbidden although other decay channels are available.

Analysis of isotopes of neon and argon using the same mass spectrometer is somewhat difficult because the 40Ar background after argon measurement can interfere with the 20Ne determination due to the very similar mass-to-charge ratios of 40Ar++ and 20Ne+. Analysis becomes even more difficult if the sample has a high abundance ratio of Ar/Ne and an extremely low amount of Ne. Here, we present a method for precise measurement of neon isotopes on a noble gas mass spectrometer (MMS) and argon isotopes on a quadruple mass spectrometer (QMS). The desorption curves of neon and argon on a charcoal trap and stainless steel trap were respectively determined, and the results demonstrated that the stainless steel trap was more suitable for the absolute separation of neon and argon despite requiring a lower temperature. The argon background effect of the MMS on the 20Ne determination was discussed emphatically; it was found that the charcoal trap immersed in liquid nitrogen (LN) near the ion source could effectively decrease the argon background. Furthermore, the liquid level of the LN should not only be located as close to the ion source as possible but should be kept constant, which is very important for the measurement of 20Ne with a small signal size. The ratio of CO2++/CO+ for MMS was 1.2 ± 0.3%, which enabled the correction of CO2++ interference in the 22Ne determination. An artificial mixture of standard gases with an abundance ratio of argon to neon as high as 1000 was prepared. 0.1 cm3 standard gas mixture with 5.50 × 10−13 mol argon and 5.53 × 10−16 mol neon was measured each time. The precisions of the isotopic ratios of neon measured by MMS were ±0.15% for 20Ne/22Ne and ±1.6% for 21Ne/22Ne. The precisions of the isotopic ratios of argon measured by QMS were ±0.5% for 40Ar/36Ar and 4.0% for 38Ar/36Ar. Although the precision of the argon isotope analysis obtained by QMS was not as good as that obtained by MMS, it fully meets the requirements for application in geochemical tracers. Moreover, this method avoids the use of the same mass spectrometer for analysis of both argon and neon, thus guaranteeing precision of the neon isotope measurements.

This work presents new analytical techniques for extraction and analysis of neon from a suite of different mineral phases, including quartz, pyroxene, hematite, apatite, zircon, topaz, and fluorite. Neon was quantitatively extracted at 1100 °C from all of these minerals using an in-vacuum lithium borate-flux fusion technique. Evolved neon was purified using a cryogenic method capable of separating Ne from He present in abundances ~8 orders of magnitude higher, typical of samples carrying nucleogenic/radiogenic noble gases. The purified neon was measured on a Helix-MC-Plus10K mass spectrometer that permits isobar-free measurement of all three neon isotopes. When operated at its highest mass resolving power (MRP) of ~10,300, the shoulder representing solely 22Ne on the low mass-side of the 22Ne-CO2+2 doublet is wide enough to permit measurement of isobar free 22Ne. Operating in this mode comes with the penalty of a 50% reduction in neon sensitivity. Coupled with a mathematical isobar-stripping method, this approach excludes 99.5% of the CO2+2 while still collecting >99% of the 22Ne beam. Routine edge-centering on the dynamic CO2+2 peak prior to introduction of a sample permits rapid and robust relocation of the desired measure point in the mass spectrum. Cosmogenic 21Ne and 22Ne concentrations obtained using these methods on the Cronus-A quartz and Cronus-P pyroxene international reference materials are in excellent agreement with previous work or expectations. Similarly, the concentration of nucleogenic 21Ne and 22Ne in Durango apatite and the CIT hematite standard agree well with previous work. Durango apatite has notable heterogeneity in neon concentrations, consistent with previous observations of heterogeneous He, U and Th concentrations in this apatite. Nucleogenic neon concentrations are also presented for previously unstudied minerals including a Sri Lanka zircon (SLC), a topaz from the Imperial Topaz mine in Brazil (ITP1), and a fluorite (W-90) from New Hampshire. Taken together this set of potential reference minerals and the associated dataset provide a starting point for intercalibration among multiple mineral phases carrying 21Ne and 22Ne of cosmogenic or nucleogenic origin.

International audience; The eastern Southwest Indian Ridge, between 61° and 67°E, has a very low melt supply and comprises several corridors of nearly amagmatic spreading that expose mantle-derived serpentinized peridotite. More volcanically active ridge portions separate these corridors. He, Ne, Pb, Nd, Hf and Sr isotopes were analyzed in basalt glasses dredged on two types of seafloor: volcanic and ultramafic. Basalts dredged in ultramafic seafloor on-axis tend to be slightly more depleted for heavy radiogenic isotopes and show slightly higher 3He/4He isotope ratios than basalts dredged in volcanic seafloor, with no systematic difference in neon isotope ratios. We propose that both types of basalts are derived from the same mantle source, but that the basalts dredged on ultramafic seafloor are more affected by melt/mantle reactions, which slightly modify their isotopic signatures. Our dataset also includes a few basalts, dredged on off-axis ultramafic seafloor, that range in age between 2.6 and 8.8 Ma. These few and widely-spaced off-axis samples, erupted at the ridge axis, are a rare opportunity to capture the potential geochemical variability of the mantle source in an ultramafic seafloor corridor over 8.8 Ma. This temporal variability appears to be minor compared to the overall range of isotopic variability of the on-axis lavas from the 61°-67°E region

The unbound nuclei \(^{25{\text {--}} 28}\)O have been studied by the invariant-mass method with SAMURAI at RIBF, RIKEN. The unbound nuclei are produced by one- and two-proton removal reactions from neutron-rich fluorine and neon isotopes at around 200 MeV/nucleon. The decay energies of the ground and first excited states of \(^{26}\)O are determined for the first time. Preliminary results of the \(^{27}\)O and \(^{28}\)O measurements are presented.

Separation of neon isotopes by rectification over a packed column is examined. The separation coefficient of the isotope pair 20Ne–22Ne is close to unity due to their similar properties. Rectification columns with contact space ~ 20 m in height are required to obtain isotopic products of high purity. The separation was carried out in a compact column using several stages because of vertical limitations. The obtained fractions were collected in gas tanks, compressed, purified, and directed for further enrichment in the same column. The degree of 22Ne extraction was shown to increase if the concentration of it in the distillate was held to the minimum. Ne isotopes could be obtained in 99.99% purity in 5–8 consecutive separation stages depending on the operating regime. An industrial pilot plant was built. A method for estimating the column operating time to produce a given volume of isotopic product was proposed.

We present He and Ne isotopes of individual presolar graphite grains from a low-density separate from Orgueil. Two grain mounts were analyzed with the same techniques but in a different sequence: The first one was measured with NanoSIMS followed by noble gas mass spectrometry, and the second one in reverse order. No grain contained (4)He and only one grain on the second mount contained (3)He. On the first mount, the grains had been extensively sputtered with NanoSIMS ion beams prior to noble gas analysis; we found only one grain out of 15 with presolar (22)Ne above detection limit. In contrast, we found presolar (22)Ne in six out of seven grains on the second mount that was not exposed to an ion beam prior to noble gas analysis. All 22 grains on the two mounts were imaged with scanning electron microscopy (SEM) and/or Auger microscopy. We present evidence that this contrasting observation is most likely due to e-beam–induced heating of the generally smaller grains on the first mount during SEM and Auger imaging, and not primarily due to the NanoSIMS analysis. If thermal contact of the grains to the substrate is absent, such that heat can only be dissipated via radiation, then the smaller, sputter-eroded grains are heated to higher temperatures such that noble gases can diffuse out. We discuss possible gas loss mechanisms and suggest solutions to reduce heating during e-beam analyses by minimizing voltages, beam currents, and dwell times. We also found small amounts of (21)Ne in five grains. Using isotope data we determined that the dominant sources of most grains are core-collapse supernovae, congruent with earlier studies of low-density presolar graphite from Murchison. Only two of the grains are most likely from AGB stars, and two others have an ambiguous origin.

Observations of cosmogenic neon concentrations in feldspars can potentially be used to constrain the surface exposure duration or surface temperature history of geologic samples. The applicability of cosmogenic neon to either application depends on the temperature-dependent diffusivity of neon isotopes. In this work, we investigate the kinetics of neon diffusion in feldspars of different compositions and geologic origins through stepwise degassing experiments on single, proton-irradiated crystals. To understand the potential causes of complex diffusion behavior that is sometimes manifest as nonlinearity in Arrhenius plots, we compare our results to argon stepwise degassing experiments previously conducted on the same feldspars. Many of the feldspars we studied exhibit linear Arrhenius behavior for neon whereas argon degassing from the same feldspars did not. This suggests that nonlinear behavior in argon experiments is an artifact of structural changes during laboratory heating. However, other feldspars that we examined exhibit nonlinear Arrhenius behavior for neon diffusion at temperatures far below any known structural changes, which suggests that some preexisting material property is responsible for the complex behavior. In general, neon diffusion kinetics vary widely across the different feldspars studied, with estimated activation energies (Ea) ranging from 83.3 to 110.7 kJ/mol and apparent pre-exponential factors (D0) spanning three orders of magnitude from 2.4 × 10−3 to 8.9 × 10−1 cm2 s−1. As a consequence of this variability, the ability to reconstruct temperatures or exposure durations from cosmogenic neon abundances will depend on both the specific feldspar and the surface temperature conditions at the geologic site of interest.

Neon isotopes are valuable gases used in high-technology. Their manufacture requires substantial improvement. Dependence of the extraction ratio of isotopes as end products on the composition of fractions obtained in the rectification column has been researched. The height of the contact space equivalent to one theoretical plate has been determined. Schematic solutions, providing a multi-stage separation of neon into isotopes 20Ne and 22Ne in a single column are presented. Examples of the technological sequence of extraction of products with an isotopic concentration of more than 99,99 % are given in the paper. The time required to produce a given amount of isotopic components at various reflux ratios and loads of the column from 20 to 80 % is calculated.

We review the design, simulation, and tests, of a detection system for measuring the energy distribution of daughter nuclei recoiling from the beta-decay of laser trapped neon isotopes. This distribution is sensitive to several new physics effects in the weak sector. Our `decay microscope' relies on imaging the velocity distribution of high energy recoil ions in coincidence with electrons shaken-off in the decay. We demonstrate by way of Monte-Carlo simulation, that the nuclear microscope increases the statistical sensitivity of kinematic measurements to the underlying energy distribution, and limits the main systematic bias caused by discrepancy in the trap position along the detection axis.

We present an experimental scheme which combines the well established method of velocity-mapimaging, with a cold trapped metastable neon target. The device is used for obtaining the branching ratios and recoil-ion energy distributions for the penning ionization process in optical collisions of ultracold metastable neon. The potential depth of the highly excited dimer potential is extracted and compared with theoretical calculations. The simplicity to construct, characterize and apply such a device, makes it a unique tool for the low-energy nuclear physics community, enabling opportunities for precision measurements in beta- and beta-delayed-neutron decays of cold, trapped, short-lived radioactive isotopes.

Low lying states of neutron-rich 32Ne were populated by means of one- and two-proton knock- out reactions at the RIKEN Radioactive Isotope Beam Factory. A new transition is observed at 1410(15) keV and assigned to the 4+ 1 → 2+ 1 decay. With this energy the R4/2 ratio is calculated to be 2.99(6), lying close to the rigid rotor limit and suggests a high degree of collectivity and strongest deformation among neutron-rich Neon isotopes. Comparisons of experimental inclusive and exclu- sive reaction cross sections with shell model and eikonal reaction dynamical calculations reveals considerable quenching for this highly asymmetric system and contributes to systematic trends.

A gas separator which makes use of the molecular exchange flow of a Knudsen pump is fabricated. The Knudsen pump makes use of the thermal transpiration of rarefied gas in several sheets of porous membrane of 8 cm × 8 cm in size. The gas separator is desktop size, and it works near atmospheric pressure. The device continuously splits the feed gas flow into two flows of product gases at the total flow rate of 3 6 sccm. The difference of mole percentage between the product gases are around 1 % for neon isotope mixture and 50 % for helium-neon mixture. Present gas separator increases the mole fraction of trace gases in the feed mixture by about 4−5 times. The feasibility of the production of high purity gases by present method is also discussed.

A study of multiplicity distribution of singly charged, doubly charged, multi charged projectile fragments and shower particles have been carried out for the peripheral collisions in 16O-emulsion,22Ne-emulsion and 28Si-emulsion interactions at an incident momentum of (4.1-4.5) AGeV/c. Events having no target fragments have been designated as peripheral collision events. Percentage of peripheral events has been found to increase with the increase of projectile mass. Dispersion of the multiplicity distribution and its dependence on projectile mass for projectile fragments and shower particles has also been investigated. Dependence of average multiplicity of projectile fragments and shower particles on the mass of the projectile beam has been studied. Study of different fragmentation mode during the emission of multi charged projectile fragments has also been carried out., arXiv admin note: text overlap with arXiv:nucl-ex/0604007 by other authors

Geothermal systems are complex environments where geochemical signatures are controlled by the influx of deep mantle fluids as well as near-surface processes that result from the high temperatures. Noble gas isotope ratios (e.g. 3He/4He, 20Ne/22Ne) are well-established tracers of deep mantle fluid provenance, and elemental fractionation of atmosphere-derived isotopes is widely used for tracing shallow processes such as solubility-dependent phase partitioning in groundwater and hydrocarbon fluids. Utilisation of these tracers for the latter purpose has been limited in geothermal systems, where they could be further extended to consider boiling and/or steam condensation. Here we report new noble gas isotope and abundance data for 21 vapour phase geothermal fluid samples collected from geothermal boreholes and naturally degassing fumaroles in Iceland. The samples were collected from active parts of the neovolcanic rift zone and include several key high-temperature geothermal localities of the Northern Rift Zone (NRZ), the Western Rift Zone (WRZ) and the Mid-Iceland Belt (MIB). Helium isotope ratios are MORB-like in the NRZ, whilst samples from the WRZ show values in excess of MORB, up to 15.9 Ra. Neon isotopes plot close to the air value, but may show a small plume mantle contribution. Argon isotopes show distinct mantle-derived 40Ar excesses (40Ar/36Ar up to 361.2), which to our knowledge are the largest measured anomalies in free geothermal fluids from Iceland. The atmosphere-derived noble gas signatures (20Ne, 36Ar, 84Kr) are consistent with high-temperature vapour-liquid phase partitioning. Atmosphere-derived xenon (130Xe) on the other hand is not consistent with the observations from the other atmosphere-derived noble gases, suggesting an additional complexity that likely relates to its unique sorption and bonding behaviour. We show that the abundance of 20Ne, 36Ar, 84Kr in the vapour phase is temperature-dependent, presenting a promising technique that can be used to estimate the temperature at which partitioning occurs in the subsurface. Using multiple noble gas species allows the effects of secondary atmospheric contamination to be corrected when using this method. We predict partitioning temperatures of 229 to 345 °C for the samples measured here, consistent with temperatures predicted using conventional geothermometers. The inert nature of the noble gases means that the technique presented here is not reliant on many of the assumptions that underpin conventional geothermometers. We suggest that this technique represents a novel and powerful geochemical tool to investigate the thermal properties of geothermal systems.

Paleocene basaltic lavas exposed on Baffin Island have the highest 3He/4He found in any terrestrial igneous rocks and potentially contain the most pristine primordial mantle material exposed on Earth's surface. By vacuum-crushing large (1–3 g) olivine mineral separates, we extracted enough magmatic gas to obtain the first coupled helium, neon, and argon isotopic compositions of Baffin Island lavas. The five Baffin Island olivine samples have 3He/4He ranging from 36.2 ± 0.6 to 48.6 ± 1.3 (1σ) times the atmospheric ratio (Ra), overlapping with the highest known mantle values. Neon isotopic results fall on a mixing line between atmosphere and a high 20Ne/22Ne mantle endmember (with a maximum 20Ne/22Ne of 12.2). The slope of this mixing line is indistinguishable from that in subglacial Holocene glass from Iceland, but distinct from other hotspots and mid-ocean ridge basalt trends. This result supports the hypothesis that Baffin Island and Iceland lavas share a common high-3He/4He mantle component, despite the fact that recent paleogeographic reconstructions place the Iceland hotspot far from Baffin Island at the time of eruption (61 Ma). Our results also demonstrate that high-3He/4He mantle reservoirs have 3He/22Ne variability that either reflects ancient mantle heterogeneity or helium addition in the upper or lower mantle.

Measurements of pressure broadening and shift coefficients for 640.2 nm Ne line were performed in an RF discharge without stabilization of neutral gas temperature. A diode laser with a short external cavity was used for metastable neon absorption spectroscopy in a natural mixture of neon isotopes. An appropriate fit function was constructed permitting deduction of Doppler and Lorentz components for the Voigt profile of the spectral line. To determine pressure broadening ξ and shift β coefficients for pure Ne and Ne:He mixture we used the information about Lorentz linewidth, position of the line center and gas temperature derived from spectral line shape fitted to a model line profile. The values of the collisional coefficients reduced to 300 K in units of 10-10 s-1 cm3, are ξNe-Ne = (1.9±0.2), ξNe-He = (3.4±0.2); βNe-Ne = -(0.7±0.1), βNe-He = (0.13±0.04).

Values of critical parameters of neon isotopes 20Ne and 22Ne are calculated. Approximate constants of the van-der-Waals, Berthelot, Dieterici I, and Redlich–Kwong equations of state are obtained. The data allow the adsorption isotherms for the neon isotopes on different adsorbents to be estimated by calculations.

Separation of Ne isotopes by fractionation at 28 K is studied. The number of transfer units in the upper and lower column sections is calculated with various loadings. Experimental characteristics of packed fractionation columns and examples of cascade systems constructed from them are given. A diagram of a cryogenic loop using a throttled high-pressure Ne cycle with intermediate N2 cooling is presented. The need and capability to create a pressure difference between the columns of the various steps were justified.

A method to obtain analytical expressions for evaluation of adsorption isotherms of neon isotopes at cryogenic temperatures is proposed. Adsorption isotherms of 20Ne and 22Ne on BAU activated carbon at 77 K are evaluated. The results allow the degree of influence of the pressure and composition of the 20Ne–22Ne isotopic mixture on the separation factor to be estimated.

—It has been revealed that the published results of measurements of the isotope shift of the ground state of even neon isotopes contain systematic errors. The errors are caused by the use of erroneous data regarding the absolute values of specific mass shifts of excited states and by the measurement errors of the isotope shifts themselves for transitions to the ground state. The isotope shift of the 2p54s[3/2]1 → 2p6(1S0) transition has been measured to be 2305 ± 20 MHz, the absolute specific mass shift of the 3p[3/2]2: (2р9) level has been determined to be 647 ± 10 MHz, and the isotope shift of the ground state has been found to be–3156 ± 30 MHz.

Four types of anomalous optical magnetic resonances shifted with respect to the zero magnetic field and with different shapes are found in radiation of a glow discharge in a mixture of even neon isotopes placed in a swept longitudinal magnetic field. This testifies to the manifestation of collective processes of synchronous light emission by oscillators belonging to isotopically different spatially separated atoms in discharge plasma. The origin of resonances is associated with nonstationary interference of reactive fields in the near radiation-field zones of emission of atoms, averaged over the lifetime of the fields (interference), while different types of resonances are associated with different methods of synchronization of the phases of the fields.

Cooling white dwarfs (WDs) can yield accurate ages when theoretical cooling models fully account for the physics of the dense plasma of WD interiors. We use MESA to investigate cooling models for a set of massive and ultra-massive WDs (0.9-1.3 $M_\odot$) for which previous models fail to match kinematic age indicators based on Gaia DR2. We find that the WDs in this population can be explained as C/O cores experiencing unexpectedly rapid $^{22}$Ne sedimentation in the strongly liquid interior just prior to crystallization. We propose that this rapid sedimentation is due to the formation of solid clusters of $^{22}$Ne in the liquid C/O background plasma. We show that these heavier solid clusters sink faster than individual $^{22}$Ne ions and enhance the sedimentation heating rate enough to dramatically slow WD cooling. MESA models including our prescription for cluster formation and sedimentation experience cooling delays of $\approx$4 Gyr on the WD Q branch, alleviating tension between cooling ages and kinematic ages. This same model then predicts cooling delays coinciding with crystallization of 6 Gyr or more in lower mass WDs (0.6-0.8 $M_\odot$). Such delays are compatible with, and perhaps required by, observations of WD populations in the local 100 pc WD sample and the open cluster NGC 6791. These results motivate new investigations of the physics of strongly coupled C/O/Ne plasma mixtures in the strongly liquid state near crystallization and tests through comparisons with observed WD cooling., Comment: 23 pages, 14 figures, accepted for publication in ApJ

A recent experimental breakthrough identified the last bound neutron-rich nuclei in fluorine and neon isotopes. Based on this finding, we perform a theoretical study of $Z=9, 10, 11, 12$ isotopes in the relativistic mean field (RMF) model. The mean field parameters are assumed from the PK1 parameterization, and the pairing correlation is described by the particle number conservation BCS (FBCS) method recently formulated in the RMF model. We show that the FBCS approach plays an essential role in reproducing experimental results of fluorine and neon isotopes. Furthermore, we predict $^{39}$Na and $^{40}$Mg to be the last bound neutron-rich nuclei in sodium and magnesium isotopes., Comment: 11 pages, 9 figures, published version

Cosmic Dust Some primitive meteorites contain presolar grains, which are solid particles that formed in the interstellar medium before being incorporated into the Solar System. Presolar grains were known to be older than the Sun but had not been precisely dated. Heck et al. examined neon isotopes in presolar silicon carbide grains extracted from the Murchison CM2 meteorite. This allowed them to calculate how long each grain had remained in the interstellar medium, a period of time ranging from 3.9 ± 1.6 million years up to 3 ± 2 billion years before the formation of the Solar System, making the grains the oldest known solid material. Most grains had presolar ages of less than 300 million years, constraining astronomers' models of how long dust survives in the interstellar medium. Proc. Natl. Acad. Sci. U.S.A. 117 , 1884 (2020).

We measured the energy dependence of the total reaction cross sections ( σ R ) for the proton drip-line nucleus of neon isotopes, 17Ne, with a solid hydrogen target. The σ R on a proton target in the low- and intermediate-energy regions were provided, where only a few values are available for unstable nuclei. The new data were compared with theoretical calculations using the Glauber model. In the low-energy region (∼100A MeV), the theoretical cross sections overestimate the experimental ones, whereas the theoretical ones significantly underestimate the experimental data in the intermediate energy region (∼300-500A MeV). We discuss several possibilities for solving this discrepancy. This work suggests the necessity of more careful investigations of the energy dependence of σ R for various nuclei on a proton target to determine the nuclear size properties precisely.

Evidence for the capture of nebular gases by planetary interiors would place important constraints on models of planet formation. These constraints include accretion timescales, thermal evolution, volatile compositions and planetary redox states1–7. Retention of nebular gases by planetary interiors also constrains the dynamics of outgassing and volatile loss associated with the assembly and ensuing evolution of terrestrial planets. But evidence for such gases in Earth’s interior remains controversial8–14. The ratio of the two primordial neon isotopes, 20Ne/22Ne, is significantly different for the three potential sources of Earth’s volatiles: nebular gas15, solar-wind-irradiated material16 and CI chondrites17. Therefore, the 20Ne/22Ne ratio is a powerful tool for assessing the source of volatiles in Earth’s interior. Here we present neon isotope measurements from deep mantle plumes that reveal 20Ne/22Ne ratios of up to 13.03 ± 0.04 (2 standard deviations). These ratios are demonstrably higher than those for solar-wind-irradiated material and CI chondrites, requiring the presence of nebular neon in the deep mantle. Furthermore, we determine a 20Ne/22Ne ratio for the primordial plume mantle of 13.23 ± 0.22 (2 standard deviations), which is indistinguishable from the nebular ratio, providing robust evidence for a reservoir of nebular gas preserved in the deep mantle today. The acquisition of nebular gases requires planetary embryos to grow to sufficiently large mass before the dissipation of the protoplanetary disk. Our observations also indicate distinct 20Ne/22Ne ratios between deep mantle plumes and mid-ocean-ridge basalts, which is best explained by addition of a chondritic component to the shallower mantle during the main phase of Earth’s accretion and by subsequent recycling of seawater-derived neon in plate tectonic processes. The distinctive 20Ne/22Ne ratio in material thought to come from deep mantle plumes provides evidence for nebular gas as a source of volatiles in Earth’s interior.

The lowest positive- and negative-parity bands of $^{20}$Ne and neutron-rich even-even Ne isotopes are investigated using a theoretical framework based on energy density functionals. Starting from a self-consistent relativistic Hartree-Bogoliubov calculation of axially-symmetric and reflection-asymmetric deformation energy surfaces, the collective symmetry-conserving states are built using projection techniques and the generator coordinate method. Overall a good agreement with the experimental excitation energies and transition rates is obtained. In particular, the model provides an accurate description of the excitation spectra and transition probabilities in $^{20}$Ne. The contribution of cluster configurations to the low-energy states is discussed, as well as the transitional character of the ground state. The analysis is extended to $^{22}$Ne and the shape-coexisting isotope $^{24}$Ne, and to the drip-line nuclei $^{32}$Ne and $^{34}$Ne. The role of valence neutrons in the formation of molecular-type bonds between clusters is discussed., Comment: 16 pages, 15 figures, 2 tables, Accepted for Publication in Physical Review C

Terrestrial in situ-produced stable cosmogenic isotope 21Ne can provide us lots of important geomorphologic information, while the prerequisite for the application of cosmogenic 21Ne in the surface process studies is the accurate measurements of three neon isotopes in the rock samples. To employ cosmogenic 21Ne in solving geological problems, we established a new analytical procedure of neon measurements on the GV 5400 noble gas mass spectrometer. Isobaric interferences on three neon isotopes have been quantified, and among them the correction for the major interference from 40Ar2+ on 20Ne+ was studied in more detail. Instead of the first-order correlation of 40Ar+/40Ar2+ ratio with the H2 partial pressure in the ion source section of the mass spectrometer reported by Professor Niedermann and co-workers in 1993, an excellent power function correlation of the 40Ar2+ counting to that of 40Ar+ has been established in our analytical system for determining the unresolved 40Ar2+ contribution by monitoring the 40Ar+ signal during sample analysis. The calibration experiment using air standard was performed, and then several aliquots of quartz standard CREU-1 were measured to assess the performance of our neon measurements. The average measured cosmogenic 21Ne concentration of CREU-1 (347 ± 7.7 × 106 atom g−1) is consistent with the published value (348 ± 10 × 106 atom g−1), which demonstrates the good analytical accuracy (0.3%) and high measurement precision (2.2%) of our neon measurements. And the MSWD value of 0.49 indicates the good agreement of the apparent dispersion of three aliquots data with their individual measurement errors. The establishment of this analytical procedure for neon measurement provides us a promising way for developing the cosmogenic 21Ne method in many fields of Earth sciences and beyond.

Collective phenomenon in neon isotopes is an interesting topic. However, even the ground-state deformations cannot be well described by theories. Recently, QJ Zhi and ZZ Ren [Phys Lett B 638: 166 (2006)] have suggested an improved Nilsson potential, which can give a suitable description of ground-state properties in magnesium isotopes. In order to test the description of neon isotopes located around the “island of inversion”, we have used this potential to provide the deformed basis for the projected-shell-model calculations. The low-lying spectra and transition properties of neon isotopes can be reproduced reasonably. The gyromagnetic factors of neon isotopes have also been investigated. The structures of excited states along the yrast line are studied in the language of band diagrams.

In the dependence of the emission of a glow discharge in a mixture of isotopes 20Ne and 22Ne on the longitudinal magnetic-field strength, we have revealed narrow resonances, while the waves have non-Lorentzian shapes and are shifted with respect to zero field. Variations in the concentration of isotopes and discharge current can vary the amplitude, the shape, and the number of resonances; however, the position of each of them on the scale of the magnetic field almost does not depend on the spectral composition of the registered emission. We have elucidated a relation between the positions of the resonances on the scale of the magnetic field and the isotope shifts of neon transitions.

A detailed study of event-by-event pseudo-rapidity fluctuations in relativistic heavy-ion collisions in terms of the Φ measure and its multiplicity and target dependence has been carried out for heavy (AgBr) and light (CNO) groups of targets present in the nuclear emulsion using O 16 (at an incident momentum of 4.5 A GeV/c), Ne 22 (at an incident momentum of 4.1 A GeV/c), Si 28 (at an incident momentum of 4.5 A GeV/c) and S 32 (at an incident momentum of 4.5 A GeV/c) projectiles. For all the interactions, the total ensemble of events has been divided into three overlapping multiplicity classes depending on the number of shower particles. For all the interactions and for each multiplicity class, the Φ values are found to be greater than zero indicating the presence of strong correlation in the multiparticle production at Dubna energy. The measured Φ values are found to decrease with the increase of average multiplicity for all the interactions. The Φ values for the AgBr target are found to be greater than that for the CNO target for all the projectiles. This observation indicates the presence of stronger correlation for heavier projectiles. The experimental results have been compared with the modified FRITIOF model. It has been seen that the modified FRITIOF model cannot reproduce the experimental results.

A series of frozen xenon targets of thicknesses ranging between 1 and 15 mg/cm2 were characterised by elastic backscattering technique using a 3 MeV proton beam. Xenon was kept solid on a gold substrate having a thickness of 1 g/cm2 which was mounted on a cold copper finger. The temperature of targets during the experiment was maintained at 55 K by a compact solid nitrogen sublimation system under pressure of 10−5 mbar. Targets were used in series of experiments for populating samarium and gadolinium isotopes in the 136Xe (18O, Xn) and 136Xe (22Ne, Xn) nuclear reactions.

The use of the noble gas isotope ratios 22 Ne/ 20 Ne and 40 Ar/ 36 Ar as geochemical tracers of environmental conditions (i.e. continental paleotemperatures from groundwater) and processes (i.e. air–sea gas exchange) requires accurate values for kinetic and equilibrium isotopic fractionations (α k and α eq ). Until now, these values have been approximated using different theoretical models. Here we evaluated both the kinetic and equilibrium fractionation factors experimentally by measuring the relative mass transfer rates of the major and secondary isotopes of argon and neon in laboratory experiments at 20 °C during exchange across the air–water interface as gas saturations evolved from 0 to 100%. The kinetic isotopic fractionation factors, α k , for argon (40/36) and neon (22/20) are determined to be 0.9961 ± 0.0001 (e k = − 3.9 ± 0.1‰) and 0.9931 ± 0.0004 (e k = − 6.9 ± 0.4‰), respectively. The kinetic isotopic fractionation factors are much closer in agreement to theoretical values determined by molecular dynamics simulations than to values calculated using the square root of molecular reduced masses. The equilibrium fractionation factor for neon (22/20) at 20 °C is determined to be 1.00104 ± 0.00005 (e eq = 1.04 ± 0.05‰). An argon equilibrium fractionation factor of 1.00107 ± 0.00002 (e eq = 1.07 ± 0.02‰) determined at 20 °C agrees with a linear interpolation of previous measured values at 2 °C and 25 °C ( Nicholson et al., 2010 ).

The paper reports the results of an experimental verification of the assumption of ideality for mixtures of 22 Ne in 20 Ne by means of binary mixtures, artificially-produced and certified by weighing and whose full isotopic compositions were then measured at KRISS using a mass-spectrometer calibrated with these mixtures. Thermal measurements on the mixtures were performed at INRIM. The assessment of the validity of the ideality condition was critical to the conclusion of a comprehensive study on the effect of neon isotopic composition on the values of its triple point temperature. At KRISS three mixtures were prepared with 22 Ne amount concentrations 22 x = 62 088(20) · 10 −6 , 91 678(22) · 10 −6 and 166 025(26) · 10 −6 in 20 Ne, respectively, the intermediate one being very close to the range of ‘natural’ compositions. The thermal measurements were performed in the same INRIM experimental apparatus of previous published studies, with an expanded uncertainty ( k = 2) of ≈30 μK for a single sample and ≈50 μK for the comparison of sample pairs, using the same model of cryogenic metal sealed cell for each sample. The results, corrected for the measured, low, content of 21 Ne and of relevant chemical impurities (H 2 and N 2 ) showed an agreement with a theoretical model for the binary mixture assuming ideal behaviour within 10 μK, with a standard uncertainty of u c = 50 μK. These results allowed to construct a ternary-mixture model for the actual neon isotopic composition, including 21 Ne, where the IUPAC recommended composition was used as the reference composition, and whose characteristics are discussed in the paper. This also allowed reassigning the T tp,90 values to all samples.

The basics of neon isotope separation by the distillation method at T = 28 K are discussed. The required numbers of transfer units at the top and bottom column sections are calculated for different loads. The experimental characteristics of packed rectification columns are presented and examples of the cascade are discussed. A configuration for a cryogenic circuit based on a high-pressure throttle neon cycle with intermediate nitrogen cooling is presented. The necessity for and the technical feasibility of creating a driver pressure difference between the columns for different stages are demonstrated.

Unusual resonances have been detected in the dependence of the discharge glow in neon on the longitudinal magnetic field. The resonances appear in fairly high magnetic fields and are observed only at low gas pressures and exclusively in a mixture of 20Ne and 22Ne isotopes. This phenomenon is an evidence of collective resonant radiation processes involving atoms of different neon isotopes.

Working within the framework of the Coulomb-modified correlation expansion for the Glauber model S-matrix, we calculate the interaction cross section ( $\sigma_{I}$ ) of neon isotopes, 17-32Ne, on 12C at 240 MeV/nucleon. The calculations involve i) up to the two-body density term in the correlation expansion, and ii) the single Gaussian approximation for the nucleon-nucleon amplitude. The colliding nuclei are described with Slater determinants consisting of the harmonic oscillator single-particle wave functions. The sole input of the density of each colliding nucleus, the oscillator constant, is fixed from the respective root-mean-square (rms) radius calculated using the relativistic mean-field approach. It is found that the calculated results for $\sigma_{I}$ generally provide fairly good agreement with the experimental data except for 31Ne, for which the required rms neutron radius comes closer to the one obtained earlier using the extended (halo-like) neutron density distribution. This finding is also supported by our predicted differential cross section of 31Ne on 12C at 240 MeV/nucleon. However, as expected, the results of the present analysis are unable to discriminate between the halo and non-halo structure of 31Ne. In conclusion, our results suggest that the present calculations can be considered as a good starting point to predict the rms matter radii of exotic neutron-rich nuclei.

There is a considerable interest in understanding the dependence of one-nucleon removal cross sections on the asymmetry of the neutron $S_n$ and proton $S_p$ separation energies, following a large amount of experimental data and theoretical analyses in a framework of sudden and eikonal approximations of the reaction dynamics. These theoretical calculations involve both the single-particle cross section and the shell-model description of the projectile initial state and final states of the reaction residues. The configuration mixing in shell-model description of nuclear states depends on the proximity of one-nucleon decay threshold but does it depend sensitively on $S_n - S_p$? To answer this question, we use the shell model embedded in the continuum to investigate the dependence of one-nucleon spectroscopic factors on the asymmetry of $S_n$ and $S_p$ for mirror nuclei $^{24}$Si, $^{24}$Ne and $^{28}$S, $^{28}$Mg and for a series of neon isotopes ($20 \leq A \leq 28$)., Comment: 5 pages, 3 figures

A measurement of the 12 C( 14 N, α 20 Ne) 2 H and 12 C( 14 N,p 23 Na) 2 Hreactions has been performed at a 14 N beam energy of 30.0 MeV. The experiment aims to explore the extent to which contributing 24 Mg excited states can be populated in the quasi-free reaction off the deuteron in 14 N. In particular, the 24 Mg excitation region explored in the measurement plays a key role in stellar carbon burning whose cross section is commonly determined by extrapolating high-energy fusion data. From preliminary results, α and proton channels are clearly identified. In particular, ground and first excited states of 20 Ne and 23 Na play a major role.

The $s$-process nucleosynthesis in Asymptotic Giant Branch (AGB) stars depends on the modeling of convective boundaries. We present models and s-process simulations that adopt a treatment of convective boundaries based on the results of hydrodynamic simulations and on the theory of mixing due to gravity waves in the vicinity of convective boundaries. Hydrodynamics simulations suggest the presence of convective boundary mixing (CBM) at the bottom of the thermal pulse-driven convective zone. Similarly, convection-induced mixing processes are proposed for the mixing below the convective envelope during third dredge-up where the 13C pocket for the s process in AGB stars forms. In this work we apply a CBM model motivated by simulations and theory to models with initial mass $M = 2$ and $M = 3M_\odot$, and with initial metal content Z = 0.01 and Z = 0.02. As reported previously, the He-intershell abundance of 12C and 16O are increased by CBM at the bottom of pulse-driven convection zone. This mixing is affecting the $^{22}Ne(��,n)^{25}Mg$ activation and the s-process effciency in the 13C-pocket. In our model CBM at the bottom of the convective envelope during the third dredgeup represents gravity wave mixing. We take further into account that hydrodynamic simulations indicate a declining mixing efficiency already about a pressure scale height from the convective boundaries, compared to mixing-length theory. We obtain the formation of the 13C-pocket with a mass of $\approx 10^{-4}M_\odot$. The final $s$-process abundances are characterized by 0.36 < [s=Fe] < 0.78 and the heavy-to-light s-process ratio is 0.23 < [hs=ls] < 0.45. Finally, we compare our results with stellar observations, pre-solar grain measurements and previous work., Submitted to ApJ on 11-24-2015. Accepted on 5-17-2016 (Manuscript #: ApJ101257)

We discuss the origin of the neon isotopic signatures in chondrites and in the terrestrial mantle. There are two primary possible origins for neon in the Earth's mantle. One origin is the dissolution of a dense primordial atmosphere with a solar composition of 20Ne/22Ne >13.4 into the mantle in a possible magma ocean stage during Earth's accretion. The second origin, developed in this study, is that mantle neon was already in Earth's parent bodies because of refractory grain irradiation by solar wind. We propose that solar wind implantation occurred early on dust within the accretion disk to allow such irradiation. Because solar wind implantation fractionates neon isotopes, the heavier isotopes are implanted deeper than the lighter ones because of different kinetic energies, and the process of implantation, if coupled with sputtering, leads to a steady state neon isotopic ratio (20Ne/22Ne ∼12.7) that is similar to what is observed in mantle-derived rocks (12.5–12.9), lunar soil grains (∼12.9) and certain gas-rich chondrites from all classes (enstatite, ordinary, rumuruti). Using a dust transport model in a turbulent and irradiated solar nebula, we estimated the equivalent irradiation age of a population of dust particles at three different distances from the sun (0.8, 1, 1.2 AU) and converted these ages into neon concentrations and isotopic ratios. The dust subsequently coagulated to form Earth's parent bodies, which have the mean neon isotopic composition of the irradiated dust (non-irradiated dust is assumed to be free of neon). If this scenario of solar wind implantation coupled with sputtering in the precursors of Earth's parent bodies is correct, it offers a simple alternative to the model of solar nebula gas incorporation by dissolution in a magma ocean.

The paper reports further results following the 2010 determinations at INRIM of the triple point temperature of the neon isotopes 20Ne and 22Ne, obtained on nearly-pure samples sealed in cryogenic cells, carrying an uncertainty much lower than the previous determinations. The further results, performed in the same experimental apparatus with an expanded uncertainty (k ≈ 2) of ≈30 μK for a single cell and ≈50 μK for the comparison of sample pairs, were obtained using the same model of cryogenic metal sealed cell for each sample, and by measuring different samples from the same gas batch of each isotope and from different gas batches showing a different content of isotopic and chemical impurities. The new determinations were intended to check the effect of measuring different samples and the gas batches, and of performing corrections based on different analytical assays for the isotopic and chemical impurities. The new results are in agreement with the previous determinations, confirming, with greater confidence, the value of the temperature difference for the two pure isotopes, 0.14658 K with an expanded uncertainty of 0.00007 K, and the temperature values on ITS-90 24.5422 K for 20Ne and 24.6888 K for 22Ne, within the larger expanded uncertainty, 0.00032 K, due to the present ambiguity of the ITS-90 definition. These values are also consistent with new determinations published by other laboratories. In addition, the ITS-90 values of INRIM 2010 determinations of Ttp of samples of neon (INRIM Ec2Ne, INRIM E4Ne, PTB Ne12, NPL Ne2) of natural isotopic composition with different 22Ne amount concentrations are reported, consistent with the values obtained for pure isotopes.

Evaluated spectroscopic data and level schemes from radioactive decay and nuclear reaction studies are presented for {sup 27}F, {sup 27}Ne, {sup 27}Na, {sup 27}Mg, {sup 27}Al, {sup 27}Si, {sup 27}P, and {sup 27}S. This evaluation for A=27 supersedes the earlier evaluation by P.M. Endt (1998En04 and 1990En08).

Interest in the triple points of neon isotopes has recently arisen as a result of the multi-institute project to understand how variations in the isotopic composition of natural neon influence the triple-point temperature of a particular sample. Given the challenges in determining with sufficiently low uncertainty both the relative isotopic concentrations, particularly of 22Ne relative to 20Ne, and the temperature differences among cells filled from different gas sources in order to determine the sensitivity coefficient with adequate confidence, modeling of the isotopic influence becomes an attractive alternative for correcting the triple points of “natural” neon samples to a common composition. The modeling requires, among other things, knowledge of the triple-point temperatures of 20Ne and 22Ne. The triple points of these pure neon isotopes have utility in their own right as secondary reference temperatures on the ITS-90, and one or both of these could replace “natural” neon in a revised International Temperature Scale or approximation to the ITS. The neon isotope triple-point temperatures (on the IPTS-68) reported by Furukawa, Kemp, and Sakurai in various publications from 1972 to 1986 predate the ITS-90, and so there is utility in contemporary measurements (on the ITS-90) with gas samples of recent production. At NRC, we find the triple point of 20Ne to be at 24.54230 K (13.80 mK below the triple point of “natural” neon) and that of 22Ne to be at 24.68889 K (132.79 mK above the triple point of “natural” neon), assuming the reference sample of “natural” neon realizes the ideal ITS-90 temperature of 24.5561 K.

The intensity tuning profile is the base for mode selection and frequency stabilization in ring laser gyro(RLG),which is decided directly by the gain-to-loss ratio(GTLR).To improve the performance of the RLG,the dependence of the output bandwidth on the GTLR for two-mode RLG with the gain medium making of the mixture of Neon isotopes(Ne20 and Ne22) is numerically analyzed,with the consideration of comprehensive broadening(both homogeneous broadening and inhomogeneous broadening).It is shown that the output bandwidth increases monotonically with the GTLR of RLG.The intensity tuning profiles with different GTLRs of RLG are simulated and the results show that the intensity tuning profiles can be divided into three typical forms,according to the relative value of the output bandwidth to the adjacent longitudinal mode spacing,exhibiting great agreement with the experimental ones.The potential influence of improper GTLR selection on the application performance of RLG is analyzed and experimentally demonstrated.The ideal selection of GTLR for RLG is proposed,that is,the output bandwidth of the RLG should be approximately equal to its adjacent longitudinal mode spacing.