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Sample records for noble gas monitoring

  1. Noble gas atmospheric monitoring at reprocessing facilities

    SciTech Connect

    Nakhleh, C.W.; Perry, R.T. Jr.; Poths, J.; Stanbro, W.D.; Wilson, W.B.; Fearey, B.L.

    1997-05-01

    The discovery in Iraq after the Gulf War of the existence of a large clandestine nuclear-weapon program has led to an across-the-board international effort, dubbed Programme 93+2, to improve the effectiveness and efficiency of International Atomic Energy Agency (IAEA) safeguards. One particularly significant potential change is the introduction of environmental monitoring (EM) techniques as an adjunct to traditional safeguards methods. Monitoring of stable noble gas (Kr, Xe) isotopic abundances at reprocessing plant stacks appears to be able to yield information on the burnup and type of the fuel being processed. To estimate the size of these signals, model calculations of the production of stable Kr, Xe nuclides in reactor fuel and the subsequent dilution of these nuclides in the plant stack are carried out for two case studies: reprocessing of PWR fuel with a burnup of 35 GWd/tU, and reprocessing of CAND fuel with a burnup of 1 GWd/tU. For each case, a maximum-likelihood analysis is used to determine the fuel burnup and type from the isotopic data.

  2. Nuclear monitoring by nonradioactive noble gas sampling and analysis

    SciTech Connect

    Fearey, B.L.; Nakhleh, C.W.; Stanbro, W.D.

    1997-10-01

    This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The perceived importance of measuring the xenon and krypton isotopics of nuclear activities has increased substantially in recent years. We have performed a systems analysis and theoretical simulation of the production, atmospheric dispersion, and isotopic abundances of noble-gas fission products, addressing several questions of interest, including: the relative isotopic variation as a function of nuclear fuel composition, reactor operational history, reactor type, distance from stack, and ambient meteorological conditions. Of particular importance in this analysis was the question of back-calculating process parameters of interest given noble-gas isotopic data. An analysis of the effect of measurement uncertainties was also performed. The results of these analyses indicate that this monitoring concept should be experimentally feasible.

  3. Applicability of Monte-Carlo Simulation to Equipment Design of Radioactive Noble Gas Monitor

    NASA Astrophysics Data System (ADS)

    Sakai, Hirotaka; Hattori, Kanako; Umemura, Norihiro

    In the nuclear facilities, radioactive noble gas is continuously monitored by using the radioactive noble gas monitor with beta-sensitive plastic scintillation radiation detector. The detection efficiency of the monitor is generally calibrated by using a calibration loop and standard radioactive noble gases such as 85Kr. In this study, the applicability of PHITS to the equipment design of the radioactive noble gas monitor was evaluated by comparing the calculated results to the test results obtained by actual calibration loop tests to simplify the radiation monitor design evaluation. It was confirmed that the calculated results were well matched to the test results of the monitor after the modeling. In addition, the key parameters for equipment design, such as thickness of detector window or depth of the sampler, were also specified and evaluated.

  4. Noble gas magnetic resonator

    DOEpatents

    Walker, Thad Gilbert; Lancor, Brian Robert; Wyllie, Robert

    2014-04-15

    Precise measurements of a precessional rate of noble gas in a magnetic field is obtained by constraining the time averaged direction of the spins of a stimulating alkali gas to lie in a plane transverse to the magnetic field. In this way, the magnetic field of the alkali gas does not provide a net contribution to the precessional rate of the noble gas.

  5. Noble gas fractionation during subsurface gas migration

    NASA Astrophysics Data System (ADS)

    Sathaye, Kiran J.; Larson, Toti E.; Hesse, Marc A.

    2016-09-01

    Environmental monitoring of shale gas production and geological carbon dioxide (CO2) storage requires identification of subsurface gas sources. Noble gases provide a powerful tool to distinguish different sources if the modifications of the gas composition during transport can be accounted for. Despite the recognition of compositional changes due to gas migration in the subsurface, the interpretation of geochemical data relies largely on zero-dimensional mixing and fractionation models. Here we present two-phase flow column experiments that demonstrate these changes. Water containing a dissolved noble gas is displaced by gas comprised of CO2 and argon. We observe a characteristic pattern of initial co-enrichment of noble gases from both phases in banks at the gas front, followed by a depletion of the dissolved noble gas. The enrichment of the co-injected noble gas is due to the dissolution of the more soluble major gas component, while the enrichment of the dissolved noble gas is due to stripping from the groundwater. These processes amount to chromatographic separations that occur during two-phase flow and can be predicted by the theory of gas injection. This theory provides a mechanistic basis for noble gas fractionation during gas migration and improves our ability to identify subsurface gas sources after post-genetic modification. Finally, we show that compositional changes due to two-phase flow can qualitatively explain the spatial compositional trends observed within the Bravo Dome natural CO2 reservoir and some regional compositional trends observed in drinking water wells overlying the Marcellus and Barnett shale regions. In both cases, only the migration of a gas with constant source composition is required, rather than multi-stage mixing and fractionation models previously proposed.

  6. Testing of a prototype of calibration facility for noble gas monitoring using 41Ar.

    PubMed

    Saibathulham, Holnisar; Wurdiyanto, Gatot; Marsum, Pujadi

    2012-09-01

    A prototype of a calibration facility for noble gas monitoring using (41)Ar in the PTKMR-BATAN has been tested. The facility was designed in such a way that the standard source of gas can be reused. The radioactive (41)Ar source was obtained by thermal neutron reaction of (40)Ar(n, γ)(41)Ar using a thermal neutron flux of 4.8×10(13) neutrons per cm(2) per second in two minutes on the multipurpose G.A. Siwabessy Reactor (Batan, Serpong, Indonesia). Gamma spectrometry was used to measure the radioactivity and purity of (41)Ar. The spectrum of the (41)Ar observed yields an energy of 1294 keV because of the highest intensity (99.2%). The activity of (41)Ar was 2821 kBq and 4% of the expanded uncertainty. The time required for (41)Ar to reach homogeneity was 7 min, and the effectiveness of resuse was 53%.

  7. Genesis Noble Gas Measurements

    NASA Technical Reports Server (NTRS)

    Hohenberg, Charles M.

    2005-01-01

    The original thrust of our Genesis funding was to extend and refine the noble gas analytical capabilities of this laboratory to improve the precision and accuracy of noble gas measurements in order to optimize the scientific return from the Genesis Mission. This process involved both instrumental improvement (supplemented by a SRLIDAP instrument grant) and refinement of technique. The Genesis landing mishap shifted our emphasis to the irregular aluminum heat shield material from the flat collector wafers. This has required redesign of our laser extraction cells to accommodate the longer focal lengths required for laser extraction from non-flat surfaces. Extraction of noble gases from solid aluminum surfaces, rather than thin coatings on transparent substrates has required refinement of controlled-depth laser ablation techniques. Both of these bring new problems, both with potentially higher blanks form larger laser cells and the larger quantities of evaporated aluminum which can coat the sapphire entrance ports. This is mainly a problem for the heavy noble gases where larger extraction areas are required, necessitating the new aluminum vapor containment techniques described below. With the Genesis Mission came three new multiple multiplier noble gas mass spectrometers to this laboratory, one built solely by us (Supergnome-M), one built in collaboration with Nu-Instruments (Noblesse), and one built in collaboration with GVI (Helix). All of these have multiple multiplier detection sections with the Nu-Instruments using a pair of electrostatic quad lenses for isotope spacing and the other two using mechanically adjustable positions for the electron multipliers. The Supergnome-M and Noblesse are installed and running. The GVI instrument was delivered a year late (in March 2005) and is yet to be installed by GVI. As with all new instruments there were some initial development issues, some of which are still outstanding. The most serious of these are performance issues

  8. Cosmogenic noble gas paleothermometry

    NASA Astrophysics Data System (ADS)

    Tremblay, Marissa M.; Shuster, David L.; Balco, Greg

    2014-08-01

    We present a theoretical basis for reconstructing paleotemperatures from the open-system behavior of cosmogenic noble gases produced in minerals at Earth's surface. Experimentally-determined diffusion kinetics predicts diffusive loss of cosmogenic 3He and 21Ne from common minerals like quartz and feldspars at ambient temperatures; incomplete retention has also been observed empirically in field studies. We show that the theory of simultaneous production and diffusion that applies to radiogenic noble gases in minerals-the basis of thermochronology-can also be applied to cosmogenic noble gases to reconstruct past surface temperatures on Earth. We use published diffusion kinetics and production rates for 3He in quartz and 21Ne in orthoclase to demonstrate the resolving power of cosmogenic noble gas paleothermometry with respect to exposure duration, temperature, and diffusion domain size. Calculations indicate that, when paired with a quantitatively retained cosmogenic nuclide such as 21Ne or 10Be, observations of cosmogenic 3He in quartz can constrain temperatures during surface exposure in polar and high altitude environments. Likewise, 21Ne retention in feldspars is sensitive to temperatures at lower latitudes and elevations, expanding the potential geographic applicability of this technique to most latitudes. As an example, we present paired measurements of 3He and 10Be in quartz from a suite of Antarctic sandstone erratics to test whether the abundances of cosmogenic 3He agree with what is predicted from first principles and laboratory-determined diffusion kinetics. We find that the amounts of cosmogenic 3He present in these samples are consistent with the known mean annual temperature (MAT) for this region of Antarctica between -25 and -30 °C. These results demonstrate the method's ability to record paleotemperatures through geologic time.

  9. Ultrahigh sensitivity heavy noble gas detectors for long-term monitoring and monitoring air. 1998 annual progress report

    SciTech Connect

    Valentine, J.D.; Gross, K.

    1998-06-01

    'The primary objective of this research project is to develop heavy noble gas (krypton, xenon, and radon) detectors for: (1) long-term monitoring of transuranic waste, spent fuel, and other uranium and thorium bearing wastes, and (2) alpha particle air monitors that discriminate between radon emissions and other alpha emitters. A University of Cincinnati/Argonne National Laboratory (UC/ANL) Team has been assembled to complete this detector development project. DOE needs that are addressed by this project include improved long-term monitoring capability and improved air monitoring capability during remedial activities. Successful development and implementation of the proposed detection systems could significantly improve current capabilities with relatively simple and inexpensive equipment. As of June 1, 1998, the UC/ANL Team has: (1) made significant progress toward characterizing the fluid transfer process which is the basis for this detector development project and (2) evaluated several radiation detectors and several potential pulse processing schemes. The following discussion describes the progress made during the first year of this project and the implications of this progress.'

  10. Noble gas trapping by laboratory carbon condensates

    NASA Technical Reports Server (NTRS)

    Niemeyer, S.; Marti, K.

    1982-01-01

    Trapping of noble gases by carbon-rich matter was investigated by synthesizing carbon condensates in a noble gas atmosphere. Laser evaporation of a solid carbon target yielded submicron grains which proved to be efficient noble gas trappers (Xe distribution coefficients up to 13 cu cm STP/g-atm). The carbon condensates are better noble gas trappers than previously reported synthetic samples, except one, but coefficients inferred for meteoritic acid-residues are still orders of magnitude higher. The trapped noble gases are loosely bound and elementally strongly fractionated, but isotopic fractionations were not detected. Although this experiment does not simulate nebular conditions, the results support the evidence that carbon-rich phases in meteorites may be carriers of noble gases from early solar system reservoirs. The trapped elemental noble gas fractionations are remarkably similar to both those inferred for meteorites and those of planetary atmospheres for earth, Mars and Venus.

  11. Noble Gas Temperature Proxy for Climate Change

    EPA Science Inventory

    Noble gases in groundwater appear to offer a practical approach for quantitatively determining past surface air temperatures over recharge areas for any watershed. The noble gas temperature (NGT) proxy should then permit a paleothermometry of a region over time. This terrestria...

  12. On a cryogenic noble gas ion catcher

    NASA Astrophysics Data System (ADS)

    Dendooven, P.; Purushothaman, S.; Gloos, K.

    2006-03-01

    In situ purification of the gas used as stopping medium in a noble gas ion catcher by operating the device at low temperatures of 60-150 K was investigated. Alpha-decay recoil ions from a 223Ra source served as energetic probes. The combined ion survival and transport efficiencies for 219Rn ions saturated below about 90 K, reaching 28.7(17)% in helium, 22.1(13)% in neon, and 17.0(10)% in argon. These values may well reflect the charge exchange and stripping cross-sections during the slowing down of the ions, and thus represent a fundamental upper limit for the efficiency of noble gas ion catcher devices. We suggest the cryogenic noble gas ion catcher as a technically simpler alternative to the ultra-high purity noble gas ion catcher operating at room temperature.

  13. Noble gas sputtering calculations using TRIM

    SciTech Connect

    Greene, J.P.; Nemanich, J.; Thomas, G.E.; Schiel, S.L.

    1996-12-31

    In conjunction with our experimental work on saddle field ion sputtering, we have attempted to apply the Monte Carlo program TRIM (Transport of Ions in Matter) to calculate the sputter yields for a variety of noble gas sputtering applications. Comparison with experiments are shown. Information extracted from these analyses have proved useful in optimizing the experimental sputtering parameters. Calculated sputter yields obtained utilizing TRIM are presented for noble gas sputtering of a variety of materials common to nuclear target production.

  14. Solubility of noble gases in serpentine - Implications for meteoritic noble gas abundances

    NASA Technical Reports Server (NTRS)

    Zaikowski, A.; Schaeffer, O. A.

    1979-01-01

    An investigation of the solubilities of the noble gases from synthesis and solubility studies of the sheet silicate mineral serpentine in carbonaceous chondrites is presented. Hydrothermal synthesis and exchange experiments were made at 340C and 1 kbar with noble gas partial pressures from 2 times 10 to the -8th power to 0.1 atm. The measured distribution coefficients for noble gases are not sufficiently high to account for the trapped noble gases in carbonaceous chondrites by exchange in solar nebula if meteoritic minerals have comparable distribution coefficients. Also, serpentine gains and loses noble gases to approach equilibrium values with the terrestrial atmosphere, indicating that this exposure may have influenced the noble gas abundances in phyllosilicate minerals of these chondrites. The dispersion of K-Ar ages of carbonaceous chondrites could be the result of phyllosilicates approaching equilibrium solubility of atmospheric Ar-40.

  15. Noble gas storage and delivery system for ion propulsion

    NASA Technical Reports Server (NTRS)

    Back, Dwight Douglas (Inventor); Ramos, Charlie (Inventor)

    2001-01-01

    A method and system for storing and delivering a noble gas for an ion propulsion system where an adsorbent bearing a noble gas is heated within a storage vessel to desorb the noble gas which is then flowed through a pressure reduction device to a thruster assembly. The pressure and flow is controlled using a flow restrictor and low wattage heater which heats an adsorbent bed containing the noble gas propellant at low pressures. Flow rates of 5-60 sccm can be controlled to within about 0.5% or less and the required input power is generally less than 50 W. This noble gas storage and delivery system and method can be used for earth orbit satellites, and lunar or planetary space missions.

  16. The Thermochemical Stability of Ionic Noble Gas Compounds.

    ERIC Educational Resources Information Center

    Purser, Gordon H.

    1988-01-01

    Presents calculations that suggest stoichiometric, ionic, and noble gas-metal compounds may be stable. Bases calculations on estimated values of electron affinity, anionic radius for the noble gases and for the Born exponents of resulting crystals. Suggests the desirability of experiments designed to prepare compounds containing anionic,…

  17. Dating native gold by noble gas analyses

    NASA Technical Reports Server (NTRS)

    Niedermann, S.; Eugster, O.; Hofmann, B.; Thalmann, CH.; Reimold, W. U.

    1993-01-01

    Our recent work on He, Ne, and Ar in Alpine gold samples has demonstrated that gold is extremely retentive for He and could thus, in principle, be used for U/Th-He-4 dating. For vein-type gold from Brusson, Northern Italy, we derived a U/Th-He-4 age of 36 Ma, in agreement with the K-Ar formation age of associated muscovites and biotites. However, in placer gold from the Napf area, Central Switzerland, we observed large excesses of both He-4 and radiogenic Ar-40 (Ar-40 sub rad, defined as Ar-40-295.5-Ar-.36). The gas release systematics indicate two distinct noble gas components, one of which is released below about 800 C and the other one at the melting point of gold (1064 C). We now present results of He and Xe measurements in a 1 g placer gold sample from the river Kruempelgraben, as well as He and Ar data for Brusson vein-type gold and for gold from the Lily Gold Mine, South Africa. We calculate reasonable U/Th-He-4 as well as U-Xe ages based on those gases which are released at approximately 800 C. Probably the low-temperature components represent in-situ-produced radiogenic He and fission Xe, whereas the gases evolving when gold melts have been trapped during gold formation. Therefore, only the low-temperature components are relevant for dating purposes.

  18. The Noble Gas Fingerprint in a UK Unconventional Gas Reservoir

    NASA Astrophysics Data System (ADS)

    McKavney, Rory; Gilfillan, Stuart; Györe, Domokos; Stuart, Fin

    2016-04-01

    In the last decade, there has been an unprecedented expansion in the development of unconventional hydrocarbon resources. Concerns have arisen about the effect of this new industry on groundwater quality, particularly focussing on hydraulic fracturing, the technique used to increase the permeability of the targeted tight shale formations. Methane contamination of groundwater has been documented in areas of gas production1 but conclusively linking this to fugitive emissions from unconventional hydrocarbon production has been controversial2. A lack of baseline measurements taken before drilling, and the equivocal interpretation of geochemical data hamper the determination of possible contamination. Common techniques for "fingerprinting" gas from discrete sources rely on gas composition and isotopic ratios of elements within hydrocarbons (e.g. δ13CCH4), but the original signatures can be masked by biological and gas transport processes. The noble gases (He, Ne, Ar, Kr, Xe) are inert and controlled only by their physical properties. They exist in trace quantities in natural gases and are sourced from 3 isotopically distinct environments (atmosphere, crust and mantle)3. They are decoupled from the biosphere, and provide a separate toolbox to investigate the numerous sources and migration pathways of natural gases, and have found recent utility in the CCS4 and unconventional gas5 industries. Here we present a brief overview of noble gas data obtained from a new coal bed methane (CBM) field, Central Scotland. We show that the high concentration of helium is an ideal fingerprint for tracing fugitive gas migration to a shallow groundwater. The wells show variation in the noble gas signatures that can be attributed to differences in formation water pumping from the coal seams as the field has been explored for future commercial development. Dewatering the seams alters the gas/water ratio and the degree to which noble gases degas from the formation water. Additionally the

  19. Biomedical Investigations with Laser-Polarized Noble Gas Magnetic Resonance

    NASA Technical Reports Server (NTRS)

    Walsworth, Ronald L.

    2003-01-01

    We pursued advanced technology development of laser-polarized noble gas nuclear magnetic resonance (NMR) as a novel biomedical imaging tool for ground-based and eventually space-based application. This new multidisciplinary technology enables high-resolution gas-space magnetic resonance imaging (MRI)-e.g., of lung ventilation-as well as studies of tissue perfusion. In addition, laser-polarized noble gases (3He and 129Xe) do not require a large magnetic field for sensitive detection, opening the door to practical MRI at very low magnetic fields with an open, lightweight, and low-power device. We pursued two technology development specific aims: (1) development of low-field (less than 0.01 T) noble gas MRI of humans; and (2) development of functional MRI of the lung using laser-polarized noble gas and related techniques.

  20. Underground Sources of Radioactive Noble Gas

    SciTech Connect

    Hayes, James C.; Bowyer, Ted W.; Cordova, Elsa A.; Kirkham, Randy R.; Misner, Alex C.; Olsen, Khris B.; Woods, Vincent T.; Emer, Dudley

    2013-05-01

    It is well known that radon is present in relatively high concentrations below the surface of the Earth due to natural decay of uranium and thorium. However, less information is available on the background levels of other isotopes such as 133Xe and 131mXe produced via spontaneous fission of either manmade or naturally occurring elements. The background concentrations of radioxenon in the subsurface are important to understand because these isotopes potentially can be used to confirm violations of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) during an On-Site Inspection (OSI). Recently, Pacific Northwest National Laboratory (PNNL) measured radioxenon concentrations from the subsurface at the Nevada Nuclear Security Site (NNSS—formerly known as the Nevada Test Site) to determine whether xenon isotope background levels could be detected from spontaneous fission of naturally occurring uranium or legacy 240Pu as a result of historic nuclear testing. In this paper, we discuss the results of those measurements and review the sources of xenon background that must be taken into account during OSI noble gas measurements.

  1. Noble gas transport during devolatilization of oceanic crust

    NASA Astrophysics Data System (ADS)

    Jackson, C.; Smye, A.; Shuster, D. L.; Parman, S. W.; Kelley, S. P.; Hesse, M. A.; Cooper, R. F.

    2014-12-01

    Here we examine the role of slab dehydration in determining the elemental pattern of recycled noble gases. As a first step, we apply newly reported measurements of He-Ne-Ar (light noble gases) solubility and diffusivity in amphibole to parameterize a 1D diffusive-reaction transport model that simulates noble gas behavior during fluid loss from down-going oceanic crust. Recent experiments demonstrate that noble gases are highly soluble in ring-structured minerals, such as amphibole and other common hydrothermal products in slabs [1]. These results suggest that ring-structured minerals have the potential to strongly influence the budget of noble gases input into subduction zones and the elemental fractionations associated with volatile loss from slabs New measurements of He-Ne-Ar solubility in a suite of amphiboles have been completed utilizing the methodology described in [1]. These new measurements confirm that all light noble gases are highly soluble in amphibole, and that noble gas solubility correlates with the availability of unoccupied ring sites. New experimental measurements of He and Ne diffusivity have also been completed using a step-degassing approach at the Berkeley Geochronology Center. These measurements suggest that vacant ring sites in amphibole act to slow noble gas diffusion. We combine the newly acquired He and Ne diffusivity measurements with literature values for Ar diffusivity [2] to parameterize the diffusive-reaction transport model. Application of these data to the diffusive-reaction transport model yields several new insights. The relative mobility of Ne compared to Ar allows for efficient extraction of Ne from "hot" slabs by shallow depths (<50 km), while Ar is effectively retained to deeper depths, potentially past sub-arc conditions. Noble gas partition coefficients sharply increase with depth, following their increasing non-ideality in supercritical fluids, causing noble gases to partition back into minerals from any fluids retained in

  2. Noble-gas-rich separates from the Allende meteorite

    NASA Technical Reports Server (NTRS)

    Ott, U.; Mack, R.; Chang, S.

    1981-01-01

    Predominantly carbonaceous HF/HCl-resistant residues from the Allende meteorite are studied. Samples are characterized by SEM/EDXA, X-ray diffraction, INAA, C, S, H, N, and noble gas analyses. Isotopic data for carbon show variations no greater than 5%, while isotopic data from noble gases confirm previously established systematics. Noble gas abundances correlate with those of C and N, and concomitant partial loss of C and normal trapped gas occur during treatments with oxidizing acids. HF/HCl demineralization of bulk meteorite results in similar fractional losses of C and trapped noble gases, which leads to the conclusion that various macromolecular carbonaceous substances serve as the main host phase for normal trapped noble gases and anomalous gases in acid-resistant residues, and as the carrier of the major part of trapped noble gases lost during HF/HCl demineralization. Limits on the possible abundances of dense mineralic host phases in the residues are obtained, and considerations of the nucleogenetic origin for CCF-XE indicate that carbonaceous host phases and various forms of organic matter in carbonaceous meteorites may have a presolar origin.

  3. Atomic forces between noble gas atoms, alkali ions, and halogen ions for surface interactions

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Outlaw, R. A.; Heinbockel, J. H.

    1988-01-01

    The components of the physical forces between noble gas atoms, alkali ions, and halogen ions are analyzed and a data base developed from analysis of the two-body potential data, the alkali-halide molecular data, and the noble gas crystal and salt crystal data. A satisfactory global fit to this molecular and crystal data is then reproduced by the model to within several percent. Surface potentials are evaluated for noble gas atoms on noble gas surfaces and salt crystal surfaces with surface tension neglected. Within this context, the noble gas surface potentials on noble gas and salt crystals are considered to be accurate to within several percent.

  4. Solubility investigations in support of ultrasensitive noble gas detector development.

    SciTech Connect

    Gross, K. C.

    1998-08-05

    Argonne National Laboratory (ANL) and the University of Cincinnati (UC) have been developing a new class of ultrasensitive noble gas detectors that are based upon the ANL discovery that corn oil has a high affinity for heavy noble gas absorption at room temperature, but releases the noble gases with warming or by other low-energy-input means. Environmental applications for this new class of fluid-based detectors include ultrahigh sensitivity radioxenon detectors for Comprehensive Test Ban Treaty Surveillance, improved fission gas detectors for enhanced environmental surveillance in the vicinity of DOE, DOD, and NRC-licensed facilities, and improved integrating Rn detectors for earthquake prediction. The purpose of the present paper is to present the results of theoretical and experimental investigations into the solubility phenomena of heavy noble gases (Rn, Xe, and Kr) in triglyceride oils. It is the authors' intention that the findings presented herein may be used to guide future selection, development, and refinement of vegetable and other hydrocarbon oils to bring further enhancements to noble gas detection efficiencies.

  5. Biomedical Investigations with Laser-Polarized Noble Gas Magnetic Resonance

    NASA Technical Reports Server (NTRS)

    Walsworth, Ronald L.

    2001-01-01

    We are developing laser-polarized noble gas nuclear magnetic resonance (NMR) as a novel biomedical imaging tool for ground-based and eventually space-based application. This emerging multidisciplinary technology enables high-resolution gas-space magnetic resonance imaging (MRI) (e.g., of lung ventilation) as well as studies of tissue perfusion. In addition, laser-polarized noble gases (He-3 and Xe-129) do not require a large magnetic field for sensitive detection, opening the door to practical MRI at very low magnetic fields with an open, lightweight, and low-power device. We are pursuing two specific aims in this research. The first aim is to develop a low-field (< 0.01 T) instrument for noble gas MRI of humans, and the second aim is to develop functional MRI of the lung using laser-polarized Xe-129 and related techniques.

  6. Defining Noble Gas Partitioning for Carbon Capture and Storage Environments

    NASA Astrophysics Data System (ADS)

    Warr, O.; Masters, A.; Rochelle, C.; Ballentine, C. J.

    2014-12-01

    For viable CCS implementation variables such as CO2 dissolution rates, reactions with the host rock and the extent of groundwater interaction must be accurately constrained. Noble gases play an important role in these systems [e.g. 1,2]. Their application, however, requires accurate Henry's constants within dense CO2-H2O systems. Current interpretations use pure noble gas-H2O partitioning data [3,4] and assume CO2-noble gas interactions are negligible, even at high (>700 kg/m3) CO2 densities [2]. To test this assumption we experimentally determined noble gas CO2-H2O partitioning for the 170-656 kg/m3 CO2 density range; representative of most CCS environments. Contrary to assumption, CO2 density significantly affected noble gas partition coefficients. For helium, increasing CO2 density resulted in a negative deviation trend from CO2-free values whilst for argon, krypton and xenon strong, positive deviations were observed. At 656 kg/m3 these deviations were -35%, 74%, 114% and 321% respectively. This is interpreted as the CO2 phase acting as a polar solvent inducing polarisation in the noble gases. Deviation trends are well defined using a 2nd order polynomial. The effect of a dense CO2 phase can now be incorporated into existing noble gas models. We also present results from a Gibbs-Ensemble Monte Carlo molecular simulation to model partitioning for this binary system. This fundamental technique makes predictions based on the pair-potentials of interaction between the molecules. Here it gives the phase compositions and Henry coefficients for noble gases. With a proven ability in accurately replicating both the CO2-H2O system and low pressure noble gas Henry constants the focus is now on fully optimising the model to match high pressure observations. [1] Gilfillan et al. (2009) Nature 458 614-618 [2] Gilfillan et al. (2008) GCA 72 1174-1198 [3] Crovetto et al. (1982) J.Chem.Phys. 76 1077-1086 [4] Ballentine et al. in Porcelli et al. (eds.) (2002) Rev.Min.Geo. 47 539-614.

  7. Calibration of Dissolved Noble Gas Mass Spectrometric Measurements by an Air-Water Equilibration System

    NASA Astrophysics Data System (ADS)

    Hillegonds, Darren; Matsumoto, Takuya; Jaklitsch, Manfred; Han, Liang-Feng; Klaus, Philipp; Wassenaar, Leonard; Aggarwal, Pradeep

    2013-04-01

    Precise measurements by mass spectrometry of dissolved noble gases (He, Ar, Ne, Kr, Xe) in water samples require careful calibration against laboratory standards with known concentrations. Currently, air pipettes are used for day-to-day calibrations, making estimation of overall analytical uncertainties for dissolved noble gas measurements in water difficult. Air equilibrated water (AEW) is often used as a matrix-equivalent laboratory standard for dissolved gases in groundwater, because of the well-known and constant fractions of noble gases in the atmosphere. AEW standards, however, are only useful if the temperature and pressure of the gas-water equilibrium can be controlled and measured precisely (i.e., to better than 0.5%); contamination and partial sample degassing must also be prevented during sampling. Here we present the details of a new custom air-water equilibration system which consists of an insulated 600 liter tank filled with deionized water, held isothermally at a precise target temperature (<0.05 °C) through the use of a heat exchanger. The temperature and total dissolved gas of the water in the tank are monitored continually, as are atmospheric pressure and air temperature in the laboratory. Different noble gas concentration standards can be reliably produced by accurately controlling the water temperature of the equilibration system. Equilibration characteristics and reproducibility of this system for production of copper tubes containing known amounts of noble gases will be presented.

  8. Isotopic mass-dependence of noble gas diffusion coefficients inwater

    SciTech Connect

    Bourg, I.C.; Sposito, G.

    2007-06-25

    Noble gas isotopes are used extensively as tracers inhydrologic and paleoclimatic studies. These applications requireknowledge of the isotopic mass (m) dependence of noble gas diffusioncoefficients in water (D), which has not been measured but is estimatedusing experimental D-values for the major isotopes along with an untestedrelationship from kinetic theory, D prop m-0.5. We applied moleculardynamics methods to determine the mass dependence of D for four noblegases at 298 K, finding that D prop m-beta with beta<0.2, whichrefutes the kinetic theory model underlying all currentapplications.

  9. Physiological response of rats to delivery of helium and xenon: implications for hyperpolarized noble gas imaging

    NASA Technical Reports Server (NTRS)

    Ramirez, M. P.; Sigaloff, K. C.; Kubatina, L. V.; Donahue, M. A.; Venkatesh, A. K.; Albert, M. S.; ALbert, M. S. (Principal Investigator)

    2000-01-01

    The physiological effects of various hyperpolarized helium and xenon MRI-compatible breathing protocols were investigated in 17 Sprague-Dawley rats, by continuous monitoring of blood oxygen saturation, heart rate, EKG, temperature and endotracheal pressure. The protocols included alternating breaths of pure noble gas and oxygen, continuous breaths of pure noble gas, breath-holds of pure noble gas for varying durations, and helium breath-holds preceded by two helium rinses. Alternate-breath protocols up to 128 breaths caused a decrease in oxygen saturation level of less than 5% for either helium or xenon, whereas 16 continuous-breaths caused a 31.5% +/- 2.3% decrease in oxygen saturation for helium and a 30.7% +/- 1. 3% decrease for xenon. Breath-hold protocols up to 25 s did not cause the oxygen saturation to fall below 90% for either of the noble gases. Oxygen saturation values below 90% are considered pathological. At 30 s of breath-hold, the blood oxygen saturation dropped precipitously to 82% +/- 0.6% for helium, and to 76.5% +/- 7. 4% for xenon. Breath-holds longer than 10 s preceded by pre-rinses caused oxygen saturation to drop below 90%. These findings demonstrate the need for standardized noble gas inhalation procedures that have been carefully tested, and for continuous physiological monitoring to ensure the safety of the subject. We find short breath-hold and alternate-breath protocols to be safe procedures for use in hyperpolarized noble gas MRI experiments. Copyright 2000 John Wiley & Sons, Ltd.

  10. An Air Noble Gas Component in the Mantle

    NASA Astrophysics Data System (ADS)

    Sarda, P.

    2005-12-01

    Noble gas geochemistry has for long attempted to recover isotopic signatures of mantle components through analyses of basalt glass or xenoliths, but this quest has been plagued by the occurrence of a conspicuous air component, which appears to have both the isotopic and elemental composition of air (except for helium). It is classically considered to be air added to samples close to the surface, in a poorly understood process called "contamination", due to the interaction of rocks and melts with air or water on emplacement. Focusing on Mid-Ocean Ridge Basalts (and Ocean Island Basalts), gases are mostly borne by vesicles and a number of puzzling observations can be made: - vesicles appear to be heterogeneous at the scale of a centimeter, as shown by stepwise crushing experiments, some vesicles having air, some having mantle gases, some having mixtures of both, - vesicles appear over-pressured (P > 1 bar) in fresh samples, as shown by highly vesiculous samples such as Popping Rocks, - the air component appears to be borne by the largest vesicles, as it is recovered in the first steps of stepwise crushing analyses, - larger samples seem to have more of the air component than smaller ones, - in Popping Rocks, the air component borne by the largest vesicles is overwhelming, - the isotopic composition of Pb-Sr-Nd in Popping Rocks was interpreted as indicating a recycled component (related to the HIMU and EM1 mantle end-members). The air noble gas component was suggested recently to be not seawater, but modern air located in fractures of the glass, which should have opened on cooling and resealed immediately [1]. This model faces some difficulties, such as keeping pressure high in the vesicles. I suggest another interpretation, namely that a large part of the air noble gases in oceanic basalts is recycled in origin [2]. It would have been carried down into the mantle at subduction zones, even if most (typically 90%) of the air noble gases in the slab returns to the

  11. Noble-gas-rich separates from ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Moniot, R. K.

    1980-02-01

    Acid-resistant residues were prepared by HCl-HF demineralization of three H-type ordinary chondrites: Brownfield 1937 (H3), Dimmitt (H3, 4), and Estacado (H6). These residues were found to contain a large proportion of the planetary-type trapped Ar, Kr, and Xe in the meteorites. The similarity of these acid residues to those from carbonaceous chondrites and LL-type ordinary chondrites suggests that the same phase carries the trapped noble gases in all these diverse meteorite types. Because the H group represents a large fraction of all meteorites, this result indicates that the gas-rich carrier phase is as universal as the trapped noble-gas component itself. When treated with an oxidizing etchant, the acid residues lost almost all their complement of noble gases.

  12. The Origin of Noble Gas Isotopic Heterogeneity in Icelandic Basalts

    NASA Technical Reports Server (NTRS)

    Dixon, E. T.; Honda, M.; McDougall, I.

    2001-01-01

    Two models for generation of heterogeneous He, Ne and Ar isotopic ratios in Icelandic basalts are evaluated using a mixing model and the observed noble gas elemental ratios in Icelandic basalts,Ocean island Basalt (OIBs) and Mid-Ocean Ridge Basalt (MORBs). Additional information is contained in the original extended abstract.

  13. Low-field MRI of laser polarized noble gas

    NASA Technical Reports Server (NTRS)

    Tseng, C. H.; Wong, G. P.; Pomeroy, V. R.; Mair, R. W.; Hinton, D. P.; Hoffmann, D.; Stoner, R. E.; Hersman, F. W.; Cory, D. G.; Walsworth, R. L.

    1998-01-01

    NMR images of laser polarized 3He gas were obtained at 21 G using a simple, homebuilt instrument. At such low fields magnetic resonance imaging (MRI) of thermally polarized samples (e.g., water) is not practical. Low-field noble gas MRI has novel scientific, engineering, and medical applications. Examples include portable systems for diagnosis of lung disease, as well as imaging of voids in porous media and within metallic systems.

  14. Noble gases in gas shales : Implications for gas retention and circulating fluids.

    NASA Astrophysics Data System (ADS)

    Basu, Sudeshna; Jones, Adrian; Verchovsky, Alexander

    2016-04-01

    Gas shales from three cores of Haynesville-Bossier formation have been analysed simultaneously for carbon, nitrogen and noble gases (He, Ne, Ar, Xe) to constrain their source compositions and identify signatures associated with high gas retention. Ten samples from varying depths of 11785 to 12223 feet from each core, retrieved from their centres, have been combusted from 200-1200°C in incremental steps of 100°C, using 5 - 10 mg of each sample. Typically, Xe is released at 200°C and is largely adsorbed, observed in two of the three cores. The third core lacked any measureable Xe. High 40Ar/36Ar ratio up to 8000, is associated with peak release of nitrogen with distinctive isotopic signature, related to breakdown of clay minerals at 500°C. He and Ne are also mostly released at the same temperature step and predominantly hosted in the pore spaces of the organic matter associated with the clay. He may be produced from the uranium related to the organic matter. The enrichment factors of noble gases defined as (iX/36Ar)sample/(iX/36Ar)air where iX denotes any noble gas isotope, show Ne and Xe enrichment observed commonly in sedimentary rocks including shales (Podosek et al., 1980; Bernatowicz et al., 1984). This can be related to interaction of the shales with circulating fluids and diffusive separation of gases (Torgersen and Kennedy, 1999), implying the possibility of loss of gases from these shales. Interaction with circulating fluids (e.g. crustal fluids) have been further confirmed using 20Ne/N2, 36Ar/N2 and 4He/N2 ratios. Deviations of measured 4He/40Ar* (where 40Ar* represents radiogenic 40Ar after correcting for contribution from atmospheric Ar) from expected values has been used to monitor gas loss by degassing. Bernatowicz, T., Podosek, F.A., Honda, M., Kramer, F.E., 1984. The Atmospheric Inventory of Xenon and Noble Gases in Shales: The Plastic Bag Experiment. Journal of Geophysical Research 89, 4597-4611. Podosek, F.A., Honda, M., Ozima, M., 1980

  15. Noble Gas Tracing of Fluid Transport in Shale Reservoirs

    NASA Astrophysics Data System (ADS)

    Heath, J. E.; Gardner, W. P.; Kuhlman, K. L.; Robinson, D. G.; Bauer, S. J.

    2014-12-01

    We investigate fluid transport mechanisms in a shale reservoir using natural noble gas tracers. Noble gas tracing is promising due to sensitivity of transport to: pore structure and sizes; phase partitioning between groundwater and liquid and gaseous hydrocarbons; and deformation from hydraulic fracturing and creation of surface area. A time-series of over thirty wellhead fluid samples were collected from two hydraulically-fractured wells with different oil-to-gas ratios, along with production data (i.e., flowrate and pressure). Tracer and production data sets can be combined to infer production flow regimes, to estimate reservoir transport parameters, and to improve forecasts of production decline. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  16. Light noble gas dissolution into ring structure-bearing materials and lattice influences on noble gas recycling

    NASA Astrophysics Data System (ADS)

    Jackson, Colin R. M.; Parman, Stephen W.; Kelley, Simon P.; Cooper, Reid F.

    2015-06-01

    Light noble gas (He-Ne-Ar) solubility has been experimentally determined in a range of materials with six-member, tetrahedral ring structures: beryl, cordierite, tourmaline, antigorite, muscovite, F-phlogopite, actinolite, and pargasite. Helium solubility in these materials is relatively high, 4 × 10-10 to 3 × 10-7 mol g-1 bar-1, which is ∼100 to 100,000× greater than He solubility in olivine, pyroxene, or spinel. Helium solubility broadly correlates with the topology of ring structures within different minerals. Distinctive He-Ne-Ar solubility patterns are associated with the different ring structure topologies. Combined, these observations suggest ring structures have a strong influence on noble gas solubility in materials and could facilitate the recycling of noble gases, along with other volatiles (i.e., water, chlorine, and fluorine), into the mantle. Measurements of Ne and Ar solubility in antigorite, however, are highly variable and correlated with each other, suggesting multiple factors contribute the solubility of noble gases in serpentine-rich materials.

  17. Noble Gas Signatures in Greenland - Tracing Glacial Meltwater Sources

    NASA Astrophysics Data System (ADS)

    Niu, Y.; Castro, M. C.; Hall, C. M.; Aciego, S.; Stevenson, E. I.; Arendt, C. A.

    2014-12-01

    This study is meant to explore the information noble gases can provide in glacial environments with respect to glacial meltwater sources, relative source contributions, water residence times, and spatial location where this glacial meltwater originates in the ice sheet. Ultimately, we seek to improve our understanding on the dynamics of these massive ice sheets, critical for the major role they play on climate change. This is possible due to the conservative nature of noble gases and temperature dependency of their concentrations in water in equilibrium with the atmosphere (ASW) allowing for calculation of noble gas temperatures (NGTs) and, under certain assumptions, estimation of the altitude at which glacial meltwater originated. In addition, crustally produced isotopes such as He accumulate in water over time, allowing for estimation of water residence times. Glacial meltwater samples were collected and analyzed for noble gas concentrations and isotopic ratios at five different locations in southern Greenland, between sea level and 1221 m. All samples are enriched in He with respect to ASW and are depleted in all other noble gases. Two patterns are apparent. The first one presents a relative Ar enrichment with respect to Ne, Kr, and Xe, a pattern first observed in high-altitude springs in the Galápagos Islands. The second one displays a mass-dependent pattern, a pattern first observed in Michigan rainwater samples. Most samples point to equilibration temperatures at ~0°C and altitudes between 1000 m and 2000 m, values which are consistent with both temperatures and elevations in Greenland. He concentrations vary between 1.1 and 7 times that of ASW and suggest glacial meltwater ages between ~170 and 1150 yrs, a result which is consistent with a preliminary tritium analysis. He isotopes point to surface (precipitation as snow and rainfall) contributions for most samples between ~60% and 90% with a ~10% - 40% crustal contribution from groundwater.

  18. Resonance ionization spectroscopy: counting noble-gas atoms

    SciTech Connect

    Hurst, G.S.; Payne, M.G.; Chen, C.H.; Willis, R.D.; Lehmann, B.E.; Kramer, S.D.

    1981-06-01

    New work on the counting of noble gas atoms, using lasers for the selective ionization and detectors for counting individual particles (electrons or positive ions) is reported. When positive ions are counted, various kinds of mass analyzers (magnetic, quadrupole, or time-of-flight) can be incorporated to provide A selectivity. It is shown that a variety of interesting and important applications can be made with atom-counting techniques which are both atomic number (Z) and mass number (A) selective.

  19. Possible solar noble-gas component in Hawaiian basalts

    USGS Publications Warehouse

    Honda, M.; McDougall, I.; Patterson, D.B.; Doulgeris, A.; Clague, D.A.

    1991-01-01

    THE noble-gas elemental and isotopic composition in the Earth is significantly different from that of the present atmosphere, and provides an important clue to the origin and history of the Earth and its atmosphere. Possible candidates for the noble-gas composition of the primordial Earth include a solar-like component, a planetary-like component (as observed in primitive meteorites) and a component similar in composition to the present atmosphere. In an attempt to identify the contributions of such components, we have measured isotope ratios of helium and neon in fresh basaltic glasses dredged from Loihi seamount and the East Rift Zone of Kilauea1-3. We find a systematic enrichment in 20Ne and 21Ne relative to 22Ne, compared with atmospheric neon. The helium and neon isotope signatures observed in our samples can be explained by mixing of solar, present atmospheric, radiogenic and nucleogenic components. These data suggest that the noble-gas isotopic composition of the mantle source of the Hawaiian plume is different from that of the present atmosphere, and that it includes a significant solar-like component. We infer that this component was acquired during the formation of the Earth.

  20. Noble Gas Analysis in the Quest to Find "Regolithic" Howardites

    NASA Technical Reports Server (NTRS)

    Cartwright, Julia A.; Hermann, S.; Herrin, J.; Mittlefehldt, D. W.; Ott, U.

    2011-01-01

    The howardite meteorites consist of approximately 200 polymict breccias of eucrite (basaltic) and diogenite (orthopyroxenitic) material (collectively, the HED group) that originate from the asteroid belt. Infrared reflectance spectroscopy of asteroids and laboratory studies of HEDs have indicated that the asteroid 4-Vesta is the likely parent body, and the partially-demolished south pole may be the source region. Asteroid regolith formation processes may be responsible for a number of observed petrological features including impact melt clasts, reworked clasts and mosaisicm. We have identified such features in a study of 30 howardites and polymict eucrites, and developed a regolith grading scheme based on petrology. However, the true regolithic nature of the howardite suite is not well defined, and previous research has suggested correlations between Ni contents of 300 - 1200 micron / g, a minimal variation in Al2O3 content around 8-9 wt% and the presence of solar wind noble gases are key hallmarks of an ancient regolith on Vesta . Through combined petrological, compositional and noble gas research, we aim to better understand howardite petrological diversity, regolith formation processes on parent asteroids, and to establish what defines a truly "regolithic" howardite. Our research will play an integral part in the interpretation of data gathered by the Dawn mission. Here we report the preliminary results from our noble gas analyses of four howardites: LEW 85313, EET 99408, MET 96500 and PCA 02066. Bulk major element compositional data have been collected, further petrological data for the HED group are reported by our colleagues, whilst trace-element analyses are underway. Our work will investigate the extent of whether previously described Ni, Al2O3 and noble gas characteristics are in fact indicative of a "regolithic" howardite.

  1. Cucurbit[6]uril: A Possible Host for Noble Gas Atoms.

    PubMed

    Pan, Sudip; Mandal, Subhajit; Chattaraj, Pratim K

    2015-08-27

    Density functional and ab initio molecular dynamics studies are carried out to investigate the stability of noble gas encapsulated cucurbit[6]uril (CB[6]) systems. Interaction energy, dissociation energy and dissociation enthalpy are calculated to understand the efficacy of CB[6] in encapsulating noble gas atoms. CB[6] could encapsulate up to three Ne atoms having dissociation energy (zero-point energy corrected) in the range of 3.4-4.1 kcal/mol, whereas due to larger size, only one Ar or Kr atom encapsulated analogues would be viable. The dissociation energy value for the second Ar atom is only 1.0 kcal/mol. On the other hand, the same for the second Kr is -0.5 kcal/mol, implying the instability of the system. The noble gas dissociation processes are endothermic in nature, which increases gradually along Ne to Kr. Kr encapsulated analogue is found to be viable at room temperature. However, low temperature is needed for Ne and Ar encapsulated analogues. The temperature-pressure phase diagram highlights the region in which association and dissociation processes of Kr@CB[6] would be favorable. At ambient temperature and pressure, CB[6] may be used as an effective noble gas carrier. Wiberg bond indices, noncovalent interaction indices, electron density, and energy decomposition analyses are used to explore the nature of interaction between noble gas atoms and CB[6]. Dispersion interaction is found to be the most important term in the attraction energy. Ne and Ar atoms in one Ng entrapped analogue are found to stay inside the cavity of CB[6] throughout the simulation at 298 K. However, during simulation Ng2 units in Ng2@CB[6] flip toward the open faces of CB[6]. After 1 ps, one Ne atom of Ne3@CB[6] almost reaches the open face keeping other two Ne atoms inside. At lower temperature (77 K), all the Ng atoms in Ngn@CB[6] remain well inside the cavity of CB[6] throughout the simulation time (1 ps).

  2. Noble gas encapsulation: clathrate hydrates and their HF doped analogues.

    PubMed

    Mondal, Sukanta; Chattaraj, Pratim Kumar

    2014-09-07

    The significance of clathrate hydrates lies in their ability to encapsulate a vast range of inert gases. Although the natural abundance of a few noble gases (Kr and Xe) is poor their hydrates are generally abundant. It has already been reported that HF doping enhances the stability of hydrogen hydrates and methane hydrates, which prompted us to perform a model study on helium, neon and argon hydrates with their HF doped analogues. For this purpose 5(12), 5(12)6(8) and their HF doped analogues are taken as the model clathrate hydrates, which are among the building blocks of sI, sII and sH types of clathrate hydrate crystals. We use the dispersion corrected and gradient corrected hybrid density functional theory for the calculation of thermodynamic parameters as well as conceptual density functional theory based reactivity descriptors. The method of the ab initio molecular dynamics (AIMD) simulation is used through atom centered density matrix propagation (ADMP) techniques to envisage the structural behaviour of different noble gas hydrates on a 500 fs timescale. Electron density analysis is carried out to understand the nature of Ng-OH2, Ng-FH and Ng-Ng interactions. The current results noticeably demonstrate that the noble gas (He, Ne, and Ar) encapsulation ability of 5(12), 5(12)6(8) and their HF doped analogues is thermodynamically favourable.

  3. Neutron detection by scintillation of noble-gas excimers

    NASA Astrophysics Data System (ADS)

    McComb, Jacob Collin

    Neutron detection is a technique essential to homeland security, nuclear reactor instrumentation, neutron diffraction science, oil-well logging, particle physics and radiation safety. The current shortage of helium-3, the neutron absorber used in most gas-filled proportional counters, has created a strong incentive to develop alternate methods of neutron detection. Excimer-based neutron detection (END) provides an alternative with many attractive properties. Like proportional counters, END relies on the conversion of a neutron into energetic charged particles, through an exothermic capture reaction with a neutron absorbing nucleus (10B, 6Li, 3He). As charged particles from these reactions lose energy in a surrounding gas, they cause electron excitation and ionization. Whereas most gas-filled detectors collect ionized charge to form a signal, END depends on the formation of diatomic noble-gas excimers (Ar*2, Kr*2,Xe* 2) . Upon decaying, excimers emit far-ultraviolet (FUV) photons, which may be collected by a photomultiplier tube or other photon detector. This phenomenon provides a means of neutron detection with a number of advantages over traditional methods. This thesis investigates excimer scintillation yield from the heavy noble gases following the boron-neutron capture reaction in 10B thin-film targets. Additionally, the thesis examines noble-gas excimer lifetimes with relationship to gas type and gas pressure. Experimental data were collected both at the National Institute of Standards and Technology (NIST) Center for Neutron Research, and on a newly developed neutron beamline at the Maryland University Training Reactor. The components of the experiment were calibrated at NIST and the University of Maryland, using FUV synchrotron radiation, neutron imaging, and foil activation techniques, among others. Computer modeling was employed to simulate charged-particle transport and excimer photon emission within the experimental apparatus. The observed excimer

  4. NOBLE GAS PRODUCTION FROM MERCURY SPALLATION AT SNS

    SciTech Connect

    DeVore, Joe R; Lu, Wei; Schwahn, Scott O

    2013-01-01

    Calculations for predicting the distribution of the products of spallation reactions between high energy protons and target materials are well developed and are used for design and operational applications in many projects both within DOE and in other arenas. These calculations are based on theory and limited experimental data that verifies rates of production of some spallation products exist. At the Spallation Neutron Source, a helium stream from the mercury target flows through a system to remove radioactivity from this mercury target offgas. The operation of this system offers a window through which the production of noble gases from mercury spallation by protons may be observed. This paper describes studies designed to measure the production rates of twelve noble gas isotopes within the Spallation Neutron Source mercury target.

  5. Noble Gas Signatures in Athabasca Glacier - Tracing Glacial Meltwater Sources

    NASA Astrophysics Data System (ADS)

    Niu, Y.; Hall, C. M.; Castro, M. C.; Aciego, S.; Arendt, C. A.

    2015-12-01

    We present a noble gas study in glacial meltwater (GMW) from the Athabasca Glacier (AG) in the Columbia Icefield, Canada. It constrains the relative contributions of GMW sources, water residence times, and spatial locations where the GMW originates in the alpine glacier. This is possible due to the conservative nature of noble gases and temperature dependency of their concentrations in water in equilibrium with the atmosphere (ASW) which allows for estimation of the altitude at which GMW originated. In addition, crustal He accumulates in water over time, allowing for estimation of water residence times. Water samples were collected in the morning on selected dates in May and July 2011 at two locations about 200 m apart near the terminus area at altitudes between 2000 m and 2100 m. Eight samples were collected in six different days. Results show that the major source of subglacial meltwater is ASW rather than old, compressed glacial ice, which has a distinct noble gas signature not seen in our samples. Given that, GMW samples from the AG do deviate to a certain extent from the ASW values corresponding to measured water temperature and altitude at collection points. Two patterns are observed in the concentrations of the AG samples. The first one presents a relative Ar enrichment with respect to Ne, Kr, and Xe, first observed in high-altitude springs in the Galápagos Islands (Warrier et al., 2012). The second one displays a mass-dependent pattern, first observed in Michigan rainwater (Warrier et al., 2013). A preliminary Xe analysis indicates equilibration altitudes between 2500 m and 3400 m, values compatible with local topography. Samples present He excess of 4% to 91%, and suggest an average residence time of ~400 yrs. References:Warrier, R. B., Castro, M. C., and Hall, C. M. (2012), Recharge and source-water insights from the Galapagos Islands using noble gases and stable isotopes, Water Resour. Res., 48, W03508, doi:10.1029/2011WR010954. Warrier, R. B., Castro

  6. Using 220Rn to calibrate liquid noble gas detectors

    NASA Astrophysics Data System (ADS)

    Kobayashi, M.; Yamashita, M.; Takeda, A.; Kishimoto, K.; Moriyama, S.

    2016-07-01

    In this paper, we describe 220Rn calibration source that was developed for liquid noble gas detectors. The key advantage of this source is that it can provide 212Bi-212 Po consecutive events, which enables us to evaluate the vertex resolution of a detector at low energy by comparing low-energy events of 212Bi and corresponding higher-energy α-rays from 212Po. Since 220Rn is a noble gas, a hot metal getter can be used when introduced using xenon as the carrier gas. In addition, no long-life radioactive isotopes are left behind in the detector after the calibration is complete; this has clear advantage over the use of 222Rn which leaves longlife radioactivity, i.e., 210Pb. Using a small liquid xenon test chamber, we developed a system to introduce 220Rn via the xenon carrier gas; we demonstrated the successful introduction of 6 × 102 220Rn atoms in our test environment.

  7. Heuristic overlap-exchange model of noble gas chemical shifts

    NASA Astrophysics Data System (ADS)

    Adrian, Frank J.

    2004-05-01

    It is now generally recognized that overlap-exchange interactions are the primary cause of the medium-dependent magnetic shielding (chemical shift) in all noble gases except helium, although the attractive electrostatic-dispersion (van der Waals) interactions play an indirect role in determining the penetration of the interacting species into the repulsive overlap-exchange region. The short-range nature of these overlap-exchange interactions, combined with the fact that they often can be approximated by simple functions of the overlap of the wave functions of the interacting species, suggests a useful semiempirical model of these chemical shifts. In it the total shielding is the sum of shieldings due to pairwise interactions of the noble gas atom with the individual atoms of the medium, with the "atomic" shielding terms either estimated by simple functions of the atomic overlap integrals averaged over their Boltzmann-weighted separations, or determined by fits to experimental data in systems whose complexity makes the former procedure impractical. Results for 129Xe chemical shifts in the noble gases and in a variety of molecular and condensed systems, including families of n-alkanes, straight-chain alcohols, and the endohedral compounds Xe@C60 and Xe@C70 are encouraging for the applicability of the model to systems of technical and biomedical interest.

  8. Long Term Field Calibration of the Noble Gas Temperature System in a Shallow Unconfined Pleistocene Aquifer

    NASA Astrophysics Data System (ADS)

    Hall, C. M.; Castro, M. C.; Lohmann, K. C.; Ma, L.

    2005-12-01

    Noble gas temperatures (NGTs) are a potentially powerful tool for paleoclimate reconstruction on continents, but the assumptions underlying the technique have not been widely tested for aquifers in colder climates. In a recent study of NGTs from S. Michigan groundwater, Ma et al. (2004) found significant NGT variation over time, but apparently modern water yielded NGTs that were ~ 3 ° C or more below that expected from the local mean annual air temperature (MAAT). For nearly a year, we have monitored NGTs and stable isotopes at a shallow water well in the glacial drift that recharges the aquifer studied by Ma et al. (2004). Initial results are in press (Hall et al., 2005) and they confirm that modern NGTs measured from Oct. to Jul. are typically 5-6°C, instead of the MAAT of 9.1°C. Measured water temperatures during sampling are within 1-2°C of MAAT. Stable isotopic analyses of local snow and rain water suggest that the groundwater is a mixture of these two end member components. Short term variations in well pH and stable isotope ratios confirm that the groundwater is indeed modern, but initial noble gas results did not show similar variations. Ground ice noble gas concentrations are very low, with the exception of He, which is enriched, with 3He/4He equal to the air value. All early noble gas concentrations in groundwater were too high for the MAAT, including both He isotopes which had 3He/4He about 1.3 times air. Measured groundwater excess He values are compatible with 4He influx from below and tritium decay for ~ 30 yr. None of the standard NGT interpretational models adequately account for the complete data set, without modifications to normal assumptions. The most recent Aug. 2005 data after a very rainy Jul. does show a dramatic rise in NGT, with typical excess He, suggesting that noble gas concentrations acquired high in the unsaturated zone can persist and mix with those below the water table. This implies that dynamic effects may be very important in

  9. Helium Solubility in Cyclosilicates and Implications for Noble Gas Recycling

    NASA Astrophysics Data System (ADS)

    Jackson, C.; Kelley, S. P.; Cooper, R. F.; Parman, S. W.

    2011-12-01

    It is commonly assumed that noble gases strictly flux from the mantle to the atmosphere, with negligible recycling, because noble gases are thought to be extremely insoluble in all minerals. To test this hypothesis, we have experimentally determined the He solubility in a suite of cyclosilicate minerals: beryl, tourmaline and cordierite. The experiments were run in a gas pressure vessel. Run products were analyzed by UV laser ablation, noble gas mass spectrometry. He has a remarkably high solubility (>1000 ppm/1.8 kbar PHe) in cyclosilicates with nominally vacant six-member Si-Al-tetrahedra rings. Cyclosilicates with nominally occupied ring sites have substantially lower solubility. This suggests that He dissolution is facilitated by unfilled six-member rings. If true, He should have a high solubility in other minerals that include ring sites, such as phyllosilicates and amphiboles. Subduction zones commonly recycle these minerals, providing a possible mechanism for recycling of noble gases back into the mantle. Gem quality, natural, polished crystals of each mineral were placed into graphite capsules. Pure He gas was used as the pressure medium (1800 bar), allowing for precise control of PHe. Temperatures were held at 750 C and the experimental durations were 8 hours. A capsule of hydrated MgO powder was loaded in the TZM to maintain a non-zero fugacity of water during the experiment. Close visual inspection of the run products gave no indication of breakdown products. Depth profiles (10s of microns) of the mineral faces were completed using a 193 nm excimer laser. Multiple measurements were made on each phase. He concentrations were homogenous, both vertically and horizontally, indicating a close approach to equilibrium and absence of inclusions. Compared to tourmaline, we observe that He is >1000 and >100 times more soluble in cordierite and beryl, respectively. The ring sites, also known as A sites, in beryl and cordierite are nominally vacant, where as the

  10. Solubility controlled noble gas fractionation during magmatic degassing: Implications for noble gas compositions of primary melts of OIB and MORB

    NASA Astrophysics Data System (ADS)

    Yamamoto, Junji; Burnard, Pete G.

    2005-02-01

    Noble gas abundances in basaltic glasses from ocean islands (OIBs) are generally lower than those of mid-oceanic ridge basalts (MORBs), contrary to most geodynamic models which usually require that the source of OIBs is less degassed (resulting in higher primordial noble gas abundances) and more trace element enriched (resulting in higher radiogenic noble gas abundances) than the MORB source. Therefore, noble gas abundances in OIBs are often thought to have been reduced by extensive gas loss from the magma before eruption. The extent of magmatic degassing can be tested as it will cause characteristic changes in the composition of the volatiles; notably the 4He/ 40Ar* ratio (where 40Ar* is 40Ar corrected for atmospheric contamination) will increase in residual volatiles due to the higher solubility of He relative to Ar. The degree of He-Ar fractionation for a given fraction of gas loss depends on the ratio of the solubilities, S He/S Ar, which is sensitive to (among other things) the CO 2 and H 2O content of the basalt at the time of degassing. From a global database of OIB and MORB glasses, we show that 4He/ 40Ar* ratios of MORB glasses are broadly consistent with degassing of a magma with an initial 40Ar of ≈1.5 × 10 -5 ccSTP/g, i.e., similar to that of the "popping rock." However, OIB glasses generally have lower 40Ar* concentration for a given 4He/ 40Ar*. While this would appear to require lower 40Ar* abundances in the undegassed OIB magmas, the higher volatile contents of OIBs will reduce S He/S Ar (relative to MORBs) during degassing. By modeling S He/S Ar in OIBs, it is possible to show that extensive degassing of OIBs can occur without dramatically increasing the 4He/ 40Ar* ratio. We show that undegassed 40Ar concentrations of OIB magmas were probably similar to those of MORBs.

  11. Mechanical response of noble gas films to an oscillating substrate

    NASA Astrophysics Data System (ADS)

    Kobayashi, Hajime; Taniguchi, Junko; Suzuki, Masaru; Miura, Kouji; Arakawa, Ichiro

    2012-12-01

    We carried out quartz-crystal microbalance (QCM) experiments for Xe films adsorbed on an exfoliated single-crystalline graphite substrate (Xe/Gr) and Kr 1ms adsorbed on a synthetic mica substrate (Kr/mica) around LN2 temperature. For Xe/Gr, it was found that the resonance frequency decreases greatly around the first layer completion, while it does not decrease at low coverages. The observed behavior is similar to that of Kr films on a graphite substrate (Kr/Gr). This demonstrates that the layer completion strongly affects the sliding motion of noble gas films on graphite.

  12. The Noble-Abel Stiffened-Gas equation of state

    NASA Astrophysics Data System (ADS)

    Le Métayer, Olivier; Saurel, Richard

    2016-04-01

    Hyperbolic two-phase flow models have shown excellent ability for the resolution of a wide range of applications ranging from interfacial flows to fluid mixtures with several velocities. These models account for waves propagation (acoustic and convective) and consist in hyperbolic systems of partial differential equations. In this context, each phase is compressible and needs an appropriate convex equation of state (EOS). The EOS must be simple enough for intensive computations as well as boundary conditions treatment. It must also be accurate, this being challenging with respect to simplicity. In the present approach, each fluid is governed by a novel EOS named "Noble Abel stiffened gas," this formulation being a significant improvement of the popular "Stiffened Gas (SG)" EOS. It is a combination of the so-called "Noble-Abel" and "stiffened gas" equations of state that adds repulsive effects to the SG formulation. The determination of the various thermodynamic functions and associated coefficients is the aim of this article. We first use thermodynamic considerations to determine the different state functions such as the specific internal energy, enthalpy, and entropy. Then we propose to determine the associated coefficients for a liquid in the presence of its vapor. The EOS parameters are determined from experimental saturation curves. Some examples of liquid-vapor fluids are examined and associated parameters are computed with the help of the present method. Comparisons between analytical and experimental saturation curves show very good agreement for wide ranges of temperature for both liquid and vapor.

  13. Structural Measurements from Images of Noble Gas Diffusion

    NASA Astrophysics Data System (ADS)

    Cadman, Robert V.; Kadlecek, Stephen J.; Emami, Kiarash; MacDuffie Woodburn, John; Vahdat, Vahid; Ishii, Masaru; Rizi, Rahim R.

    2009-03-01

    Magnetic resonance imaging of externally polarized noble gases such as ^3He has been used for pulmonary imaging for more than a decade. Because gas diffusion is impeded by the alveoli, the diffusion coefficient of gas in the lung, measured on a time scale of milliseconds, is reduced compared to that of the same gas mixture in the absence of restrictions. When the alveolar walls decay, as in emphysema, diffusivity in the lung increases. In this paper, the relationship between diffusion measurements and the size of the restricting structures will be discussed. The simple case of diffusion in an impermeable cylinder, a structure similar to the upper respiratory airways in mammals, has been studied. A procedure will be presented by which airways of order 2 mm in diameter may be accurately measured; demonstration experiments with plastic tubes will also be presented. The additional developments needed before this technique becomes practical will be briefly discussed.

  14. Interaction of the Fe + cation with heavy noble gas atoms

    NASA Astrophysics Data System (ADS)

    Heinemann, Christoph; Schwarz, Joseph; Koch, Wolfram; Schwarz, Helmut

    1995-09-01

    The diatomic iron-noble gas complexes FeAr+, FeKr+, FeXe+, and FeRn+ have been theoretically investigated by means of quantum-chemical calculations including an extensive treatment of electron correlation. Potential energy curves and spectroscopic constants for the lowest 4Δ and 6Δ states are derived from an open-shell coupled-cluster approach and the relative energies of all seven low-lying electronic states are evaluated by the multireference configuration interaction method. While in FeAr+ the lowest quartet and sextet states are found to be energetically almost degenerate, the heavier Fe+-noble gas molecules are predicted to exhibit 4Φ ground states. From a qualitative point of view bonding in these species is shown to be electrostatic in origin with intrinsically higher interaction energies for the quartet as compared to the sextet states. For calibration purposes, also an accurate calculation of the 4F(4s03d7)-6D(4s13d6) energy difference in the atomic Fe+ cation is provided.

  15. Noble gas isotopic composition as a key reference parameter in a planetary atmospheric evolution model

    NASA Astrophysics Data System (ADS)

    Ozima, M.

    2010-12-01

    The isotopic composition of noble gases is a key reference parameter in discussing the evolution of planetary atmospheres. Currently, two widely occurring noble gas components are identified in the early solar system, one is the Solar Wind noble gas (SW-noble gas, hereafter) and another is the Q-noble gas in unaltered meteorites: both noble gases are characterized by their ubiquitous occurrence and high isotopic homogeneity. Since the SW-noble gas is directly ejected from the Sun, it has been assumed to be a good proxy of the average noble gas isotopic composition in the Sun, namely the solar noble gas. The systematic enrichment of the heavier isotopes in the Q-noble gas relative to the SW-noble gas is then commonly attributed to its isotopic fractionation from the SW-noble gas. However, the isotopic compositions of the SW-noble gas either implanted on lunar soils or trapped by artificial targets show considerable isotopic variation depending on the velocity of the Solar Wind. Therefore, it is important to examine how closely the SW-noble gas represents the indigenous solar noble gas component or the mean isotopic composition of noble gases of the Sun. Here we show that the isotopic composition of the SW-noble gas is substantially fractionated relative to the solar value, and therefore should not be used as a reference parameter. We further suggest that the post D-burning Q-noble gas (see below) is the better proxy of the solar noble gas, and this should be used as a reference of the Solar noble gas isotopic composition in discussing the planetary atmospheric evolution. The most distinct difference between the Q- and the SW-noble gas is apparent in a 3He/4He isotopic ratio: 4.64e-4 in Q-He [1], but 1.23e-4 in SW-He[2]. The difference is attributed to the conversion of deuteron (D) to 3He in the Sun, namely the D-burning [3], due to high temperature during the pre-main sequence stage of the Sun. With the use of recent data on D/H ratios from helio-seismology [4] and

  16. Noble Gas Migration Experiment to Support the Detection of Underground Nuclear Explosions

    SciTech Connect

    Olsen, Khris B.; Kirkham, Randy R.; Woods, Vincent T.; Haas, Derek A.; Hayes, James C.; Bowyer, Ted W.; Mendoza, Donaldo P.; Lowrey, Justin D.; Lukins, Craig D.; Suarez, Reynold; Humble, Paul H.; Ellefson, Mark D.; Ripplinger, Mike D.; Zhong, Lirong; Mitroshkov, Alexandre V.; Aalseth, Craig E.; Prinke, Amanda M.; Mace, Emily K.; McIntyre, Justin I.; Stewart, Timothy L.; Mackley, Rob D.; Milbrath, Brian D.; Emer, Dudley; Biegalski, S.

    2016-03-01

    A Noble Gas Migration Experiment (NGME) funded by the National Center for Nuclear Security and conducted at the Nevada National Security Site (NNSS) in collaboration with Lawrence Livermore national Laboratory and National Security Technology provided critical on-site inspection (OSI) information related to the detection of an underground nuclear explosion (UNE) event using noble gas signatures.

  17. Development of a Liquefied Noble Gas Time Projection Chamber

    NASA Astrophysics Data System (ADS)

    Lesser, Ezra; White, Aaron; Aidala, Christine

    2015-10-01

    Liquefied noble gas detectors have been used for various applications in recent years for detecting neutrinos, neutrons, photons, and potentially dark matter. The University of Michigan is developing a detector with liquid argon to produce scintillation light and ionization electrons. Our data collection method will allow high-resolution energy measurement and spatial reconstruction of detected particles by using multi-pixel silicon photomultipliers (SiPM) and a cylindrical time projection chamber (TPC) with a multi-wire endplate. We have already designed a liquid argon condenser and purification unit surrounded by an insulating vacuum, constructed circuitry for temperature and pressure sensors, and created software to obtain high-accuracy sensor readouts. The status of detector development will be presented. Funded through the Michigan Memorial Phoenix Project.

  18. INGAS: Iranian Noble Gas Analyzing System for radioxenon measurement

    NASA Astrophysics Data System (ADS)

    Doost-Mohammadi, V.; Afarideh, H.; Etaati, G. R.; Safari, M. J.; Rouhi, H.

    2016-03-01

    In this article, Iranian Noble Gas Analyzing System (INGAS) will be introduced. This system is based on beta-gamma coincidence technique and consists of a well-type NaI(Tl) as gamma or X radiation detector and a cylindrical plastic scintillator to detect beta or conversion electron. Standard NIM modules were utilized to detect coincidence events of detectors. Both the beta and gamma detectors were appropriately calibrated. The efficiency curve of gamma detector for volume geometry was obtained by comparing the results of gamma point sources measurements and simulations of GATE V7.0 Monte Carlo code. The performance of detection system was checked by injection of 222Rn and 131mXe gaseous source in the detection cell. The minimum detectable activity of the system for 133Xe is 1.240±0.024 mBq for 24 h measurement time.

  19. Noble gas partitioning behavior in the Sleipner Vest hydrocarbon field

    NASA Astrophysics Data System (ADS)

    Barry, P. H.; Lawson, M.; Warr, O.; Mabry, J.; Byrne, D. J.; Meurer, W. P.; Ballentine, C. J.

    2015-12-01

    Noble gases are chemically inert and variably soluble in crustal fluids. They are primarily introduced into hydrocarbon reservoirs through exchange with formation waters, and can be used to assess migration pathways, mechanisms and reservoir storage. Of particular interest is the role groundwater plays in hydrocarbon transport, which is reflected in hydrocarbon-water volume ratios. We present compositional, stable isotope and noble gas isotope and abundance data from the Sleipner Vest field, in the Norwegian North Sea. Sleipner gases are generated from primary cracking of kerogen and the thermal cracking of oil, sourced from type II marine source, with relatively homogeneous maturities and a range in vitrinite reflectance (1.2-1.7%). Gases are hosted in the lower shoreface sandstones of the Jurassic Hugin formation, which is sealed by the Jurassic Upper Draupne and Heather formations. Gases are composed of N2 (0.6-0.9%), CO2 (5.4-15.3%) and hydrocarbons (69-80%). Helium isotopes (3He/4He) are radiogenic and range from 0.065 to 0.116 RA, showing a small mantle contribution, consistent with Ne isotopes (20Ne/22Ne from 9.70-9.91; 21Ne/22Ne from 0.0290-0.0344) and Ar isotopes (40Ar/36Ar from 315-489). 20Ne/36Ar, 84Kr/36Ar and 132Xe/36Ar values are systematically higher relative to air saturated water ratios. These data are discussed within the framework of several conceptual models: i) Total gas-stripping model, which defines the minimum volume of water to have interacted with the hydrocarbon phase; ii) Equilibrium model, assuming simple equilibration between groundwater and hydrocarbon phase at reservoir P,T and salinity; and iii) Open and closed system gas-stripping models. Using Ne-Ar, we estimate gas-water ratios for the Sleipner system of 0.02-0.09, which compare with geologic gas-water estimates of ~0.24, and suggest more groundwater interaction than a static system estimate. Kr and Xe show evidence for an additional source or process involving oil or sediments.

  20. Evaluating Gas-Phase Transport And Detection Of Noble Gas Signals From Underground Nuclear Explosions Using Chemical Tracers

    NASA Astrophysics Data System (ADS)

    Carrigan, C. R.; Hunter, S. L.; Sun, Y.; Wagoner, J. L.; Ruddle, D.; Anderson, G.; Felske, D.; Myers, K.; Zucca, J. J.; Emer, D. F.; Townsend, M.; Drellack, S.; Chipman, V.; Snelson, C. M.

    2013-12-01

    The 1993 Non-Proliferation Experiment (NPE) involved detonating 1 kiloton of chemical explosive in a subsurface cavity which also contained bottles of tracer gases (ref 1). That experiment provided an improved understanding of transport processes relevant to the detection of noble gas signals at the surface emanating from a clandestine underground nuclear explosion (UNE). As an alternative to performing large chemical detonations to simulate gas transport from UNEs, we have developed a test bed for subsurface gas transport, sampling and detection studies using a former UNE cavity. The test bed site allows for the opportunity to evaluate pathways to the surface created by the UNE as well as possible transport mechanisms including barometric pumping and cavity pressurization (ref 2). With the test bed we have monitored long-term chemical tracers as well as newly injected tracers. In order to perform high temporal resolution tracer gas monitoring, we have also developed a Subsurface Gas Smart Sampler (SGSS) which has application during an actual On Site Inspection (OSI) and is available for deployment in OSI field exercises planned for 2014. Deployment of five SGSS at the remote test bed has provided unparalleled detail concerning relationships involving tracer gas transport to the surface, barometric fluctuations and temporal variations in the natural radon concentration. We anticipate that the results of our tracer experiments will continue to support the development of improved noble gas detection technology for both OSI and International Monitoring System applications. 1. C.R. Carrigan et al., 1996, Nature, 382, p. 528. 2. Y. Sun and C.R. Carrigan, 2012, Pure Appl. Geophys., DOI 10.1007/s00024-012-0514-4.

  1. Computational phase diagrams of noble gas hydrates under pressure

    SciTech Connect

    Teeratchanan, Pattanasak Hermann, Andreas

    2015-10-21

    We present results from a first-principles study on the stability of noble gas-water compounds in the pressure range 0-100 kbar. Filled-ice structures based on the host water networks ice-I{sub h}, ice-I{sub c}, ice-II, and C{sub 0} interacting with guest species He, Ne, and Ar are investigated, using density functional theory (DFT) with four different exchange-correlation functionals that include dispersion effects to various degrees: the non-local density-based optPBE-van der Waals (vdW) and rPW86-vdW2 functionals, the semi-empirical D2 atom pair correction, and the semi-local PBE functional. In the He-water system, the sequence of stable phases closely matches that seen in the hydrogen hydrates, a guest species of comparable size. In the Ne-water system, we predict a novel hydrate structure based on the C{sub 0} water network to be stable or at least competitive at relatively low pressure. In the Ar-water system, as expected, no filled-ice phases are stable; however, a partially occupied Ar-C{sub 0} hydrate structure is metastable with respect to the constituents. The ability of the different DFT functionals to describe the weak host-guest interactions is analysed and compared to coupled cluster results on gas phase systems.

  2. An isotope separator for small noble gas samples

    NASA Astrophysics Data System (ADS)

    Lehmann, B. E.; Rauber, D. F.; Thonnard, N.; Willis, R. D.

    1987-11-01

    A Wien filter isotope enrichment system has been combined with a small turbomolecular pump to form a closed isotope separator for small noble gas samples. Atoms which leave the exit aperture of the plasma discharge ion source without being ionized are circulated back into the source through a feedback line. The system can be operated for several hours in a closed mode to collect up to 50% of the total number of atoms of a selected isotope (e.g. 81Kr) out of a small gas sample of only 2 × 10 -3 cm 3 STP. Ions are implanted at 10 kV into an aluminized Kapton foil after a flight distance of 150 cm. A beam stabilization system centers the ion beam in two perpendicular directions onto a target aperture to maintain a high enrichment factor of at least 10 3 over extended periods of time. Calibration of the enrichment process is achieved by isotope dilution. The system is a key part of the sample processing for 81Kr and 85Kr analysis by laser resonance ionization spectroscopy for applications in isotope geophysics.

  3. Computational phase diagrams of noble gas hydrates under pressure

    NASA Astrophysics Data System (ADS)

    Teeratchanan, Pattanasak; Hermann, Andreas

    2015-10-01

    We present results from a first-principles study on the stability of noble gas-water compounds in the pressure range 0-100 kbar. Filled-ice structures based on the host water networks ice-Ih, ice-Ic, ice-II, and C0 interacting with guest species He, Ne, and Ar are investigated, using density functional theory (DFT) with four different exchange-correlation functionals that include dispersion effects to various degrees: the non-local density-based optPBE-van der Waals (vdW) and rPW86-vdW2 functionals, the semi-empirical D2 atom pair correction, and the semi-local PBE functional. In the He-water system, the sequence of stable phases closely matches that seen in the hydrogen hydrates, a guest species of comparable size. In the Ne-water system, we predict a novel hydrate structure based on the C0 water network to be stable or at least competitive at relatively low pressure. In the Ar-water system, as expected, no filled-ice phases are stable; however, a partially occupied Ar-C0 hydrate structure is metastable with respect to the constituents. The ability of the different DFT functionals to describe the weak host-guest interactions is analysed and compared to coupled cluster results on gas phase systems.

  4. Noble gas trapping and fractionation during synthesis of carbonaceous matter. [in meteorites

    NASA Technical Reports Server (NTRS)

    Frick, U.; Mack, R.; Chang, S.

    1979-01-01

    An investigation of noble gas entrapment during synthesis of carbonaceous, macromolecular, and kerogen-like substances is presented. High molecular weight organic matter synthesized in aqueous condensation reactions contained little gas, and the composition was consistent with fractionation due to noble gas solubility in water; however, propane soot produced during a modified Miller-Urey experiment in an aritificial gas mixture contained high concentrations of trapped noble gases that displayed strong elemental fractionation from their reservoirs. It is concluded that theses experiemnts show that processes exist for synthesis of carbonaceous carriers that result in high noble gas concentrations and strong elemental fractionation at temperatures well above those required by absorption to achieve similar effects.

  5. Determination of natural in vivo noble-gas concentrations in human blood.

    PubMed

    Tomonaga, Yama; Brennwald, Matthias S; Livingstone, David M; Tomonaga, Geneviève; Kipfer, Rolf

    2014-01-01

    Although the naturally occurring atmospheric noble gases He, Ne, Ar, Kr, and Xe possess great potential as tracers for studying gas exchange in living beings, no direct analytical technique exists for simultaneously determining the absolute concentrations of these noble gases in body fluids in vivo. In this study, using human blood as an example, the absolute concentrations of all stable atmospheric noble gases were measured simultaneously by combining and adapting two analytical methods recently developed for geochemical research purposes. The partition coefficients determined between blood and air, and between blood plasma and red blood cells, agree with values from the literature. While the noble-gas concentrations in the plasma agree rather well with the expected solubility equilibrium concentrations for air-saturated water, the red blood cells are characterized by a distinct supersaturation pattern, in which the gas excess increases in proportion to the atomic mass of the noble-gas species, indicating adsorption on to the red blood cells. This study shows that the absolute concentrations of noble gases in body fluids can be easily measured using geochemical techniques that rely only on standard materials and equipment, and for which the underlying concepts are already well established in the field of noble-gas geochemistry.

  6. Pyroxenes from Governador Valadares and Lafayette: A Nitrogen and Noble Gas Study

    NASA Astrophysics Data System (ADS)

    Schwenzer, S. P.; Herrmann, S.; Ott, U.

    2006-03-01

    We present new noble gas and nitrogen data on pyroxene separates from Lafayette and Governador Valadares [rad. 4He, cosmogenic nuclides (in Ne, Ar), martian interior, fractionated and unfractionated martian, and fractionated terrestrial atmosphere].

  7. Analysis of the physical atomic forces between noble gas atoms, alkali ions and halogen ions

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Heinbockel, J. H.; Outlaw, R. A.

    1986-01-01

    The physical forces between atoms and molecules are important in a number of processes of practical importance, including line broadening in radiative processes, gas and crystal properties, adhesion, and thin films. The components of the physical forces between noble gas atoms, alkali ions, and halogen ions are analyzed and a data base for the dispersion forces is developed from the literature based on evaluations with the harmonic oscillator dispersion model for higher order coefficients. The Zener model of the repulsive core is used in the context of the recent asymptotic wave functions of Handler and Smith; and an effective ionization potential within the Handler and Smith wave functions is defined to analyze the two body potential data of Waldman and Gordon, the alkali-halide molecular data, and the noble gas crystal and salt crystal data. A satisfactory global fit to this molecular and crystal data is then reproduced by the model to within several percent. Surface potentials are evaluated for noble gas atoms on noble gas and salt crystal surfaces with surface tension neglected. Within this context, the noble gas surface potentials on noble gas and salt crystals are considered to be accurate to within several percent.

  8. Noble Gas Polarimetry Using Rb EPR Frequency Shifts

    NASA Astrophysics Data System (ADS)

    Ma, Z. L.; Jeong, K.; Houghtby, E.; Paskvan, T.; Limes, M. E.; Saam, B.

    2014-05-01

    EPR frequency shifts of optically polarized alkali-metal atoms can be exploited for polarimetry of noble-gas nuclei polarized by spin-exchange optical pumping. Our group recently measured the enhancement factor κ0 = 493 for Rb-129Xe, which characterizes the electron wave-function overlap during collisions and is crucial to the calibration of the frequency-shift for 129Xe polarimetry. This type of polarimetry is useful in several applications involving optically polarized 129Xe; our particular motivation is an in situ measurement of absolute 129Xe polarization within the optical pumping cell of a flow-through 129Xe polarizer. This application has some particular challenges, and we have initially observed some unexpected shifts in the 87Rb EPR frequency measurement on board the polarizer. In effort to disentangle these apparent systematic effects, we have constructed a separate experiment to characterize Rb EPR shifts for both 3He and 129Xe in sealed cells. We present results and analysis of these experiments and discuss implications for using this method in flow-through polarizers. NSF PHY-0855482

  9. EXTERNAL PHOTOEVAPORATION OF THE SOLAR NEBULA: JUPITER's NOBLE GAS ENRICHMENTS

    SciTech Connect

    Monga, Nikhil; Desch, Steven

    2015-01-01

    We present a model explaining the elemental enrichments in Jupiter's atmosphere, particularly the noble gases Ar, Kr, and Xe. While He, Ne, and O are depleted, seven other elements show similar enrichments (∼3 times solar, relative to H). Being volatile, Ar is difficult to fractionate from H{sub 2}. We argue that external photoevaporation by far-ultraviolet (FUV) radiation from nearby massive stars removed H{sub 2}, He, and Ne from the solar nebula, but Ar and other species were retained because photoevaporation occurred at large heliocentric distances where temperatures were cold enough (≲ 30 K) to trap them in amorphous water ice. As the solar nebula lost H, it became relatively and uniformly enriched in other species. Our model improves on the similar model of Guillot and Hueso. We recognize that cold temperatures alone do not trap volatiles; continuous water vapor production is also necessary. We demonstrate that FUV fluxes that photoevaporated the disk generated sufficient water vapor in regions ≲ 30 K to trap gas-phase species in amorphous water ice in solar proportions. We find more efficient chemical fractionation in the outer disk: whereas the model of Guillot and Hueso predicts a factor of three enrichment when only <2% of the disk mass remains, we find the same enrichments when 30% of the disk mass remains. Finally, we predict the presence of ∼0.1 M {sub ⊕} of water vapor in the outer solar nebula and protoplanetary disks in H II regions.

  10. The MSFC Noble Gas Research Laboratory (MNGRL): A NASA Investigator Facility

    NASA Technical Reports Server (NTRS)

    Cohen, Barbara

    2016-01-01

    Noble-gas isotopes are a well-established technique for providing detailed temperature-time histories of rocks and meteorites. We have established the MSFC Noble Gas Research Laboratory (MNGRL) at Marshall Space Flight Center to serve as a NASA investigator facility in the wake of the closure of the JSC laboratory formerly run by Don Bogard. The MNGRL lab was constructed to be able to measure all the noble gases, particularly Ar-Ar and I-Xe radioactive dating to find the formation age of rocks and meteorites, and Ar/Kr/Ne cosmic-ray exposure ages to understand when the meteorites were launched from their parent planets.

  11. Review: gas-phase ion chemistry of the noble gases: recent advances and future perspectives.

    PubMed

    Grandinetti, Felice

    2011-01-01

    This review article surveys recent experimental and theoretical advances in the gas-phase ion chemistry of the noble gases. Covered issues include the interaction of the noble gases with metal and non-metal cations, the conceivable existence of covalent noble-gas anions, the occurrence of ion-molecule reactions involving singly-charged xenon cations, and the occurrence of bond-forming reactions involving doubly-charged cations. Research themes are also highlighted, that are expected to attract further interest in the future.

  12. Experimental studies and model analysis of noble gas fractionation in porous media

    USGS Publications Warehouse

    Ding, Xin; Kennedy, B. Mack.; Evans, William C.; Stonestrom, David A.

    2016-01-01

    The noble gases, which are chemically inert under normal terrestrial conditions but vary systematically across a wide range of atomic mass and diffusivity, offer a multicomponent approach to investigating gas dynamics in unsaturated soil horizons, including transfer of gas between saturated zones, unsaturated zones, and the atmosphere. To evaluate the degree to which fractionation of noble gases in the presence of an advective–diffusive flux agrees with existing theory, a simple laboratory sand column experiment was conducted. Pure CO2 was injected at the base of the column, providing a series of constant CO2 fluxes through the column. At five fixed sampling depths within the system, samples were collected for CO2 and noble gas analyses, and ambient pressures were measured. Both the advection–diffusion and dusty gas models were used to simulate the behavior of CO2 and noble gases under the experimental conditions, and the simulations were compared with the measured depth-dependent concentration profiles of the gases. Given the relatively high permeability of the sand column (5 ´ 10−11 m2), Knudsen diffusion terms were small, and both the dusty gas model and the advection–diffusion model accurately predicted the concentration profiles of the CO2 and atmospheric noble gases across a range of CO2 flux from ?700 to 10,000 g m−2 d−1. The agreement between predicted and measured gas concentrations demonstrated that, when applied to natural systems, the multi-component capability provided by the noble gases can be exploited to constrain component and total gas fluxes of non-conserved (CO2) and conserved (noble gas) species or attributes of the soil column relevant to gas transport, such as porosity, tortuosity, and gas saturation.

  13. Appraisal of transport and deformation in shale reservoirs using natural noble gas tracers

    SciTech Connect

    Heath, Jason E.; Kuhlman, Kristopher L.; Robinson, David G.; Bauer, Stephen J.; Gardner, William Payton

    2015-09-01

    This report presents efforts to develop the use of in situ naturally-occurring noble gas tracers to evaluate transport mechanisms and deformation in shale hydrocarbon reservoirs. Noble gases are promising as shale reservoir diagnostic tools due to their sensitivity of transport to: shale pore structure; phase partitioning between groundwater, liquid, and gaseous hydrocarbons; and deformation from hydraulic fracturing. Approximately 1.5-year time-series of wellhead fluid samples were collected from two hydraulically-fractured wells. The noble gas compositions and isotopes suggest a strong signature of atmospheric contribution to the noble gases that mix with deep, old reservoir fluids. Complex mixing and transport of fracturing fluid and reservoir fluids occurs during production. Real-time laboratory measurements were performed on triaxially-deforming shale samples to link deformation behavior, transport, and gas tracer signatures. Finally, we present improved methods for production forecasts that borrow statistical strength from production data of nearby wells to reduce uncertainty in the forecasts.

  14. Carbon and Noble Gas Isotope Banks in Two-Phase Flow: Changes in Gas Composition During Migration

    NASA Astrophysics Data System (ADS)

    Sathaye, K.; Larson, T.; Hesse, M. A.

    2015-12-01

    In conjunction with the rise of unconventional oil and gas production, there has been a recent rise in interest in noble gas and carbon isotope changes that can occur during the migration of natural gas. Natural gas geochemistry studies use bulk hydrocarbon composition, carbon isotopes, and noble gas isotopes to determine the migration history of gases from source to reservoir, and to trace fugitive gas leaks from reservoirs to shallow groundwater. We present theoretical and experimental work, which helps to explain trends observed in gas composition in various migration scenarios. Noble gases are used as tracers for subsurface fluid flow due to distinct initial compositions in air-saturated water and natural gases. Numerous field studies have observed enrichments and depletions of noble gases after gas-water interaction. A theoretical two-phase gas displacement model shows that differences in noble gas solubility will cause volatile gas components will become enriched at the front of gas plumes, leaving the surrounding residual water stripped of dissolved gases. Changes in hydrocarbon gas composition are controlled by gas solubility in both formation water and residual oil. In addition to model results, we present results from a series of two-phase flow experiments. These results demonstrate the formation of a noble gas isotope banks ahead of a main CO2 gas plume. Additionally, we show that migrating hydrocarbon gas plumes can sweep biogenic methane from groundwater, significantly altering the isotope ratio of the gas itself. Results from multicomponent, two-phase flow experiments qualitatively agree with the theoretical model, and previous field studies. These experimentally verified models for gas composition changes can be used to aid source identification of subsurface gases.

  15. Determining noble gas partitioning within a CO2-H2O system at elevated temperatures and pressures

    NASA Astrophysics Data System (ADS)

    Warr, Oliver; Rochelle, Christopher A.; Masters, Andrew; Ballentine, Christopher J.

    2015-06-01

    Quantifying the distribution of noble gases between phases is essential for using these inert trace gases to track the processes controlling multi-phase subsurface systems. Here we present experimental data that defines noble gas partitioning for two phase CO2-water systems. These are at the pressure and temperature range relevant for engineered systems used for anthropogenic carbon capture and geological storage (CCS) technologies, and CO2-rich natural gas reservoirs (CO2 density range 169-656 kg/m3 at 323-377 K and 89-134 bar). The new partitioning data are compared to predictions of noble gas partitioning determined in low-pressure, pure noble gas-water systems for all noble gases except neon and radon. At low CO2 density there was no difference between measured noble gas partitioning and that predicted in pure noble gas-water systems. At high CO2 density, however, partition coefficients express significant deviation from pure noble gas-water systems. At 656 kg/m3, these deviations are -35%, 74%, 113% and 319% for helium, argon, krypton and xenon, respectively. A second order polynomial fit to the data for each noble gas describes the deviation from the pure noble gas-water system as a function of CO2 density. We argue that the difference between pure noble gas-water systems and the high density CO2-water system is due to an enhanced degree of molecular interactions occurring within the dense CO2 phase due to the combined effect of inductive and dispersive forces acting on the noble gases. As the magnitude of these forces are related to the size and polarisability of each noble gas, xenon followed by krypton and argon become significantly more soluble within dense CO2. In the case of helium repulsive forces dominate and so it becomes less soluble as a function of CO2 density.

  16. Helium Isotopes and Noble Gas Abundances of Cave Dripping Water in Three Caves in East Asia

    NASA Astrophysics Data System (ADS)

    Chen, A. T.; Shen, C. C.; Tan, M.; Li, T.; Uemura, R.; Asami, R.

    2015-12-01

    Paleo-temperature recorded in nature archives is a critical parameter to understand climate change in the past. With advantages of unique inert chemical characteristics and sensitive solubilities with temperature, dissolved noble gases in speleothem inclusion water were recently proposed to retrieve terrestrial temperature history. In order to accurately apply this newly-developed speleothem noble gas temperature (NGT) as a reliable proxy, a fundamental issue about behaviors of noble gases in the karst should be first clarified. In this study, we measured noble gas contents in air and dripping water to evaluate any ratio deviation between noble gases. Cave dripping water samples was collected from three selected caves, Shihua Cave in northern China, Furong Cave in southwestern, and Gyukusen Cave in an island located in the western Pacific. For these caves are characterized by a thorough mixing and long-term storage of waters in a karst aquifer by the absence of seasonal oxygen isotope shifts. Ratios of dripping water noble gases are statistically insignificant from air data. Helium isotopic ratios in the dripping water samples match air value. The results indicate that elemental and isotopic signatures of noble gases from air can be frankly preserved in the epikarst and support the fidelity of NGT techniques.

  17. Signal-to-noise ratio comparison of encoding methods for hyperpolarized noble gas MRI

    NASA Technical Reports Server (NTRS)

    Zhao, L.; Venkatesh, A. K.; Albert, M. S.; Panych, L. P.

    2001-01-01

    Some non-Fourier encoding methods such as wavelet and direct encoding use spatially localized bases. The spatial localization feature of these methods enables optimized encoding for improved spatial and temporal resolution during dynamically adaptive MR imaging. These spatially localized bases, however, have inherently reduced image signal-to-noise ratio compared with Fourier or Hadamad encoding for proton imaging. Hyperpolarized noble gases, on the other hand, have quite different MR properties compared to proton, primarily the nonrenewability of the signal. It could be expected, therefore, that the characteristics of image SNR with respect to encoding method will also be very different from hyperpolarized noble gas MRI compared to proton MRI. In this article, hyperpolarized noble gas image SNRs of different encoding methods are compared theoretically using a matrix description of the encoding process. It is shown that image SNR for hyperpolarized noble gas imaging is maximized for any orthonormal encoding method. Methods are then proposed for designing RF pulses to achieve normalized encoding profiles using Fourier, Hadamard, wavelet, and direct encoding methods for hyperpolarized noble gases. Theoretical results are confirmed with hyperpolarized noble gas MRI experiments. Copyright 2001 Academic Press.

  18. Noble gas loss may indicate groundwater flow across flow barriers in southern Nevada

    USGS Publications Warehouse

    Thomas, J.M.; Bryant, Hudson G.; Stute, M.; Clark, J.F.

    2003-01-01

    Average calculated noble gas temperatures increase from 10 to 22oC in groundwater from recharge to discharge areas in carbonate-rock aquifers of southern Nevada. Loss of noble gases from groundwater in these regional flow systems at flow barriers is the likely process that produces an increase in recharge noble gas temperatures. Emplacement of low permeability rock into high permeability aquifer rock and the presence of low permeability shear zones reduce aquifer thickness from thousands to tens of meters. At these flow barriers, which are more than 1,000 m lower than the average recharge altitude, noble gases exsolve from the groundwater by inclusion in gas bubbles formed near the barriers because of greatly reduced hydrostatic pressure. However, re-equilibration of noble gases in the groundwater with atmospheric air at the low altitude spring discharge area, at the terminus of the regional flow system, cannot be ruled out. Molecular diffusion is not an important process for removing noble gases from groundwater in the carbonate-rock aquifers because concentration gradients are small.

  19. Performance of the High Resolution, Multi-collector Helix MC Plus Noble Gas Mass Spectrometer at the Australian National University

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaodong; Honda, Masahiko; Hamilton, Doug

    2016-12-01

    Performance of the Helix MC Plus noble gas mass spectrometer installed at the Australian National University (ANU) is reported. Results for sensitivity, mass discrimination and their linearity against partial pressure of noble gases, and mass resolution of the mass spectrometer are presented, and the results are compared with those of conventional noble gas mass spectrometers. The application of the five detectors on the Helix MC Plus in measuring various noble gas isotopes in multi-collector modes and the integration of the software drivers of peripheral hardware devices into the controlling program Qtegra of the mass spectrometer are discussed. High mass resolution (>1800) and mass resolving power (>8000) make this mass spectrometer unique in noble gas cosmo-geochemistry. It provides the capability to measure isobaric interference-free noble gas isotopes in multi-collector mode, significantly improves the accuracy to determine isotopic ratios, and greatly increases the efficiency of data acquisition.

  20. Solar Noble Gases in Polymict Ureilites and an Update on Ureilite Noble Gas Data

    NASA Astrophysics Data System (ADS)

    Ott, U.; Lohr, H. P.; Begemann, F.

    1993-07-01

    Ureilites are one of the least understood classes of meteorites; they show signs of being processed, but also appear to be primitive, with abundant carbon and trapped noble gases [1-6]. We have now begun to analyze a number of recently recovered specimens: one from the Saharan desert (Acfer 277) amd five from the Antarctic (LEW 85328, LEW 85440, EET 87720, FRO 90036, and FRO 90054). Analyses of Acfer 277, LEW 85328, and EET 87720 are complete (Table 1). Solar noble gases are present in polymict EET 87720, as shown by the three- isotope plot of Fig. 1. There, in contrast to the bulk data point for Acfer 277, data points for EET 87720 deviate from a mixing line between "typical" spallation Ne (as approximated here by the spallation-dominated 1800 degrees C step for EET 87720) and Ne-U [7] toward higher ^20Ne/^22Ne. A line fitted to the EET 87720 data points passes slightly below Ne-B [8]. The situation is similar for sample F1 from polymict EET 83309 [9], which is shown for comparison. Additional support for the presence of solar gases arises from the abundance of ^4He (~9 x 10^-5 cm^3 STP/g in EET 87720-F1, corrected for spallogenic contributions), which in both cases is far higher than in other ureilite bulk samples [6,10]. Also, in the ratio of spallation-corrected ^4He to trapped ^36Ar, these two polymict ureilites clearly stand out. Helium-4/argon-36 ratios in EET 87720-F1 and EET 83309-F1 are ~20 and ~28 respectively, at least 1 order of magnitude higher than in bulk monomict ureilites and 2 orders of magnitude higher than what appears typical of ureilite diamonds [6]. Nilpena, another polymict ureilite [11], also has a ^4He/^36Ar ratio (2.1 in Nilpena II-1 [7]) higher than all monomict ureilites but one (Dingo Pup Donga), indicating the presence of solar noble gases (in variable contents) as a possible general feature of polymict ureilites, similar to the presence in them of nitrogen with high delta(^15N/^14N) [12]. Monomict LEW 85328 has a very high (^22Ne

  1. Noble gas encapsulation into carbon nanotubes: Predictions from analytical model and DFT studies

    NASA Astrophysics Data System (ADS)

    Balasubramani, Sree Ganesh; Singh, Devendra; Swathi, R. S.

    2014-11-01

    The energetics for the interaction of the noble gas atoms with the carbon nanotubes (CNTs) are investigated using an analytical model and density functional theory calculations. Encapsulation of the noble gas atoms, He, Ne, Ar, Kr, and Xe into CNTs of various chiralities is studied in detail using an analytical model, developed earlier by Hill and co-workers. The constrained motion of the noble gas atoms along the axes of the CNTs as well as the off-axis motion are discussed. Analyses of the forces, interaction energies, acceptance and suction energies for the encapsulation enable us to predict the optimal CNTs that can encapsulate each of the noble gas atoms. We find that CNTs of radii 2.98 - 4.20 Å (chiral indices, (5,4), (6,4), (9,1), (6,6), and (9,3)) can efficiently encapsulate the He, Ne, Ar, Kr, and Xe atoms, respectively. Endohedral adsorption of all the noble gas atoms is preferred over exohedral adsorption on various CNTs. The results obtained using the analytical model are subsequently compared with the calculations performed with the dispersion-including density functional theory at the M06 - 2X level using a triple-zeta basis set and good qualitative agreement is found. The analytical model is however found to be computationally cheap as the equations can be numerically programmed and the results obtained in comparatively very less time.

  2. Noble gas encapsulation into carbon nanotubes: Predictions from analytical model and DFT studies

    SciTech Connect

    Balasubramani, Sree Ganesh; Singh, Devendra; Swathi, R. S.

    2014-11-14

    The energetics for the interaction of the noble gas atoms with the carbon nanotubes (CNTs) are investigated using an analytical model and density functional theory calculations. Encapsulation of the noble gas atoms, He, Ne, Ar, Kr, and Xe into CNTs of various chiralities is studied in detail using an analytical model, developed earlier by Hill and co-workers. The constrained motion of the noble gas atoms along the axes of the CNTs as well as the off-axis motion are discussed. Analyses of the forces, interaction energies, acceptance and suction energies for the encapsulation enable us to predict the optimal CNTs that can encapsulate each of the noble gas atoms. We find that CNTs of radii 2.98 − 4.20 Å (chiral indices, (5,4), (6,4), (9,1), (6,6), and (9,3)) can efficiently encapsulate the He, Ne, Ar, Kr, and Xe atoms, respectively. Endohedral adsorption of all the noble gas atoms is preferred over exohedral adsorption on various CNTs. The results obtained using the analytical model are subsequently compared with the calculations performed with the dispersion-including density functional theory at the M06 − 2X level using a triple-zeta basis set and good qualitative agreement is found. The analytical model is however found to be computationally cheap as the equations can be numerically programmed and the results obtained in comparatively very less time.

  3. Method and apparatus for noble gas atom detection with isotopic selectivity

    DOEpatents

    Hurst, G. Samuel; Payne, Marvin G.; Chen, Chung-Hsuan; Parks, James E.

    1984-01-01

    Apparatus and methods of operation are described for determining, with isotopic selectivity, the number of noble gas atoms in a sample. The analysis is conducted within an evacuated chamber which can be isolated by a valve from a vacuum pumping system capable of producing a pressure of 10.sup.-8 Torr. Provision is made to pass pulses of laser beams through the chamber, these pulses having wavelengths appropriate for the resonance ionization of atoms of the noble gas under analysis. A mass filter within the chamber selects ions of a specific isotope of the noble gas, and means are provided to accelerate these selected ions sufficiently for implantation into a target. Specific types of targets are discussed. An electron measuring device produces a signal relatable to the number of ions implanted into the target and thus to the number of atoms of the selected isotope of the noble gas removed from the gas sample. The measurement can be continued until a substantial fraction, or all, of the atoms in the sample have been counted. Furthermore, additional embodiments of the apparatus are described for bunching the atoms of a noble gas for more rapid analysis, and for changing the target for repetitive cycling of the gas in the chamber. The number of repetitions of the cyclic steps depend upon the concentration of the isotope of interest, the separative efficiency of the mass filter, etc. The cycles are continued until a desired selectivity is achieved. Also described are components and a method of operation for a pre-enrichment operation for use when an introduction of a total sample would elevate the pressure within the chamber to levels in excess of those for operation of the mass filter, specifically a quadrupole mass filter. Specific examples of three noble gas isotope analyses are described.

  4. Noble Gas Signatures in Groundwater and Rainwater on the Island of Maui, Hawaii - Developing a New Noble Gas Application in Fractured, Volcanic Systems

    NASA Astrophysics Data System (ADS)

    Castro, M. C.; Niu, Y.; Warrier, R. B.; Hall, C. M.; Gingerich, S. B.; Scholl, M. A.; Bouvier, L.

    2014-12-01

    Recent work in the Galapagos Islands suggests that noble gas temperatures (NGTs) in fractured groundwater systems reflect the temperature of the ground surface at the time of infiltration rather than the mean annual air temperature (MAAT) value as commonly assumed in sedimentary systems where NGTs are typically used as indicators of past climate. This suggests that noble gases in fractured areas may record seasonality, and thus, provide information about timing of recharge in addition to location. Calculation of NGTs assumes that rain-derived recharge at the water table is in equilibrium with ground air. Lack of noble gas equilibration with respect to surface conditions, however, was observed in high-altitude springs in the Galapagos Islands and in a rainwater pilot study in Michigan, supporting the NGT seasonality hypothesis. Developing this new NGT application will lead to a better understanding of fractured groundwater flow systems and will contribute to improved water resource management plans. This study, carried out on Maui, Hawaii, is meant to test these hypotheses while improving knowledge of this island's groundwater flow system where limited hydrologic data are available. Here, we present the first results of noble gas analyses from samples collected in springs, groundwater wells and rainwater on northeast Maui. Results show that like most Michigan rainwater samples, rainwater from Maui is in disequilibrium with surface conditions and follows a mass-dependent pattern. Spring samples follow a similar pattern to that of rainwater and suggest that spring water originates directly from rainfall. These findings further support the hypothesis of NGT seasonality. However, while the atmospheric composition of noble gases points to direct supply from rainfall to spring aquifer systems, a direct connection between spring water and deeper aquifer levels or the mantle is apparent from He isotopic ratios which display an almost pure He mantle component in some springs.

  5. Mass fractionation of noble gases in synthetic methane hydrate: Implications for naturally occurring gas hydrate dissociation

    USGS Publications Warehouse

    Hunt, Andrew G.; Stern, Laura; Pohlman, John W.; Ruppel, Carolyn; Moscati, Richard J.; Landis, Gary P.

    2013-01-01

    As a consequence of contemporary or longer term (since 15 ka) climate warming, gas hydrates in some settings may presently be dissociating and releasing methane and other gases to the ocean-atmosphere system. A key challenge in assessing the impact of dissociating gas hydrates on global atmospheric methane is the lack of a technique able to distinguish between methane recently released from gas hydrates and methane emitted from leaky thermogenic reservoirs, shallow sediments (some newly thawed), coal beds, and other sources. Carbon and deuterium stable isotopic fractionation during methane formation provides a first-order constraint on the processes (microbial or thermogenic) of methane generation. However, because gas hydrate formation and dissociation do not cause significant isotopic fractionation, a stable isotope-based hydrate-source determination is not possible. Here, we investigate patterns of mass-dependent noble gas fractionation within the gas hydrate lattice to fingerprint methane released from gas hydrates. Starting with synthetic gas hydrate formed under laboratory conditions, we document complex noble gas fractionation patterns in the gases liberated during dissociation and explore the effects of aging and storage (e.g., in liquid nitrogen), as well as sampling and preservation procedures. The laboratory results confirm a unique noble gas fractionation pattern for gas hydrates, one that shows promise in evaluating modern natural gas seeps for a signature associated with gas hydrate dissociation.

  6. A Rapid, Low-Cost Method to Determine Travel Times at Managed Aquifer Recharge Operations Using Noble Gas Tracers

    NASA Astrophysics Data System (ADS)

    Moran, J. E.; Visser, A.; Singleton, M. J.; Esser, B. K.; Halliwell, M.; Hillegonds, D. J.

    2012-12-01

    Managed aquifer recharge is a key component for the sustainable use of surface water and groundwater in the arid western U.S. When recycled water is a recharge water source, subsurface residence time, required for bacteria and virus deactivation, is best verified by application of an extrinsic tracer. Desirable tracer properties include: no real or perceived health risk, inexpensive even for a large volume of tagged water, large dynamic range, efficient introduction, convenient sampling methods, and rapid, low-cost analysis. We have developed and tested a dissolved noble gas tracer technique ideally suited for tracing large water volumes at managed aquifer recharge facilities. In an application of the method at a water district's facilities in the San Francisco Bay area, Xenon was introduced into a 106 m3 pond over a period of 7 days using a 300 m length of gas-permeable silicone tubing. Samples from the pond, near-field shallow monitoring wells, and production wells about 400 m from the recharge pond were analyzed for dissolved Xe by noble gas membrane inlet mass spectrometry (NGMIMS). The NGMIMS uses a syringe pump, gas-permeable membrane inlet, and quadrupole residual gas analyzer for measurement of noble gas concentrations. Samples are collected in VOA vials, and analysis can be carried out in real-time, with a measurement uncertainty of about 5% for Xe. Tracer first appeared in a production well 136 days after starting the tracer introduction at 0.7% (C/C0) of the peak pond xenon concentration. The cost of the tracer is about US650/106 m3 water, and the NGMIMS was assembled with parts totaling approximately US50,000, making application of the tracer method feasible for most managed aquifer recharge projects. This project is part of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program.

  7. Perspectives of hyperpolarized noble gas MRI beyond 3He

    NASA Astrophysics Data System (ADS)

    Lilburn, David M. L.; Pavlovskaya, Galina E.; Meersmann, Thomas

    2013-04-01

    Nuclear Magnetic Resonance (NMR) studies with hyperpolarized (hp) noble gases are at an exciting interface between physics, chemistry, materials science and biomedical sciences. This paper intends to provide a brief overview and outlook of magnetic resonance imaging (MRI) with hp noble gases other than hp 3He. A particular focus are the many intriguing experiments with 129Xe, some of which have already matured to useful MRI protocols, while others display high potential for future MRI applications. Quite naturally for MRI applications the major usage so far has been for biomedical research but perspectives for engineering and materials science studies are also provided. In addition, the prospects for surface sensitive contrast with hp 83Kr MRI is discussed.

  8. Photoionization of noble-gas atoms by ultrashort electromagnetic pulses

    SciTech Connect

    Astapenko, V. A. Svita, S. Yu.

    2014-11-15

    The photoionization of atoms of noble gases (Ar, Kr, and Xe) by ultrashort electromagnetic pulses of a corrected Gaussian shape is studied theoretically. Computations are performed in the context of perturbation theory using a simple expression for the total probability of photoionization of an atom by electromagnetic pulses. The features of this process are revealed and analyzed for various ranges of the parameters of the problem.

  9. Relationship between recent cave temperatures and noble gas temperatures derived from fluid inclusions of modern soda straw stalactites

    NASA Astrophysics Data System (ADS)

    Palcsu, Laszlo; Papp, Laszlo; Major, Zoltan; Molnar, Mihaly

    2010-05-01

    Recently, strong effort is devoted to establish a new method to derive palaeotemperatures from noble gas (Ne, Ar, Kr, Xe) concentrations dissolved in fluid inclusions of speleothems [1-2]. It has been already shown that the water content of the speleothems can be determined via the water vapour pressure after the water has been released from the carbonate samples and collected in a cold finger and then heated up to room temperature. Additionally, the noble gas contents can be precisely measured with noble gas mass spectrometers. Based on these noble gas concentration data sets, a so-called noble gas temperature (NGT) can be calculated meaning a temperature at which the noble gases have been dissolved in water. To use these NGT's as a palaeoclimate proxy, one of the main questions is how these noble gas temperatures reflect the prevailing cave temperature in which the carbonate has grown. We studied noble gas significances in recent soda straw stalactites from more than ten Central European caves covering a temperature range of 1 to 14 °C. Kluge et al. (2008) has shown the soda straw stalactites might contain less excess air, hence they are more suitable samples to derive NGT's, because noble gas abundances from large air inclusions can mask the temperature information. The 14C ages of these soda straw dripstones were obtained to be recent or at least Holocene ages. Thus one can assume that the cave temperatures during carbonate formation were as same as at present. We measured the water and noble gas contents of numerous carbonate samples from soda straw stalactites and calculated noble gas temperatures by a precision of 1 °C or better. Comparing these temperatures with cave temperatures we obtained that they agree well within the uncertainty of the noble gas temperature determination. Therefore, we can conclude if diffusion of noble gas isotopes does not play a significant role in the carbonate lattice this new tool helps the palaeoclimate community to gain

  10. A xenon gas purity monitor for EXO

    NASA Astrophysics Data System (ADS)

    Dobi, A.; Hall, C.; Herrin, S.; Odian, A.; Prescott, C. Y.; Rowson, P. C.; Ackerman, N.; Aharmin, B.; Auger, M.; Barbeau, P. S.; Barry, K.; Benitez-Medina, C.; Breidenbach, M.; Cook, S.; Counts, I.; Daniels, T.; DeVoe, R.; Dolinski, M. J.; Donato, K.; Fairbank, W.; Farine, J.; Giroux, G.; Gornea, R.; Graham, K.; Gratta, G.; Green, M.; Hagemann, C.; Hall, K.; Hallman, D.; Hargrove, C.; Karelin, A.; Kaufman, L. J.; Kuchenkov, A.; Kumar, K.; Lacey, J.; Leonard, D. S.; LePort, F.; Mackay, D.; MacLellan, R.; Mong, B.; Montero Díez, M.; Müller, A. R.; Neilson, R.; Niner, E.; O'Sullivan, K.; Piepke, A.; Pocar, A.; Pushkin, K.; Rollin, E.; Sinclair, D.; Slutsky, S.; Stekhanov, V.; Twelker, K.; Voskanian, N.; Vuilleumier, J.-L.; Wichoski, U.; Wodin, J.; Yang, L.; Yen, Y.-R.

    2011-12-01

    We discuss the design, operation, and calibration of two versions of a xenon gas purity monitor (GPM) developed for the EXO double beta decay program. The devices are sensitive to concentrations of oxygen well below 1 ppb at an ambient gas pressure of one atmosphere or more. The theory of operation of the GPM is discussed along with the interactions of oxygen and other impurities with the GPM's tungsten filament. Lab tests and experiences in commissioning the EXO-200 double beta decay experiment are described. These devices can also be used on other noble gases.

  11. Experimental evidence for high noble gas solubilities in silicate melts under mantle pressures

    NASA Astrophysics Data System (ADS)

    Schmidt, Burkhard C.; Keppler, Hans

    2002-02-01

    The solubilities of Ar and Xe in Fe-free synthetic haplogranitic and tholeiitic melts were experimentally determined in the pressure range of 1-11 GPa and at temperatures between 1500 and 2000°C. Experiments were performed in a piston cylinder apparatus (1-3 GPa) and in a multi-anvil apparatus (2-11 GPa). The noble gas concentrations in the quenched glasses were determined with electron microprobe. As a function of pressure, Ar solubility increases linearly up to about 4-5 GPa where it reaches about 4.0 and 0.8 wt% for the haplogranitic and tholeiitic melt, respectively. At higher pressure the amount of dissolved Ar remains constant, suggesting that some threshold concentration is reached. The Xe solubility in tholeiite melt exhibits a very similar pattern. It increases linearly up to about 6 GPa, where a threshold concentration of 0.8 wt% is reached. A further increase of pressure up to 11 GPa does not result in changes in Xe solubility. The leveling off in noble gas solubility at high pressures may imply that the interstitial sites in the melt structure, suitable for the accommodation of noble gas atoms, are fully occupied. Indeed, the experimental data can be successfully reproduced with the Langmuir isotherm, implying a solubility model in which the gas atoms occupy a certain population of interstitial sites. However, the data can be equally well described by a model assuming mixing of the noble gas atoms with the oxygen atoms of the silicate melt. From a thermodynamic point of view, the constant noble gas solubility at high pressures simply implies that the partial molar volumes of the respective noble gas in the fluid and in the melt are equal. Our results differ from those of Chamorro-Perez et al. [Earth Planet. Sci. Lett. 145 (1996) 97-107; Nature 393 (1998) 352-355] who reported an abrupt, order-of-magnitude drop of Ar solubility in silica and olivine melt at around 5 GPa, suggesting that melt densification results in an abrupt decrease of the hole size

  12. Targets Involved in Cardioprotection by the Non-Anesthetic Noble Gas Helium.

    PubMed

    Weber, Nina C; Smit, Kirsten F; Hollmann, Markus W; Preckel, Benedikt

    2015-01-01

    Research data from the past decade indicate that noble gases like xenon and helium exert profound cardioprotection when applied before, during or after organ ischemia. Of all noble gases, especially helium, has gained interest in the past years because it does not have an anesthetic "side effect" like xenon, allowing application of this specific gas in numerous clinical ischemia/reperfusion situations. Because helium has several unique characteristics and no hemodynamic side effects, helium could be administered in severely ill patients. Investigations in animals as well as in humans have proven that this noble gas is not completely inert and can induce several biological effects. Though the underlying molecular mechanisms of helium-induced cardiac protection are still not yet fully understood, recently different signaling pathways have been elucidated.

  13. Noble gas isotopes in mineral springs within the Cascadia Forearc, Wasihington and Oregon

    USGS Publications Warehouse

    McCrory, Patricia A.; Constantz, James E.; Hunt, Andrew G.

    2014-01-01

    This U.S. Geological Survey report presents laboratory analyses along with field notes for a pilot study to document the relative abundance of noble gases in mineral springs within the Cascadia forearc of Washington and Oregon. Estimates of the depth to the underlying Juan de Fuca oceanic plate beneath the sample sites are derived from the McCrory and others (2012) slab model. Some of these springs have been previously sampled for chemical analyses (Mariner and others, 2006), but none currently have publicly available noble gas data. Helium isotope values as well as the noble gas values and ratios presented below will be used to determine the sources and mixing history of these mineral waters.

  14. A Philippinite with an Unusually Large Bubble: Gas Pressure and Noble Gas Composition

    NASA Astrophysics Data System (ADS)

    Matsuda, J.; Maruoka, T.; Pinti, D. L.; Koeberl, C.

    1995-09-01

    Bubbles are common in tektites, but usually their sizes range up to only a few mm. They are most abundant in Muong Nong-type tektites. The gases contained in these bubbles are of terrestrial atmospheric composition, with pressures below 1 atm (e.g., [1]). The abundances of light noble gases (He, Ne) are controlled by diffusion from the atmosphere [2], and noble gases dissolved in tektite glass indicate that the glass solidified at atmospheric pressures equivalent to about 40 km altitude [3]. Large bubbles in splash-form tektites are rather rare. Thus, the finding that a philippinite (size: 6.0 x 4.5 cm; weight: 199.6 g) contains an unusually large bubble justified a detailed study. The volume of the bubble, which was confirmed by X-ray photography, was estimated at 5.4 cm^3, by comparing the density of this tektite (2.288 g/cm^3) to that of normal philippinites (2.438 g/cm^3). A device was specifically constructed for crushing the present sample under vacuum. The 10x10 cm cylindrical device has a piston that allows to gently crush the sample by turning a handle. Various disk spacers can be used to adjust the inner height to that of the sample. The device is made of stainless steel, yielding a low noble gas blank. The crushing device is connected to a purification line and a noble gas sector-type mass spectrometer (VG 5400) [4]. Before crushing, the complete tektite was wrapped in aluminum foil. A first crushing attempt, using stainless steel disk spacers, failed and resulted in damage to the steel spacers, indicating a high strength of the tektite. Using iron disk spacers resulted in an ambient pressure increase (probably due to hydrogen from the Fe) in the sample chamber. However, the noble gas blanks were negligible. The background pressure, at 2 x 10-4 Torr, increased to 3 x 10-4 Torr when the sample was crushed. From the volume of the crushing device and that of the bubble in the tektite, the total gas pressure in the bubble was estimated at about 1 x 10-4 atm

  15. Isotopic and noble gas geochemistry in geothermal research

    SciTech Connect

    Kennedy, B.M.; DePaolo, D.J.

    1997-12-31

    The objective of this program is to provide, through isotopic analyses of fluids, fluid inclusions, and rocks and minerals coupled with improved methods for geochemical data analysis, needed information regarding sources of geothermal heat and fluids, the spatial distribution of fluid types, subsurface flow, water-rock reaction paths and rates, and the temporal evolution of geothermal systems. Isotopic studies of geothermal fluids have previously been limited to the light stable isotopes of H, C, and O. However, other isotopic systems such as the noble gases (He, Ne, Ar, Kr and Xe) and reactive elements (e.g. B, N, S, Sr and Pb) are complementary and may even be more important in some geothermal systems. The chemistry and isotopic composition of a fluid moving through the crust will change in space and time in response to varying chemical and physical parameters or by mixing with additional fluids. The chemically inert noble gases often see through these variations, making them excellent tracers for heat and fluid sources. Whereas, the isotopic compositions of reactive elements are useful tools in characterizing water-rock interaction and modeling the movement of fluids through a geothermal reservoir.

  16. Potential Energy Curves and Associated Line Shape of Alkali-Metal and Noble-Gas Interactions

    DTIC Science & Technology

    2014-10-20

    xii I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Motivation...150 xii POTENTIAL ENERGY CURVES AND ASSOCIATED LINE SHAPE OF ALKALI-METAL AND NOBLE-GAS INTERACTIONS I. Introduction 1.1 Motivation...starting point for all modern developments of a quantum picture of pressure broadening, and show how this theory reduces to the classical theory under

  17. Holocene noble gas paleothermometry from springs in the Olympic Mountains, Washington.

    EPA Science Inventory

    Noble gas temperature proxies are examined from 52 springs in the Olympic Mountains, Washington. Groundwater flows from seeps to pooled springs at <0.1 L s-1 - 2.5 L s-1 in the Elwha watershed (≈692 km2). About 85% of sampled springs issue from confined fracture reservoirs preser...

  18. Non-Adiabatic Atomic Transitions: Computational Cross Section Calculations of Alkali Metal-Noble Gas Collisions

    DTIC Science & Technology

    2011-09-01

    collisions were computationally simulated. The alkali metals were potassium, rubidium, and cesium and the noble gas partners were helium, neon, and argon...195 20. Spin-Orbit split energies of Potassium, Rubidium, and Cesium ...composed of an alkali metal typically Rubidium[26, 37] or Cesium [5, 18]. The unique character of the alkali atoms, having a single valence electron in

  19. Experimental determination of noble gas, SF6 and CO2 flow profiles through a porous sandstone

    NASA Astrophysics Data System (ADS)

    Kilgallon, Rachel; Gilfillan, Stuart; Edlmann, Katriona; McDermott, Chris

    2016-04-01

    The noble gases (He, Ne, Ar, Kr and Xe) and SF6 have recently been used as artificial and inherent tracers of CO2 flow and migration from within[1,2] and from geological reservoirs[3]. However, outstanding questions remain, particularly regarding the flow behaviour of the noble gases compared to CO2. Here we present results from specially constructed experimental equipment, which has been used to determine the factors affecting transport of noble gases relative to CO2 in a porous sandstone. The experimental setup consists of a sample loop that can be loaded with a desired gas mixture. This sample can be released as a pulse into a feeder gas stream through a flow cell. The flow cell consists of a 3.6 cm diameter core, which can be of any length. The sample is surrounded by aluminium foil and treated with epoxy resin inside stainless steel tubing. The flow cell is encased by two purpose designed dispersion end plates. Real-time analysis of the arrival peaks of the gases downstream is recorded using a Quadrupole Mass Spectrometer (QMS). For the experiments, a 0.96 m core of Fell Sandstone was selected to represent a porous media. Noble gases and SF6 pulses were flowed through a CO2 carrier gas at five different pressure gradients (10 - 50 kPa) with arrival profiles measured using the QMS. Surprisingly, peak arrival times of He were slower than the other noble gases at each pressure gradient. The differences in peak arrival times between He and other noble gases increased as pressure decreased and the curve profiles for each noble gas differ significantly. The heavier noble gases (Kr and Xe) along with SF6 show a steeper peak rise at initial appearance, but have a longer duration profile than the He curves. Interestingly, the breakthrough curve profiles for both Kr and Xe were similar to SF6 indicating that Kr and Xe could be substituted for SF6, which is a potent greenhouse gas, in tracing applications. In addition, CO2 pulses were passed through a N2 carrier gas. The

  20. Formation of noble-gas hydrides and decay of solvated protons revisited: diffusion-controlled reactions and hydrogen atom losses in solid noble gases.

    PubMed

    Tanskanen, Hanna; Khriachtchev, Leonid; Lignell, Antti; Räsänen, Markku; Johansson, Susanna; Khyzhniy, Ivan; Savchenko, Elena

    2008-02-07

    UV photolysis and annealing of C2H2/Xe, C2H2/Xe/Kr, and HBr/Xe matrices lead to complicated photochemical processes and reactions. The dominating products in these experiments are noble-gas hydrides with general formula HNgY (Ng = noble-gas atom, Y = electronegative fragment). We concentrate on distinguishing the local and global mobility and losses of H atoms, barriers of the reactions, and the decay of solvated protons. Different deposition temperatures change the amount of lattice imperfections and thus the amount of traps for H atoms. The averaged distance between reacting species influencing the reaction kinetics is controlled by varying the precursor concentration. A number of solid-state processes connected to the formation of noble-gas hydrides and decay of solvated protons are discussed using a simple kinetic model. The most efficient formation of noble-gas hydrides is connected with global (long-range) mobility of H atoms leading to the H + Xe + Y reaction. The highest concentration of noble-gas hydrides was obtained in matrices of highest optical quality, which probably have the lowest concentration of defects and H-atom losses. In matrices with high amount of geometrical imperfections, the product formation is inefficient and dominated by a local (short-range) process. The decay of solvated protons is rather local than a global process, which is different from the formation of noble-gas molecules. However, the present data do not allow distinguishing local proton and electron mobilities. Our previous results indicate that these are electrons which move to positively-charged centers and neutralize them. It is believed that the image obtained here for solid xenon is applicable to solid krypton whereas the case of argon deserves special attention.

  1. Bartlett's discovery of noble gas fluorides, a milestone in chemical history.

    PubMed

    Christe, Karl O

    2013-05-21

    In 1962, Neil Bartlett published a terse note in Proc. Chem. Soc. eradicating the long held dogma that noble gases are inert and cannot form stable compounds. This historical discovery has revolutionized our views on chemistry and has given rise to thousands of papers on noble gas chemistry. The fact that his proposed reaction product "Xe(+)[PtF6](-)" has eluded experimental detection for more than half a century and actually was a mixture of XeF(+) and Xe2F3(+) salts does not diminish the enormous impact of his discovery. A plausible explanation for the failures to observe "Xe(+)[PtF6](-)" experimentally is presented.

  2. Element distribution and noble gas isotopic abundances in lunar meteorite Allan Hills A81005

    NASA Technical Reports Server (NTRS)

    Kraehenbuehl, U.; Eugster, O.; Niedermann, S.

    1986-01-01

    Antarctic meteorite ALLAN HILLS A81005, an anorthositic breccia, is recognized to be of lunar origin. The noble gases in this meteorite were analyzed and found to be solar-wind implanted gases, whose absolute and relative concentrations are quite similar to those in lunar regolith samples. A sample of this meteorite was obtained for the analysis of the noble gas isotopes, including Kr(81), and for the determination of the elemental abundances. In order to better determine the volume derived from the surface correlated gases, grain size fractions were prepared. The results of the instrumental measurements of the gamma radiation are listed. From the amounts of cosmic ray produced noble gases and respective production rates, the lunar surface residence times were calculated. It was concluded that the lunar surface time is about half a billion years.

  3. New interatomic potentials for studying the behavior of noble gas atoms in tungsten

    NASA Astrophysics Data System (ADS)

    Zhou, Fen; Fang, Jingzhong; Deng, Huiqiu; Liu, Jianglong; Xiao, Shifang; Shu, Xiaolin; Gao, Fei; Hu, Wangyu

    2015-12-01

    To study the behavior of noble gas atoms (He, Ne and Ar) in bulk tungsten, new DFT-based potentials for W-He, W-Ne and W-Ar interactions were developed by fitting the results obtained from density functional theory calculations. The new potentials adopt the embedded atom method (EAM) formalism, and the "s-band model" is used to describe the many-body interactions between each of the noble gas atoms and its neighboring W atoms. These potentials reproduce the formation energies of point defects and the migration barriers of single noble gas atoms. The simulations using these potentials successfully predict that the tetrahedral interstitial site is more stable than the octahedral interstitial site for X (= He, Ne or Ar) interstitials. Based on these new potentials, the binding interactions of a single X atom with the Xn and Xn-Vacancy clusters and the diffusion properties of Xn clusters in bulk W were studied using molecular dynamics (MD) simulations. The present results indicate that the binding energies obtained using the new potentials are good in agreement with the results of DFT calculations. The migration energies of the clusters increase with both the increase in the atomic radius of noble gases and the increase in the size of the clusters.

  4. Computational investigation of noble gas adsorption and separation by nanoporous materials.

    SciTech Connect

    Allendorf, Mark D.; Sanders, Joseph C.; Greathouse, Jeffery A.

    2008-10-01

    Molecular simulations are used to assess the ability of metal-organic framework (MOF) materials to store and separate noble gases. Specifically, grand canonical Monte Carlo simulation techniques are used to predict noble gas adsorption isotherms at room temperature. Experimental trends of noble gas inflation curves of a Zn-based material (IRMOF-1) are matched by the simulation results. The simulations also predict that IRMOF-1 selectively adsorbs Xe atoms in Xe/Kr and Xe/Ar mixtures at total feed gas pressures of 1 bar (14.7 psia) and 10 bar (147 psia). Finally, simulations of a copper-based MOF (Cu-BTC) predict this material's ability to selectively adsorb Xe and Kr atoms when present in trace amounts in atmospheric air samples. These preliminary results suggest that Cu-BTC may be an ideal candidate for the pre-concentration of noble gases from air samples. Additional simulations and experiments are needed to determine the saturation limit of Cu-BTC for xenon, and whether any krypton atoms would remain in the Cu-BTC pores upon saturation.

  5. Noble Metal Catalysts for Mercury Oxidation in Utility Flue Gas: Gold, Palladium and Platinum Formulations

    SciTech Connect

    Presto, A.A.; Granite, E.J

    2008-07-01

    The use of noble metals as catalysts for mercury oxidation in flue gas remains an area of active study. To date, field studies have focused on gold and palladium catalysts installed at pilot scale. In this article, we introduce bench-scale experimental results for gold, palladium and platinum catalysts tested in realistic simulated flue gas. Our initial results reveal some intriguing characteristics of catalytic mercury oxidation and provide insight for future research into this potentially important process.

  6. Noble Gas Thermometry and Hydrologic Ages: Evidence for Late Holocene Warming in Southwest Texas

    NASA Astrophysics Data System (ADS)

    Castro, M.; Goblet, P.

    2003-12-01

    Paleoclimatic reconstruction through the use of noble gases dissolved in groundwater has been the object of numerous studies in recent years. Unlike many other continental temperature proxies, noble gases have the advantage of providing direct information on atmospheric temperatures at the time rainwater penetrated the ground and joined a particular groundwater reservoir. In recent years, new methods for determination of noble gas temperatures have been developed, which provide a high level of accuracy on such temperature estimations. The issue of paleoclimatic reconstruction through noble gases however, is not only one of accurate temperature determination, but also one of accurate water age estimation so that a correct correspondence between noble gas temperatures and groundwater age can be established and proper paleoclimatic reconstruction attempted. The typical approach to estimate groundwater ages has been based on computing water travel times along streamlines from the recharge to the observation point taking into account only advection. This approach is limited because, like any other tracer, the movement of water in porous media is also affected by cinematic dispersion and molecular diffusion. We have therefore undertaken the formulation of hydrologic models that yield significantly better constraints on groundwater ages in the Carrizo aquifer and surrounding formations of south Texas, where noble gas temperatures have already been determined. To account for groundwater mixing we treat age as one would treat a solute concentration. In order to simulate groundwater ages we used a finite element model of groundwater flow that has been validated by 4He and 3He. The finite model spans a 120.6 Km cross-section between altitudes of +220m and -2210 m, and comprises 58,968 elements and 31,949 nodes. Combination of these newly calculated water ages and previously reported noble gas temperatures reveals new aspects of late Pleistocene and Holocene climate in

  7. ORIGIN OF THERMAL FLUIDS AT LASSEN VOLCANIC NATIONAL PARK: EVIDENCE FROM NOBLE AND REACTIVE GAS ABUNDANCES.

    USGS Publications Warehouse

    Truesdell, Alfred H.; Mazor, Emanuel; Nehring, Nancy L.

    1983-01-01

    Thermal fluid discharges at Lassen are dominated by high-altitude fumaroles and acid-sulfate hot springs in the Park, and lower altitude, neutral, high-chloride hot springs in Mill Valley 7-10 km to the south. The interrelations of these fluids have been studied by noble and reactive gas analyses. Atmospheric noble gas (ANG) contents of superheated fumaroles are similar to those of air-saturated recharge water (ASW) at 5 degree C and 2500-m elevation. Low-elevation, high-chloride, hot-spring waters are highly depleted in ANG, relative to the ASW. The surface temperatures and gas chemistry of the fumaroles and hot springs suggest that steam originating from partial to near-complete vaporization of liquid from a boiling, high-chloride, hot water aquifer is decompressed adiabatically, and more or less mixed with shallow groundwater to form superheated and drowned fumaroles within the Park. Refs.

  8. Fluorinated noble-gas cyanides FKrCN, FXeCN, and FXeNC

    SciTech Connect

    Zhu, Cheng; Räsänen, Markku; Khriachtchev, Leonid

    2015-08-21

    We report on three new noble-gas molecules, FKrCN, FXeCN, and FXeNC, prepared in low-temperature Kr and Xe matrices. These molecules are made by UV photolysis of FCN in the matrices and subsequent thermal annealing. The FCN precursor is produced by deposition of the matrix gas containing (FCN){sub 3} through a microwave discharge. The new noble-gas molecules are assigned with the help of quantum chemical calculations at the MP2(full) and CCSD(T) levels of theory. Similar Ar compounds (FArCN and FArNC) as well as FKrNC are not found in these experiments, which is in agreement with the calculated energetics.

  9. Positron Impact Ionization in Noble Gas Atoms and Diatomic Molecules

    NASA Astrophysics Data System (ADS)

    Marler, J. P.

    2005-05-01

    Results are presented for absolute positronium formation and direct ionization by positron impact on Ne, Ar, Kr, Xe, N2, CO and O2 at energies from threshold up to 90 eV. The experiments use a high-resolution, trap-based positron beam and exploit the properties of positron orbits in a magnetic field [1]. Results for the noble gases are compared with theoretical predictions and with measurements obtained using a significantly different method [2]. Results for diatomic molecules are compared to other available measurements and theoretical calculations where available. There is generally good agreement between the experimental measurements, providing an important benchmark for theoretical calculations. Intriguing features in Ar and O2 will be discussed. [1] J.P. Sullivan, S.J. Gilbert, J.P. Marler, R.G. Greaves, S.J. Buckman and C.M. Surko., Phys. Rev. A. 66, 042708 (2002) [2] J.P. Marler, J.P. Sullivan and C.M. Surko, Phys. Rev. A (2005), in press.

  10. The Noble Gas Record of Gas-Water Phase Interaction in the Tight-Gas-Sand Reservoirs of the Rocky Mountains

    NASA Astrophysics Data System (ADS)

    Ballentine, C. J.; Zhou, Z.; Harris, N. B.

    2015-12-01

    The mass of hydrocarbons that have migrated through tight-gas-sandstone systems before the permeability reduces to trap the hydrocarbon gases provides critical information in the hydrocarbon potential analysis of a basin. The noble gas content (Ne, Ar, Kr, Xe) of the groundwater has a unique isotopic and elemental composition. As gas migrates through the water column, the groundwater-derived noble gases partition into the hydrocarbon phase. Determination of the noble gases in the produced hydrocarbon phase then provides a record of the type of interaction (simple phase equilibrium or open system Rayleigh fractionation). The tight-gas-sand reservoirs of the Rocky Mountains represent one of the most significant gas resources in the United States. The producing reservoirs are generally developed in low permeability (averaging <0.1mD) Upper Cretaceous fluvial to marginal marine sandstones and commonly form isolated overpressured reservoir bodies encased in even lower permeability muddy sediments. We present noble gas data from producing fields in the Greater Green River Basin, Wyoming; the the Piceance Basin, Colorado; and in the Uinta Basin, Utah. The data is consistent from all three basins. We show how in each basin the noble gases record open system gas migration through a water column at maximum basin burial. The data within an open system model indicates that the gas now in-place represents the last ~10% of hydrocarbon gas to have passed through the water column, most likely prior to permeability closedown.

  11. Investigating noble gas mixtures for use in TPCs

    NASA Astrophysics Data System (ADS)

    Jungbluth, Anna

    2017-01-01

    MITPC is a gas-based time projection chamber used for detecting fast, MeV-scale neutrons. MITPC relies on a CCD camera and the TPC (time projection chamber) technique to visualize and reconstruct tracks of neutron-induced nuclear recoils within a chosen gas. The standard version of the detector uses a mixture of 600 torr gas composed of 87.5% helium-4 and and 12.5% tetrafluoromethane (CF4) for precise measurements of the energy and direction of neutron-induced nuclear recoils. Previous studies demonstrated advantages of using neon as a replacement gas for helium-4. This talk will present a discussion of studies performed with helium and neon, as well as argon and krypton as primary neutron targets in the gas mixture with CF4.

  12. Investigating the nature of noble gas-copper bonds by the quantum theory of atoms in molecules.

    PubMed

    Rodrigues, Eduardo F F; de Sá, Eduardo L; Haiduke, Roberto L A

    2010-04-22

    We investigated noble gas-copper bonds in linear complexes represented by the NgCuX general formula in which Ng and X stand for a noble gas (neon, argon, krypton, or xenon) and a halogen (fluorine, chlorine or bromine), respectively, by coupled cluster methods and modified cc-pVQZ basis sets. The quantum theory of atoms in molecules (QTAIM) shows a linear relation between the dissociation energy of noble gas-copper bonds and the amount of electronic charge transferred mainly from the noble gas to copper during complexation. Large changes in the QTAIM quadrupole moments of copper and noble gases resulting from this bonding and a comparison between NgCuX and NgNaCl systems indicate that these noble gas-copper bonds should be better interpreted as predominantly covalent. Finally, QTAIM atomic dipoles of noble gases in NgNaCl systems agree satisfactorily with atomic dipoles given by a simple model for these NgNa van der Waals bonds.

  13. Noble gases solubility models of hydrocarbon charge mechanism in the Sleipner Vest gas field

    NASA Astrophysics Data System (ADS)

    Barry, P. H.; Lawson, M.; Meurer, W. P.; Warr, O.; Mabry, J. C.; Byrne, D. J.; Ballentine, C. J.

    2016-12-01

    Noble gases are chemically inert and variably soluble in crustal fluids. They are primarily introduced into hydrocarbon reservoirs through exchange with formation waters, and can be used to assess migration pathways and mechanisms, as well as reservoir storage conditions. Of particular interest is the role groundwater plays in hydrocarbon transport, which is reflected in hydrocarbon-water volume ratios. Here, we present compositional, stable isotope and noble gas isotope and abundance data from the Sleipner Vest field, in the Norwegian North Sea. Sleipner Vest gases are generated from primary cracking of kerogen and the thermal cracking of oil. Gas was emplaced into the Sleipner Vest from the south and subsequently migrated to the east, filling and spilling into the Sleipner Ost fields. Gases principally consist of hydrocarbons (83-93%), CO2 (5.4-15.3%) and N2 (0.6-0.9%), as well as trace concentrations of noble gases. Helium isotopes (3He/4He) are predominantly radiogenic and range from 0.065 to 0.116 RA; reported relative to air (RA = 1.4 × 10-6; Clarke et al., 1976; Sano et al., 1988), showing predominantly (>98%) crustal contributions, consistent with Ne (20Ne/22Ne from 9.70 to 9.91; 21Ne/22Ne from 0.0290 to 0.0344) and Ar isotopes (40Ar/36Ar from 315 to 489). Air-derived noble gas isotopes (20Ne, 36Ar, 84Kr, 132Xe) are introduced into the hydrocarbon system by direct exchange with air-saturated water (ASW). The distribution of air-derived noble gas species are controlled by phase partitioning processes; in that they preferentially partition into the gas (i.e., methane) phase, due to their low solubilities in fluids. Therefore, the extent of exchange between hydrocarbon phases and formation waters - that have previously equilibrated with the atmosphere - can be determined by investigating air-derived noble gas species. We utilize both elemental ratios to address process (i.e., open vs. closed system) and concentrations to quantify the extent of hydrocarbon

  14. Temporal changes in noble gas compositions within the Aidlinsector ofThe Geysers geothermal system

    SciTech Connect

    Dobson, Patrick; Sonnenthal, Eric; Kennedy, Mack; van Soest,Thijs; Lewicki, Jennifer

    2006-05-03

    The use of nonreactive isotopic tracers coupled to a full thermal-hydrological reservoir simulation allows for an improved method of investigating how reservoir fluids contained within matrix and fractures contribute over time to fluids produced from geothermal systems. A combined field and modeling study has been initiated to evaluate the effects of injection, production, and fracture-matrix interaction on produced noble gas contents and isotopic ratios. Gas samples collected periodically from the Aidlin steam field at The Geysers, California, between 1997 and 2006 have been analyzed for their noble gas compositions, and reveal systematic shifts in abundance and isotopic ratios over time. Because of the low concentrations of helium dissolved in the injection waters, the injectate itself has little impact on the helium isotopic composition of the reservoir fluids over time. However, the injection process may lead to fracturing of reservoir rocks and an increase in diffusion-controlled variations in noble gas compositions, related to gases derived from fluids within the rock matrix.

  15. Noble gas contents of shergottites and implications for the Martian origin of SNC meteorites

    NASA Astrophysics Data System (ADS)

    Bogard, D. D.; Nyquist, L. E.; Johnson, P.

    1984-09-01

    Three meteorites belonging to the rare group of SNC achondrites, which may have originated in the planet Mars, have been subjected to noble gas isotopic concentration measurements. The elemental and isotopic ratios obtained are unlike those for any other noble gas components except those obtained in analyses of the Martian atmosphere by Viking spacecraft. It is hypothesized that the Kr and Xe gases represent a portion of the Martian atmosphere which was shock-implanted in the case of Elephant Moraine A79001, and that they constitute direct evidence of a Martian origin for the shergottite meteorites. If the SNC meteorites were ejected from Mars at the shergottite shock age of about 180 My ago, they must have been objects more than 6 m in diameter which experienced at least three space collisions to initiate cosmic ray exposure.

  16. Noble gas contents of shergottites and implications for the Martian origin of SNC meteorites

    NASA Technical Reports Server (NTRS)

    Bogard, D. D.; Nyquist, L. E.; Johnson, P.

    1984-01-01

    Three meteorites belonging to the rare group of SNC achondrites, which may have originated in the planet Mars, have been subjected to noble gas isotopic concentration measurements. The elemental and isotopic ratios obtained are unlike those for any other noble gas components except those obtained in analyses of the Martian atmosphere by Viking spacecraft. It is hypothesized that the Kr and Xe gases represent a portion of the Martian atmosphere which was shock-implanted in the case of Elephant Moraine A79001, and that they constitute direct evidence of a Martian origin for the shergottite meteorites. If the SNC meteorites were ejected from Mars at the shergottite shock age of about 180 My ago, they must have been objects more than 6 m in diameter which experienced at least three space collisions to initiate cosmic ray exposure.

  17. Quantum-chemical modeling of boron and noble gas dopants in silicon

    NASA Technical Reports Server (NTRS)

    Aronowitz, S.

    1983-01-01

    The electron effects of the presence of boron and noble gas dopants in a model silicon lattice were investigated using a self-consistent charge extended Hueckel program. The extent of electronic interaction of the noble gas with the lattice is given by: Kr greater than Ar greater than Ne. Theoretically, boron diffusion in the presence of neon, argon or krypton was examined using a self-consistent charge extended Hueckel program. The net energy of interaction between boron and neon is strongly repulsive while argon-boron exhibits a region of relative stability; krypton exhibits behavior similar to argon though no region of stability was found for the range of separations used in the calculations. Finally, it is noted, from the relative energy of the topmost filled molecular orbital associated with boron (in an interstitial position), that activation of the boron does not require boron movement but can be accomplished by indirect transitions.

  18. Comparison of the bonding between ML(+) and ML2(+) (M = metal, L = noble gas)

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Partridge, Harry; Langhoff, Stephen R.

    1990-01-01

    Ab initio calculations are reported of the spectroscopic constants for the low-lying states of the molecular ions ML2(+), where M = Li, Na, Mg, V, Fe, Co, Ni and Cu, and where L is usually Ar. Comparison with existing analogous calculations on the ML(+) ions shows how the bonding and binding energy change with the addition of a second noble gas atom. The second binding energy is predicted to be essentially the same as the first for the Li, Na, Mg, and V ions, but larger for the Fe, Co, Ni and Cu ions. The binding energies of the transition metal noble gas ions are not accurately predicted at the SCF level, because correlation is required to describe their M(0)Ln(+) character. All trends can be explained in terms of promotion and hybridization on the metal ion.

  19. Noble Gas Partitioning Behaviour During Mantle Melting: A Possible Explanation for 'The He Paradox'?

    NASA Astrophysics Data System (ADS)

    Brooker, R. A.; Heber, V.; Kelley, S. P.; Wood, B. J.

    2003-12-01

    New UVLAMP measurements of experimental noble gas crystal/melt partitioning values (including He) suggest reasonably incompatible behaviour for both olivine and cpx and no significant fractionation of noble gases relative to one another. This is consistent with models of noble gas incorporation at crystal lattice sites in both crystals (1). However the determined D values of approximately 8 x10-4 for cpx and 5 x10-3 for olivine suggest a small but significant amount of noble gas might be retained in the mantle after melting. It is also apparent that He is three orders of magnitude less incompatible than U and Th in olivine. As opx is predicted to show similar characteristic to olivine, melting to produce a highly depleted harzbugitic (low-cpx) mantle would involve the preferential removal of U+Th relative to He. This in turn would allow a relatively undisturbed primordial/radiogenic 3He/4He ratio to be retained in association with low He abundance. Thus, recycling of previously depleted mantle into the source region of 'hot spots' provides one possible explanation for the paradox of high 3/4 He ratios previously thought to indicate an undegassed, primordial lower mantle reservoir, with low He abundance indicating a degassed source (2). Preliminary UVLAMP depth profiles for noble gas diffusion in mantle minerals confirm that although sub-solidus diffusive removal of He relative to other noble gases from a gas-rich mantle plum is theoretically possible, the short distances involved are unlikely to produce an effect that can be sustained though a hot spot melting event. The slow diffusion rates and lack of fractionation of noble gases in our partitioning experiments suggests that low He/Ar (and Ne/Ar) ratios observed at hot spots are most likely to be features inherited from the source, or subsequently imposed by some shallow level process. In our partitioning experiments, it proved surprisingly difficult to grow olivine crystals that are free of bubbles, even from

  20. A Simple Model for Fine Structure Transitions in Alkali-Metal Noble-Gas Collisions

    DTIC Science & Technology

    2015-03-01

    fine- structure transition rates of the alkali atoms . The integration of this integral is primarily performed nu- merically, using an adaptive Romberg...Previous work on the fine structure transitions of alkali atoms as they collide with noble gas atoms includes a full quantum mechanical calculation of...adiabaticity in alkali atom fine structure mixing”. SPIE LASE, 896207–896207. International Society for Optics and Photonics, 2014. 4. Griffiths, David J

  1. Prediction of a neutral noble gas compound in the triplet state.

    PubMed

    Manna, Debashree; Ghosh, Ayan; Ghanty, Tapan K

    2015-05-26

    Discovery of the HArF molecule associated with H-Ar covalent bonding [Nature, 2000, 406, 874-876] has revolutionized the field of noble gas chemistry. In general, this class of noble gas compound involving conventional chemical bonds exists as closed-shell species in a singlet electronic state. For the first time, in a bid to predict neutral noble gas chemical compounds in their triplet electronic state, we have carried out a systematic investigation of xenon inserted FN and FP species by using quantum chemical calculations with density functional theory and various post-Hartree-Fock-based correlated methods, including the multireference configuration interaction technique. The FXeP and FXeN species are predicted to be stable by all the computational methods employed in the present work, such as density functional theory (DFT), second-order Møller-Plesset perturbation theory (MP2), coupled-cluster theory (CCSD(T)), and multireference configuration interaction (MRCI). For the purpose of comparison we have also included the Kr-inserted compounds of FN and FP species. Geometrical parameters, dissociation energies, transition-state barrier heights, atomic charge distributions, vibrational frequency data, and atoms-in-molecules properties clearly indicate that it is possible to experimentally realize the most stable state of FXeP and FXeN molecules, which is triplet in nature, through the matrix isolation technique under cryogenic conditions.

  2. A review of noble gas geochemistry in relation to early Earth history

    NASA Technical Reports Server (NTRS)

    Kurz, M. D.

    1985-01-01

    One of the most fundamental noble gas constraints on early Earth history is derived from isotopic differences in (129)Xe/(130)Xe between various terrestrial materials. The short half life (17 m.y.) of extinct (129I, parent of (129)Xe, means that these differences must have been produced within the first 100 m.y. after terrestrial accretion. The identification of large anomalies in (129)Xe/(130)Xe in mid ocean ridge basalts (MORB), with respect to atmospheric xenon, suggests that the atmosphere and upper mantle have remained separate since that time. This alone is a very strong argument for early catastrophic degassing, which would be consistent with an early fractionation resulting in core formation. However, noble gas isotopic systematics of oceanic basalts show that the mantle cannot necessarily be regarded as a homogeneous system, since there are significant variations in (3)He/(4)He, (40)Ar/(36)Ar, and (129)Xe/(130)Xe. Therefore, the early degassing cannot be considered to have acted on the whole mantle. The specific mechanisms of degassing, in particular the thickness and growth of the early crust, is an important variable in understanding present day noble gas inventories. Another constraint can be obtained from rocks that are thought to be derived from near the lithosphere asthenosphere boundary: ultramafic xenoliths.

  3. Atomistic-Scale Simulations of Defect Formation in Graphene under Noble Gas Ion Irradiation.

    PubMed

    Yoon, Kichul; Rahnamoun, Ali; Swett, Jacob L; Iberi, Vighter; Cullen, David A; Vlassiouk, Ivan V; Belianinov, Alex; Jesse, Stephen; Sang, Xiahan; Ovchinnikova, Olga S; Rondinone, Adam J; Unocic, Raymond R; van Duin, Adri C T

    2016-09-27

    Despite the frequent use of noble gas ion irradiation of graphene, the atomistic-scale details, including the effects of dose, energy, and ion bombardment species on defect formation, and the associated dynamic processes involved in the irradiations and subsequent relaxation have not yet been thoroughly studied. Here, we simulated the irradiation of graphene with noble gas ions and the subsequent effects of annealing. Lattice defects, including nanopores, were generated after the annealing of the irradiated graphene, which was the result of structural relaxation that allowed the vacancy-type defects to coalesce into a larger defect. Larger nanopores were generated by irradiation with a series of heavier noble gas ions, due to a larger collision cross section that led to more detrimental effects in the graphene, and by a higher ion dose that increased the chance of displacing the carbon atoms from graphene. Overall trends in the evolution of defects with respect to a dose, as well as the defect characteristics, were in good agreement with experimental results. Additionally, the statistics in the defect types generated by different irradiating ions suggested that the most frequently observed defect types were Stone-Thrower-Wales (STW) defects for He(+) irradiation and monovacancy (MV) defects for all other ion irradiations.

  4. Atomistic-scale simulations of defect formation in graphene under noble gas ion irradiation

    DOE PAGES

    Yoon, Kichul; Rahnamoun, Ali; Swett, Jacob L.; ...

    2016-08-17

    Despite the frequent use of noble gas ion irradiation of graphene, the atomistic-scale details, including the effects of dose, energy, and ion bombardment species on defect formation, and the associated dynamic processes involved in the irradiations and subsequent relaxation have not yet been thoroughly studied. Here, we simulated the irradiation of graphene with noble gas ions and the subsequent effects of annealing. Lattice defects, including nanopores, were generated after the annealing of the irradiated graphene, which was the result of structural relaxation that allowed the vacancy-type defects to coalesce into a larger defect. Larger nanopores were generated by irradiation withmore » a series of heavier noble gas ions, due to a larger collision cross section that led to more detrimental effects in the graphene, and by a higher ion dose that increased the chance of displacing the carbon atoms from graphene. Overall trends in the evolution of defects with respect to a dose, as well as the defect characteristics, were in good agreement with experimental results. In addition, the statistics in the defect types generated by different irradiating ions suggested that the most frequently observed defect types were Stone-Thrower-Wales (STW) defects for He+ irradiation and monovacancy (MV) defects for all other ion irradiations.« less

  5. Atomistic-scale simulations of defect formation in graphene under noble gas ion irradiation

    SciTech Connect

    Yoon, Kichul; Rahnamoun, Ali; Swett, Jacob L.; Iberi, Vighter; Cullen, David A.; Vlassiouk, Ivan V.; Belianinov, Alex; Jesse, Stephen; Sang, Xiahan; Ovchinnikova, Olga S.; Rondinone, Adam Justin; Unocic, Raymond R.; van Duin, Adri C. T.

    2016-08-17

    Despite the frequent use of noble gas ion irradiation of graphene, the atomistic-scale details, including the effects of dose, energy, and ion bombardment species on defect formation, and the associated dynamic processes involved in the irradiations and subsequent relaxation have not yet been thoroughly studied. Here, we simulated the irradiation of graphene with noble gas ions and the subsequent effects of annealing. Lattice defects, including nanopores, were generated after the annealing of the irradiated graphene, which was the result of structural relaxation that allowed the vacancy-type defects to coalesce into a larger defect. Larger nanopores were generated by irradiation with a series of heavier noble gas ions, due to a larger collision cross section that led to more detrimental effects in the graphene, and by a higher ion dose that increased the chance of displacing the carbon atoms from graphene. Overall trends in the evolution of defects with respect to a dose, as well as the defect characteristics, were in good agreement with experimental results. In addition, the statistics in the defect types generated by different irradiating ions suggested that the most frequently observed defect types were Stone-Thrower-Wales (STW) defects for He+ irradiation and monovacancy (MV) defects for all other ion irradiations.

  6. Geostatistical Analysis of Tritium, 3H/3He Age and Noble Gas Derived Parameters in California Groundwater

    NASA Astrophysics Data System (ADS)

    Visser, A.; Singleton, M. J.; Moran, J. E.; Fram, M. S.; Kulongoski, J. T.; Esser, B. K.

    2014-12-01

    Key characteristics of California groundwater systems related to aquifer vulnerability, sustainability, recharge locations and mechanisms, and anthropogenic impact on recharge, are revealed in a spatial geostatistical analysis of the data set of tritium, dissolved noble gas and helium isotope analyses collected for the California State Water Resources Control Board's Groundwater Ambient Monitoring and Assessment (GAMA) and California Aquifer Susceptibility (CAS) programs. Over 4,000 tritium and noble gas analyses are available from wells across California. 25% of the analyzed samples contained less than 1 pCi/L indicating recharge occurred before 1950. The correlation length of tritium concentration is 120 km. Nearly 50% of the wells show a significant component of terrigenic helium. Over 50% of these samples show a terrigenic helium isotope ratio (Rter) that is significantly higher than the radiogenic helium isotope ratio (Rrad = 2×10-8). Rter values of more than three times the atmospheric isotope ratio (Ra = 1.384×10-6) are associated with known faults and volcanic provinces in Northern California. In the Central Valley, Rter varies from radiogenic to 2.25 Ra, complicating 3H/3He dating. The Rter was mapped by kriging, showing a correlation length of less than 50 km. The local predicted Rter was used to separate tritiogenic from atmospheric and terrigenic 3He. Regional groundwater recharge areas, indicated by young groundwater ages, are located in the southern Santa Clara Basin and in the upper LA basin and in the eastern San Joaquin Valley and along unlined canals carrying Colorado River water. Recharge in California is dominated by agricultural return flows, river recharge and managed aquifer recharge rather than precipitation excess. Combined application of noble gases and other groundwater tracers reveal the impact of engineered groundwater recharge and prove invaluable for the study of complex groundwater systems. This work was performed under the

  7. Issues Involving The OSI Concept of Operation For Noble Gas Radionuclide Detection

    SciTech Connect

    Carrigan, C R; Sun, Y

    2011-01-21

    The development of a technically sound protocol for detecting the subsurface release of noble gas radionuclides is critical to the successful operation of an on site inspection (OSI) under the CTBT and has broad ramifications for all aspects of the OSI regime including the setting of specifications for both sampling and analysis equipment used during an OSI. With NA-24 support, we are investigating a variety of issues and concerns that have significant bearing on policy development and technical guidance regarding the detection of noble gases and the creation of a technically justifiable OSI concept of operation. The work at LLNL focuses on optimizing the ability to capture radioactive noble gases subject to the constraints of possible OSI scenarios. This focus results from recognizing the difficulty of detecting gas releases in geologic environments - a lesson we learned previously from the LLNL Non-Proliferation Experiment (NPE). Evaluation of a number of important noble gas detection issues, potentially affecting OSI policy, has awaited the US re-engagement with the OSI technical community. Thus, there have been numerous issues to address during the past 18 months. Most of our evaluations of a sampling or transport issue necessarily involve computer simulations. This is partly due to the lack of OSI-relevant field data, such as that provided by the NPE, and partly a result of the ability of LLNL computer-based models to test a range of geologic and atmospheric scenarios far beyond what could ever be studied in the field making this approach very highly cost effective. We review some highlights of the transport and sampling issues we have investigated during the past year. We complete the discussion of these issues with a description of a preliminary design for subsurface sampling that is intended to be a practical solution to most if not all the challenges addressed here.

  8. The noble gas geochemistry of natural CO 2 gas reservoirs from the Colorado Plateau and Rocky Mountain provinces, USA

    NASA Astrophysics Data System (ADS)

    Gilfillan, Stuart M. V.; Ballentine, Chris J.; Holland, Greg; Blagburn, Dave; Lollar, Barbara Sherwood; Stevens, Scott; Schoell, Martin; Cassidy, Martin

    2008-02-01

    Identification of the source of CO 2 in natural reservoirs and development of physical models to account for the migration and interaction of this CO 2 with the groundwater is essential for developing a quantitative understanding of the long term storage potential of CO 2 in the subsurface. We present the results of 57 noble gas determinations in CO 2 rich fields (>82%) from three natural reservoirs to the east of the Colorado Plateau uplift province, USA (Bravo Dome, NM., Sheep Mountain, CO. and McCallum Dome, CO.), and from two reservoirs from within the uplift area (St. John's Dome, AZ., and McElmo Dome, CO.). We demonstrate that all fields have CO 2/ 3He ratios consistent with a dominantly magmatic source. The most recent volcanics in the province date from 8 to 10 ka and are associated with the Bravo Dome field. The oldest magmatic activity dates from 42 to 70 Ma and is associated with the McElmo Dome field, located in the tectonically stable centre of the Colorado Plateau: CO 2 can be stored within the subsurface on a millennia timescale. The manner and extent of contact of the CO 2 phase with the groundwater system is a critical parameter in using these systems as natural analogues for geological storage of anthropogenic CO 2. We show that coherent fractionation of groundwater 20Ne/ 36Ar with crustal radiogenic noble gases ( 4He, 21Ne, 40Ar) is explained by a two stage re-dissolution model: Stage 1: Magmatic CO 2 injection into the groundwater system strips dissolved air-derived noble gases (ASW) and accumulated crustal/radiogenic noble gas by CO 2/water phase partitioning. The CO 2 containing the groundwater stripped gases provides the first reservoir fluid charge. Subsequent charges of CO 2 provide no more ASW or crustal noble gases, and serve only to dilute the original ASW and crustal noble gas rich CO 2. Reservoir scale preservation of concentration gradients in ASW-derived noble gases thus provide CO 2 filling direction. This is seen in the Bravo Dome

  9. ABOUT THE POSSIBLE ROLE OF HYDROCARBON LAKES IN THE ORIGIN OF TITAN'S NOBLE GAS ATMOSPHERIC DEPLETION

    SciTech Connect

    Cordier, D.; Mousis, O.; Lebonnois, S.; Lavvas, P.; Lobo, L. Q.; Ferreira, A. G. M.

    2010-10-01

    An unexpected feature of Titan's atmosphere is the strong depletion in primordial noble gases revealed by the Gas Chromatograph Mass Spectrometer aboard the Huygens probe during its descent on 2005 January 14. Although several plausible explanations have already been formulated, no definitive response to this issue has yet been found. Here, we investigate the possible sequestration of these noble gases in the liquid contained in lakes and wet terrains on Titan and the consequences for their atmospheric abundances. Considering the atmosphere and the liquid existing on the soil as a whole system, we compute the abundance of each noble gas relative to nitrogen. To do so, we make the assumption of thermodynamic equilibrium between the liquid and the atmosphere, the abundances of the different constituents being determined via regular solution theory. We find that xenon's atmospheric depletion can be explained by its dissolution at ambient temperature in the liquid presumably present on Titan's soil. In the cases of argon and krypton, we find that the fractions incorporated in the liquid are negligible, implying that an alternative mechanism must be invoked to explain their atmospheric depletion.

  10. Apparatus for preparing a solution of a hyperpolarized noble gas for NMR and MRI analysis

    DOEpatents

    Pines, Alexander; Budinger, Thomas; Navon, Gil; Song, Yi-Qiao; Appelt, Stephan; Bifone, Angelo; Taylor, Rebecca; Goodson, Boyd; Seydoux, Roberto; Room, Toomas; Pietrass, Tanja

    2008-06-10

    The present invention relates generally to nuclear magnetic resonance (NMR) techniques for both spectroscopy and imaging. More particularly, the present invention relates to methods in which hyperpolarized noble gases (e.g., Xe and He) are used to enhance and improve NMR and MRI. Additionally, the hyperpolarized gas solutions of the invention are useful both in vitro and in vivo to study the dynamics or structure of a system. When used with biological systems, either in vivo or in vitro, it is within the scope of the invention to target the hyperpolarized gas and deliver it to specific regions within the system.

  11. Noble gas measurements from tiny water amounts: fluid inclusions in carbonates of speleothemes and coral skeletons

    NASA Astrophysics Data System (ADS)

    Papp, Laszlo; Palcsu, Laszlo; Major, Zoltan

    2010-05-01

    Based on the concentrations of dissolved noble gases in fluid inclusions in speleothems and corals, noble gas temperatures (NGT) might be derived, that would be important climate information [1]. In the case of terrestrial carbonates, it means that the temperature dependency of noble gases in the evolving fluid inclusions is suitable to determine the prevailing temperature. This recognition provides new opportunities for the research of paleoclimate. Additionally, the dissolved noble gases in the fluid inclusions represented in corals could be used to study past sea surface temperatures that are one of the most essential parameter of climate reconstructions. To measure dissolved noble gases in fluid inclusions of a few micro-litres, a noble gas mass spectrometer equipped with an ultra high vacuum preparation line is the most suitable way. The preparation of the carbonate samples is performed in a sample preparation system connected to a static mode VG 5400 noble gas mass spectrometer. As a first step of the sample preparation, one piece of a sample is put into a crusher of the preparation line and then evacuated and heated at night. The crushing of dripstone and coral samples is carried out in a stainless steel pipe with a ferro-magnetic ball at 150 °C temperature, in such a way that the ball is kept on elevating and falling down onto the carbonate sample one hundred times. The aim of the heating is to avoid the water released from the fluid inclusions not to be adsorbed on the surface of the freshly broken carbonate [2]. The water released from the fluid inclusions is frozen into a cold finger, being held at temperature of -70 °C for 15 minutes. In this case, the collection efficiency is better than 99.7 %. Then the cold finger is warmed to 27 °C, and the pressure of the water vapour expanded to the volume of the cold finger is determined by a pressure gauge, which accuracy is better than 0.2 % in the pressure range of 10-2 mbar to 11 mbar. The water vapour

  12. Calibration of stack monitors for measurement of noble gases in nuclear facilities.

    PubMed

    Kovar, Petr; Dryak, Pavel; Suran, Jiri; Gudelis, Arunas

    2012-09-01

    In nuclear facilities stack monitors are used for the measurement of the volumetric activity of noble gases. Spectrometric measurement is needed because the content of stack effluents is always a mixture of radionuclides. In some nuclear power plants new types of monitors were installed based on HPGe detectors. For efficiency calibration a standard with the radionuclide Xe-127 was developed and calibration curve constructed in the energy range 81 keV-1293 keV. Experiental efficiencies were checked using an MC model.

  13. Noble gas tracers of ventilation during deep-water formation in the Weddell Sea

    NASA Astrophysics Data System (ADS)

    Nicholson, D. P.; Khatiwala, S.; Heimbach, P.

    2016-05-01

    To explore the dynamics and implications of incomplete air-sea equilibration during the formation of abyssal water masses, we simulated noble gases in the Estimating the Circulation & Climate of the Ocean (ECCO) global ocean state estimate. A novel computation approach utilizing a matrix-free Newton-Krylov (MFNK) scheme was applied to quickly compute the periodic seasonal solutions for noble gas tracers. MFNK allows for quick computation of a cyclo-stationary solution for tracers (i.e., a spun-up, repeating seasonal cycle), which would otherwise be computationally infeasible due to the long time scale of dynamic adjustment of the abyssal ocean (1000’s of years). A suite of experiments isolates individual processes, including atmospheric pressure effects, the solubility pump and air-sea bubble fluxes. In addition to these modeled processes, a volumetric contribution of 0.28 ± 0.07% of glacial melt water is required to reconcile deep-water observations in the Weddell Sea. Another primary finding of our work is that the saturation anomaly of heavy noble gases in model simulations is in excess of two-fold more negative than is suggested from Weddell Sea observations. This result suggests that model water masses are insufficiently ventilated prior to subduction and thus there is insufficient communication between atmosphere and ocean at high latitudes. The discrepancy between noble gas observations and ECCO simulations highlights that important inadequacies remain in how we model high-latitude ventilation with large implications for the oceanic uptake and storage of carbon.

  14. Using noble gas ratios to determine the origin of ground ice

    NASA Astrophysics Data System (ADS)

    Utting, Nicholas; Lauriol, Bernard; Lacelle, Denis; Clark, Ian

    2016-01-01

    Argon, krypton and xenon have different solubilities in water, meaning their ratios in water are different from those in atmospheric air. This characteristic is used in a novel method to distinguish between ice bodies which originate from the compaction of snow (i.e. buried snow banks, glacial ice) vs. ice which forms from the freezing of groundwater (i.e. pingo ice). Ice which forms from the compaction of snow has gas ratios similar to atmospheric air, while ice which forms from the freezing of liquid water is expected to have gas ratios similar to air-equilibrated water. This analysis has been conducted using a spike dilution noble gas line with gas extraction conducted on-line. Samples were mixed with an aliquot of rare noble gases while being melted, then extracted gases are purified and cryogenically separated. Samples have been analysed from glacial ice, buried snow bank ice, intrusive ice, wedge ice, cave ice and two unknown ice bodies. Ice bodies which have formed from different processes have different gas ratios relative to their formation processes.

  15. A new noble gas paleoclimate record in Texas — Basic assumptions revisited

    NASA Astrophysics Data System (ADS)

    Castro, Maria Clara; Hall, Chris Michael; Patriarche, Delphine; Goblet, Patrick; Ellis, Brian Robert

    2007-05-01

    A generally accepted basic principle in relation to the use of the noble gas thermometer in groundwater flow systems is that high-frequency noble gas climatic signals are lost due to the effect of dispersion. This loss of signal, combined with 14C dating issues, makes it only suited to identify major climatic events such as the Last Glacial Maximum (LGM). Consequently, the identification of significant noble gas temperature (NGT) cooling (≥ 5 °C) with respect to present time has systematically been associated with the occurrence of the LGM even when reasonable water age controls were unavailable. It has also become apparent at a number of studied sites that modern NGTs estimated through standard models [M. Stute, P. Schlosser, Principles and applications of the noble gas paleothermometer, in: P.K. Swart, K.C. Lohmann, J.A. McKenzie, S. Savin, (Eds), Climate change in continental isotopic records, Geophysical monograph 78, AGU (1993) 89-100.; W. Aeschbach-Hertig, F. Peeters, U. Beyerle, R. Kipfer, Paleotemperature reconstruction from noble gases in ground water taking into account equilibration with entrapped air, Nature 405(6790) (2000) 1040-1044.] are unable to reproduce ground temperatures at the interface with the unsaturated zone, a basic requirement for proper paleoclimate reconstruction through noble gases. Instead, a systematic bias to low NGTs in recharge areas is observed. The Carrizo aquifer, in which the LGM was previously identified [M. Stute, P. Schlosser, J.F. Clark, W.S. Broecker, Paleotemperatures in the Southwestern United States derived from noble gases in ground water, Science 256(5059) (1992) 1000-1001.] and which presents an NGT bias of over 4 °C, is an ideal setting to analyze and revise basic principles and assumptions in relation with the use of the noble gas thermometer. Here, we present a new noble gas data set (49 measurements) collected at 20 different locations in the Carrizo aquifer. This new data set together with previously

  16. Development of Laser-Polarized Noble Gas Magnetic Resonance Imaging (MRI) Technology

    NASA Technical Reports Server (NTRS)

    Walsworth, Ronald L.

    2004-01-01

    We are developing technology for laser-polarized noble gas nuclear magnetic resonance (NMR), with the aim of enabling it as a novel biomedical imaging tool for ground-based and eventually space-based application. This emerging multidisciplinary technology enables high-resolution gas-space magnetic resonance imaging (MRI)-e.g., of lung ventilation, perfusion, and gas-exchange. In addition, laser-polarized noble gases (3He and 1BXe) do not require a large magnetic field for sensitive NMR detection, opening the door to practical MRI with novel, open-access magnet designs at very low magnetic fields (and hence in confined spaces). We are pursuing two specific aims in this technology development program. The first aim is to develop an open-access, low-field (less than 0.01 T) instrument for MRI studies of human gas inhalation as a function of subject orientation, and the second aim is to develop functional imaging of the lung using laser-polarized He-3 and Xe-129.

  17. Noble gas isotopes and halogens in volatile-rich inclusions in diamonds

    NASA Technical Reports Server (NTRS)

    Burgess, Raymond; Turner, Grenville

    1994-01-01

    Application of the (40)Ar-(39)Ar method and noble gas studies to diamonds has increased our understanding of their age relationships to the host kimberlite or lamproite, and of the source and composition of volatile-rich fluids in the upper mantle. The properties of diamond (inert, high mechanical strength and low gas diffusivities) means they are especially useful samples for studying gases trapped deep within the earth (less than 150 km) as they are unlikely to have undergone loss or exchange of entrapped material since formation. Volatile-rich fluids (H2O-CO2) are important agents for metasomatic processes in the upper mantle, and the noble gases and halogens preferentially partition into this phase leading to a strong geochemical coherence between these groups of elements. The abundances of the halogens in the major reservoirs of the Earth shows a marked progression from chlorine, concentrated in the oceans, through to iodine which, through its affinity to organic material, is concentrated mainly in sediments. Abundances in the upper mantle are low. This is particularly true for iodine which is of special interest in view of its potential significance as an indicator of sediment recycling and by way of its link to (129)Xe amomalies in the mantle through the low extinct isotope (129)I. Extensions of the (40)Ar-(39)Ar technique enable measurements of halogens and other elements (K, Ca, Ba, U) by production of noble gas isotopes from these species during neutron irradiation. Samples analyzed in this way include 15 coated stones from an unknown source in Zaire, 3 boarts from the Jwaneng and 1 boart from the Orapa kimberlites, both in Botswana.

  18. Looking for a correlation between terrestrial age and noble gas record of H chondrites

    NASA Astrophysics Data System (ADS)

    Loeken, Th.; Schultz, L.

    1994-07-01

    On the basis of statistically significant concentration differences of some trace elements, it has been suggested that H chondrites found in Antarctica and Modern Falls represent members of different extraterrestrial populations with different thermal histories. It was also concluded that H chondrites found in Victoria Land (Allan Hills) differ chemically from those found in Queen Maud Land (Yamato Mountains), an effect that could be based on the different terrestrial age distribution of both groups. This would imply a change of the meteoroid flux hitting the Earth on a timescale that is comparable to typical terrestrial ages of Antarctic chondrites. A comparison of the noble gas record of H chondrites from the Allan Hills icefields and Modern Fall shows that the distributions of cosmic-ray exposure ages and the concentrations of radiogenic He-4 and Ar-40 are very similar. In an earlier paper we compared the noble gas measurements of 20 Yamato H contents with meteorites from the Allan Hills region and Modern Falls. Similar distributions were found. The distribution of cosmic-ray exposure ages and radiogenic He-4 and Ar-40 gas contents as a function of the terrestrial age is investigated in these chondrites. The distribution shows the well-known 7-Ma-cluster indicating that about 40% of the H chondrites were excavated from their parent body in a single event. Both populations, Antarctic Meteorites and Modern Falls, exhibit the same characteristic feature: a major meteoroid-producing event about 7 Ma. This indicates that one H-group population delivers H chondrites to Antarctica and the rest of the world. Cosmic-ray exposure ages and thermal-history indicaters like radiogenic noble gases show no evidence of a change in the H chondrite meteoroid population during the last 200,000 years.

  19. Noble gas excimer scintillation following neutron capture in boron thin films

    SciTech Connect

    McComb, Jacob C.; Al-Sheikhly, Mohamad; Coplan, Michael A.; Thompson, Alan K.; Vest, Robert E.; Clark, Charles W.

    2014-04-14

    Far-ultraviolet scintillation signals have been measured in heavy noble gases (argon, krypton, xenon) following boron-neutron capture ({sup 10}B(n,α){sup 7}Li) in {sup 10}B thin films. The observed scintillation yields are comparable to the yields from some liquid and solid neutron scintillators. At noble gas pressures of 107 kPa, the number of photons produced per neutron absorbed following irradiation of a 1200 nm thick {sup 10}B film was 14 000 for xenon, 11 000 for krypton, and 6000 for argon. The absolute scintillation yields from the experimental configuration were calculated using data from (1) experimental irradiations, (2) thin-film characterizations, (3) photomultiplier tube calibrations, and (4) photon collection modeling. Both the boron films and the photomultiplier tube were characterized at the National Institute of Standards and Technology. Monte Carlo modeling of the reaction cell provided estimates of the photon collection efficiency and the transport behavior of {sup 10}B(n,α){sup 7}Li reaction products escaping the thin films. Scintillation yields increased with gas pressure due to increased ionization and excitation densities of the gases from the {sup 10}B(n,α){sup 7}Li reaction products, increased frequency of three-body, excimer-forming collisions, and reduced photon emission volumes (i.e., larger solid angle) at higher pressures. Yields decreased for thicker {sup 10}B thin films due to higher average energy loss of the {sup 10}B(n,α){sup 7}Li reaction products escaping the films. The relative standard uncertainties in the measurements were determined to lie between 14% and 16%. The observed scintillation signal demonstrates that noble gas excimer scintillation is promising for use in practical neutron detectors.

  20. Anatomy of a cluster IDP. Part 2: Noble gas abundances, trace element geochemistry, isotopic abundances, and trace organic chemistry of several fragments from L2008#5

    NASA Technical Reports Server (NTRS)

    Thomas, K. L.; Clemett, S. J.; Flynn, G. J.; Keller, L. P.; Mckay, David S.; Messenger, S.; Nier, A. O.; Schlutter, D. J.; Sutton, S. R.; Walker, R. M.

    1994-01-01

    The topics discussed include the following: noble gas content and release temperatures; trace element abundances; heating summary of cluster fragments; isotopic measurements; and trace organic chemistry.

  1. Confinement induced binding in noble gas atoms within a BN-doped carbon nanotube

    NASA Astrophysics Data System (ADS)

    Chakraborty, Debdutta; Chattaraj, Pratim Kumar

    2015-02-01

    Confinement induced binding interaction patterns for noble gas atoms (Hen/m, Arn, Krn; n = 2, m = 3) atoms inside pristine and -BN doped (3, 3) single walled carbon nanotube (SWCNT) have been studied through density functional theory calculations. The kinetic stability for He dimer and trimer has been investigated at 100 K and 300 K through an ab initio molecular dynamics simulation. The positive role of doping in SWCNT in enhancing the nature of interaction as well as the kinetic stability of the said systems has been found.

  2. A model to explain the various paradoxes associated with mantle noble gas geochemistry

    PubMed Central

    Anderson, Don L.

    1998-01-01

    As a result of an energetic accretion, the Earth is a volatile-poor and strongly differentiated planet. The volatile elements can be accounted for by a late veneer (≈1% of total mass of the Earth). The incompatible elements are strongly concentrated into the exosphere (atmosphere, oceans, sediments, and crust) and upper mantle. Recent geochemical models invoke a large primordial undegassed reservoir with chondritic abundances of uranium and helium, which is clearly at odds with mass and energy balance calculations. The basic assumption behind these models is that excess “primordial” 3He is responsible for 3He/4He ratios higher than the average for midocean ridge basalts. The evidence however favors depletion of 3He and excessive depletion of 4He and, therefore, favors a refractory, residual (low U, Th) source Petrological processes such as melt-crystal and melt-gas separation fractionate helium from U and Th and, with time, generate inhomogeneities in the 3He/4He ratio. A self-consistent model for noble gases involves a gas-poor planet with trapping of CO2 and noble gases in the shallow mantle. Such trapped gases are released by later tectonic and magmatic processes. Most of the mantle was depleted and degassed during the accretion process. High 3He/4He gases are viewed as products of ancient gas exsolution stored in low U environments, rather than products of primordial reservoirs. PMID:9689038

  3. Mechanisms of disruptions caused by noble gas injection into tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Morozov, D. Kh.; Yurchenko, E. I.; Lukash, V. E.; Baronova, E. O.; Pozdnyakov, Yu. I.; Rozhansky, V. A.; Senichenkov, I. Yu.; Veselova, I. Yu.; Schneider, R.

    2005-08-01

    Noble gas injection for disruption mitigation in DIII-D is simulated. The simulation of the first two stages of the disruption is performed: the first one is the neutral gas jet penetration through the background plasmas, and the second one is the instability growth. In order to simulate the first stage, the MHD pellet code LLP with improved radiation model for noble gas is used. Plasma cooling at this stage is provided by the energy exchange with the jet. The opacity effects in radiation losses are found to be important in the energy balance calculations. The magnetic surfaces in contact with the jet are cooled significantly; however, the temperature as well as the electric conductivity, remains high. The cooling front propagates towards the plasma centre. It has been shown that the cooling front is accompanied by strongly localized 'shark fin-like' perturbation in toroidal current density profile. The simplified cylindrical model shows that the cooling front is able to produce the internal kink-like mode with growth rate significantly higher than the tearing mode. The unstable kink perturbation obtained is non-resonant for any magnetic surface, both inside the plasma column, and in the vacuum space outside the separatrix. The mode disturbs mainly the core region. The growth time of the 'shark fin-like' mode is higher than the Alfven time by a factor of 10-100 for DIII-D parameters.

  4. Disruption mitigation by injection of small quantities of noble gas in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Pautasso, G.; Bernert, M.; Dibon, M.; Duval, B.; Dux, R.; Fable, E.; Fuchs, J. C.; Conway, G. D.; Giannone, L.; Gude, A.; Herrmann, A.; Hoelzl, M.; McCarthy, P. J.; Mlynek, A.; Maraschek, M.; Nardon, E.; Papp, G.; Potzel, S.; Rapson, C.; Sieglin, B.; Suttrop, W.; Treutterer, W.; The ASDEX Upgrade Team; The EUROfusion MST1 Team

    2017-01-01

    The most recent experiments of disruption mitigation by massive gas injection in ASDEX Upgrade have concentrated on small—relatively to the past—quantities of noble gas injected, and on the search for the minimum amount of gas necessary for the mitigation of the thermal loads on the divertor and for a significant reduction of the vertical force during the current quench. A scenario for the generation of a long-lived runaway electron beam has been established; this allows the study of runaway current dissipation by moderate quantities of argon injected. This paper presents these recent results and discusses them in the more general context of physical models and extrapolation, and of the open questions, relevant for the realization of the ITER disruption mitigation system.

  5. Noble Gas Analysis for Mars Robotic Missions: Evaluating K-Ar Age Dating for Mars Rock Analogs and Martian Shergottites

    NASA Technical Reports Server (NTRS)

    Park, J.; Ming, D. W.; Garrison, D. H.; Jones, J. H.; Bogard, D. D.; Nagao, K.

    2009-01-01

    The purpose of this noble gas investigation was to evaluate the possibility of measuring noble gases in martian rocks and air by future robotic missions such as the Mars Science Laboratory (MSL). The MSL mission has, as part of its payload, the Sample Analysis at Mars (SAM) instrument, which consists of a pyrolysis oven integrated with a GCMS. The MSL SAM instrument has the capability to measure noble gas compositions of martian rocks and atmosphere. Here we suggest the possibility of K-Ar age dating based on noble gas release of martian rocks by conducting laboratory simulation experiments on terrestrial basalts and martian meteorites. We provide requirements for the SAM instrument to obtain adequate noble gas abundances and compositions within the current SAM instrumental operating conditions, especially, a power limit that prevents heating the furnace above approx.1100 C. In addition, Martian meteorite analyses from NASA-JSC will be used as ground truth to evaluate the feasibility of robotic experiments to constrain the ages of martian surface rocks.

  6. Light noble gas chemistry: Structures, stabilities, and bonding of helium, neon and argon compounds

    SciTech Connect

    Frenking, G. ); Koch, W. ); Reichel, F. ); Cremer, D. )

    1990-05-23

    Theoretically determined geometries are reported for the light noble gas ions Ng{sub 2}C{sup 2+}, Ng{sub 2}N{sup 2+}, Ng{sub 2}O{sup 2+}, NgCCNg{sup 2+}, NgCCH{sup +}, NgCN{sup +}, and NgNC{sup +} (Ng = He, Ne, Ar) at the MP2/6-31G(d,p) level of theory. In a few cases, optimizations were carried out at CASSCF/6-31G(d,p). The thermodynamic stability of the Ng compounds is investigated at MP4(SDTQ)/6-311G(2df,2pd) for Ng = He, Ne and at MP4(SDTQ)/6-311G(d,p) for Ng = Ar. The structures and stabilities of the molecules are discussed in terms of donor-acceptor interactions between Ng and the respective fragment cation, by using molecular orbital arguments and utilizing the analysis of the electron density distribution and its associated Laplace field. Generally, there is an increase in Ng,X binding interactions of a noble gas molecule NgX with increasing atomic size of Ng. In some cases the Ne,X stabilization energies are slightly smaller than the corresponding He,X values because of repulsive p-{pi} interactions in the neon compounds. The argon molecules are in all cases significantly stronger bound.

  7. Noble gas patterns in the atmospheres of Mars and Earth: A comparison via the SNC meteorites

    NASA Technical Reports Server (NTRS)

    Pepin, R. O.; Becker, R. H.

    1985-01-01

    Noble gas and nitrogen compositions in the glassy phase of the EETA 79001 shergottite correspond closely with Viking measurements. This direct evidence for the origin of the SNC meteorites on Mars, and for trapping of an unfractionated sample of Martian atmospheric gases in the 79001 glass, provides a reasonable basis for comparing the Martian and terrestrial atmospheres with more precision than that afforded by the Viking data set. Results are that, with one exception, elemental and isotopic compositions of nonradiogenic Martian noble gases are similar to those in the Earth's atmosphere; relatively small isotopic discrepancies in Kr and perhaps Xe may be attributable to different degrees of mass fractionation of a common parent reservoir. The anomaly is in Ar composition, where Martian Ar-36/AR-38 approx. 4 is strikingly lower than the values near 5.3 that characterize both the Earth and major meteoritic gas carriers. Although a primordial Martian ratio of 5.3 could in principle be altered by some planet specific process (e.g., cosmic ray spallation of surface materials) operating over geologic time, one has not been found that works.

  8. Non-solar noble gas abundances in the atmosphere of Jupiter

    NASA Technical Reports Server (NTRS)

    Lunine, Jonathan I.; Stevenson, David J.

    1986-01-01

    The thermodynamic stability of clathrate hydrate is calculated to predict the formation conditions corresponding to a range of solar system parameters. The calculations were performed using the statistical mechanical theory developed by van der Waals and Platteeuw (1959) and existing experimental data concerning clathrate hydrate and its components. Dissociation pressures and partition functions (Langmuir constants) are predicted at low pressure for CO clathrate (hydrate) using the properties of chemicals similar to CO. It is argued that nonsolar but well constrained noble gas abundances may be measurable by the Galileo spacecraft in the Jovian atmosphere if the observed carbon enhancement is due to bombardment of the atmosphere by clathrate-bearing planetesimals sometime after planetary formation. The noble gas abundances of the Jovian satellite Titan are predicted, assuming that most of the methane in Titan is accreted as clathrate. It is suggested that under thermodynamically appropriate conditions, complete clathration of water ice could have occurred in high-pressure nebulas around giant planets, but probably not in the outer solar nebula. The stability of clathrate in other pressure ranges is also discussed.

  9. Migration of noble gas atoms in interaction with vacancies in silicon

    NASA Astrophysics Data System (ADS)

    Pizzagalli, L.; Charaf-Eddin, A.

    2015-08-01

    First principles calculations in combination with the nudged elastic band method have been performed in order to determine the mobility properties of various noble gas species (He, Ne, Ar, Kr, and Xe) in silicon, a model semiconducting material. We focussed on single impurity, in interstitial configuration or forming a complex with a mono- or a di-vacancy, since the latter are known to be present and to play a key role in the formation of extended defects like bubbles or platelets. We determined several migration mechanisms and associated activation energies and have discussed these results in relation to available experiments. In particular, conflicting measured values of the migration energy of helium are explained by the present calculations. We also predict that helium diffuses solely as an interstitial, while an opposite behaviour is found for heavier species such as Ar, Kr, and Xe, with the prevailing role of complexes in that case. Finally, our calculations indicate that extended defects evolution by Ostwald ripening is possible for helium and maybe neon, but is rather unlikely for heavier noble gas species.

  10. Atmospheric noble gases as tracers of biogenic gas dynamics in a shallow unconfined aquifer

    NASA Astrophysics Data System (ADS)

    Jones, Katherine L.; Lindsay, Matthew B. J.; Kipfer, Rolf; Mayer, K. Ulrich

    2014-03-01

    Atmospheric noble gases (NGs) were used to investigate biogenic gas dynamics in a shallow unconfined aquifer impacted by a crude oil spill, near Bemidji, MN. Concentrations of 3,4He, 20,22Ne, 36,40Ar, Kr, and Xe were determined for gas- and aqueous-phase samples collected from the vadose and saturated zones, respectively. Systematic elemental fractionation of Ne, Ar, Kr, and Xe with respect to air was observed in both of these hydrogeologic zones. Within the vadose zone, relative ratios of Ne and Ar to Kr and Xe revealed distinct process-related trends when compared to corresponding ratios for air. The degree of NG deviation from atmospheric concentrations generally increased with greater atomic mass (i.e., ΔXe > ΔKr > ΔAr > ΔNe), indicating that Kr and Xe are the most sensitive NG tracers in the vadose zone. Reactive transport modeling of the gas data confirms that elemental fractionation can be explained by mass-dependent variations in diffusive fluxes of NGs opposite to a total pressure gradient established between different biogeochemical process zones. Depletion of atmospheric NGs was also observed within a methanogenic zone of petroleum hydrocarbon degradation located below the water table. Solubility normalized NG abundances followed the order Xe > Kr > Ar > Ne, which is indicative of dissolved NG partitioning into the gas phase in response to bubble formation and possibly ebullition. Observed elemental NG ratios of Ne/Kr, Ne/Xe, Ar/Xe, and Kr/Xe and a modeling analysis provide strong evidence that CH4 generation below the water table caused gas exsolution and possibly ebullition and carbon transfer from groundwater to the vadose zone. These results suggest that noble gases provide sensitive tracers in biologically active unconfined aquifers and can assist in identifying carbon cycling and transfer within the vadose zone, the capillary fringe, and below the water table.

  11. Noble gas composition of subcontinental lithospheric mantle: An extensively degassed reservoir beneath Southern Patagonia

    NASA Astrophysics Data System (ADS)

    Jalowitzki, Tiago; Sumino, Hirochika; Conceição, Rommulo V.; Orihashi, Yuji; Nagao, Keisuke; Bertotto, Gustavo W.; Balbinot, Eduardo; Schilling, Manuel E.; Gervasoni, Fernanda

    2016-09-01

    Patagonia, in the Southern Andes, is one of the few locations where interactions between the oceanic and continental lithosphere can be studied due to subduction of an active spreading ridge beneath the continent. In order to characterize the noble gas composition of Patagonian subcontinental lithospheric mantle (SCLM), we present the first noble gas data alongside new lithophile (Sr-Nd-Pb) isotopic data for mantle xenoliths from Pali-Aike Volcanic Field and Gobernador Gregores, Southern Patagonia. Based on noble gas isotopic compositions, Pali-Aike mantle xenoliths represent intrinsic SCLM with higher (U + Th + K)/(3He, 22Ne, 36Ar) ratios than the mid-ocean ridge basalt (MORB) source. This reservoir shows slightly radiogenic helium (3He/4He = 6.84-6.90 RA), coupled with a strongly nucleogenic neon signature (mantle source 21Ne/22Ne = 0.085-0.094). The 40Ar/36Ar ratios vary from a near-atmospheric ratio of 510 up to 17700, with mantle source 40Ar/36Ar between 31100-6800+9400 and 54000-9600+14200. In addition, the 3He/22Ne ratios for the local SCLM endmember, at 12.03 ± 0.15 to 13.66 ± 0.37, are higher than depleted MORBs, at 3He/22Ne = 8.31-9.75. Although asthenospheric mantle upwelling through the Patagonian slab window would result in a MORB-like metasomatism after collision of the South Chile Ridge with the Chile trench ca. 14 Ma, this mantle reservoir could have remained unhomogenized after rapid passage and northward migration of the Chile Triple Junction. The mantle endmember xenon isotopic ratios of Pali-Aike mantle xenoliths, which is first defined for any SCLM-derived samples, show values indistinguishable from the MORB source (129Xe/132Xe =1.0833-0.0053+0.0216 and 136Xe/132Xe =0.3761-0.0034+0.0246). The noble gas component observed in Gobernador Gregores mantle xenoliths is characterized by isotopic compositions in the MORB range in terms of helium (3He/4He = 7.17-7.37 RA), but with slightly nucleogenic neon (mantle source 21Ne/22Ne = 0.065-0.079). We

  12. Pressure disequilibria induced by rapid valve closure in noble gas extraction lines

    USGS Publications Warehouse

    Morgan, Leah; Davidheiser-Kroll, Brett

    2015-01-01

    Pressure disequilibria during rapid valve closures can affect calculated molar quantities for a range of gas abundance measurements (e.g., K-Ar geochronology, (U-Th)/He geochronology, noble gas cosmogenic chronology). Modeling indicates this effect in a system with a 10 L reservoir reaches a bias of 1% before 1000 pipette aliquants have been removed from the system, and a bias of 10% before 10,000 aliquants. Herein we explore the causes and effects of this problem, which is the result of volume changes during valve closure. We also present a solution in the form of an electropneumatic pressure regulator that can precisely control valve motion. This solution reduces the effect to ∼0.3% even after 10,000 aliquants have been removed from a 10 L reservoir.

  13. A system for low field imaging of laser-polarized noble gas

    NASA Technical Reports Server (NTRS)

    Wong, G. P.; Tseng, C. H.; Pomeroy, V. R.; Mair, R. W.; Hinton, D. P.; Hoffmann, D.; Stoner, R. E.; Hersman, F. W.; Cory, D. G.; Walsworth, R. L.

    1999-01-01

    We describe a device for performing MRI with laser-polarized noble gas at low magnetic fields (<50 G). The system is robust, portable, inexpensive, and provides gas-phase imaging resolution comparable to that of high field clinical instruments. At 20.6 G, we have imaged laser-polarized (3)He (Larmor frequency of 67 kHz) in both sealed glass cells and excised rat lungs, using approximately 0.1 G/cm gradients to achieve approximately 1 mm(2) resolution. In addition, we measured (3)He T(2)(*) times greater than 100 ms in excised rat lungs, which is roughly 20 times longer than typical values observed at high ( approximately 2 T) fields. We include a discussion of the practical considerations for working at low magnetic fields and conclude with evidence of radiation damping in this system. Copyright 1999 Academic Press.

  14. MRI of the lung gas-space at very low-field using hyperpolarized noble gases

    NASA Technical Reports Server (NTRS)

    Venkatesh, Arvind K.; Zhang, Adelaide X.; Mansour, Joey; Kubatina, Lyubov; Oh, Chang Hyun; Blasche, Gregory; Selim Unlu, M.; Balamore, Dilip; Jolesz, Ferenc A.; Goldberg, Bennett B.; Albert, Mitchell S.

    2003-01-01

    In hyperpolarized (HP) noble-gas magnetic resonance imaging, large nuclear spin polarizations, about 100,000 times that ordinarily obtainable at thermal equilibrium, are created in 3He and 129Xe. The enhanced signal that results can be employed in high-resolution MRI studies of void spaces such as in the lungs. In HP gas MRI the signal-to-noise ratio (SNR) depends only weakly on the static magnetic field (B(0)), making very low-field (VLF) MRI possible; indeed, it is possible to contemplate portable MRI using light-weight solenoids or permanent magnets. This article reports the first in vivo VLF MR images of the lungs in humans and in rats, obtained at a field of only 15 millitesla (150 Gauss).

  15. Demonstration of neutron detection utilizing open cell foam and noble gas scintillation

    SciTech Connect

    Lavelle, C. M. Miller, E. C.; Coplan, M.; Thompson, Alan K.; Vest, Robert E.; Yue, A. T.; Kowler, A. L.; Koeth, T.; Al-Sheikhly, M.; Clark, Charles W.

    2015-03-02

    We present results demonstrating neutron detection via a closely spaced converter structure coupled to low pressure noble gas scintillation instrumented by a single photo-multiplier tube (PMT). The converter is dispersed throughout the gas volume using a reticulated vitreous carbon foam coated with boron carbide (B{sub 4}C). A calibrated cold neutron beam is used to measure the neutron detection properties, using a thin film of enriched {sup 10}B as a reference standard. Monte Carlo computations of the ion energy deposition are discussed, including treatment of the foam random network. Results from this study indicate that the foam shadows a significant portion of the scintillation light from the PMT. The high scintillation yield of Xe appears to overcome the light loss, facilitating neutron detection and presenting interesting opportunities for neutron detector design.

  16. Noble Gases

    NASA Astrophysics Data System (ADS)

    Podosek, F. A.

    2003-12-01

    The noble gases are the group of elements - helium, neon, argon, krypton, xenon - in the rightmost column of the periodic table of the elements, those which have "filled" outermost shells of electrons (two for helium, eight for the others). This configuration of electrons results in a neutral atom that has relatively low electron affinity and relatively high ionization energy. In consequence, in most natural circumstances these elements do not form chemical compounds, whence they are called "noble." Similarly, much more so than other elements in most circumstances, they partition strongly into a gas phase (as monatomic gas), so that they are called the "noble gases" (also, "inert gases"). (It should be noted, of course, that there is a sixth noble gas, radon, but all isotopes of radon are radioactive, with maximum half-life a few days, so that radon occurs in nature only because of recent production in the U-Th decay chains. The factors that govern the distribution of radon isotopes are thus quite different from those for the five gases cited. There are interesting stories about radon, but they are very different from those about the first five noble gases, and are thus outside the scope of this chapter.)In the nuclear fires in which the elements are forged, the creation and destruction of a given nuclear species depends on its nuclear properties, not on whether it will have a filled outermost shell when things cool off and nuclei begin to gather electrons. The numerology of nuclear physics is different from that of chemistry, so that in the cosmos at large there is nothing systematically special about the abundances of the noble gases as compared to other elements. We live in a very nonrepresentative part of the cosmos, however. As is discussed elsewhere in this volume, the outstanding generalization about the geo-/cosmochemistry of the terrestrial planets is that at some point thermodynamic conditions dictated phase separation of solids from gases, and that the

  17. The contribution of hydrothermally altered ocean crust to the mantle halogen and noble gas cycles

    NASA Astrophysics Data System (ADS)

    Chavrit, Déborah; Burgess, Ray; Sumino, Hirochika; Teagle, Damon A. H.; Droop, Giles; Shimizu, Aya; Ballentine, Chris J.

    2016-06-01

    Recent studies suggest that seawater-derived noble gases and halogens are recycled into the deep mantle by the subduction of oceanic crust. To understand the processes controlling the availability of halogens and noble gases for subduction, we determined the noble gas elemental and isotopic ratios and halogen (Cl, Br, I) concentrations in 28 igneous samples from the altered oceanic crust (AOC) from 5 ODP sites in the Eastern and Western Pacific Ocean. Crushing followed by heating experiments enabled determination of noble gases and halogens in fluid inclusions and mineral phases respectively. Except for He and Ar, Ne, Kr and Xe isotopic ratios were all air-like suggesting that primary MORB signatures have been completely overprinted by air and/or seawater interaction. In contrast, 3He/4He ratios obtained by crushing indicate that a mantle helium component is still preserved, and 40Ar/36Ar values are affected by radiogenic decay in the mineral phases. The 130Xe/36Ar and 84Kr/36Ar ratios are respectively up to 15 times and 5 times higher than those of seawater and the highest ratios are found in samples affected by low temperature alteration (shallower than 800-900 m sub-basement). We consider three possible processes: (i) adsorption onto the clays present in the samples; (ii) fluid inclusions with a marine pore fluid composition; and (iii) fractionation of seawater through phase separation caused by boiling. Ninety percent of the Cl, Br and I were released during the heating experiments, showing that halogens are dominantly held in mineral phases prior to subduction. I/Cl ratios vary by 4 orders of magnitude, from 3 × 10-6 to 2 × 10-2. The mean Br/Cl ratio is 30% lower than in MORB and seawater. I/Cl ratios lower than MORB values are attributed to Cl-rich amphibole formation caused by hydrothermal alteration at depths greater than 800-900 m sub-basement together with different extents of I loss during low and high temperature alteration. At shallower depths, I

  18. Noble gas isotopes in mineral springs and wells within the Cascadia forearc, Washington, Oregon, and California

    USGS Publications Warehouse

    McCrory, Patricia A.; Constantz, James E.; Hunt, Andrew G.

    2017-01-31

    IntroductionThis U.S. Geological Survey report presents laboratory analyses along with field notes for an exploratory study to document the relative abundance of noble gases in mineral springs and water wells within the Cascadia forearc of Washington, Oregon, and California (fig. 1). This report describes 14 samples collected in 2014 and 2015 and complements a previous report that describes 9 samples collected in 2012 and 2013 (McCrory and others, 2014b). Estimates of the depth to the underlying Juan de Fuca oceanic plate beneath sample sites are derived from the McCrory and others (2012) slab model. Some of the springs have been previously sampled for chemical analyses (Mariner and others, 2006), but none of the springs or wells currently has publicly available noble gas data. The helium and neon isotope values and ratios presented below are used to determine the sources and mixing history of these mineral and well waters (for example, McCrory and others, 2016).

  19. Optimizing detection of noble gas emission at a former UNE site: sample strategy, collection, and analysis

    NASA Astrophysics Data System (ADS)

    Kirkham, R.; Olsen, K.; Hayes, J. C.; Emer, D. F.

    2013-12-01

    Underground nuclear tests may be first detected by seismic or air samplers operated by the CTBTO (Comprehensive Nuclear-Test-Ban Treaty Organization). After initial detection of a suspicious event, member nations may call for an On-Site Inspection (OSI) that in part, will sample for localized releases of radioactive noble gases and particles. Although much of the commercially available equipment and methods used for surface and subsurface environmental sampling of gases can be used for an OSI scenario, on-site sampling conditions, required sampling volumes and establishment of background concentrations of noble gases require development of specialized methodologies. To facilitate development of sampling equipment and methodologies that address OSI sampling volume and detection objectives, and to collect information required for model development, a field test site was created at a former underground nuclear explosion site located in welded volcanic tuff. A mixture of SF-6, Xe127 and Ar37 was metered into 4400 m3 of air as it was injected into the top region of the UNE cavity. These tracers were expected to move towards the surface primarily in response to barometric pumping or through delayed cavity pressurization (accelerated transport to minimize source decay time). Sampling approaches compared during the field exercise included sampling at the soil surface, inside surface fractures, and at soil vapor extraction points at depths down to 2 m. Effectiveness of various sampling approaches and the results of tracer gas measurements will be presented.

  20. Hyperpolarized noble gas magnetic resonance imaging of the animal lung: Approaches and applications

    NASA Astrophysics Data System (ADS)

    Santyr, Giles E.; Lam, Wilfred W.; Parra-Robles, Juan M.; Taves, Timothy M.; Ouriadov, Alexei V.

    2009-05-01

    Hyperpolarized noble gas (HNG) magnetic resonance (MR) imaging is a very promising noninvasive tool for the investigation of animal models of lung disease, particularly to follow longitudinal changes in lung function and anatomy without the accumulated radiation dose associated with x rays. The two most common noble gases for this purpose are H3e (helium 3) and X129e (xenon 129), the latter providing a cost-effective approach for clinical applications. Hyperpolarization is typically achieved using spin-exchange optical pumping techniques resulting in ˜10 000-fold improvement in available magnetization compared to conventional Boltzmann polarizations. This substantial increase in polarization allows high spatial resolution (<1 mm) single-slice images of the lung to be obtained with excellent temporal resolution (<1 s). Complete three-dimensional images of the lungs with 1 mm slice thickness can be obtained within reasonable breath-hold intervals (<20 s). This article provides an overview of the current methods used in HNG MR imaging with an emphasis on ventilation studies in animals. Special MR hardware and software considerations are described in order to use the strong but nonrecoverable magnetization as efficiently as possible and avoid depolarization primarily by molecular oxygen. Several applications of HNG MR imaging are presented, including measurement of gross lung anatomy (e.g., airway diameters), microscopic anatomy (e.g., apparent diffusion coefficient), and a variety of functional parameters including dynamic ventilation, alveolar oxygen partial pressure, and xenon diffusing capacity.

  1. Noble gas and hydrocarbon tracers in multiphase unconventional hydrocarbon systems: Toward integrated advanced reservoir simulators

    NASA Astrophysics Data System (ADS)

    Darrah, T.; Moortgat, J.; Poreda, R. J.; Muehlenbachs, K.; Whyte, C. J.

    2015-12-01

    Although hydrocarbon production from unconventional energy resources has increased dramatically in the last decade, total unconventional oil and gas recovery from black shales is still less than 25% and 9% of the totals in place, respectively. Further, the majority of increased hydrocarbon production results from increasing the lengths of laterals, the number of hydraulic fracturing stages, and the volume of consumptive water usage. These strategies all reduce the economic efficiency of hydrocarbon extraction. The poor recovery statistics result from an insufficient understanding of some of the key physical processes in complex, organic-rich, low porosity formations (e.g., phase behavior, fluid-rock interactions, and flow mechanisms at nano-scale confinement and the role of natural fractures and faults as conduits for flow). Noble gases and other hydrocarbon tracers are capably of recording subsurface fluid-rock interactions on a variety of geological scales (micro-, meso-, to macro-scale) and provide analogs for the movement of hydrocarbons in the subsurface. As such geochemical data enrich the input for the numerical modeling of multi-phase (e.g., oil, gas, and brine) fluid flow in highly heterogeneous, low permeability formations Herein we will present a combination of noble gas (He, Ne, Ar, Kr, and Xe abundances and isotope ratios) and molecular and isotopic hydrocarbon data from a geographically and geologically diverse set of unconventional hydrocarbon reservoirs in North America. Specifically, we will include data from the Marcellus, Utica, Barnett, Eagle Ford, formations and the Illinois basin. Our presentation will include geochemical and geological interpretation and our perspective on the first steps toward building an advanced reservoir simulator for tracer transport in multicomponent multiphase compositional flow (presented separately, in Moortgat et al., 2015).

  2. Numerical models, geochemistry and the zero-paradox noble-gas mantle.

    PubMed

    Ballentine, Chris J; Van Keken, Peter E; Porcelli, Don; Hauri, Erik H

    2002-11-15

    Numerical models of whole-mantle convection demonstrate that degassing of the mantle is an inefficient process, resulting in ca. 50% of the (40)Ar being degassed from the mantle system. In this sense the numerical simulations are consistent with the (40)Ar mass balance between the atmosphere and mantle reservoir. These models, however, are unable to preserve the large-scale heterogeneity predicted by models invoking geochemical layering of the mantle system. We show that the three most important noble-gas constraints on the geochemically layered mantle are entirely dependent on the (3)He concentration of the convecting mantle derived from the (3)He flux into the oceans and the average ocean-crust generation rate. A factor of 3.5 increase in the convecting-mantle noble-gas concentration removes all requirements for: a (3)He flux into the upper mantle from a deeper high (3)He source; a boundary in the mantle capable of separating heat from helium; and a substantial deep-mantle reservoir to contain a hidden (40)Ar rich reservoir. We call this model concentration for the convecting mantle the 'zero-paradox' concentration. The time-integrated flux of (3)He into the oceans is a robust observation, but only representative of the ocean-floor activity over the last 1000 years. In contrast, ocean-floor generation occurs over tens of millions of years. We argue that combining these two observations to obtain the (3)He concentration of the mantle beneath mid-ocean ridges is unsound. Other indicators of mantle (3)He concentration suggest that the real value may be at least a factor of two higher. As the zero-paradox concentration is approached, the noble-gas requirement for mantle layering is removed. We further consider the role that recycled material plays in ocean-island-basalt generation and show that a source with high (3)He and (3)He/(4)He must exist within the mantle. Nevertheless, only a small amount of this material is required to generate both the observed ocean

  3. Noble gas as tracers for CO2 deep input in petroleum reservoirs

    NASA Astrophysics Data System (ADS)

    Pujol, Magali; Stuart, Finlay; Gilfillan, Stuart; Montel, François; Masini, Emmanuel

    2016-04-01

    The sub-salt hydrocarbon reservoirs in the deep offshore part of the Atlantic Ocean passive margins are a new key target for frontier oil and gas exploration. Type I source rocks locally rich in TOC (Total Organic Carbon) combined with an important secondary connected porosity of carbonate reservoirs overlain by an impermeable salt layer gives rise to reservoirs with high petroleum potential. However, some target structures have been found to be mainly filled with CO2 rich fluids. δ13C of the CO2 is generally between -9 and -4 permil, compatible with a deep source (metamorphic or mantle). Understanding the origin of the CO2 and the relative timing of its input into reservoir layers in regard to the geodynamic context appears to be a key issue for CO2 risk evaluation. The inertness and ubiquity of noble gases in crustal fluids make them powerful tools to trace the origin and migration of mixed fluids (Ballentine and Burnard 2002). The isotopic signature of He, Ne and Ar and the elemental pattern (He to Xe) of reservoir fluid from pressurized bottom hole samples provide an insight into fluid source influences at each reservoir depth. Three main end-members can be mixed into reservoir fluids (e.g. Gilfillan et al., 2008): atmospheric signature due to aquifer recharge, radiogenic component from organic fluid ± metamorphic influence, and mantle input. Their relative fractionation provides insights into the nature of fluid transport (Burnard et al., 2012)and its relative migration timing. In the studied offshore passive margin reservoirs, from both sides of South Atlantic margin, a strong MORB-like magmatic CO2 influence is clear. Hence, CO2 charge must have occurred during or after lithospheric break-up. CO2 charge(s) history appears to be complex, and in some cases requires several inputs to generate the observed noble gas pattern. Combining the knowledge obtained from noble gas (origin, relative timing, number of charges) with organic geochemical and thermodynamic

  4. Recycle and fractionation of U and K in the mantle via slab subduction; noble gas isotopic evidence from Polynesian HIMU

    NASA Astrophysics Data System (ADS)

    Hanyu, Takeshi; Tatsumi, Yoshiyuki; Kimura, Jun-Ichi

    2013-04-01

    The abundance and distribution of U and K in the Earth are critical not only for isotope and noble gas geochemistry but also for internal heat production in the mantle. While the concentration of U in bulk silicate Earth (BSE) has been estimated from the chondritic value, K concentration in BSE is poorly constrained. K concentration in BSE has been estimated using U concentration in BSE multiplied by the canonical K/U ratio (13000) on the ground that crustal and mantle-derived rocks show uniform K/U. However, such theory might be uncertain if the subducted slab had fractionated K/U and it remained isolated as a hidden reservoir. We present He-Ne-Ar isotopic compositions for Polynesian HIMU lavas with radiogenic Pb isotopic compositions. It has been widely accepted that the HIMU lavas are sourced from subducted ancient oceanic crust. K/U of the HIMU reservoir is constrained using the relative abundances of radiogenic and nucleogenic noble gases, because 40Ar/36Ar evolves by decay of 40K while production of 4He and 21Ne is related with U and Th decay. In 4He/40Ar*-4He/21Ne* space (asterisks denote radiogenic component), the HIMU lavas define a trend that is parallel to, but offset from the trend previously observed for other ocean island basalts. Using 4He/21Ne* as a monitor of elemental fractionation of noble gasses, fractionation-corrected 4He/40Ar* is higher than that expected for the mantle with the canonical K/U of 13000. K/U of the HIMU reservoir converted from 4He/40Ar* is approximately 3000. Low K/U of the HIMU reservoir is best explained by a model where this reservoir originates from subducted oceanic crust that preferentially lost K relative to U via dehydration during its subduction. Since the HIMU reservoir, involving subducted oceanic crust, is enriched in U, but not in K, previous estimates of K/U and K concentrations for BSE, that did not take this reservoir into consideration, will be too high. The mass balance calculation, considering continental

  5. Assessing Compositional Variability and Migration of Natural Gas in the Antrim Shale in the Michigan Basin Using Noble Gas Geochemistry

    NASA Astrophysics Data System (ADS)

    Wen, T.; Castro, M. C.; Ellis, B. R.; Hall, C. M.; Lohmann, K. C.

    2015-12-01

    The Antrim Shale was one of the first economic shale gas plays in the U.S. and has been actively produced since the 1980's. While previous studies suggest co-produced water in the Antrim is a mixture of brine from deeper formations and freshwater recharge, the extent of water-gas interactions has yet to be determined. The extent and source of thermogenic methane in the Antrim Shale are also under debate. This study uses stable noble gases' (He, Ne, Ar, Kr, Xe) isotopic ratios and their volume fractions from the Antrim Shale gases to assess compositional variability and vertical fluid migration, in addition to distinguishing between the presence of thermogenic versus biogenic methane. R/Ra values of Antrim Shale gases (where R and Ra are the measured and atmospheric 3He/4He ratios, respectively) vary from 0.01 to 0.34 suggesting dominant crustal 4He in addition to minor mantle and atmospheric He. Elevated 20Ne/22Ne ratios (up to 10.4) point to mantle Ne. Similarly crustal 21Ne*, 40Ar* and 136Xe* are also suggested. High variability of noble gas signatures in the Antrim Shale are observed, which are mainly due to variable noble gas input from deep brines and, to a smaller extent, variable in-situ production in the Antrim Shale. Estimated 4He ages considering external 4He flux for Antrim water match well with timings of three major glaciation periods (Wisconsin, Illinoian and Kansan glaciations) in the Michigan Basin, suggesting that all our Antrim samples were more or less influenced by glaciation recharge. Consistency in measured and predicted 40Ar/36Ar assuming Ar release temperatures ≥ 250°C supports a thermogenic origin for the majority of the methane in our Antrim Shale gas samples. Thermogenic methane is likely to originate at greater depth, either from deeper portions of the Antrim Shale in the central Michigan Basin or from deeper formations underlying the Antrim Shale, as the thermal maturity of the Antrim Shale in our study area is low.

  6. Using noble gas tracers to constrain a groundwater flow model with recharge elevations: A novel approach for mountainous terrain

    NASA Astrophysics Data System (ADS)

    Doyle, Jessica M.; Gleeson, Tom; Manning, Andrew H.; Mayer, K. Ulrich

    2015-10-01

    Environmental tracers provide information on groundwater age, recharge conditions, and flow processes which can be helpful for evaluating groundwater sustainability and vulnerability. Dissolved noble gas data have proven particularly useful in mountainous terrain because they can be used to determine recharge elevation. However, tracer-derived recharge elevations have not been utilized as calibration targets for numerical groundwater flow models. Herein, we constrain and calibrate a regional groundwater flow model with noble-gas-derived recharge elevations for the first time. Tritium and noble gas tracer results improved the site conceptual model by identifying a previously uncertain contribution of mountain block recharge from the Coast Mountains to an alluvial coastal aquifer in humid southwestern British Columbia. The revised conceptual model was integrated into a three-dimensional numerical groundwater flow model and calibrated to hydraulic head data in addition to recharge elevations estimated from noble gas recharge temperatures. Recharge elevations proved to be imperative for constraining hydraulic conductivity, recharge location, and bedrock geometry, and thus minimizing model nonuniqueness. Results indicate that 45% of recharge to the aquifer is mountain block recharge. A similar match between measured and modeled heads was achieved in a second numerical model that excludes the mountain block (no mountain block recharge), demonstrating that hydraulic head data alone are incapable of quantifying mountain block recharge. This result has significant implications for understanding and managing source water protection in recharge areas, potential effects of climate change, the overall water budget, and ultimately ensuring groundwater sustainability.

  7. Using noble gas tracers to constrain a groundwater flow model with recharge elevations: A novel approach for mountainous terrain

    USGS Publications Warehouse

    Doyle, Jessica M.; Gleeson, Tom; Manning, Andrew H.; Mayer, K. Ulrich

    2015-01-01

    Environmental tracers provide information on groundwater age, recharge conditions, and flow processes which can be helpful for evaluating groundwater sustainability and vulnerability. Dissolved noble gas data have proven particularly useful in mountainous terrain because they can be used to determine recharge elevation. However, tracer-derived recharge elevations have not been utilized as calibration targets for numerical groundwater flow models. Herein, we constrain and calibrate a regional groundwater flow model with noble-gas-derived recharge elevations for the first time. Tritium and noble gas tracer results improved the site conceptual model by identifying a previously uncertain contribution of mountain block recharge from the Coast Mountains to an alluvial coastal aquifer in humid southwestern British Columbia. The revised conceptual model was integrated into a three-dimensional numerical groundwater flow model and calibrated to hydraulic head data in addition to recharge elevations estimated from noble gas recharge temperatures. Recharge elevations proved to be imperative for constraining hydraulic conductivity, recharge location, and bedrock geometry, and thus minimizing model nonuniqueness. Results indicate that 45% of recharge to the aquifer is mountain block recharge. A similar match between measured and modeled heads was achieved in a second numerical model that excludes the mountain block (no mountain block recharge), demonstrating that hydraulic head data alone are incapable of quantifying mountain block recharge. This result has significant implications for understanding and managing source water protection in recharge areas, potential effects of climate change, the overall water budget, and ultimately ensuring groundwater sustainability.

  8. Detection of a noble gas molecular ion, 36ArH+, in the Crab Nebula.

    PubMed

    Barlow, M J; Swinyard, B M; Owen, P J; Cernicharo, J; Gomez, H L; Ivison, R J; Krause, O; Lim, T L; Matsuura, M; Miller, S; Olofsson, G; Polehampton, E T

    2013-12-13

    Noble gas molecules have not hitherto been detected in space. From spectra obtained with the Herschel Space Observatory, we report the detection of emission in the 617.5- and 1234.6-gigahertz J = 1-0 and 2-1 rotational lines of (36)ArH(+) at several positions in the Crab Nebula, a supernova remnant known to contain both molecular hydrogen and regions of enhanced ionized argon emission. Argon-36 is believed to have originated from explosive nucleosynthesis in massive stars during core-collapse supernova events. Its detection in the Crab Nebula, the product of such a supernova event, confirms this expectation. The likely excitation mechanism for the observed (36)ArH(+) emission lines is electron collisions in partially ionized regions with electron densities of a few hundred per centimeter cubed.

  9. Solar wind neon from Genesis: implications for the lunar noble gas record.

    PubMed

    Grimberg, Ansgar; Baur, Heinrich; Bochsler, Peter; Bühler, Fritz; Burnett, Donald S; Hays, Charles C; Heber, Veronika S; Jurewicz, Amy J G; Wieler, Rainer

    2006-11-17

    Lunar soils have been thought to contain two solar noble gas components with distinct isotopic composition. One has been identified as implanted solar wind, the other as higher-energy solar particles. The latter was puzzling because its relative amounts were much too large compared with present-day fluxes, suggesting periodic, very high solar activity in the past. Here we show that the depth-dependent isotopic composition of neon in a metallic glass exposed on NASA's Genesis mission agrees with the expected depth profile for solar wind neon with uniform isotopic composition. Our results strongly indicate that no extra high-energy component is required and that the solar neon isotope composition of lunar samples can be explained as implantation-fractionated solar wind.

  10. Detection of a Noble Gas Molecular Ion, 36ArH+, in the Crab Nebula

    NASA Astrophysics Data System (ADS)

    Barlow, M. J.; Swinyard, B. M.; Owen, P. J.; Cernicharo, J.; Gomez, H. L.; Ivison, R. J.; Krause, O.; Lim, T. L.; Matsuura, M.; Miller, S.; Olofsson, G.; Polehampton, E. T.

    2013-12-01

    Noble gas molecules have not hitherto been detected in space. From spectra obtained with the Herschel Space Observatory, we report the detection of emission in the 617.5- and 1234.6-gigahertz J = 1-0 and 2-1 rotational lines of 36ArH+ at several positions in the Crab Nebula, a supernova remnant known to contain both molecular hydrogen and regions of enhanced ionized argon emission. Argon-36 is believed to have originated from explosive nucleosynthesis in massive stars during core-collapse supernova events. Its detection in the Crab Nebula, the product of such a supernova event, confirms this expectation. The likely excitation mechanism for the observed 36ArH+ emission lines is electron collisions in partially ionized regions with electron densities of a few hundred per centimeter cubed.

  11. Imaging the impulsive alignment of noble-gas dimers via Coulomb explosion

    NASA Astrophysics Data System (ADS)

    Veltheim, A. von; Borchers, B.; Steinmeyer, G.; Rottke, H.

    2014-02-01

    The impulsive alignment of the noble-gas dimers Ne2, Ar2, Kr2, and Xe2 is experimentally investigated by determining the alignment through Coulomb explosion imaging after their double ionization. This approach yields a favorably detailed insight into the temporal evolution of the alignment succeeding the aligning laser pulse. Particular emphasis is put on analyzing higher order coherences induced in the density matrix as these coherences determine the details of the temporal evolution of the aligned molecular ensemble. The recorded data enable an extraction of polarizability anisotropies for the dimers and of their rotational constants in the vibrational ground state. At the elevated level of rotational excitation obtained, centrifugal distortion starts influencing the temporal evolution of the alignment.

  12. Mechanoluminescence of terbium and cerium sulfates in a noble-gas atmosphere

    NASA Astrophysics Data System (ADS)

    Tukhbatullin, A. A.; Sharipov, G. L.; Abdrakhmanov, A. M.; Muftakhutdinov, M. R.

    2014-05-01

    Lines of Ne (3 p-3 s, 550-800 nm) and Xe (6 p-6 s, 800-1050 nm; 7 p-6 s, 475 nm) have been detected in the mechanoluminescence spectrum of terbium and cerium sulfate crystallohydrates. The luminescence of noble gas is observed jointly with the known bands of Ce3+ and Tb3+ ions and N*2 lines. The lines corresponding to excited Xe+ ions (500-550 nm), indicative of achievement of electric-field strengths on the order of 107 V/cm during mechanoluminescence, are also observed. It is established that, during mechanoluminescence of Tb2(SO4)3 · 8D2O in an argon atmosphere under a pressure of 1.3 atm, mechanochemical reactions of decomposition of crystallization water (D2O) molecules cause luminescence of OD radicals; this luminescence is initiated by electron impact occurring during electrization and in discharges in crystals during destruction.

  13. Delineation of Fast Flow Paths in Porous Media Using Noble Gas Tracers

    SciTech Connect

    Hudson, G B; Moran, J E

    2002-03-21

    Isotopically enriched xenon isotopes are ideal for tracking the flow of relatively large volumes of groundwater. Dissolved noble gas tracers behave conservatively in the saturated zone, pose no health risk to drinking water supplies, and can be used with a large dynamic range. Different Xe isotopes can be used simultaneously at multiple recharge sources in a single experiment. Results from a tracer experiment at a California water district suggests that a small fraction of tracer moved from the recharge ponds through the thick, unconfined, coarse-grained alluvial aquifer to high capacity production wells at a horizontal velocity of 6 m/day. In contrast, mean water residence times indicate that the average rate of transport is 0.5 to 1 m/day.

  14. Infrared and density functional theory studies of formic acid hydrate clusters in noble gas matrices

    NASA Astrophysics Data System (ADS)

    Ito, Fumiyuki

    2016-08-01

    Infrared absorption spectra of formic acid hydrate clusters (HCOOH)m(H2O)n have been measured in noble gas matrices (Ar and Kr). The concentration dependence of the spectra and the comparison with a previous experimental study on HCOOH(H2O) and HCOOH(H2O)2 [Geoge et al., Spectrochim. Acta, Part A 60 (2004) 3225] led to the identification of large clusters. Density functional theory calculations at the B3LYP-DCP/6-31+G(2d,2p) level were carried out to determine the anharmonic vibrational properties of the clusters, enabling a consistent assignment of the observed vibrational peaks to specific clusters.

  15. Noble gases identify the mechanisms of fugitive gas contamination in drinking-water wells overlying the Marcellus and Barnett Shales.

    PubMed

    Darrah, Thomas H; Vengosh, Avner; Jackson, Robert B; Warner, Nathaniel R; Poreda, Robert J

    2014-09-30

    Horizontal drilling and hydraulic fracturing have enhanced energy production but raised concerns about drinking-water contamination and other environmental impacts. Identifying the sources and mechanisms of contamination can help improve the environmental and economic sustainability of shale-gas extraction. We analyzed 113 and 20 samples from drinking-water wells overlying the Marcellus and Barnett Shales, respectively, examining hydrocarbon abundance and isotopic compositions (e.g., C2H6/CH4, δ(13)C-CH4) and providing, to our knowledge, the first comprehensive analyses of noble gases and their isotopes (e.g., (4)He, (20)Ne, (36)Ar) in groundwater near shale-gas wells. We addressed two questions. (i) Are elevated levels of hydrocarbon gases in drinking-water aquifers near gas wells natural or anthropogenic? (ii) If fugitive gas contamination exists, what mechanisms cause it? Against a backdrop of naturally occurring salt- and gas-rich groundwater, we identified eight discrete clusters of fugitive gas contamination, seven in Pennsylvania and one in Texas that showed increased contamination through time. Where fugitive gas contamination occurred, the relative proportions of thermogenic hydrocarbon gas (e.g., CH4, (4)He) were significantly higher (P < 0.01) and the proportions of atmospheric gases (air-saturated water; e.g., N2, (36)Ar) were significantly lower (P < 0.01) relative to background groundwater. Noble gas isotope and hydrocarbon data link four contamination clusters to gas leakage from intermediate-depth strata through failures of annulus cement, three to target production gases that seem to implicate faulty production casings, and one to an underground gas well failure. Noble gas data appear to rule out gas contamination by upward migration from depth through overlying geological strata triggered by horizontal drilling or hydraulic fracturing.

  16. Noble gases identify the mechanisms of fugitive gas contamination in drinking-water wells overlying the Marcellus and Barnett Shales

    PubMed Central

    Darrah, Thomas H.; Vengosh, Avner; Jackson, Robert B.; Warner, Nathaniel R.; Poreda, Robert J.

    2014-01-01

    Horizontal drilling and hydraulic fracturing have enhanced energy production but raised concerns about drinking-water contamination and other environmental impacts. Identifying the sources and mechanisms of contamination can help improve the environmental and economic sustainability of shale-gas extraction. We analyzed 113 and 20 samples from drinking-water wells overlying the Marcellus and Barnett Shales, respectively, examining hydrocarbon abundance and isotopic compositions (e.g., C2H6/CH4, δ13C-CH4) and providing, to our knowledge, the first comprehensive analyses of noble gases and their isotopes (e.g., 4He, 20Ne, 36Ar) in groundwater near shale-gas wells. We addressed two questions. (i) Are elevated levels of hydrocarbon gases in drinking-water aquifers near gas wells natural or anthropogenic? (ii) If fugitive gas contamination exists, what mechanisms cause it? Against a backdrop of naturally occurring salt- and gas-rich groundwater, we identified eight discrete clusters of fugitive gas contamination, seven in Pennsylvania and one in Texas that showed increased contamination through time. Where fugitive gas contamination occurred, the relative proportions of thermogenic hydrocarbon gas (e.g., CH4, 4He) were significantly higher (P < 0.01) and the proportions of atmospheric gases (air-saturated water; e.g., N2, 36Ar) were significantly lower (P < 0.01) relative to background groundwater. Noble gas isotope and hydrocarbon data link four contamination clusters to gas leakage from intermediate-depth strata through failures of annulus cement, three to target production gases that seem to implicate faulty production casings, and one to an underground gas well failure. Noble gas data appear to rule out gas contamination by upward migration from depth through overlying geological strata triggered by horizontal drilling or hydraulic fracturing. PMID:25225410

  17. Using Noble Gas Geochemistry to Determine the Source and Mechanism of Natural Gas Leakage into Shallow Aquifers Near Unconventional Drilling

    NASA Astrophysics Data System (ADS)

    Darrah, T.; Whyte, C. J.

    2015-12-01

    Horizontal drilling and hydraulic fracturing have enhanced energy production but raised concerns about drinking-water contamination and other environmental impacts associated with unconventional energy development. The occurrence of fugitive gas contamination in drinking-water wells near unconventional natural gas development has been central to the debate about the environmental impacts of hydraulic fracturing, but still has a controversial origin that has variably been attributed to natural geogenic occurrences, poor well bore integrity, and crustal-scale migration of natural gas along natural deformation features. Differentiating amongst these possibilities is critical to ongoing efforts to understand the environmental implications for the presence of elevated methane and aliphatic hydrocarbons (ethane, propane, etc.) in drinking-water and a necessary step toward the development of implementable solutions that limit the occurrence of future fugitive gas events. Here we will expand upon our recent work in the Marcellus and Barnett gas fields (Jackson et al., 2013; Darrah et al., 2014; 2015) that developed noble gas techniques for distinguishing natural and anthropogenic mechanisms of natural gas migration by integrating the molecular and isotopic composition of non-hydrocarbon molecules (N2, H2S, CO2) in addition to compound specific isotopes of hydrocarbons (d2H of CH4 and d2H-C2H6 and d13C of CH4, C2H6, and C3H8) and non-hydrocarbon compounds (d15N-N2). The expanded data sets validate our initial study and support the hypothesis that a subset of drinking-water wells experience natural gas contamination following faulty well construction or poor well integrity amid a background of naturally occurring gas and salt-rich groundwater.

  18. Unprecedented Enhancement of Noble Gas-Noble Metal Bonding in NgAu3(+) (Ng = Ar, Kr, and Xe) Ion through Hydrogen Doping.

    PubMed

    Ghosh, Ayan; Ghanty, Tapan K

    2016-12-22

    Behavior of gold as hydrogen in certain gold compounds and a very recent experimental report on the noble gas-noble metal interaction in Ar complexes of mixed Au-Ag trimers have motivated us to investigate the effect of hydrogen doping on the Ng-Au (Ng = Ar, Kr, and Xe) bonding through various ab initio based techniques. The calculated results show considerable strengthening of the Ng-Au bond in terms of bond length, bond energy, stretching vibrational frequency, and force constant. Particularly, an exceptional enhancement of Ar-Au bonding strength has been observed in ArAuH2(+) species as compared to that in ArAu3(+) system, as revealed from the CCSD(T) calculated Ar-Au bond energy value of 32 and 72 kJ mol(-1) for ArAu3(+) and ArAuH2(+), respectively. In the calculated IR spectra, the Ar-Au stretching frequency is blue-shifted by 65% in going from ArAu3(+) to ArAuH2(+) species. Similar trends have been obtained in the case of all Ar, Kr, and Xe complexes with Ag and Cu trimers. Among all the NgM3-kHk(+) complexes (where k = 0-2), the strongest binding in NgMH2(+) complex is attributed to significant enhancement in the covalent characteristics of the Ng-M bond and considerable increase in charge-induced dipole interaction, as shown from the topological analysis.

  19. The role of soil air composition for noble gas tracer applications in tropical groundwater

    NASA Astrophysics Data System (ADS)

    Mayer, Simon; Jenner, Florian; Aeschbach, Werner; Weissbach, Therese; Peregovich, Bernhard; Machado, Carlos

    2016-04-01

    Dissolved noble gases (NGs) in groundwater provide a well-established tool for paleo temperature reconstruction. However, reliable noble gas temperature (NGT) determination needs appropriate assumptions or rather an exact knowledge of soil air composition. Deviations of soil air NG partial pressures from atmospheric values have already been found in mid latitudes during summer time as a consequence of subsurface oxygen depletion. This effect depends on ambient temperature and humidity and is thus expected to be especially strong in humid tropical soils, which was not investigated so far. We therefore studied NGs in soil air and shallow groundwater near Santarém (Pará, Brazil) at the end of the rainy and dry seasons, respectively. Soil air data confirms a correlation between NG partial pressures, the sum value of O2+CO2 and soil moisture contents. During the rainy season, we find significant NG enhancements in soil air by up to 7% with respect to the atmosphere. This is twice as much as observed during the dry season. Groundwater samples show neon excess values between 15% and 120%. Nearly all wells show no seasonal variations of excess air, even though the local river level seasonally fluctuates by about 8 m. Assuming atmospheric NG contents in soil air, fitted NGTs underestimate the measured groundwater temperature by about 1-2° C. However, including enhanced soil air NG contents as observed during the rainy season, resulting NGTs are in good agreement with local groundwater temperatures. Our presented data allows for a better understanding of subsurface NG variations. This is essential with regard to NG tracer applications in humid tropical areas, for which reliable paleoclimate data is of major importance for modern climate research.

  20. Mineralogy and noble gas isotopes of micrometeorites collected from Antarctic snow

    NASA Astrophysics Data System (ADS)

    Okazaki, Ryuji; Noguchi, Takaaki; Tsujimoto, Shin-ichi; Tobimatsu, Yu; Nakamura, Tomoki; Ebihara, Mitsuru; Itoh, Shoichi; Nagahara, Hiroko; Tachibana, Shogo; Terada, Kentaro; Yabuta, Hikaru

    2015-06-01

    We have investigated seven micrometeorites (MMs) from Antarctic snow collected in 2003 and 2010 by means of electron microscopy, X-ray diffraction, micro-Raman spectroscopy, transmission electron microscopy (TEM) observation, and noble-gas isotope analysis. Isotopic ratios of He and Ne indicate that the noble gases in these MMs are mostly of solar wind (SW). Based on the release patterns of SW 4He, which should reflect the degree of heating during atmospheric entry, the seven MMs were classified into three types including two least heated, three moderately heated, and two severely heated MMs. The heating degrees are well correlated to their mineralogical features determined by TEM observation. One of the least heated MMs is composed of phyllosilicates, whereas the other consists of anhydrous minerals within which solar flare tracks were observed. The two severely heated MMs show clear evidence of atmospheric heating such as partial melt of the uppermost surface layer in one and abundant patches of dendritic magnetite and Si-rich glass within an olivine grain in the other. It is noteworthy that a moderately heated MM composed of a single crystal of olivine has a 3He/4He ratio of 8.44 × 10-4, which is higher than the SW value of 4.64 × 10-4, but does not show a cosmogenic 21Ne signature such as 20Ne/21Ne/22Ne = 12.83/0.0284/1. The isotopic compositions of He and Ne in this sample cannot be explained by mixing of a galactic cosmic ray (GCR)-produced component and SW gases. The high 3He/4He ratio without cosmogenic 21Ne signature likely indicates the presence of a 3He-enriched component derived from solar energetic particles.

  1. U.S. Geological Survey Noble Gas Laboratory’s standard operating procedures for the measurement of dissolved gas in water samples

    USGS Publications Warehouse

    Hunt, Andrew G.

    2015-08-12

    This report addresses the standard operating procedures used by the U.S. Geological Survey’s Noble Gas Laboratory in Denver, Colorado, U.S.A., for the measurement of dissolved gases (methane, nitrogen, oxygen, and carbon dioxide) and noble gas isotopes (helium-3, helium-4, neon-20, neon-21, neon-22, argon-36, argon-38, argon-40, kryton-84, krypton-86, xenon-103, and xenon-132) dissolved in water. A synopsis of the instrumentation used, procedures followed, calibration practices, standards used, and a quality assurance and quality control program is presented. The report outlines the day-to-day operation of the Residual Gas Analyzer Model 200, Mass Analyzer Products Model 215–50, and ultralow vacuum extraction line along with the sample handling procedures, noble gas extraction and purification, instrument measurement procedures, instrumental data acquisition, and calculations for the conversion of raw data from the mass spectrometer into noble gas concentrations per unit mass of water analyzed. Techniques for the preparation of artificial dissolved gas standards are detailed and coupled to a quality assurance and quality control program to present the accuracy of the procedures used in the laboratory.

  2. Hydrochemistry and noble gas origin of geothermal waters of Icheon and Pocheon area in South Korea

    NASA Astrophysics Data System (ADS)

    Jeong, Chan Ho; Shin, Seon Ho; Nagao, Keisuke; Kim, Kyu Han; Koh, Yung Kwon; Kim, Gun Young

    2010-05-01

    Hydrochemical, stable isotopic (δ18O and δD) and noble gas isotopic analyses of seven geothermal water samples, eleven groundwater samples and six surface water samples collected from the Icheon and Pocheon area were carried out to find out hydrochemical characteristics, and to interpret the source of noble gases and the geochemical evolution of the geothermal waters. The geothermal waters show low temperature type ranging from 21.5 to 31.4 ℃ and the pH value between 6.69 and 9.21. Electrical conductivity of geothermal waters has the range from 310 to 735 μS/cm. Whereas the geothermal in the Icheon area shows the geochemical characteristics of neutral pH, the Ca-HCO3(or Ca(Na)-HCO3) chemical type and a high uranium content, the geothermal water in the Pocheon area shows the characteristics of alkaline pH, the Na-HCO3 chemical type and a high fluorine content. These characteristics indicate that the geothermal water in the Icheon area is under the early stage in the geochemical evolution, and that geothermal water in the Pocheon area has been geochemically evolved. The δ18O and δD values of geothermal waters show the range of -10.1˜-8.69‰ and from -72.2˜-60.8‰, respectively, and these values supply the information of the recharge area of geothermal waters. The 3He/4He ratios of the geothermal waters range from 0.09×10-6 to 0.65×10-6 which are plotted above the mixing line between air and crustal components. Whereas the helium gas in the Icheon geothermal water was mainly provided from the atmospheric source mixing with the mantle(or magma) origin, the origin of helium gas in the Pocheon geothermal water shows a dominant crustal source. 40Ar/36Ar ratios of geothermal water are in the range of an atmosphere source. Key words: hot spring water, hydrochemical composition, low temperature type, 3He/4He ratios, crustal source

  3. The ATTA-Hefei Instrument for Radioactive Noble-gas Dating

    NASA Astrophysics Data System (ADS)

    Hu, S.; Cheng, C.; Cheng, G.; Sun, Y. R.; Tu, L.; Yang, G.

    2013-12-01

    Long-lived noble-gas isotopes 85Kr (10.8 y), 39Ar (269 y) and 81Kr (229 ky) are ideal tracers for dating environmental samples such as groundwater and ice. Together with 14C, these nuclides can be used to cover the whole range of 100-106 y. Atom Trap Trace Analysis (ATTA) is an emerging method for the analysis of these isotopes at an isotopic abundance level as low as 10^-16 [1,2]. The ATTA instrument built in Hefei, China, can determine the isotopic abundances of 85Kr and 81Kr with typically 5-10% accuracy using krypton gas samples of a few micro-liters (STP) krypton gas [3]. The krypton gas sample can be extracted from several liters of air using a distillation-chromatograph setup with a typical efficiency of 85%, while the air sample can be extracted from groundwater or ices. The typical sample size for ATTA measurement is 100L groundwater or 40Kg ices. One such ATTA beamline can handle about 100 samples per year. [1] Chen, C. Y. et al. Ultrasensitive isotope trace analyses with a magneto-optical trap. Science 286, 1139-1141 (1999). [2] Jiang, W. et al. 39Ar detection at the 10-16 isotopic abundance level with atom trap trace analysis. Phys. Rev. Lett. 106, 103001 (2011). [3] Yang, G. -M. et al. Analysis of 85Kr: a comparison at the 10-14 level using micro-liter samples, Sci. Rep. 3, 1596 (2013). Relative uncertainty of the determined 85Kr abundance by the ATTA-Hefei instrument.

  4. Cross-Calibration of Secondary Electron Multiplier in Noble Gas Analysis

    NASA Astrophysics Data System (ADS)

    Santato, Alessandro; Hamilton, Doug; Deerberg, Michael; Wijbrans, Jan; Kuiper, Klaudia; Bouman, Claudia

    2015-04-01

    The latest generation of multi-collector noble gas mass spectrometers has decisively improved the precision in isotopic ratio analysis [1, 2] and helped the scientific community to address new questions [3]. Measuring numerous isotopes simultaneously has two significant advantages: firstly, any fluctuations in signal intensity have no effect on the isotope ratio and secondly, the analysis time is reduced. This particular point becomes very important in static vacuum mass spectrometry where during the analysis, the signal intensity decays and at the same time the background increases. However, when multi-collector analysis is utilized, it is necessary to pay special attention to the cross calibration of the detectors. This is a key point in order to have accurate and reproducible isotopic ratios. In isotope ratio mass spectrometry, with regard to the type of detector (i.e. Faraday or Secondary Electron Multiplier, SEM), analytical technique (TIMS, MC-ICP-MS or IRMS) and isotope system of interest, several techniques are currently applied to cross-calibrate the detectors. Specifically, the gain of the Faraday cups is generally stable and only the associated amplifier must be calibrated. For example, on the Thermo Scientific instrument control systems, the 1011 and 1012 ohm amplifiers can easily be calibrated through a fully software controlled procedure by inputting a constant electric signal to each amplifier sequentially [4]. On the other hand, the yield of the SEMs can drift up to 0.2% / hour and other techniques such as peak hopping, standard-sample bracketing and multi-dynamic measurement must be used. Peak hopping allows the detectors to be calibrated by measuring an ion beam of constant intensity across the detectors whereas standard-sample bracketing corrects the drift of the detectors through the analysis of a reference standard of a known isotopic ratio. If at least one isotopic pair of the sample is known, multi-dynamic measurement can be used; in this

  5. Gas House Autonomous System Monitoring

    NASA Technical Reports Server (NTRS)

    Miller, Luke; Edsall, Ashley

    2015-01-01

    Gas House Autonomous System Monitoring (GHASM) will employ Integrated System Health Monitoring (ISHM) of cryogenic fluids in the High Pressure Gas Facility at Stennis Space Center. The preliminary focus of development incorporates the passive monitoring and eventual commanding of the Nitrogen System. ISHM offers generic system awareness, adept at using concepts rather than specific error cases. As an enabler for autonomy, ISHM provides capabilities inclusive of anomaly detection, diagnosis, and abnormality prediction. Advancing ISHM and Autonomous Operation functional capabilities enhances quality of data, optimizes safety, improves cost effectiveness, and has direct benefits to a wide spectrum of aerospace applications.

  6. Indigenous nitrogen in the Moon: Constraints from coupled nitrogen-noble gas analyses of mare basalts

    NASA Astrophysics Data System (ADS)

    Füri, Evelyn; Barry, Peter H.; Taylor, Lawrence A.; Marty, Bernard

    2015-12-01

    Nitrogen and noble gas (Ne-Ar) abundances and isotope ratios, determined by step-wise CO2 laser-extraction, static-mass spectrometry analysis, are reported for bulk fragments and mineral separates of ten lunar mare basalts (10020, 10057, 12008, 14053, 15555, 70255, 71557, 71576, 74255, 74275), one highland breccia (14321), and one ferroan anorthosite (15414). The mare basalt sub-samples 10057,183 and 71576,12 contain a large amount of solar noble gases, whereas neon and argon in all other samples are purely cosmogenic, as shown by their 21Ne/22Ne ratios of ≈0.85 and 36Ar/38Ar ratios of ≈0.65. The solar-gas-free basalts contain a two-component mixture of cosmogenic 15N and indigenous nitrogen (<0.5 ppm). Mare basalt 74255 and the olivine fraction of 15555,876 record the smallest proportion of 15Ncosm; therefore, their δ15 N values of -0.2 to + 26.7 ‰ (observed at the low-temperature steps) are thought to well represent the isotopic composition of indigenous lunar nitrogen. However, δ15 N values ≤ - 30 ‰ are found in several basalts, overlapping with the isotopic signature of Earth's primordial mantle or an enstatite chondrite-like impactor. While the lowest δ15 N values allow for nitrogen trapped in the Moon's interior to be inherited from the proto-Earth and/or the impactor, the more 15N-enriched compositions require that carbonaceous chondrites provided nitrogen to the lunar magma ocean prior to the solidification of the crust. Since nitrogen can efficiently be incorporated into mafic minerals (olivine, pyroxene) under oxygen fugacities close to or below the iron-wustite buffer (Li et al., 2013), the mare basalt source region is likely characterized by a high nitrogen storage capacity. In contrast, anorthosite 15414 shows no traces of indigenous nitrogen, suggesting that nitrogen was not efficiently incorporated into the lunar crust during magma ocean differentiation.

  7. Determining the source and genetic fingerprint of natural gases using noble gas geochemistry: a northern Appalachian Basin case study

    USGS Publications Warehouse

    Hunt, Andrew G.; Darrah, Thomas H.; Poreda, Robert J.

    2012-01-01

    Silurian and Devonian natural gas reservoirs present within New York state represent an example of unconventional gas accumulations within the northern Appalachian Basin. These unconventional energy resources, previously thought to be noneconomically viable, have come into play following advances in drilling (i.e., horizontal drilling) and extraction (i.e., hydraulic fracturing) capabilities. Therefore, efforts to understand these and other domestic and global natural gas reserves have recently increased. The suspicion of fugitive mass migration issues within current Appalachian production fields has catalyzed the need to develop a greater understanding of the genetic grouping (source) and migrational history of natural gases in this area. We introduce new noble gas data in the context of published hydrocarbon carbon (C1,C2+) (13C) data to explore the genesis of thermogenic gases in the Appalachian Basin. This study includes natural gases from two distinct genetic groups: group 1, Upper Devonian (Marcellus shale and Canadaway Group) gases generated in situ, characterized by early mature (13C[C1  C2][13C113C2]: –9), isotopically light methane, with low (4He) (average, 1  103 cc/cc) elevated 4He/40Ar and 21Ne/40Ar (where the asterisk denotes excess radiogenic or nucleogenic production beyond the atmospheric ratio), and a variable, atmospherically (air-saturated–water) derived noble gas component; and group 2, a migratory natural gas that emanated from Lower Ordovician source rocks (i.e., most likely, Middle Ordovician Trenton or Black River group) that is currently hosted primarily in Lower Silurian sands (i.e., Medina or Clinton group) characterized by isotopically heavy, mature methane (13C[C1 – C2] [13C113C2]: 3), with high (4He) (average, 1.85  103 cc/cc) 4He/40Ar and 21Ne/40Ar near crustal production levels and elevated crustal noble gas content (enriched 4He,21Ne, 40Ar). Because the release of each crustal noble gas (i.e., He, Ne, Ar

  8. Trace Gas Monitoring

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Space technology is contributing to air pollution control primarily through improved detectors and analysis methods. Miniaturized mass spectrometer is under development to monitor vinyl chloride and other hydrocarbon contaminants in an airborne laboratory. Miniaturized mass spectrometer can be used to protect personnel in naval and medical operations as well as aboard aircraft.

  9. USGS-NoGaDat - A global dataset of noble gas concentrations and their isotopic ratios in volcanic systems

    USGS Publications Warehouse

    Abedini, Atosa A.; Hurwitz, S.; Evans, William C.

    2006-01-01

    The database (Version 1.0) is a MS-Excel file that contains close to 5,000 entries of published information on noble gas concentrations and isotopic ratios from volcanic systems in Mid-Ocean ridges, ocean islands, seamounts, and oceanic and continental arcs (location map). Where they were available we also included the isotopic ratios of strontium, neodymium, and carbon. The database is sub-divided both into material sampled (e.g., volcanic glass, different minerals, fumarole, spring), and into different tectonic settings (MOR, ocean islands, volcanic arcs). Included is also a reference list in MS-Word and pdf from which the data was derived. The database extends previous compilations by Ozima (1994), Farley and Neroda (1998), and Graham (2002). The extended database allows scientists to test competing hypotheses, and it provides a framework for analysis of noble gas data during periods of volcanic unrest.

  10. The degassing history of the Earth: Noble gas studies of Archaean cherts and zero age glassy submarine basalts

    NASA Technical Reports Server (NTRS)

    Hart, R.; Hogan, L.

    1985-01-01

    Recent noble gas studies suggests the Earth's atmosphere outgassed from the Earth's upper mantle synchronous with sea floor spreading, ocean ridge hydrothermal activity and the formation of continents by partial melting in subduction zones. The evidence for formation of the atmosphere by outgassing of the mantle is the presence of radionuclides H3.-4, Ar-040 and 136 Xe-136 in the atmosphere that were produced from K-40, U and Th in the mantle. How these radionuclides were formed is reviewed.

  11. Making channeling visible: keV noble gas ion trails on Pt(111)

    NASA Astrophysics Data System (ADS)

    Redinger, A.; Standop, S.; Rosandi, Y.; Urbassek, H. M.; Michely, T.

    2011-01-01

    The impact of argon and xenon noble gas ions on Pt(111) in grazing incidence geometry are studied through direct comparison of scanning tunneling microscopy images and molecular dynamics simulations. The energy range investigated is 1-15 keV and the angles of incidence with respect to the surface normal are between 78.5° and 88°. The focus of the paper is on events where ions gently enter the crystal at steps and are guided in channels between the top most layers of the crystal. The trajectories of the subsurface channeled ions are visible as trails of surface damage. The mechanism of trail formation is analyzed using simulations and analytical theory. Significant differences between Xe+ and Ar+ projectiles in damage, in the onset energy of subsurface channeling as well as in ion energy dependence of trail length and appearance are traced back to the projectile and ion energy dependence of the stopping force. The asymmetry of damage production with respect to the ion trajectory direction is explained through the details of the channel shape and subchannel structure as calculated from the continuum approximation of the channel potential. Measured and simulated channel switching in directions normal and parallel to the surface as well as an increase of ions entering into channels from the perfect surface with increasing angles of incidence are discussed.

  12. Communication: Nuclear quadrupole moment-induced Cotton-Mouton effect in noble gas atoms

    SciTech Connect

    Fu, Li-juan; Vaara, Juha; Rizzo, Antonio

    2013-11-14

    New, high-sensitivity and high-resolution spectroscopic and imaging methods may be developed by exploiting nuclear magneto-optic effects. A first-principles electronic structure formulation of nuclear electric quadrupole moment-induced Cotton-Mouton effect (NQCME) is presented for closed-shell atoms. In NQCME, aligned quadrupole moments alter the index of refraction of the medium along with and perpendicular to the direction of nuclear alignment. The roles of basis-set convergence, electron correlation, and relativistic effects are investigated for three quadrupolar noble gas isotopes: {sup 21}Ne, {sup 83}Kr, and {sup 131}Xe. The magnitude of the resulting ellipticities is predicted to be 10{sup −4}–10{sup −6} rad/(M cm) for fully spin-polarized nuclei. These should be detectable in the Voigt setup. Particularly interesting is the case of {sup 131}Xe, in which a high degree of spin polarization can be achieved via spin-exchange optical hyperpolarization.

  13. Comparing Meteorite and Spacecraft Noble Gas Measurements to Trace Processes in the Martian Crust and Atmosphere

    NASA Astrophysics Data System (ADS)

    Swindle, T. D.

    2014-12-01

    Our knowledge of the noble gas abundances and isotopic compositions in the Martian crust and atmosphere come from two sources, measurements of meteorites from Mars and in situ measurements by spacecraft. Measurements by the Viking landers had large uncertainties, but were precise enough to tie the meteorites to Mars. Hence most of the questions we have are currently defined by meteorite measurements. Curiosity's SAM has confirmed that the Ar isotopic composition of the atmosphere is highly fractionated, presumably representing atmospheric loss that can now be modeled with more confidence. What turns out to be a more difficult trait to explain is the fact that the ratio of Kr/Xe in nakhlites, chassignites and ALH84001 is distinct from the atmospheric ratio, as defined by measurements from shergottites. This discrepancy has been suggested to be a result of atmosphere/groundwater/rock interaction, polar clathrate formation, or perhaps local temperature conditions. More detailed atmospheric measurements, along with targeted simulation experiments, will be needed to make full use of this anomaly.

  14. High precision nitrogen isotope measurements in oceanic basalts using a static triple collection noble gas mass spectrometer

    NASA Astrophysics Data System (ADS)

    Barry, P. H.; Hilton, D. R.; Halldórsson, S. A.; Hahm, D.; Marti, K.

    2012-01-01

    We describe a new system for the simultaneous static triple-collection of nitrogen isotopes at the <10μcm3 STP [N2] (<1 × 10-5 cm3STP; <0.5 nmol) level using a modified VG-5440 noble gas mass spectrometer. The system consists of an internal N2-STD with aδ15N value of -0.11 ± 0.22 ‰ (1σ) calibrated against an air-standard (Air-STD). The N2-STD was measured repeatedly with an average uncertainty on an individualδ15N measurement being 0.03 ‰ (1σ) versus an average single day reproducibility of 0.38 ‰ (1σ). Additional refinements include (1) monitoring of interfering CO contributions at mass 30, allowing a comprehensive CO correction to be applied to all samples, (2) quantification of procedural N2 blanks (n = 22) in both size (4.2 ± 0.5 μcm3 STP) and isotopic composition (δ15N = 12.64 ± 2.04 ‰), allowing consistent blank corrections to all samples, and (3) independent measurement of N2/Ar ratios using a quadrupole mass spectrometer (QMS). The new system was tested by measuring nitrogen isotopes (δ15N), concentrations and N2/Ar ratios on 11 submarine basalt glasses. Results show that the uncertainty on the δ15N data is improved as a consequence of multiple standards being run per day. Reduced analytical times, afforded by triple collection, also minimize sample depletion and memory effects, thus improving measurement statistics. Additionally, we show that CO corrections can be accomplished using mass 30 to monitor CO interferences, leading to substantial improvements in reproducibility and the overall accuracy of results when the contribution of CO is significant.

  15. Potential interstellar noble gas molecules: ArOH+ and NeOH+ rovibrational analysis from quantum chemical quartic force fields

    NASA Astrophysics Data System (ADS)

    Theis, Riley A.; Fortenberry, Ryan C.

    2016-03-01

    The discovery of ArH+ in the interstellar medium has shown that noble gas chemistry may be of more chemical significance than previously believed. The present work extends the known chemistry of small noble gas molecules to NeOH+ and ArOH+. Besides their respective neonium and argonium diatomic cation cousins, these hydroxyl cation molecules are the most stable small noble gas molecules analyzed of late. ArOH+ is once again more stable than the neon cation, but both are well-behaved enough for a complete quartic force field analysis of their rovibrational properties. The Ar-O bond in ArOH+ , for instance, is roughly three-quarters of the strength of the Ar-H bond in ArH+ highlighting the rigidity of this system. The rotational constants, geometries, and vibrational frequencies for both molecules and their various isotopologues are computed from ab initio quantum chemical theory at high-level, and it is shown that these cations may form in regions where peroxy or weakly-bound alcohols may be present. The resulting data should be of significant assistance for the laboratory or observational analysis of these potential interstellar molecules.

  16. Noble gas systematics for coexisting glass and olivine crystals in basalts and dunite xenoliths from Loihi Seamount

    USGS Publications Warehouse

    Kaneoka, I.; Takaoka, N.; Clague, D.A.

    1983-01-01

    Noble gas isotopes including 3He 4He, 40Ar 36Ar and Xe isotope ratios were determined for coexisting glass and olivine crystals in tholeiitic and alkalic basalts and dunite xenoliths from Loihi Seamount. Glass and coexisting olivine crystals have similar 3He 4He ratios (2.8-3.4) ?? 10-5, 20 to 24 times the atmospheric ratio (RA), but different 40Ar 36Ar ratios (400-1000). Based on the results of noble gas isotope ratios and microscopic observation, some olivine crystals are xenocrysts. We conclude that He is equilibrated between glass and olivine xenocrysts, but Ar is not. The apparent high 3He 4He ratio (3 ?? 10-5; = 21 RA) coupled with a relatively high 40Ar 36Ar ratio (4200) for dunite xenoliths (KK 17-5) may be explained by equilibration of He between MORB-type cumulates and the host magma. Except for the dunite xenoliths, noble gas data for these Loihi samples are compatible with a model in which samples from hot spot areas may be explained by mixing between P (plume)-type and M (MORB)-type components with the addition of A (atmosphere)-type component. Excess 129Xe has not been observed due to apparent large mass fractionation among Xe isotopes. ?? 1983.

  17. Noble Gas Isotopic Evidence for Primordial Evolution of the Earth's Atmosphere in Three Distinct Stages

    NASA Astrophysics Data System (ADS)

    Harper, C. L., Jr.; Jacobsen, S. B.

    1995-09-01

    The deep Earth is the key to understanding the primordial evolution of the Earth's atmosphere. However the atmosphere was not derived by degassing of the Earth, as widely held. Isotopic characterization of mantle noble gases and modeling based on this information [1] suggests the atmosphere experienced a 3-stage early history. This follows from 5 basic observations: (i) Ne in the mantle is solar-like, with light (high) 20Ne/22Ne relative to the atmosphere [2]; (ii) mantle Xe has higher 128Xe/130Xe than the atmosphere [3], which carries an extreme heavy isotope enriched mass fractionation signature of >3%/amu (iii) most of the radiogenic Xe from l29I and 244Pu decay in the Earth is not present either in the mantle or in the atmosphere; (iv) the inferred abundances of noble gases in the deep Earth "plume source" are insufficient to generate the present atmospheric abundances, even for whole mantle degassing; and (v) mantle noble gases indicate a 2 component structure, with solar light gases (He and Ne) and planetary heavy gases [4]. The present day noble gas budgets (and likely also N2) must derive from late accretion of a volatile-rich "veneer." This is stage III. Stage II is a naked (no atmosphere) epoch indicated by evidence for Hadean degassing of 244Pu (T1/2 = 80 Ma) fission Xe from the whole mantle, which was not retained in the present atmosphere. The naked stage must have lasted for more than ~200 Ma, and was supported by the early intense solar EUV luminosity. Stage I, a massive solar-composition protoatmosphere, occurred during the Earth's early accretion phase. Its existence is indicated by the presence of the solar gas component in the Earth. This is not attributable to subduction of solar wind rich cosmic dust, or solar wind irradiation of coagulating objects. It is best explained by accretion of a solar composition atmosphere from the nebula. This provided a thermal blanket supporting a magma ocean in which solar gases dissolved. Under these conditions

  18. Nature of sonoluminescence: noble gas radiation excited by hot electrons in cold water

    PubMed

    Garcia; Levanyuk; Osipov

    2000-08-01

    It was proposed before that single bubble sonoluminescence (SBSL) may be caused by strong electric fields occurring in water near the surface of collapsing gas bubbles because of the flexoelectric effect involving polarization resulting from a gradient of pressure. Here we show that these fields can indeed provoke dynamic electric breakdown in a micron-size region near the bubble and consider the scenario of the SBSL. The scenario is (i) at the last stage of incomplete collapse of the bubble, the gradient of pressure in water near the bubble surface has such a value and a sign that the electric field arising from the flexoelectric effect exceeds the threshold field of the dynamic electrical breakdown of water and is directed to the bubble center; (ii) mobile electrons are generated because of thermal ionization of water molecules near the bubble surface; (iii) these electrons are accelerated in "cold" water by the strong electric fields; (iv) these hot electrons transfer noble gas atoms dissolved in water to high-energy excited states and optical transitions between these states produce SBSL UV flashes in the transparency window of water; (v) the breakdown can be repeated several times and the power and duration of the UV flash are determined by the multiplicity of the breakdowns. The SBSL spectrum is found to resemble a black-body spectrum where temperature is given by the effective temperature of the hot electrons. The pulse energy and some other characteristics of the SBSL are found to be in agreement with the experimental data when realistic estimates are made.

  19. Modulation by the noble gas argon of the catalytic and thrombolytic efficiency of tissue plasminogen activator.

    PubMed

    David, Hélène N; Haelewyn, Benoît; Risso, Jean-Jacques; Abraini, Jacques H

    2013-01-01

    Argon has been shown to provide cortical as well as, under certain conditions, subcortical neuroprotection in all models so far (middle cerebral artery occlusion, trauma, neonatal asphyxia, etc.). This has led to the suggestion that argon could be a cost-efficient alternative to xenon, a metabolically inert gas thought to be gold standard in gas pharmacology but whose clinical development suffers its little availability and excessive cost of production. However, whether argon interacts with the thrombolytic agent tissue plasminogen activator, which is the only approved therapy of acute ischemic stroke to date, still remains unknown. This latter point is not trivial since previous data have clearly demonstrated the inhibiting effect of xenon on tPA enzymatic and thrombolytic efficiency and the critical importance of the time at which xenon is administered, during or after ischemia, in order not to block thrombolysis and to obtain neuroprotection. Here, we investigated the effect of argon on tPA enzymatic and thrombolytic efficiency using in vitro methods shown to provide reliable prediction of the in vivo effects of both oxygen and the noble inert gases on tPA-induced thrombolysis. We found that argon has a concentration-dependent dual effect on tPA enzymatic and thrombolytic efficiency. Low and high concentrations of argon of 25 and 75 vol% respectively block and increase tPA enzymatic and thrombolytic efficiency. The possible use of argon at low and high concentrations in the treatment of acute ischemic stroke if given during ischemia or after tPA-induced reperfusion is discussed as regards to its neuroprotectant action and its inhibiting and facilitating effects on tPA-induced thrombolysis. The mechanisms of argon-tPA interactions are also discussed.

  20. Noble Gas Proxy Evidence Of Holocene Climate Fluctuations In The Elwha Watershed, Olympic Mountains, Washington

    EPA Science Inventory

    Paleotempertures retrieved from the groundwater archives in the largest watershed (≈800 km2) in the Olympic Mountains suggest asynchronous Olympic Peninsula climate responses during the Everson interstade period after the last continental glacial maximum. Dissolved noble gases fr...

  1. Laser microprobe analyses of noble gas isotopes and halogens in fluid inclusions: Analyses of microstandards and synthetic inclusions in quartz

    USGS Publications Warehouse

    Böhlke, J.K.; Irwin, J.J.

    1992-01-01

    Ar, Kr, Xe, Cl, Br, I, and K abundances and isotopic compositions have been measured in microscopic fluid inclusions in minerals by noble gas mass spectrometry following neutron irradiation and laser extraction. The laser microprobe noble gas mass spectrometric (LMNGMS) technique was quantified by use of microstandards, including air-filled capillary tubes, synthetic basalt glass grains, standard hornblende grains, and synthetic fluid inclusions in quartz. Common natural concentrations of halogens (Cl, Br, and I) and noble gases (Ar and Kr) in trapped groundwaters and hydrothermal fluids can be analyzed simultaneously by LMNGMS in as little as 10-11 L of inclusion fluid, with accuracy and precision to within 5-10% for element and isotope ratios. Multicomponent element and isotope correlations indicate contaminants or persistent reservoirs of excess Xe and/or unfractionated air in some synthetic and natural fluid inclusion samples. LMNGMS analyses of natural fluid inclusions using the methods and calibrations reported here may be used to obtain unique information on sources of fluids, sources of fluid salinity, mixing, boiling (or unmixing), and water-rock interactions in ancient fluid flow systems. ?? 1992.

  2. Detection of Noble Gas Radionuclides from an Underground Nuclear Explosion During a CTBT On-Site Inspection

    NASA Astrophysics Data System (ADS)

    Carrigan, Charles R.; Sun, Yunwei

    2014-03-01

    The development of a technically sound approach to detecting the subsurface release of noble gas radionuclides is a critical component of the on-site inspection (OSI) protocol under the Comprehensive Nuclear Test Ban Treaty. In this context, we are investigating a variety of technical challenges that have a significant bearing on policy development and technical guidance regarding the detection of noble gases and the creation of a technically justifiable OSI concept of operation. The work focuses on optimizing the ability to capture radioactive noble gases subject to the constraints of possible OSI scenarios. This focus results from recognizing the difficulty of detecting gas releases in geologic environments—a lesson we learned previously from the non-proliferation experiment (NPE). Most of our evaluations of a sampling or transport issue necessarily involve computer simulations. This is partly due to the lack of OSI-relevant field data, such as that provided by the NPE, and partly a result of the ability of computer-based models to test a range of geologic and atmospheric scenarios far beyond what could ever be studied by field experiments, making this approach very highly cost effective. We review some highlights of the transport and sampling issues we have investigated and complete the discussion of these issues with a description of a preliminary design for subsurface sampling that addresses some of the sampling challenges discussed here.

  3. A preliminary report on noble gas isotope analyses using the Helix-MC multi-collector mass spectrometer

    NASA Astrophysics Data System (ADS)

    Honda, M.; Zhang, X.; Phillips, D.; Szczepanski, S.; Deerberg, M.; Hamilton, D.; Krummen, M.; Schwieters, J.

    2013-12-01

    Analyses of noble gas isotopes by multi-collector mass spectrometry substantially improve measurement precision and accuracy, with the potential to revolutionise applications to cosmo-geo-sciences. The Helix-MC noble gas mass spectrometer manufactured by Thermo-Fisher is a 350mm, 120 degree extended geometry, high resolution, multi-collector mass spectrometer for the simultaneous analysis of noble gas isotopes. The detector array includes a fixed axial (Ax) detector, 2 adjustable high mass (H1 and H2) detectors and 2 adjustable low mass (L1 and L2) detectors. Each detector is equipped with a Faraday/ion counting multiplier CFM (Combined Faraday and CDD Multiplier) detector. Mass resolution and mass resolving power on the H2, Ax and L2 detectors of the Helix-MC installed at the Australian National University (ANU) are approximately 1,800 and 8,000, respectively. The noble gas handling system on-line to the Helix-MC consists of: (1) a resistively-heated, double-vacuum, tantalum furnace system, (2) air actuated vacuum crusher, (3) Photon-Machines diode laser heating system, (4) Janis He cryogenic trap assembly, (5) gas purification system and (6) standard gas pipette tanks, which are totally automated and controlled by the Qtegra software platform developed by Thermo-Fisher. Eleven repeat measurements of atmospheric Ar using the H2 Faraday (1E11 ohm resistor) and L2 CDD collectors on the Helix-MC, yield a mean 40Ar/36Ar ratio of 322.09 +- 0.28 (0.089%) with a 4,700 fA 40Ar beam current. This result compares favourably with the precision achieved by the Argus VI at the University of Melbourne (318.12 +- 0.17; 0.052%; n = 10) with a similar beam size of 4,200 fA. The high mass resolution of the L2 collector permits complete separation of the 36Ar and interfering 3 x 12C (required mass resolution (MR) of 1,100) and partial separation of H35Cl (MR = 3,900). This capability enables evaluation of the significance of Ar isotopic interferences related to the correction of

  4. WLS R&D for the detection of noble gas scintillation at LBL: seeing the light from neutrinos, to dark matter, to double beta decay

    NASA Astrophysics Data System (ADS)

    Gehman, V. M.

    2013-09-01

    Radiation detectors with noble gasses as the active medium are becoming increasingly common in experimental programs searching for physics beyond the standard model. Nearly all of these experiments rely to some degree on collecting scintillation light from noble gasses. The VUV wavelengths associated with noble gas scintillation mean that most of these experiments use a fluorescent material to shift the direct scintillation light into the visible or near UV band. We present an overview of the R&D program at LBL related to noble gas detectors for neutrino physics, double beta decay, and dark matter. This program ranges from precise measurements of the fluorescence behavior of wavelength shifting films, to the prototyping of large are VUV sensitive light guides for multi-kiloton detectors.

  5. A Novel Infrared Gas Monitor

    NASA Astrophysics Data System (ADS)

    Wang, Yingding; Zhong, Hongjie

    2000-03-01

    In the paper a novel non-dispersive infrared(IR) gas monitor is described.It is based on the principle that certain gases absorb IR radiation at specific(and often unique) wavelengths.Conventional devices typically include several primary components:a broadband source, usually an incandescent filament,a rotating chopper shutter,a narrow-band filter,a sample tube and a detector. We have developed a number of IR light emitting diodes(LED) having narrow optical bandwidths and which can be intensity modulated by electrical means,for example InAsSbP(4.2 micron)LED.The IR LED can thus replace the thermal source,narrow-band filter and chopper assembly of the conventional IR gas monitor,yielding a solid state,low- powered,compact and almost maintenance-free instrument with high sensitivity and stability and which free of the effects of mechanical vibration too. The detector used in the IR gas monitor is the solid-state detector,such as PbS,PbSe, InSb,HgCdTe,TGS,LT and PZT detector etc. The different configuration of the IR gas monitor is designed.For example,two-path version for measuring methane concentration by monitoring the 3.31 micron absorption band,it can eliminate the interference effects,such as to compensate for LED intensity changes caused by power and temperature variations,and for signal fluctuations due to changes in detector bias. we also have designed portable single-beam version without the sample tube.Its most primary advantage is very cheap(about cost USD 30 ).It measures carbon dioxide concentration by monitoring the 4.25 micron absorption band.Thought its precisions is low,it is used to control carbon dioxide concentration in the air in the green houses and plastic houses(there are about twenty millon one in the China).Because more carbon dioxide will increase the quanity of vegetable and flower production to a greatextent. It also is used in medical,sanitary and antiepidemic applications,such as hospital, store,hotel,cabin and ballroom etc. Key words

  6. Identifying the Sources of Methane in Shallow Groundwaters in Parker and Hood Counties, Texas through Noble Gas Signatures

    NASA Astrophysics Data System (ADS)

    Wen, T.; Castro, M. C.; Nicot, J. P.; Hall, C. M.; Mickler, P. J.; Darvari, R.

    2015-12-01

    With rising demands for cleaner domestic energy resources, horizontal drilling and hydraulic fracturing techniques in unconventional hydrocarbon exploration have been extensively developed. However, the observation that some water wells have showed elevated concentrations of dissolved methane and other light hydrocarbons has caused public concern regarding unconventional energy extraction. In this contribution, we present noble gas data of production shale gases from the Barnett and Strawn Formations, as well as nearby groundwater samples in south-central Texas. The Barnett Shale located in the Fort Worth Basin at an average depth of ~2300 m is one of the most prominent shale gas plays in the U.S. This DOE-sponsored study explores the potential of noble gases for fingerprinting shale gas and thus, for identifying the sources of gas in aquifers overlying the Barnett Shale, due either to natural hydrocarbon occurrences or potentially related to gas production from unconventional energy resources. A total of 35 groundwater samples were collected in Parker and Hood counties in areas where high amounts of methane (>10 mg/L) were detected in shallow groundwater. Two gas samples were also collected directly from groundwater wells where bubbling methane was present. Preliminary results show that He concentrations in water samples, in excess of up to three orders of magnitude higher than expected atmospheric values are directly correlated with methane concentrations. 3He/4He ratio values vary from 0.030 to 0.889 times the atmospheric ratio with the lowest, more pure radiogenic contributions being associated with highest methane levels. The presence of crustally-produced radiogenic 40Ar is also apparent in groundwater samples with 40Ar/36Ar ratios up to 316. A combined analysis of 40Ar/36Ar ratios from groundwater wells bubbling gas and that of shale gas suggests that the source of this methane is not the heavily exploited Barnett Shale, but rather, the Strawn Formation.

  7. Single-bubble sonoluminescence from noble gases.

    PubMed

    Yasui, K

    2001-03-01

    Single-bubble sonoluminescence (SBSL) from noble gases in water is studied theoretically in order to clarify the reason of the distinguished feature that the luminescence is strong for all noble gases, while the other systems of cavitation luminescence are greatly enhanced by the presence of the heavy noble gas(xenon). It is clarified that in spite of the larger thermal conductivity of lighter noble gases the maximum temperature in a SBSL bubble of lighter noble gases is higher due both to the segregation of water vapor and noble gas inside a SBSL bubble and the stronger acoustic drive of a SBSL bubble of lighter noble gases.

  8. Single-bubble sonoluminescence from noble gases

    NASA Astrophysics Data System (ADS)

    Yasui, Kyuichi

    2001-03-01

    Single-bubble sonoluminescence (SBSL) from noble gases in water is studied theoretically in order to clarify the reason of the distinguished feature that the luminescence is strong for all noble gases, while the other systems of cavitation luminescence are greatly enhanced by the presence of the heavy noble gas(xenon). It is clarified that in spite of the larger thermal conductivity of lighter noble gases the maximum temperature in a SBSL bubble of lighter noble gases is higher due both to the segregation of water vapor and noble gas inside a SBSL bubble and the stronger acoustic drive of a SBSL bubble of lighter noble gases.

  9. Noble gas isotope signals of mid-ocean ridge basalts and their implication for upper mantle structure

    NASA Astrophysics Data System (ADS)

    Stroncik, Nicole A.; Niedermann, Samuel

    2016-04-01

    The geochemical structure of the upper mantle in general and its noble gas isotopic structure in particular have been the subject of countless studies, as both provide important insights into mantle dynamic processes and are essential for the formulation of mantle geodynamic models. This contribution presents a noble gas study of basaltic glasses derived from the Mid-Atlantic-Ridge (MAR) between 4 and 12° S, an area well known for its high degree of lithophile isotope heterogeneity and exhibiting anomalous crustal thickness. The Sr, Nd, Pb and Hf isotopies along this segment of the MAR range from ultra-depleted (more than NMORB) to highly enriched, and different concepts have been proposed to explain the observed isotopic signatures. Here we show that the high degree of heterogeneity is not confined to the isotopes of the lithophile elements, but is also shown by the noble gas isotopes and noble gas interelement ratios, such as e.g. 3He/22NeM or 4He/40Ar*. 3He/4He, 21Ne/22Neextra and 40Ar/36Ar range from 7.3 to 9.3 RA, from 0.05 to 0.08, and from 346 to 37,400, respectively. Nevertheless, the majority of the Ne isotope data are clearly aligned along a single mixing line in the Ne-three-isotope diagram, represented by the equation 20Ne/22Ne=70.5 x 21Ne/22Ne + 7.782, with a slope distinctly different from that of the MORB line, indicating that the ultra-depleted material is characterised by a significantly more nucleogenic 21Ne/22Ne isotopy than the normal depleted mantle. We show, based on covariations between 3He/4He and 21Ne/22Neextra with 206Pb/204Pb and 178Hf/177Hf, that the ultra-depleted material erupted at this MAR segment was most likely produced by an ancient, deep melting event. This implies that isotopic heterogeneities in the upper mantle are not solely caused by the injection of enriched materials from deep-seated mantle plumes or by crustal recycling but may also be due to differences in the depth and degree of melting of upper mantle material within

  10. Stability of noble-gas-bound SiH₃⁺ clusters.

    PubMed

    Pan, Sudip; Moreno, Diego; Merino, Gabriel; Chattaraj, Pratim K

    2014-11-10

    The stability of noble gas (Ng)-bound SiH3(+) clusters is explored by ab initio computations. Owing to a high positive charge (+1.53 e(-)), the Si center of SiH3(+) can bind two Ng atoms. However, the Si-Ng dissociation energy for the first Ng atom is considerably larger than that for the second one. As we go down group 18, the dissociation energy gradually increases, and the largest value is observed for the case of Rn. For NgSiH3(+) clusters, the Ar-Rn dissociation processes are endergonic at room temperature. For He and Ne, a much lower temperature is required for it to be viable. The formation of Ng2SiH3(+) clusters is also feasible, particularly for the heavier members and at low temperature. To shed light on the nature of Si-Ng bonding, natural population analysis, Wiberg bond indices computations, electron-density analysis, and energy-decomposition analysis were performed. Electron transfer from the Ng centers to the electropositive Si center occurs only to a small extent for the lighter Ng atoms and to a somewhat greater extent for the heavier analogues. The Si-Xe/Rn bonds can be termed covalent bonds, whereas the Si-He/Ne bonds are noncovalent. The Si-Ar/Kr bonds possess some degree of covalent character, as they are borderline cases. Contributions from polarization and charge transfer and exchange are key terms in forming Si-Ng bonds. We also studied the effect of substituting the H atoms of SiH3(+) by halide groups (-X) on the Ng binding ability. SiF3(+) showed enhanced Ng binding ability, whereas SiCl3(+) and SiBr3(+) showed a lower ability to bind Ng than SiH3(+). A compromise originates from the dual play of the inductive effect of the -X groups and X→Si π backbonding (p(z)-p(z) interaction).

  11. Study of medical isotope production facility stack emissions and noble gas isotopic signature using automatic gamma-spectra analysis platform

    NASA Astrophysics Data System (ADS)

    Zhang, Weihua; Hoffmann, Emmy; Ungar, Kurt; Dolinar, George; Miley, Harry; Mekarski, Pawel; Schrom, Brian; Hoffman, Ian; Lawrie, Ryan; Loosz, Tom

    2013-04-01

    The nuclear industry emissions of the four CTBT (Comprehensive Nuclear-Test-Ban Treaty) relevant radioxenon isotopes are unavoidably detected by the IMS along with possible treaty violations. Another civil source of radioxenon emissions which contributes to the global background is radiopharmaceutical production companies. To better understand the source terms of these background emissions, a joint project between HC, ANSTO, PNNL and CRL was formed to install real-time detection systems to support 135Xe, 133Xe, 131mXe and 133mXe measurements at the ANSTO and CRL 99Mo production facility stacks as well as the CANDU (CANada Deuterium Uranium) primary coolant monitoring system at CRL. At each site, high resolution gamma spectra were collected every 15 minutes using a HPGe detector to continuously monitor a bypass feed from the stack or CANDU primary coolant system as it passed through a sampling cell. HC also conducted atmospheric monitoring for radioxenon at approximately 200 km distant from CRL. A program was written to transfer each spectrum into a text file format suitable for the automatic gamma-spectra analysis platform and then email the file to a server. Once the email was received by the server, it was automatically analysed with the gamma-spectrum software UniSampo/Shaman to perform radionuclide identification and activity calculation for a large number of gamma-spectra in a short period of time (less than 10 seconds per spectrum). The results of nuclide activity together with other spectrum parameters were saved into the Linssi database. This database contains a large amount of radionuclide information which is a valuable resource for the analysis of radionuclide distribution within the noble gas fission product emissions. The results could be useful to identify the specific mechanisms of the activity release. The isotopic signatures of the various radioxenon species can be determined as a function of release time. Comparison of 133mXe and 133Xe activity

  12. Groundwater noble gas, age, and temperature signatures in an Alpine watershed: Valuable tools in conceptual model development

    USGS Publications Warehouse

    Manning, A.H.; Caine, J.S.

    2007-01-01

    [1] Bedrock groundwater in alpine watersheds is poorly understood, mainly because of a scarcity of wells in alpine settings. Groundwater noble gas, age, and temperature data were collected from springs and wells with depths of 3-342 m in Handcart Gulch, an alpine watershed in Colorado. Temperature profiles indicate active groundwater circulation to a maximum depth (aquifer thickness) of about 200 m, or about 150 m below the water table. Dissolved noble gas data show unusually high excess air concentrations (>0.02 cm3 STP/g, ??Ne > 170%) in the bedrock, consistent with unusually large seasonal water table fluctuations (up to 50 m) observed in the upper part of the watershed. Apparent 3H/3He ages are positively correlated with sample depth and excess air concentrations. Integrated samples were collected from artesian bedrock wells near the trunk stream and are assumed to approximate flow-weighted samples reflecting bedrock aquifer mean residence times. Exponential mean ages for these integrated samples are remarkably consistent along the stream, four of five being from 8 to 11 years. The tracer data in combination with other hydrologic and geologic data support a relatively simple conceptual model of groundwater flow in the watershed in which (1) permeability is primarily a function of depth; (2) water table fluctuations increase with distance from the stream; and (3) recharge, aquifer thickness, and porosity are relatively uniform throughout the watershed in spite of the geological complexity of the Proterozoic crystalline rocks that underlie it. Copyright 2007 by the American Geophysical Union.

  13. Noble Gas Inventory of Micrometeorites Collected at the Transantarctic Mountains (TAM) and Indications for Their Provenance

    NASA Technical Reports Server (NTRS)

    Ott, U.; Baecker, B.; Folco, L.; Cordier, C.

    2016-01-01

    A variety of processes have been considered possibly contributing the volatiles including noble gases to the atmospheres of the terrestrial planets (e.g., [1-3]). Special consideration has been given to the concept of accretion of volatile-rich materials by the forming planets. This might include infalling planetesimals and dust, and could include material from the outer asteroid belt, as well as cometary material from the outer solar system. Currently, the dominant source of extraterrestrial material accreted by the Earth is represented by micrometeorites (MMs) with sizes mostly in the 100-300 micron range [3, 4]). Their role has been assessed by [3], who conclude that accretion of early micrometeorites played a major role in the formation of the terrestrial atmosphere and oceans. We have therefore set out to investigate in more detail the inventory of noble gases in MMs. Here we summarize some of our results obtained on MMs collected in micrometeorite traps of the Transantarctic Mountains [5].

  14. Experimental Investigations of Halogen and Noble Gas Geochemistry as Constraints on Planetary Outgassing

    NASA Astrophysics Data System (ADS)

    Musselwhite, D. S.; Drake, M. J.; Swindle, T. D.

    1992-07-01

    Introduction The ^129Xe/^132Xe ratio in Mid-Ocean Ridge Basalts (MORBs) is higher than in the atmosphere and Ocean Island Basalts. Enhanced ^129Xe/^132Xe ratios are widely regarded to be the result of ^129I decay (t(sub)1/2 = 16 m.y.) early in solar system history (e.g. Swindle et al., 1986). Allegre et al. (1983, 1988) proposed a catastrophic degassing scheme to explain this excess. Both Musselwhite et al. (1990) and Hiyagon and Ozima (1990) have noted that because mineral/melt partition coefficients (D) for I appear lower than for Xe, the I/Xe ratio may not be enhanced in the mantle by mineral/melt fractionation. Musselwhite et al. (1990) proposed recycling of I back into the mantle following outgassing, and Hiyagon and Ozima (1990) proposed impact degassing of the mantle as a way around this problem. Knowledge of the relative values of D(I) and D(Xe) is important to the discussion of early planetary outgassing models. Although the dataset for D(I) values is not complete, the known values so far are uniformly low. The dataset for Xe on the other hand is quite ambiguous. Experimentally determined values for D(Xe) vary widely--ranging from 0.05 to >> 1 (Hiyagon and Ozima, 1986; Broadhurst et al., 1992), and it is unclear which of the values is the geologically significant one. Particularly important is the question of whether D(Xe) is greater than or less than unity. Partitioning Experiments: We have undertaken to simultaneously determine the D(I) and D(Ar) values directly, then calculate the D(Xe) from D(Ar). This approach is possible because experiments investigating the mineral/melt partitioning of noble gases, while not consistent in an absolute sense between experiments, do display a consistent trend with the lightest noble gases being most incompatible and Xe most compatible. We are adapting our technique to determine D(Kr) and D(Xe) directly. Finely crushed silica glass (~100 micrometer grain size) was placed in a gas pressure vessel. The vessel was

  15. Noble Gas Tracing of Subsurface CO2 Origin and the Role of Groundwater as a CO2 Sink

    NASA Astrophysics Data System (ADS)

    Zhou, Z.; Ballentine, C. J.; Schoell, M.; Stevens, S. H.

    2003-12-01

    The source, generation, migration and accumulation of CO2 gas associated either alone or with hydrocarbons are unclear and therefore hard to predict. So far, noble gases provide one of the best tools to resolve this question, because they are conservative within the subsurface system. The atmosphere-derived noble gases dissolved in groundwater do not react with the rock system, while noble gases produced in the rock phase by radioactive decay or input from magmatic source are isotopically distinct and can be resolved from the dissolved air-derived noble gases. 10 samples were taken from a CO2-rich natural gas reservoir in Jackson Dome, Mississippi, USA to investigate its origin and extent of interaction with the groundwater system. The area lies within the Mississippi Interior Salt Basin. It is bounded on the north by the Pickens-Gilbertown fault system, the updip limit of the Jurassic Louann Salt unit, and on the south by basement highs of the Wiggins, South Mississippi, and Lasalle uplifts. We present compositional, stable isotope and noble gas results of Jackson Dome samples. Gas composition is 98.75-99.38% CO2, with small amounts of methane and nitrogen. CO2 content increases linearly with the decrease of CH4. d13C(CO2) in all samples ranges between -3.55 and -2.57 per mil, increasing with the increase of the CO2 content. Atmosphere-derived He contributions are negligible in all cases. 3He/4He ratios are between 4.27 and 5.01Ra, indicating a strong mantle signature. Crustal 4He in these samples therefore accounts for between 7.0% and 20.8%, the remainder being magmatic in origin. 40Ar/36Ar ratios are all above air ratio, ranging between 4071 and 6420. Air corrected 40Ar* vary between 92.7 and 95.4%, to give 4He/40Ar* ratios of between 1.26 and 2.52. This range is comparable with values estimated for the upper mantle. CO2/3He values are between 1.09E+9 and 4.62E+9, and also fall in the mantle range, indicating that the CO2 gas in Jackson Dome is also

  16. Gas transport below artificial recharge ponds: insights from dissolved noble gases and a dual gas (SF6 and 3He) tracer experiment.

    PubMed

    Clark, Jordan F; Hudson, G Bryant; Avisar, Dror

    2005-06-01

    A dual gas tracer experiment using sulfur hexafluoride (SF6) and an isotope of helium (3He) and measurements of dissolved noble gases was performed at the El Rio spreading grounds to examine gas transport and trapped air below an artificial recharge pond with a very high recharge rate (approximately 4 m day(-1)). Noble gas concentrations in the groundwater were greater than in surface water due to excess air formation showing that trapped air exists below the pond. Breakthrough curves of SF6 and 3He at two nearby production wells were very similar and suggest that nonequilibrium gas transfer was occurring between the percolating water and the trapped air. At one well screened between 50 and 90 m below ground, both tracers were detected after 5 days and reached a maximum at approximately 24 days. Despite the potential dilution caused by mixing within the production well, the maximum concentration was approximately 25% of the mean pond concentration. More than 50% of the SF6 recharged was recovered by the production wells during the 18 month long experiment. Our results demonstrate that at artificial recharge sites with high infiltration rates and moderately deep water tables, transport times between recharge locations and wells determined with gas tracer experiments are reliable.

  17. Noble gas paleotemperatures and water contents of stalagmites - a new extraction tool and a new paleoclimate proxy

    NASA Astrophysics Data System (ADS)

    Vogel, N.; Scheidegger, Y.; Brennwald, M. S.; Fleitmann, D.; Figura, S.; Wieler, R.; Kipfer, R.

    2012-04-01

    Stalagmites represent excellent multi-proxy paleoclimate archives as they cover long timescales and can be dated with high precision [e.g., 1]. The absolute temperature at which a stalagmite grew, can be deduced from the amounts of atmospheric noble gases dissolved in the stalagmite's fluid inclusion water (= noble gas temperature, NGT) [2-4]. We present technical advances towards more robust NGT determinations and also propose a new paleoclimate proxy, namely the stalagmite's water content, which is a "by-product" of NGT determination. Water contents and oxygen isotope records of two Holocene stalagmites from Socotra Island (Yemen) were found to vary systematically: progressively lighter oxygen is accompanied by decreasing water contents and vice versa. Via the oxygen isotope records [5] the stalagmites' water contents are linked to the amounts of precipitation on Socotra Island. High precipitation, i.e., high drip rates lead to homogeneous calcite growth with low porosity and therefore a small number of water-filled inclusions, i.e. low water contents. A reduction of drip water supply fosters irregular crystal growth with higher porosity, leading to higher water contents of the calcite (see also [6]). Therefore the stalagmites' water contents seem to record changes in drip water supply and, under favourable conditions, changes in regional precipitation. The current method to extract water and noble gases from stalagmite samples is experimentally challenging and subject to certain limitations (e.g., time-consuming sample preparation in a glove box, temperature restrictions for water extraction, and the often inadequate correction for air from residual air-filled inclusions [3, 4]). To overcome these limitations we have developed a new type of crusher directly attached to our noble gas line. It not only allows crushing and separating the samples into different grain size fractions in vacuo, but the separates can be individually heated to significantly higher

  18. The intrusion of new magma triggered the 2011-2012 unrest at Santorini: evidence from noble-gas isotopes

    NASA Astrophysics Data System (ADS)

    Rizzo, A.; Barberi, F.; Carapezza, M.; Di Piazza, A.; Francalanci, L.; Sortino, F.; D'Alessandro, W.

    2013-12-01

    Santorini is one of the most famous active volcanoes of the world for its catastrophic explosive eruption that occurred during the Minoan civilization. Since then the Kameni eruptive centers that formed within the caldera erupted repeatedly until 1950. In 2011-2012 the volcano has been characterized by a seismic unrest, that was unprecedented at Santorini at least since the 1950 eruption, and that led to fear for an imminent eruption. Because more than 100,000 visitors are present on the island during the tourist season, and considering the eruptive potential of Santorini, it is crucial to evaluate the hazard of this volcano, which depends on the type of magma actually present in the volcanic system. With the aim to address this question, this research shows the first comparison between noble-gas isotope composition of the present fumarolic gases with that of fluid inclusions hosted in enclaves contained in the 1570 and 1925 AD dacitic magmas erupted at Nea Kameni. These enclaves are a portion of mafic magma batches that replenished the shallow chamber of the plumbing system hosting cooler and more silicic melts. Their Sr-Nd isotope ratios are quite similar to those measured in the host dacitic rocks, implying a common parental magma. Therefore, the analyzed enclaves may be considered representative of the historic magma erupted at Nea Kameni which could be still present in the volcano plumbing system feeding the crater fumaroles. The 3He/4He ratios of enclaves, once corrected for air contamination (3.1-3.6 Ra), partially overlap those of the gases (3.5-4.0 Ra) collected from Nea and Palea Kameni. The range of 3He/4He ratios (3.1-4.0 Ra) is appreciably lower than typical arc volcanoes (R/Ra ~7-8), implying that a contamination by 4He-rich fluids occurred either directly in the mantle and/or in the plumbing system. Comparison of 3He/4He and 4He/40Ar* ratios measured in enclaves with those of gases, as well as long-term monitoring of R/Ra in the latters, coherently

  19. Noble gas composition and 40Ar/39Ar age in eclogites from the main hole of the Chinese Continental Scientific Drilling project

    NASA Astrophysics Data System (ADS)

    Hopp, Jens; Schwarz, Winfried H.; Trieloff, Mario; Meyer, Hans-Peter; Hanel, Michael; Altherr, Rainer

    2016-10-01

    We present the first comprehensive noble gas study on eclogites. The four eclogite samples were recovered during the Chinese Continental Scientific Drilling and are from two distinct profile depth sections differing in their degree of interaction with meteoric water, based on their δ 18O-values (surface related and of mantle-type). Hence, noble gas analyses offer the potential to further discriminate between shallow (meteoric) and deep (mantle) fluid sources. Noble gas compositions reveal typical crustal fluid compositions, characterized by a variable mixture of atmospheric gases with significant contributions of nucleogenic neon, radiogenic 4He*, radiogenic 40Ar*, fissiogenic 131-136Xe, and presumably bariogenic 131Xe, but no significant addition of mantle gases. This signature can be also considered to represent one endmember component of eclogitic diamonds. Concentrations of non-radiogenic noble gases are rather low, with depletion of light relative to the heavier noble gases. Eclogites from lower depth which experienced a higher degree of interaction with meteoric water also showed higher contributions of atmospheric gas compared with eclogites recovered from greater depth. This is interpreted to result from interaction with high-salinity fluids during ultrahigh pressure (UH P). It demonstrates that the atmospheric noble gas abundance is a proxy for interaction with surface related fluids. 40Ar/39Ar (inverse) isochron ages of two phengite separates (241.2 ± 0.4 Ma and 275.0 ± 1.8 Ma, 1 σ-errors) predate the main phase of UH P metamorphism (ca. 220 Ma). Biotite yields an integrated age of about 1100 Ma. These age values are interpreted to reflect the likely addition of excess 40Ar without any chronological meaning.

  20. Modeling nuclear and electronic recoils in noble gas detectors with NEST

    NASA Astrophysics Data System (ADS)

    Mock, Jeremy; NEST Collaboration

    2015-10-01

    Noble gases such as xenon and argon are used as targets in single and dual phased rare event detectors like those used in the search for dark matter. Such experiments require an understanding of the behavior of the target material in the presence of low-energy ionizing radiation. This understanding allows an exploration of detector effects such as threshold, energy and position reconstruction, and pulse shape discrimination. The Noble Element Simulation Technique (NEST) package is a comprehensive code base that models the scintillation and ionization yields from liquid and gaseous xenon and argon in the energy regimes of interest to many types of experiments, like dark matter and neutrino detectors. NEST is built on multiple physics models, which are constrained by available data for both electronic and nuclear recoils. A substantial body of data exists in the literature, and we are reaching an era in which sub-keV yields can be explored experimentally. Here we present a new global analysis of all available nuclear recoil data, and the latest updates to the electronic recoil model, in light of recent low-energy measurements and an improved understanding of detector systematics.

  1. A Concept for a Low Pressure Noble Gas Fill Intervention in the IFE Fusion Test Facility (FTF) Target Chamber

    SciTech Connect

    Gentile, C. A.; Blanchard, W. R.; Kozub, T. A.; Aristova, M.; McGahan, C.; Natta, S.; Pagdon, K.; Zelenty, J.

    2010-01-14

    An engineering evaluation has been initiated to investigate conceptual engineering methods for implementing a viable gas shield strategy in the Fusion Test Facility (FTF) target chamber. The employment of a low pressure noble gas in the target chamber to thermalize energetic helium ions prior to interaction with the wall could dramatically increase the useful life of the first wall in the FTF reactor1. For the purpose of providing flexibility, two target chamber configurations are addressed: a five meter radius sphere and a ten meter radius sphere. Experimental studies at Nike have indicated that a low pressure, ambient gas resident in the target chamber during laser pulsing does not appear to impair the ability of laser light from illuminating targets2. In addition, current investigations into delivering, maintaining, and processing low pressure gas appear to be viable with slight modification to current pumping and plasma exhaust processing technologies3,4. Employment of a gas fill solution for protecting the dry wall target chamber in the FTF may reduce, or possibly eliminate the need for other attenuating technologies designed for keeping He ions from implanting in first wall structures and components. The gas fill concept appears to provide an effective means of extending the life of the first wall while employing mostly commercial off the shelf (COTS) technologies. Although a gas fill configuration may provide a methodology for attenuating damage inflicted on chamber surfaces, issues associated with target injection need to be further analyzed to ensure that the gas fill concept is viable in the integrated FTF design5. In the proposed system, the ambient noble gas is heated via the energetic helium ions produced by target detonation. The gas is subsequently cooled by the chamber wall to approximately 800oC, removed from the chamber, and processed by the chamber gas processing system (CGPS). In an optimized scenario of the above stated concept, the chamber

  2. Coordination of ScO+ and YO+ by multiple Ar, Kr, and Xe atoms in noble gas matrixes: a matrix isolation infrared spectroscopic and theoretical study.

    PubMed

    Zhao, Yanying; Gong, Yu; Chen, Mohua; Ding, Chuanfan; Zhou, Mingfei

    2005-12-29

    The combination of matrix isolation infrared spectroscopic and quantum chemical calculation results provide strong evidence that scandium and yttrium monoxide cations, ScO+ and YO+, coordinate multiple noble gas atoms in forming noble gas complexes. The results showed that ScO+ coordinates five Ar, Kr, or Xe atoms, and YO+ coordinates six Ar or Kr and five Xe atoms in solid noble gas matrixes. Hence, the ScO+ and YO+ cations trapped in solid noble gas matrixes should be regarded as the [ScO(Ng)5]+ (Ng = Ar, Kr, or Xe), [YO(Ng)6]+ (Ng = Ar or Kr) or [YO(Xe)5]+ complexes. Experiments with dilute krypton or xenon in argon or krypton in xenon produced new IR bands, which are due to the stepwise formation of the [ScO(Ar)(5-n)(Kr)n]+, [ScO(Kr)(5-n)(Xe)n]+ (n = 1-5), [YO(Ar)(6-n)(Kr)n]+ (n = 1-6), and [YO(Ar)(6-n)(Xe)n]+ (n = 1-4) complexes.

  3. Determining CO2 storage potential during miscible CO2 enhanced oil recovery: Noble gas and stable isotope tracers

    USGS Publications Warehouse

    Shelton, Jenna L.; McIntosh, Jennifer C.; Hunt, Andrew; Beebe, Thomas L; Parker, Andrew D; Warwick, Peter; Drake, Ronald; McCray, John E.

    2016-01-01

    Rising atmospheric carbon dioxide (CO2) concentrations are fueling anthropogenic climate change. Geologic sequestration of anthropogenic CO2 in depleted oil reservoirs is one option for reducing CO2 emissions to the atmosphere while enhancing oil recovery. In order to evaluate the feasibility of using enhanced oil recovery (EOR) sites in the United States for permanent CO2 storage, an active multi-stage miscible CO2flooding project in the Permian Basin (North Ward Estes Field, near Wickett, Texas) was investigated. In addition, two major natural CO2 reservoirs in the southeastern Paradox Basin (McElmo Dome and Doe Canyon) were also investigated as they provide CO2 for EOR operations in the Permian Basin. Produced gas and water were collected from three different CO2 flooding phases (with different start dates) within the North Ward Estes Field to evaluate possible CO2 storage mechanisms and amounts of total CO2retention. McElmo Dome and Doe Canyon were sampled for produced gas to determine the noble gas and stable isotope signature of the original injected EOR gas and to confirm the source of this naturally-occurring CO2. As expected, the natural CO2produced from McElmo Dome and Doe Canyon is a mix of mantle and crustal sources. When comparing CO2 injection and production rates for the CO2 floods in the North Ward Estes Field, it appears that CO2 retention in the reservoir decreased over the course of the three injections, retaining 39%, 49% and 61% of the injected CO2 for the 2008, 2010, and 2013 projects, respectively, characteristic of maturing CO2 miscible flood projects. Noble gas isotopic composition of the injected and produced gas for the flood projects suggest no active fractionation, while δ13CCO2 values suggest no active CO2dissolution into formation water, or mineralization. CO2 volumes capable of dissolving in residual formation fluids were also estimated along with the potential to store pure-phase supercritical CO2. Using a combination

  4. Ultrabright multikilovolt x-ray source: saturated amplification on noble gas transition arrays from hollow atom states

    DOEpatents

    Rhodes, Charles K.; Boyer, Keith

    2004-02-17

    An apparatus and method for the generation of ultrabright multikilovolt x-rays from saturated amplification on noble gas transition arrays from hollow atom states is described. Conditions for x-ray amplification in this spectral region combine the production of cold, high-Z matter, with the direct, selective multiphoton excitation of hollow atoms from clusters using ultraviolet radiation and a nonlinear mode of confined, self-channeled propagation in plasmas. Data obtained is consistent with the presence of saturated amplification on several transition arrays of the hollow atom Xe(L) spectrum (.lambda..about.2.9 .ANG.). An estimate of the peak brightness achieved is .about.10.sup.29 .gamma..multidot.s.sup.-1.multidot.mm.sup.-2.multidot.mr.sup.-2 (0.1% Bandwidth).sup.-1, that is .about.10.sup.5 -fold higher than presently available synchotron technology.

  5. Neutralization of solvated protons and formation of noble-gas hydride molecules: Matrix-isolation indications of tunneling mechanisms?

    SciTech Connect

    Khriachtchev, Leonid; Lignell, Antti; Raesaenen, Markku

    2005-08-08

    The (NgHNg){sup +} cations (Ng=Ar and Kr) produced via the photolysis of HF/Ar, HF/Kr, and HBr/Kr solid mixtures are studied, with emphasis on their decay mechanisms. The present experiments provide a large variety of parameters connected to this decay phenomenon, which allows us to reconsider various models for the decay of the (NgHNg){sup +} cations in noble-gas matrices. As a result, we propose that this phenomenon could be explained by the neutralization of the solvated protons by electrons. The mechanism of this neutralization reaction probably involves tunneling of an electron from an electronegative fragment or another trap to the (NgHNg){sup +} cation. The proposed electron-tunneling mechanism should be considered as a possible alternative to the literature models based on tunneling-assisted or radiation-induced diffusion of protons in noble-gas solids. As a novel experimental observation of this work, the efficient formation of HArF molecules occurs at 8 K in a photolyzed HF/Ar matrix. It is probable that the low-temperature formation of HArF involves local tunneling of the H atom to the Ar-F center, which in turn supports the locality of HF photolysis in solid Ar. In this model, the decay of (ArHAr){sup +} ions and the formation of HArF molecules observed at low temperatures are generally unconnected processes; however, the decaying (ArHAr){sup +} ions may contribute to some extent to the formation of HArF molecules.

  6. Noble gas studies in vapor-growth diamonds: Comparison with shock-produced diamonds and the origin of diamonds in ureilites

    SciTech Connect

    Matsuda, Junichi; Fukunaga, Kazuya; Ito, Keisuke )

    1991-07-01

    The authors synthesized vapor-trowth diamonds by two kinds of Chemical Vapor Deposition (CVD) using microwave (MWCVD) and hot filament (HFCVD) ionization of gases, and examined elemental abundances and isotopic compositions of the noble gases trapped in the diamonds. It is remarkable that strong differences existed in the noble gas concentrations in the two kinds of CVD diamonds: large amounts of noble gases were trapped in the MWCVD diamonds, but not in the HFCVD diamonds. The heavy noble gases (Ar to Xe) in the MWCVD diamonds were highly fractionated compared with those in the ambient atmosphere, and are in good agreement with the calculated fractionation patterns for plasma at an electron temperature of 7,000-9,000 K. These results strongly suggest that the trapping mechanism of noble gases in CVD diamonds is ion implantation during diamond growth. The degrees of fractionation of heavy noble gases were also in good agreement with those in ureilites. The vapor-growth hypothesis is discussed in comparison with the impact-shock hypothesis as a better model for the origin of diamonds in ureilites. The diamond (and graphite, amorphous carbon, too) may have been deposited on early condensates such as Re, Ir, W, etc. This model explains the chemical features of vein material in ureilites; the refractory siderophile elements are enriched in carbon and noble gases and low in normal siderophiles. The vapor-growth model is also compatible with the oxygen isotopic data of ureilites which suggests that nebular processes are primarily responsible for the composition of ureilites.

  7. Evaluating the accretion of meteoritic debris and interplanetary dust particles in the GPC-3 sediment core using noble gas and mineralogical tracers

    NASA Astrophysics Data System (ADS)

    Darrah, Thomas H.; Poreda, Robert J.

    2012-05-01

    Extraterrestrial (ET) noble gases (helium and neon) in 35 sediment samples from Central Pacific core LL-44 GPC-3 demonstrate the variable flux of interplanetary dust particles (IDPs) and major meteorite impacts over the past 70 Ma (21-72 Ma). Spinel mineralogical and chemical compositions clearly distinguish major impact events from the continuous flux of IDPs, including the well-established Cretaceous/Tertiary (K/T) and late Eocene (E/O) impact boundaries. No spinel grains with chemical or mineralogical evidence of a distinctly ET origin were found in an extensive survey of 'background' samples (i.e. non E/O or K/T boundary) suggesting that either the carrier grains for ET noble gas occur within the Fe-Ti oxide mineral fraction observed in this study (found to include ilmenite and ulvospinel) or are too small for identification by SEM. The presence of ilmenite and ulvospinel suggest lunar regolith is a potential source for ET noble gas-rich particles. Noble gas analysis on both the EMF (extractable magnetic fraction) and the Bulk minus EMF (Bulk - EMF) show that the He and Ne compositions are consistent with partially degassed noble gas signatures of zero-age magnetic grains (Z-MAG) and stratospheric interplanetary dust particles (IDPs). Conclusive evidence for a 'planetary' (Ne-A) noble gas signature is found only in the bulk sediments at the K/T boundary, although all GPC-3 K/T fractions (Bulk, EMF, and HF Digestion) plot along a mixing line between planetary (Ne-A) and solar wind (SW). Spinels from major impact boundaries (K/T; E/O) exhibit dendritic texture and elevated [Ni], consistent with previous reports. In contrast to the otherwise consistent [3He] signal from IDPs, the [3He] at the known impact boundaries (K/T and E/O) actually decreases. These anomalously low [3He] are accompanied by significantly elevated [Ne] and significantly lower (3He/20Ne)solar ratios (˜10× lower) produced by both preferentially degassing of He relative to Ne at times of

  8. Ore genesis constraints on the Idaho Cobalt Belt from fluid inclusion gas, noble gas isotope, and ion ratio analyses

    USGS Publications Warehouse

    Hofstra, Albert H.; Landis, Gary P.

    2012-01-01

    The Idaho cobalt belt is a 60-km-long alignment of deposits composed of cobaltite, Co pyrite, chalcopyrite, and gold with anomalous Nb, Y, Be, and rare-earth elements (REEs) in a quartz-biotite-tourmaline gangue hosted in Mesoproterozoic metasedimentary rocks of the Lemhi Group. It is the largest cobalt resource in the United States with historic production from the Blackbird Mine. All of the deposits were deformed and metamorphosed to upper greenschist-lower amphibolite grade in the Cretaceous. They occur near a 1377 Ma anorogenic bimodal plutonic complex. The enhanced solubility of Fe, Co, Cu, and Au as chloride complexes together with gangue biotite rich in Fe and Cl and gangue quartz containing hypersaline inclusions allows that hot saline fluids were involved. The isotopes of B in gangue tourmaline are suggestive of a marine source, whereas those of Pb in ore suggest a U ± Th-enriched source. The ore and gangue minerals in this belt may have trapped components in fluid inclusions that are distinct from those in post-ore minerals and metamorphic minerals. Such components can potentially be identified and distinguished by their relative abundances in contrasting samples. Therefore, we obtained samples of Co and Cu sulfides, gangue quartz, biotite, and tourmaline and post-ore quartz veins as well as Cretaceous metamorphic garnet and determined the gas, noble gas isotope, and ion ratios of fluid inclusion extracts by mass spectrometry and ion chromatography. The most abundant gases present in extracts from each sample type are biased toward the gas-rich population of inclusions trapped during maximum burial and metamorphism. All have CO2/CH4 and N2/Ar ratios of evolved crustal fluids, and many yield a range of H2-CH4-CO2-H2S equilibration temperatures consistent with the metamorphic grade. Cretaceous garnet and post-ore minerals have high RH and RS values suggestive of reduced sulfidic conditions. Most extracts have anomalous 4He produced by decay of U and Th and

  9. Multi-Gas Monitor (MGM)

    NASA Technical Reports Server (NTRS)

    Pilgrim, Jeff; Limero, Thomas

    2015-01-01

    Multi-Gas Monitor is a flight experiment, a technology demonstration to test the ability of tunable diode laser spectroscopy based instrument to stay in calibration long term and follow events and dynamics occurring with the cabin atmosphere. MGM measures 4 gases: oxygen, carbon monoxide, ammonia and water vapor, as well as temperature and pressure. This month marked one year of successful and continuous MGM operation on ISS. The crew successfully tested the ammonia channel using a commercially available inhalant. MGM has detected some interesting dynamics inside Japanese Experiment Module (JEM) as a result of CO2 thruster firings from the SPHERES/RINGS payload and water spikes from dry out cycling of the JEM heat exchangers. Results to date have given us high confidence in the technology such that we believe this could have applications in the energy and medical sectors. This presentation will summarize the testing and results of the unit on ISS and suggest areas of use within the energy and medical arenas.

  10. Magma dynamics at mid-ocean ridges by noble gas kinetic fractionation: Assessment of magmatic ascent rates

    NASA Astrophysics Data System (ADS)

    Paonita, A.; Martelli, M.

    2006-01-01

    Despite its impact in understanding oceanic crust formation and eruptive styles of related volcanism, magma dynamics at mid-ocean ridges are poorly known. Here, we propose a new method to assess ascent rates of mid-ocean ridge basalt (MORB) magmas, as well as their pre- and sin-eruptive dynamics. It is based on the idea that a rising magma can reach a variable degree of both CO2 supersaturation in melt and kinetic fractionation among noble gases in vesicles in relation to its ascent rate through the crust. To quantify the relationship, we have used a model of multicomponent bubble growth in MORB melts, developed by extending the single-component model of Proussevitch and Sahagian [A.A. Proussevitch, D.L. Sahagian, Dynamics and energetics of bubble growth in magmas: analytical formulation and numerical modeling, J. Geophys. Res. 103 (1998), 18223-18251.] to CO2-He-Ar gas mixtures. After proper parameterization, we have applied it to published suites of data having the required features (glasses from Pito Seamount and mid-Atlantic ridges). Our results highlight that the investigated MORB magmas display very different ranges of ascent rates: slow rises of popping rock forming-magmas that cross the crust (0.01-0.5 m/s), slightly faster rates of energetic effusions (0.1-1 m/s), up to rates of 1-10 m/s which fall on the edge between lava effusion and Hawaiian activity. Inside a single plumbing system, very dissimilar magma dynamics highlight the large differences in compressive stress of the oceanic crust on a small scale. Constraints on how the systems of ridges work, as well as the characteristics of the magmatic source, can also be obtained. Our model shows how measurements of both the dissolved gas concentration in melt and the volatile composition of vesicles in the same sample are crucial in recognizing the kinetic effects and definitively assessing magma dynamics. An effort should be made to correctly set the studied samples in the sequence of volcanic submarine

  11. Conceptual Engineering Method for Attenuating He Ion Interactions on First Wall Components in the Fusion Test Facility (FTF) Employing a Low-Pressure Noble Gas

    SciTech Connect

    C.A.Gentile, W.R.Blanchard, T.Kozub, C.Priniski, I.Zatz, S.Obenschain

    2009-09-21

    It has been shown that post detonation energetic helium ions can drastically reduce the useful life of the (dry) first wall of an IFE reactor due to the accumulation of implanted helium. For the purpose of attenuating energetic helium ions from interacting with first wall components in the Fusion Test Facility (FTF) target chamber, several concepts have been advanced. These include magnetic intervention (MI), deployment of a dynamically moving first wall, use of a sacrificial shroud, designing the target chamber large enough to mitigate the damage caused by He ions on the target chamber wall, and the use of a low pressure noble gas resident in the target chamber during pulse power operations. It is proposed that employing a low-pressure (~ 1 torr equivalent) noble gas in the target chamber will thermalize energetic helium ions prior to interaction with the wall. The principle benefit of this concept is the simplicity of the design and the utilization of (modified) existing technologies for pumping and processing the noble ambient gas. Although the gas load in the system would be increased over other proposed methods, the use of a "gas shield" may provide a cost effective method of greatly extending the first wall of the target chamber. An engineering study has been initiated to investigate conceptual engineering metmethods for implementing a viable gas shield strategy in the FTF.

  12. Heterogeneous upper mantle Ne, Ar and Xe isotopic compositions and a possible Dupal noble gas signature recorded in basalts from the Southwest Indian Ridge

    NASA Astrophysics Data System (ADS)

    Parai, R.; Mukhopadhyay, S.; Standish, J. J.

    2012-12-01

    Variations in heavy noble gas (Ne, Ar, Xe) isotopic compositions provide unique insights into the nature of heterogeneities in the mantle. However, few precise constraints on mantle source heavy noble gas isotopic compositions are available due to ubiquitous shallow-level atmospheric contamination. As a result, the extent of heterogeneity in mid-ocean ridge basalt (MORB) mantle source Ne, Ar and Xe isotopic compositions is unknown. Basalts from the ultra-slow spreading Southwest Indian Ridge (SWIR) between 7°E and 25°E exhibit remarkable variability in He isotopic composition: SWIR 4He/3He spans half the total range observed in all mantle-derived basalts. Therefore, basalts from the SWIR provide a unique window into upper mantle heterogeneity and present an ideal opportunity to characterize variations in upper mantle heavy noble gas isotopic composition. Here we present new high-precision Ne, Ar and Xe isotopic compositions as well as He, CO2, Ne, Ar and Xe abundances measured in basalt glasses from the SWIR. After correcting the measured values for shallow-level atmospheric contamination, significant and systematic variations in mantle source Ne, Ar and Xe compositions are observed. We note that large variations in source 40Ar/36Ar and 129Xe/130Xe are observed in basalts removed from the influence of known hotspots, indicating a heterogeneous mid-ocean ridge basalt source. Thus, SWIR heavy noble gas data reveal a greater degree of source heterogeneity than is evident in the 4He/3He systematics alone. The observed heavy noble gas isotopic heterogeneities imply that the average MORB source 40Ar/36Ar and 129Xe/130Xe ratios are not yet well-determined. Variation in MORB source 40Ar/36Ar and 129Xe/130Xe at a given 4He/3He and 21Ne/22Ne may reflect heterogeneous recycling of atmospheric Ar and Xe. In particular, we find low mantle source 40Ar/36Ar and 129Xe/130Xe ratios in the eastern region of the study area, which may reflect the noble gas signature of the Dupal

  13. GAS-PHASE SEQUESTRATION OF NOBLE GASES IN THE PROTOSOLAR NEBULA: POSSIBLE CONSEQUENCES ON THE OUTER SOLAR SYSTEM COMPOSITION

    SciTech Connect

    Pauzat, F.; Ellinger, Y.; Ozgurel, O.; Mousis, O.; Ali Dib, M. E-mail: ellinger@lct.jussieu.fr E-mail: olivier.mousis@obs-besancon.fr

    2013-11-01

    We address the problem of the sequestration of Ar, Kr, and Xe by H{sub 3}{sup +} in the gas-phase conditions encountered during the cooling of protoplanetary disks when H{sub 3}{sup +} is competing with other species present in the same environment. Using high-level ab initio simulations, we try to quantify other sequestration possibilities involving He, H{sub 5}{sup +}, H{sub 2}O, and H{sub 3}O{sup +} present in the protosolar nebula. Apart from the fact that H{sub 3}{sup +} complexes formed with heavy noble gases are found to be by far much more stable than those formed with He or H{sub 2}O, we show that H{sub 2}D{sup +} and H{sub 3}O{sup +}, both products of the reactions of H{sub 3}{sup +} with HD and H{sub 2}O, can also be efficient trapping agents for Ar, Kr, and Xe. Meanwhile, the abundance profile of H{sub 3}{sup +} in the outer part of the nebula is revisited with the use of an evolutionary accretion disk model that allows us to investigate the possibility that heavy noble gases can be sequestered by H{sub 3}{sup +} at earlier epochs than those corresponding to their trapping in planetesimals. We find that H{sub 3}{sup +} might be abundant enough in the outer protosolar nebula to trap Xe and Kr prior their condensation epochs, implying that their abundances should be solar in Saturn's current atmosphere and below the observational limit in Titan. The same scenario predicts that comets formed at high heliocentric distances should also be depleted in Kr and Xe. In situ measurements, such as those planed with the Rosetta mission on 67P/Churyumov-Gerasimenko, will be critical to check the validity of our hypotheses.

  14. Noble gas component organization in Apollo 14 breccia 14318: /sup 129/I and /sup 244/Pu regolith chronology

    SciTech Connect

    Swindle, T.D.; Caffee, M.W.; Hohenberg, C.M.; Hudson, G.B.; Laul, J.C.; Simon, S.B.; Papike, J.J.

    1985-02-15

    Noble gas, petrological, and chemical studies made on grain-size separates from lunar regolith breccia 14318 demonstrate that the noble gases are organized into two functional components, volume-correlated and surface-correlated. As in regolith breccia 14301, volume-correlated xenon in 14318 is primarily spallation-derived and the surface-correlated component contains not only solar wind xenon but also significant amounts of ''parentless' xenon from the fission of now extinct /sup 244/Pu and the decay of now extinct /sup 129/I (''parentless'' means the daughter products were incorporated onto grain surfaces following decay of the parent nuclide elsewhere). The ratio of /sup 129/Xe//sup 136/Xe in the total surface-correlated parentless component, as identified in grain-size analysis, is substantially higher than in the least tightly bound parentless component identified in stepwise heating analyses, confirming the trend seen in 14301. If the order of release of gases in stepwise heating is related to the order of incorporation in the simplest way (first in, last out), incorporation of these grain-surface components was probably time-ordered. The /sup 129/Xe//sup 136/Xe ratio in each identifiable parentless component would then be characteristic of the xenon available for surface adsorption at the particular time of acquisition. Continuous variations in this ratio further suggest that incorporation of the parentless xenon was closely coupled with production. Such observations provide the basis for a new chronometer from which we conclude that acquisition of parentless xenon was an ongoing process spanning at least 90 m.y., beginning no more than 44 +- 34 m.y. after the formation of the most meteorites and possibly predating xenon acquisition for the earth.

  15. Hydrochemistry and origin of CO2 gas and noble gas of carbonated mineral water in the Gyeongbuk-Gangwon Province, South Korea

    NASA Astrophysics Data System (ADS)

    Jeong, C. H.; Yoo, S. W.

    2012-04-01

    Hydrochemical, carbon isotopic (δ13CDIC) analyses of 11 samples, and noble gas isotopic analyses of 8 samples collected in the Gangwon and the Gyeongbuk area of South Korea were carried out to elucidate hydrochemical characteristics and to interpret the source of noble gases and CO2 gas. The carbonated mineral waters show a weak acidic pH between 5.59 and 6.04. An electrical conductivity of carbonated mineral waters ranges from 302 to 864 μS/cm. The chemical composition of all carbonated mineral waters can be grouped into only one type such as Ca-HCO3. A high content of Fe and Mn in carbonated mineral waters exceeds a regulation limit of drinking water. The δ13CDIC values of carbonated mineral waters show the range of -5.30~-2.84 ‰. This range indicates that the carbon of carbonated mineral waters is mainly supplied from a deep-seated source and partly from an inorganic carbonate source. The 3He/4He ratios of the carbonated mineral waters show the range of 1.51×10-6 to 6.45×10-6. The carbonated mineral waters on the 3He/4He and 4He/20Ne diagram are plotted into three groups: deep seated area such as mantle source, atmospheric area, and air-mantle mixing area. A wide range of 4He/20Ne ratios is observed (0.036×10-6 to 1.76×10-6), showing evidence that while radiogenic 4He is dominant in these water samples, He of mantle-origin is also supplied to these waters. It is estimated that supply of CO2 gas and noble gas of a deep-seated source into carbonated waters is closely related to geologic structures such as fault and geologic boundary. Key words: carbonated mineral waters, hydrochemical composition, carbon isotope, 3He/4He, deep-seated origin

  16. The Role of Boron-Chloride and Noble Gas Isotope Ratios in TVZ Geothermal Systems

    SciTech Connect

    Hulston, J.R.

    1995-01-01

    The model of the geothermal system in which deep circulating groundwater containing noble gases, at air saturated water concentrations, mixes with hot fluids of mantle origin at depth, is extended to include the effect of interaction of the ascending fluid with both solid and gaseous phases of basement (or other) rocks en route to the surface. It is demonstrated that this interaction is responsible for most of the CO{sub 2} in the Taupo Volcanic Zone (TVZ) geothermal systems. It is proposed that the modeling of this interaction might be accomplished by techniques similar to those used for the understanding of the oxygen isotope shift found in geothermal systems. The water rock interaction experiments of Ellis and Mahon (1964, 1967) provides some data on the kinetic rates for B and Cl dissolution from rocks likely to be encountered in the geothermal system, but further information on the behavior of B may be needed. If these problems can be overcome this modeling technique has promise for the estimation of the recharge of geothermal systems and hence the sustainability of these systems.

  17. Geostatistical analysis of tritium, groundwater age and other noble gas derived parameters in California.

    PubMed

    Visser, A; Moran, J E; Hillegonds, Darren; Singleton, M J; Kulongoski, Justin T; Belitz, Kenneth; Esser, B K

    2016-03-15

    Key characteristics of California groundwater systems related to aquifer vulnerability, sustainability, recharge locations and mechanisms, and anthropogenic impact on recharge are revealed in a spatial geostatistical analysis of a unique data set of tritium, noble gases and other isotopic analyses unprecedented in size at nearly 4000 samples. The correlation length of key groundwater residence time parameters varies between tens of kilometers ((3)H; age) to the order of a hundred kilometers ((4)Heter; (14)C; (3)Hetrit). The correlation length of parameters related to climate, topography and atmospheric processes is on the order of several hundred kilometers (recharge temperature; δ(18)O). Young groundwater ages that highlight regional recharge areas are located in the eastern San Joaquin Valley, in the southern Santa Clara Valley Basin, in the upper LA basin and along unlined canals carrying Colorado River water, showing that much of the recent recharge in central and southern California is dominated by river recharge and managed aquifer recharge. Modern groundwater is found in wells with the top open intervals below 60 m depth in the southeastern San Joaquin Valley, Santa Clara Valley and Los Angeles basin, as the result of intensive pumping and/or managed aquifer recharge operations.

  18. Updated compilations of electron scattering from ground-state, noble gas atoms

    NASA Astrophysics Data System (ADS)

    Biagi, S. F.

    2011-10-01

    An updated analysis of the cross sections for electron scattering from ground state atoms for noble gases in the energy range from thermalto 10 MeV is outlined. The work was driven by the necessity tounderstand the Penning transfers and light emission in detectors of high energy particles and dark matter. The published experimental data for electron scattering up to 2010 have been used in the analysis. Recent, theoretically improved cross sections have been used in the important threshold region for both the singlet and triplet states. Experimental or theoretical oscillator strengths and BEF scaling have been used above the resonance region for the singlet states. The number of excitation levels considered (typically about 40) is chosen so that the sum of the oscillator strengths for the considered levels is within a few percent of the theoretical sum rule. The resulting total cross sections are within a few percent of the measured values, and the calculated Fano factors are consistent with available data. These data are now available on the LXCat website. This work is part of the RD51 collaboration at CERN.

  19. Ground-Water Temperature, Noble Gas, and Carbon Isotope Data from the Espanola Basin, New Mexico

    USGS Publications Warehouse

    Manning, Andrew H.

    2009-01-01

    Ground-water samples were collected from 56 locations throughout the Espanola Basin and analyzed for general chemistry (major ions and trace elements), carbon isotopes (delta 13C and 14C activity) in dissolved inorganic carbon, noble gases (He, Ne, Ar, Kr, Xe, and 3He/4He ratio), and tritium. Temperature profiles were measured at six locations in the southeastern part of the basin. Temperature profiles suggest that ground water generally becomes warmer with distance from the mountains and that most ground-water flow occurs at depths 50 years old, consistent with the 14C ages. Terrigenic He (Heterr) concentrations in ground water are high (log Delta Heterr of 2 to 5) throughout much of the basin. High Heterr concentrations are probably caused by in situ production in the Tesuque Formation from locally high concentrations of U-bearing minerals (Northeast zone only), or by upward diffusive/advective transport of crustal- and mantle-sourced He possibly enhanced by basement piercing faults, or by both. The 3He/4He ratio of Heterr (Rterr) is commonly high (Rterr/Ra of 0.3-2.0, where Ra is the 3He/4He ratio in air) suggesting that Espanola Basin ground water commonly contains mantle-sourced He. The 3He/4He ratio of Heterr is generally the highest in the western and southern parts of the basin, closest to the western border fault system and the Quaternary to Miocene volcanics of the Jemez Mountains and Cerros del Rio.

  20. Noble Gas Systematics in MORBs and OIBs and Reconstitution of the Time-Evolution of Mantle Composition for Heavy Noble Gases: the Role of Subduction of Atmospheric Noble Gases.

    NASA Astrophysics Data System (ADS)

    Roubinet, C.; Moreira, M. A.

    2014-12-01

    Chondrites are considered as the building rocks of the Earth as they represent remnants of the protoplanetary accretion stage. Among all chondritic classes, heavy noble gases are mainly concentrated in phase Q [1] hence it represents a likely primordial composition of the Earth. This is supported by the observation of [2] who detected this peculiar composition in CO2 well gases thanks to Kr isotopes. As CO2 well gases are supposed to derive from the same reservoir as MORBs [3], this signature should be observed in MORBs and OIBs as well. In this perspective, we will present analyses performed by mass spectrometry of MORBs and OIBs samples for all noble gases. Preliminary results are quite promising as the same trend seems to appear into OIB and MORB data for Kr isotopes. However, our analyses show that this primordial composition isn't displayed for stable isotopes of Xe as already observed by [4-5] and remains a trace in the mantle signature, which appears at first sight atmospheric. We thus propose that subduction of atmospheric noble gases has gradually covered this meteoritic imprint. In order to test this scenario, we will present a modelling performed for Ar and Xe in three distinct reservoirs: mantle, atmosphere and continental crust. The mantle is considered as homogenized by convection and similar to the MORB reservoir. Its degasing is divided in two stages: a massive early degasing followed by a decreasing one describing the cooling of the Earth's interior. Extraction of parent elements from the mantle to the continental crust is also taken into account as well as distillation of atmospheric Xe needed to explain the missing Xe paradox and the present Xe isotopic signature of the atmosphere. Finally, subduction of noble gases is assimilated to simple incorporation into the mantle of elementally fractionated air, enriched in heavy noble gases as supported by [6]. Thus, we show that starting with a chondritic composition, the present mantle composition can

  1. Evolved gas composition monitoring by repetitive injection gas chromatography.

    PubMed

    White, Robert L

    2015-11-20

    Performance characteristics and applications of a small volume gas chromatograph oven are described. Heating and cooling properties of the apparatus are evaluated and examples are given illustrating the advantages of greatly reducing the air bath volume surrounding fused silica columns. Fast heating and cooling of the oven permit it to be employed for repetitive injection analyses. By using fast gas chromatography separations to achieve short assay cycle times, the apparatus can be employed for on-line species-specific gas stream composition monitoring when volatile species concentrations vary on time scales of a few minutes or longer. This capability facilitates repeated sampling and fast gas chromatographic separations of volatile product mixtures produced during thermal analyses. Applications of repetitive injection gas chromatography-mass spectrometry evolved gas analyses to monitoring purge gas effluent streams containing volatile acid catalyzed polymer cracking products are described. The influence of thermal analysis and chromatographic experimental parameters on effluent sampling frequency are delineated.

  2. EFFECTS OF ALTERNATE ANTIFOAM AGENTS, NOBLE METALS, MIXING SYSTEMS AND MASS TRANSFER ON GAS HOLDUP AND RELEASE FROM NONNEWTONIAN SLURRIES

    SciTech Connect

    Guerrero, H; Mark Fowley, M; Charles Crawford, C; Michael Restivo, M; Robert Leishear, R

    2007-12-24

    Gas holdup tests performed in a small-scale mechanically-agitated mixing system at the Savannah River National Laboratory (SRNL) were reported in 2006. The tests were for a simulant of waste from the Hanford Tank 241-AZ-101 and featured additions of DOW Corning Q2-3183A Antifoam agent. Results indicated that this antifoam agent (AFA) increased gas holdup in the waste simulant by about a factor of four and, counter intuitively, that the holdup increased as the simulant shear strength decreased (apparent viscosity decreased). These results raised questions about how the AFA might affect gas holdup in Hanford Waste Treatment and Immobilization Plant (WTP) vessels mixed by air sparging and pulse-jet mixers (PJMs). And whether the WTP air supply system being designed would have the capacity to handle a demand for increased airflow to operate the sparger-PJM mixing systems should the AFA increase retention of the radiochemically generated flammable gases in the waste by making the gas bubbles smaller and less mobile, or decrease the size of sparger bubbles making them mix less effectively for a given airflow rate. A new testing program was developed to assess the potential effects of adding the DOW Corning Q2-3183A AFA to WTP waste streams by first confirming the results of the work reported in 2006 by Stewart et al. and then determining if the AFA in fact causes such increased gas holdup in a prototypic sparger-PJM mixing system, or if the increased holdup is just a feature of the small-scale agitation system. Other elements of the new program include evaluating effects other variables could have on gas holdup in systems with AFA additions such as catalysis from trace noble metals in the waste, determining mass transfer coefficients for the AZ-101 waste simulant, and determining whether other AFA compositions such as Dow Corning 1520-US could also increase gas holdup in Hanford waste. This new testing program was split into two investigations, prototypic sparger

  3. Martian fluid and Martian weathering signatures identified in Nakhla, NWA 998 and MIL 03346 by halogen and noble gas analysis

    NASA Astrophysics Data System (ADS)

    Cartwright, J. A.; Gilmour, J. D.; Burgess, R.

    2013-03-01

    We report argon (Ar) noble gas, Ar-Ar ages and halogen abundances (Cl, Br, I) of Martian nakhlites Nakhla, NWA 998 and MIL 03346 to determine the presence of Martian hydrous fluids and weathering products. Neutron-irradiated samples were either crushed and step-heated (Nakhla only), or simply step-heated using a laser or furnace, and analysed for noble gases using an extension of the 40Ar-39Ar technique to determine halogen abundances. The data obtained provide the first isotopic evidence for a trapped fluid that is Cl-rich, has a strong correlation with 40ArXS (40ArXS = 40Armeasured - 40Arradiogenic) and displays 40ArXS/36Ar of ˜1000 - consistent with the Martian atmosphere. This component was released predominantly in the low temperature and crush experiments, which may suggest a fluid inclusion host. For the halogens, we observe similar Br/Cl and I/Cl ratios between the nakhlites and terrestrial reservoirs, which is surprising given the absence of crustal recycling, organic matter and frequent fluid activity on Mars. In particular, Br/Cl ratios in our Nakhla samples (especially olivine) are consistent with previously analysed Martian weathering products, and both low temperature and crush analyses show a similar trend to the evaporation of seawater. This may indicate that surface brines play an important role on Mars and on halogen assemblages within Martian meteorites and rocks. Elevated I/Cl ratios in the low temperature NWA 998 and MIL 03346 releases may relate to in situ terrestrial contamination, though we are unable to distinguish between low temperature terrestrial or Martian components. Whilst estimates of the amount of water present based on the 36Ar concentrations are too high to be explained by a fluid component alone, they are consistent with a mixed-phase inclusion (gas and fluid) or with shock-implanted Martian atmospheric argon. The observed fluid is dilute (low salinity, but high Br/Cl and I/Cl ratios), contains a Martian atmospheric component

  4. Gas-laser power monitor

    NASA Technical Reports Server (NTRS)

    Russ, C. E., Jr.

    1981-01-01

    Device attaches simply to front of laser housing for continuous monitoring of power output. Monitor is calibrated to read either total output or power generated in test volume. It is fabricated from four black-anodized aluminum parts; crown glass positioned at Brewster angle reflects 0.33 percent of beam onto photodiode calibrated for electrical output proportional to laser power. Unlike conventional calorimeter, monitor does not interrupt laser beams, and fast-response diode allows instantaneous tracking of power fluctuations.

  5. Laboratory Connections. Gas Monitoring Transducers.

    ERIC Educational Resources Information Center

    Powers, Michael H.

    1988-01-01

    Discusses three types of sensors; pressure, gas detection, and relative humidity. Explains their use for laboratory measurements of gas pressure and detection of specific gaseous species. Shows diagrams of devices and circuits along with examples and applications including microcomputer interfacing. (RT)

  6. Recycling of volatiles at subduction zones: Noble gas evidence from the Tabar-Lihir-Tanga-Feni arc of papua New Guinea

    NASA Technical Reports Server (NTRS)

    Farley, Kenneth; Mcinnes, Brent; Patterson, Desmond

    1994-01-01

    Convergent margin processes play an important but poorly understood role in the distribution of terrestrial volatile species. For example, subduction processes filter volatiles from the subducting package, thereby restricting their return to the mantle. In addition, once extracted from the downgoing slab, volatiles become an essential component in the petrogenesis of island arc magmas. The noble gases, with their systematic variation in physical properties and diversity of radiogenic isotopes, should carry a uniquely valuable record of these processes. However, thus far studies of noble gases in arc volcanics have achieved only limited success in this regard. Subduction-related lavas and geothermal fluids carry (3)He/(4)He ratios equal to or slightly lower than those found in the depleted upper mantle source of mid-ocean ridge basalts. Apparently slab-derived helium (which should have (3)He/(4)He much less than MORB) is extensively diluted by MORB-like helium from the mantle wedge, making it difficult to use helium as a tracer of convergent margin processes. Interpretation of the heavier noble gases (Ne-Ar-Kr-Xe) in arc lavas has also proven difficult, because the lavas carry low noble gas concentrations and hence are subject to pervasive atmospheric contamination. The low noble gas concentrations may be a consequence of degassing in the high level magma chambers characteristic of arc stratovolcanos. We have recently initiated a project to better constrain the behavior of volatiles in subduction zones through geochemical studies of the tectonically unusual volcanoes of the Tabar-Lihir-Tanga-Feni (TLTF) arc in the Bismarck Archipelago, Papua New Guinea.

  7. Tracing groundwater input into Lake Vanda, Wright Valley, Antarctica using major ions, stable isotopes and noble gas

    NASA Astrophysics Data System (ADS)

    Dowling, C. B.; Poreda, R. J.; Snyder, G. T.

    2008-12-01

    The McMurdo Dry Valleys (MDV), Antarctica, is the largest ice-free region on Antarctica. Lake Vanda, located in central Wright Valley, is the deepest lake among the MDV lakes. It has a relatively fresh water layer above 50 m with a hypersaline calcium-chloride brine below (50-72 m). The Onyx River is the only stream input into Lake Vanda. It flows westward from the coastal Lower Wright Glacier and discharges into Lake Vanda. Suggested by the published literature and this study, there has been and may still be groundwater input into Lake Vanda. Stable isotopes, major ions, and noble gas data from this study coupled with previously published data indicate that the bottom waters of Lake Vanda have had significant contributions from a deep groundwater system. The dissolved gas of the bottom waters of Lake Vanda display solubility concentrations rather than the Ar-enriched dissolved gas seen in the Taylor Valley lakes (such as Lake Bonney). The isotopic data indicate that the bottom calcium-chloride-brine of Lake Vanda has undergone very little evaporation. The calcium-chloride chemistry of the groundwater that discharges into Lake Vanda most likely results from the chemical weathering and dissolution of cryogenic evaporites (antarcticite and gypsum) within the glacial sediments of Wright Valley. The high calcium concentrations of the brine have caused gypsum to precipitate on the lake bottom. Our work also supports previous physical and chemical observations suggesting that the upper portion actively circulates and the hypersaline bottom layer does not. The helium and calcium chloride values are concentrated at the bottom, with a very narrow transition layer between it and the above fresh water. If the freshwater layer did not actively circulate, then diffusion over time would have caused the helium and calcium chloride to slowly permeate upwards through the water column.

  8. Comparison of induced damage, range, reflection, and sputtering yield between amorphous, bcc crystalline, and bubble-containing tungsten materials under hydrogen isotope and noble gas plasma irradiations

    NASA Astrophysics Data System (ADS)

    Saito, Seiki; Nakamura, Hiroaki; Tokitani, Masayuki

    2017-01-01

    Binary-collision-approximation simulation of hydrogen isotope (i.e., hydrogen, deuterium, and tritium) and noble gas (i.e., helium, neon, and argon) injections into tungsten materials is performed. Three tungsten structures (i.e., amorphous, bcc crystalline, and helium bubble-containing structures) are prepared as target materials. Then, the trajectories of incident atoms, the distribution of recoil atoms, the penetration depth range of incident atoms, the sputtering yield, and the reflection rate are carefully investigated for these target materials.

  9. Comparative Study on the Noble-Gas Binding Ability of BeX Clusters (X = SO4, CO3, O).

    PubMed

    Saha, Ranajit; Pan, Sudip; Merino, Gabriel; Chattaraj, Pratim K

    2015-06-25

    Ab initio computations are carried out to assess the noble gas (Ng) binding capability of BeSO4 cluster. We have further compared the stability of NgBeSO4 with that of the recently detected NgBeCO3 cluster. The Ng-Be bond in NgBeCO3 is somewhat weaker than that in NgBeO cluster. In NgBeSO4, the Ng-Be bond is found to be stronger compared with not only the Ng-Be bond in NgBeCO3 but also that in NgBeO, except the He case. The Ar-Rn-bound BeSO4 analogues are viable even at room temperature. The Wiberg bond indices of Be-Ng bonds and the degree of electron transfer from Ng to Be are somewhat larger in NgBeSO4 than those in NgBeCO3 and NgBeO. Electron density and energy decomposition analyses are performed in search of the nature of interaction in the Be-Ng bond in NgBeSO4. The orbital energy term (ΔE(orb)) contributes the maximum (ca. 80-90%) to the total attraction energy. The Ar/Kr/Xe/Rn-Be bonds in NgBeSO4 could be of partial covalent type with a gradual increase in covalency along Ar to Rn.

  10. Coulomb explosion in dicationic noble gas clusters: A genetic algorithm-based approach to critical size estimation for the suppression of Coulomb explosion and prediction of dissociation channels

    NASA Astrophysics Data System (ADS)

    Nandy, Subhajit; Chaudhury, Pinaki; Bhattacharyya, S. P.

    2010-06-01

    We present a genetic algorithm based investigation of structural fragmentation in dicationic noble gas clusters, Arn+2, Krn+2, and Xen+2, where n denotes the size of the cluster. Dications are predicted to be stable above a threshold size of the cluster when positive charges are assumed to remain localized on two noble gas atoms and the Lennard-Jones potential along with bare Coulomb and ion-induced dipole interactions are taken into account for describing the potential energy surface. Our cutoff values are close to those obtained experimentally [P. Scheier and T. D. Mark, J. Chem. Phys. 11, 3056 (1987)] and theoretically [J. G. Gay and B. J. Berne, Phys. Rev. Lett. 49, 194 (1982)]. When the charges are allowed to be equally distributed over four noble gas atoms in the cluster and the nonpolarization interaction terms are allowed to remain unchanged, our method successfully identifies the size threshold for stability as well as the nature of the channels of dissociation as function of cluster size. In Arn2+, for example, fissionlike fragmentation is predicted for n =55 while for n =43, the predicted outcome is nonfission fragmentation in complete agreement with earlier work [Golberg et al., J. Chem. Phys. 100, 8277 (1994)].

  11. Using noble-gas and stable-isotope data to determine groundwater origin and flow regimes: Application to the Ceneri Base Tunnel (Switzerland)

    NASA Astrophysics Data System (ADS)

    Tomonaga, Yama; Marzocchi, Roberto; Pera, Sebastian; Pfeifer, Hans-Rudolf; Kipfer, Rolf; Decrouy, Laurent; Vennemann, Torsten

    2017-02-01

    Tunnel drilling provides a unique opportunity to sample and study deep groundwaters that are otherwise difficult to access. Understanding deep groundwater flow is of primary importance in assessing the possible impacts of tunnelling on hydrogeological systems. During this study, water was sampled for noble-gas analysis from tunnel inflows in the AlpTransit Ceneri Base Tunnel (Canton Ticino, southern Switzerland), which passes through an area mainly characterized by metamorphic rocks (gneiss). Furthermore, water was sampled from springs located in the same geological environment. Based on the measurement of noble-gas concentrations and isotope ratios, tritium concentrations, the stable isotope composition of hydrogen (δ2H) and oxygen (δ18O), and the concentrations of major ions in the water, a conceptual hydrogeological model was established for this case study that allowed the most probable origin of the groundwaters sampled at different locations to be determined. The measured abundances of 3He, 4He, and 20Ne allow the geochemical characterization of old groundwaters strongly enriched in terrigenic helium of crustal origin and the identification of mixing with water that circulates preferentially through cataclastic structures. Noble-gas concentrations and isotope ratios as well as tritium are useful proxies for the characterization of faults that may be critical for tunnel drilling because of their active hydrogeological role and their influence on the mechanics of the rocks.

  12. Theoretical prediction of maximum capacity of C₈₀ and Si₈₀ fullerenes for noble gas storage.

    PubMed

    Mahdavifar, Zabiollah

    2014-11-01

    In this paper, we try to demonstrate that how many helium, neon and argon atoms can be trapped into fullerene cages until the pressure becomes large enough to break the C80 and Si80 frameworks. The maximum number of helium, neon and argon atoms which can be encapsulated into C80 fullerene, is found with 46, 24 and 10 atoms respectively. Having investigated the mechanism of C80 opening, we found that if the number of helium and argon atoms reaches to 50 and 12 respectively, the C-C bonds of C80 are broken and the gas molecules escaped from the fullerene cage. The final optimization geometries of latter complexes are similar to the shopping cart. Therefore, this appearance is named as molecular cart. Moreover, the maximum capacity of Si80 fullerene for encapsulated noble gas atoms is found 95, 56 and 22 for helium, neon and argon atoms correspondingly. It is worth highlighting that the new phenomenon of trapping argon atoms into Si80 cage is observed, when a Si atom randomly added to the center of Ar19@Si80 structures. In this case, the Si-Si bonds of Si80 are broken and two argon atoms will escape from the cage. After that, the framework rebuilds its structure like the initial one. This phenomenon is introduced as molecular cesarean section. The estimated internal pressure of Ng atoms trapped into the fullerene cages is also investigated. Results show that the maximum calculated internal pressure is related to He46@C80 and He95@Si80 structures with 212.3 and 144.1GPa respectively.

  13. Simultaneous measurement of rock permeability and effective porosity using laser-polarized noble gas NMR

    NASA Astrophysics Data System (ADS)

    Wang, R.; Mair, R. W.; Rosen, M. S.; Cory, D. G.; Walsworth, R. L.

    2004-08-01

    We report simultaneous measurements of the permeability and effective porosity of oil-reservoir rock cores using one-dimensional NMR imaging of the penetrating flow of laser-polarized xenon gas. The permeability result agrees well with industry standard techniques, whereas effective porosity is not easily determined by other methods. This NMR technique may have applications to the characterization of fluid flow in a wide variety of porous and granular media.

  14. Common versus noble Bacillus subtilis differentially responds to air and argon gas plasma.

    PubMed

    Winter, Theresa; Bernhardt, Jörg; Winter, Jörn; Mäder, Ulrike; Schlüter, Rabea; Weltmann, Klaus-Dieter; Hecker, Michael; Kusch, Harald

    2013-09-01

    The applications of low-temperature plasma are not only confined to decontamination and sterilization but are also found in the medical field in terms of wound and skin treatment. For the improvement of already established and also for new plasma techniques, in-depth knowledge on the interactions between plasma and microorganism is essential. In an initial study, the interaction between growing Bacillus subtilis and argon plasma was investigated by using a growth chamber system suitable for low-temperature gas plasma treatment of bacteria in liquid medium. In this follow-up investigation, a second kind of plasma treatment-namely air plasma-was applied. With combined proteomic and transcriptomic analyses, we were able to investigate the plasma-specific stress response of B. subtilis toward not only argon but also air plasma. Besides an overlap of cellular responses due to both argon and air plasma treatment (DNA damage and oxidative stress), a variety of gas-dependent cellular responses such as growth retardation and morphological changes were observed. Only argon plasma treatments lead to a phosphate starvation response whereas air plasma induced the tryptophan operon implying damage by photooxidation. Biological findings were supported by the detection of reactive plasma species by optical emission spectroscopy and Fourier transformed infrared spectroscopy measurements.

  15. Automated soil gas monitoring chamber

    DOEpatents

    Edwards, Nelson T.; Riggs, Jeffery S.

    2003-07-29

    A chamber for trapping soil gases as they evolve from the soil without disturbance to the soil and to the natural microclimate within the chamber has been invented. The chamber opens between measurements and therefore does not alter the metabolic processes that influence soil gas efflux rates. A multiple chamber system provides for repetitive multi-point sampling, undisturbed metabolic soil processes between sampling, and an essentially airtight sampling chamber operating at ambient pressure.

  16. Understanding the interaction of injected CO2 and reservoir fluids in the Cranfield enhanced oil recovery (EOR) field (MS, USA) by non-radiogenic noble gas isotopes

    NASA Astrophysics Data System (ADS)

    Gyore, Domokos; Stuart, Finlay; Gilfillan, Stuart

    2016-04-01

    Identifying the mechanism by which the injected CO2 is stored in underground reservoirs is a key challenge for carbon sequestration. Developing tracing tools that are universally deployable will increase confidence that CO2 remains safely stored. CO2 has been injected into the Cranfield enhanced oil recovery (EOR) field (MS, USA) since 2008 and significant amount of CO2 has remained (stored) in the reservoir. Noble gases (He, Ne, Ar, Kr, Xe) are present as minor natural components in the injected CO2. He, Ne and Ar previously have been shown to be powerful tracers of the CO2 injected in the field (Györe et al., 2015). It also has been implied that interaction with the formation water might have been responsible for the observed CO2 loss. Here we will present work, which examines the role of reservoir fluids as a CO2 sink by examining non-radiogenic noble gas isotopes (20Ne, 36Ar, 84Kr, 132Xe). Gas samples from injection and production wells were taken 18 and 45 months after the start of injection. We will show that the fractionation of noble gases relative to Ar is consistent with the different degrees of CO2 - fluid interaction in the individual samples. The early injection samples indicate that the CO2 injected is in contact with the formation water. The spatial distribution of the data reveal significant heterogeneity in the reservoir with some wells exhibiting a relatively free flow path, where little formation water is contacted. Significantly, in the samples, where CO2 loss has been previously identified show active and ongoing contact. Data from the later stage of the injection shows that the CO2 - oil interaction has became more important than the CO2 - formation water interaction in controlling the noble gas fingerprint. This potentially provides a means to estimate the oil displacement efficiency. This dataset is a demonstration that noble gases can resolve CO2 storage mechanisms and its interaction with the reservoir fluids with high resolution

  17. The Thermo Scientific HELIX-SFT noble gas mass spectrometer: (preliminary) performance for 40Ar/39Ar geochronology

    NASA Astrophysics Data System (ADS)

    Barfod, D. N.; Mark, D. F.; Morgan, L. E.; Tomkinson, T.; Stuart, F.; Imlach, J.; Hamilton, D.

    2011-12-01

    The Thermo Scientific HELIX-platform Split Flight Tube (HELIX-SFT) noble gas mass spectrometer is specifically designed for simultaneous collection of helium isotopes. The high mass spur houses a switchable 1011 - 1012 Ω resistor Faraday cup and the low mass spur a digital pulse-counting secondary electron multiplier (SEM). We have acquired the HELIX-SFT with the specific intention to measure argon isotopes for 40Ar/39Ar geochronology. This contribution will discuss preliminary performance (resolution, reproducibility, precision etc.) with respect to measuring argon isotope ratios for 40Ar/39Ar dating of geological materials. We anticipate the greatest impact for 40Ar/39Ar dating will be increased accuracy and precision, especially as we approach the techniques younger limit. Working with Thermo Scientific we have subtly modified the source, alpha and collector slits of the HELIX-SFT mass spectrometer to improve its resolution for resolving isobaric interferences at masses 36 to 40. The enhanced performance will allow for accurate and precise measurement of argon isotopes. Preliminary investigations show that we can obtain a valley resolution of >700 and >1300 (compared to standard HELIX-SFT specifications of >400 and >700) for the high and low mass spurs, respectively. The improvement allows for full resolution of hydrocarbons (C3+) at masses 37 - 40 and almost full resolution at mass 36. The HELIX-SFT will collect data in dual collection mode with 40Ar+ ion beams measured using the switchable 1011 - 1012 Ω resistor Faraday cup and 39Ar through 36Ar measured using the SEM. The HELIX-SFT requires Faraday-SEM inter-calibration but negates the necessity to inter-calibrate multiple electron multipliers. We will further present preliminary data from the dating of mineral standards: Alder Creek sanidine, Fish Canyon sanidine and Mount Dromedary biotite (GA1550).

  18. Molecular dynamics simulation of framework flexibility effects on noble gas diffusion in HKUST-1 and ZIF-8

    DOE PAGES

    Parkes, Marie V.; Demir, Hakan; Teich-McGoldrick, Stephanie L.; ...

    2014-03-28

    Molecular dynamics simulations were used to investigate trends in noble gas (Ar, Kr, Xe) diffusion in the metal-organic frameworks HKUST-1 and ZIF-8. Diffusion occurs primarily through inter-cage jump events, with much greater diffusion of guest atoms in HKUST-1 compared to ZIF-8 due to the larger cage and window sizes in the former. We compare diffusion coefficients calculated for both rigid and flexible frameworks. For rigid framework simulations, in which the framework atoms were held at their crystallographic or geometry optimized coordinates, sometimes dramatic differences in guest diffusion were seen depending on the initial framework structure or the choice of frameworkmore » force field parameters. When framework flexibility effects were included, argon and krypton diffusion increased significantly compared to rigid-framework simulations using general force field parameters. Additionally, for argon and krypton in ZIF-8, guest diffusion increased with loading, demonstrating that guest-guest interactions between cages enhance inter-cage diffusion. No inter-cage jump events were seen for xenon atoms in ZIF-8 regardless of force field or initial structure, and the loading dependence of xenon diffusion in HKUST-1 is different for rigid and flexible frameworks. Diffusion of krypton and xenon in HKUST-1 depends on two competing effects: the steric effect that decreases diffusion as loading increases, and the “small cage effect” that increases diffusion as loading increases. Finally, a detailed analysis of the window size in ZIF-8 reveals that the window increases beyond its normal size to permit passage of a (nominally) larger krypton atom.« less

  19. Molecular dynamics simulation of framework flexibility effects on noble gas diffusion in HKUST-1 and ZIF-8

    SciTech Connect

    Parkes, Marie V.; Demir, Hakan; Teich-McGoldrick, Stephanie L.; Sholl, David S.; Greathouse, Jeffery A.; Allendorf, Mark D.

    2014-03-28

    Molecular dynamics simulations were used to investigate trends in noble gas (Ar, Kr, Xe) diffusion in the metal-organic frameworks HKUST-1 and ZIF-8. Diffusion occurs primarily through inter-cage jump events, with much greater diffusion of guest atoms in HKUST-1 compared to ZIF-8 due to the larger cage and window sizes in the former. We compare diffusion coefficients calculated for both rigid and flexible frameworks. For rigid framework simulations, in which the framework atoms were held at their crystallographic or geometry optimized coordinates, sometimes dramatic differences in guest diffusion were seen depending on the initial framework structure or the choice of framework force field parameters. When framework flexibility effects were included, argon and krypton diffusion increased significantly compared to rigid-framework simulations using general force field parameters. Additionally, for argon and krypton in ZIF-8, guest diffusion increased with loading, demonstrating that guest-guest interactions between cages enhance inter-cage diffusion. No inter-cage jump events were seen for xenon atoms in ZIF-8 regardless of force field or initial structure, and the loading dependence of xenon diffusion in HKUST-1 is different for rigid and flexible frameworks. Diffusion of krypton and xenon in HKUST-1 depends on two competing effects: the steric effect that decreases diffusion as loading increases, and the “small cage effect” that increases diffusion as loading increases. Finally, a detailed analysis of the window size in ZIF-8 reveals that the window increases beyond its normal size to permit passage of a (nominally) larger krypton atom.

  20. The noble gas argon modifies extracellular signal-regulated kinase 1/2 signaling in neurons and glial cells.

    PubMed

    Fahlenkamp, Astrid V; Rossaint, Rolf; Haase, Hajo; Al Kassam, Hussam; Ryang, Yu-Mi; Beyer, Cordian; Coburn, Mark

    2012-01-15

    Recently, the noble gas argon has been identified as a potent neuroprotective agent, but little is known about its cellular effects. In this in vitro study, we investigated argon's influence on the extracellular signal-regulated kinase (ERK) 1/2, a ubiquitous enzyme with numerous functions in cell proliferation and survival. Primary neuronal and astroglial cell cultures and the microglial cell line BV-2 were exposed to 50 vol.% argon. Further possible effects were studied following stimulation of microglia with 50 ng/ml LPS. ERK 1/2 activation was assessed by phosphorylation state-specific western blotting, cytokine levels by real-time PCR and western blotting. Total phosphotyrosine phosphatase activity was examined with p-nitrophenylphosphate. After 30 min exposure, argon significantly activated ERK 1/2 signaling in microglia. Enhanced phosphorylation of ERK 1/2 was also found in astrocytes and neurons following argon exposure, but it lacked statistical significance. In microglia, argon did not substantially interfere with LPS-induced ERK1/2 activation and inflammatory cytokine induction. Addition of the MEK-Inhibitor U0126 abolished the induced ERK 1/2 phosphorylation. Cellular phosphatase activity and the inactivation of phosphorylated ERK 1/2 were not altered by argon. In conclusion, argon enhanced ERK 1/2 activity in microglia via the upstream kinase MEK, probably through a direct mode of activation. ERK 1/2 signaling in astrocytes and neurons in vitro was also influenced, although not with statistical significance. Whether ERK 1/2 activation by argon affects cellular functions like differentiation and survival in the brain in vivo will have to be determined in future experiments.

  1. Fluid circulation and reservoir conditions of the Los Humeros Geothermal Field (LHGF), Mexico, as revealed by a noble gas survey

    NASA Astrophysics Data System (ADS)

    Pinti, Daniele L.; Castro, M. Clara; Lopez-Hernandez, Aida; Han, Guolei; Shouakar-Stash, Orfan; Hall, Chris M.; Ramírez-Montes, Miguel

    2017-03-01

    Los Humeros Geothermal Field (LHGF) is one of four geothermal fields currently operating in Mexico, in exploitation since 1990. Located in a caldera complex filled with very low-permeability rhyolitic ignimbrites that are the reservoir cap-rock, recharge of the geothermal field is both limited and localized. Because of this, planning of any future geothermal exploitation must be based on a clear understanding of the fluid circulation. To this end, a first noble gas survey was carried out in which twenty-two production wells were sampled for He, Ne, Ar, Kr, and Xe isotope analysis. Air-corrected 3He/4He ratios (Rc) measured in the fluid, normalized to the helium atmospheric ratio (Ra; 1.384 × 10- 6), are consistently high across the field, with an average value of 7.03 ± 0.40 Ra. This value is close to that of the sub-continental upper mantle, indicating that LHGF mines heat from an active magmatic system. Freshwater recharge does not significantly affect He isotopic ratios, contributing 1-10% of the total fluid amount. The presence of radiogenic 40Ar* in the fluid suggests a fossil fluid component that might have circulated within the metacarbonate basement with radiogenic argon produced from detrital dispersed illite. Solubility-driven elemental fractionation of Ne/Ar, Kr/Ar, and Xe/Ar confirm extreme boiling in the reservoir. However, a combined analysis of these ratios with 40Ar/36Ar reveals mixing with an air component, possibly introduced by re-injected geothermal fluids.

  2. Quantum dynamics of an excited alkali atom in a noble gas cluster: lithium attached to a helium cluster.

    PubMed

    Pacheco, Alexander B; Thorndyke, Brian; Reyes, Andrés; Micha, David A

    2007-12-28

    An alkali atom-noble gas cluster system is considered as a model for solvation effects in optical spectra, within a quantum-classical description based on the density operator of a many-atom system and its partial Wigner transform. This leads to an eikonal-time-dependent molecular orbital treatment suitable for a time-dependent description of the coupling of light emission and atom dynamics in terms of the time-dependent electric dipole of the whole system. As an application, we consider an optically excited lithium atom as the dopant in a helium cluster at 0.5 K. We describe the motions of the excited Li atom interacting with a cluster of He atoms and calculate the time-dependent electric dipole of the Li-He(99) system during the dynamics. The electronic Hamiltonian is taken as a sum of three-body Li-He diatomic potentials including electronic polarization and repulsion, with l-dependent atomic pseudopotentials for Li and He, while we use a modified pair potential for He-He. The calculations involve the coupling of 12 quantum states with 300 classical degrees of freedom. We present results for the dynamics and spectra of a Li atom interacting with a model cluster surface of He atoms and also interacting with a droplet of He. We have found that the Li atom is attracted or repulsed from the He surface, depending on the orientation of its 2p orbitals. The spectra and dynamics of Li inside and at the surface of a cluster are found to be strongly dependent on its electronic states, its velocity direction, and whether light is present during emission or not.

  3. PARAMETRIC EFFECTS OF ANTI-FOAM COMPOSITION, SIMULANT PROPERTIES AND NOBLE METALS ON THE GAS HOLDUP AND RELEASE OF A NON-NEWTONIAN WASTE SLURRY SIMULANT

    SciTech Connect

    Guerrero, H; Charles Crawford, C; Mark Fowley, M

    2008-08-07

    Gas holdup tests were performed in bench-scale and small-scale mechanically-agitated mixing systems at the Savannah River National Laboratory (SRNL) for a simulant of waste from the Hanford Tank 241-AZ-101. These featured additions of DOW Corning Q2-3183A anti-foam agent. Results indicated that this anti-foam agent (AFA) increased gas holdup in the waste simulant by about a factor of four and, counter-intuitively, that the holdup increased as the non-newtonian simulant shear strength decreased (apparent viscosity decreased). Such results raised the potential of increased flammable gas retention in Hanford Waste Treatment and Immobilization Plant (WTP) vessels mixed by air sparging and pulse-jet mixers (PJMs) during a Design Basis Event (DBE). Additional testing was performed to determine the effects of simulant properties, composition of alternate AFAs, and presence of trace noble metals. Key results are that: (1) Increased gas holdup resulting from addition of Q2-3183A is due to a decrease in surface tension that supports small bubbles which have low rise velocities. (2) Dow Corning 1520-US AFA shows it to be a viable replacement to Dow Corning Q2-3183A AFA. This alternative AFA, however, requires significantly higher dosage for the same anti-foam function. (3) Addition of noble metals to the AZ-101 waste simulant does not produce a catalytic gas retention effect with the AFA.

  4. Fundamental study on gas monitoring in celss

    NASA Astrophysics Data System (ADS)

    Nishi, I.; Tateishi, T.; Tomizawa, G.; Nitta, K.; Oguchi, M.

    A mass spectrometer and computer system was developed for conducting a fundamental study on gas monitoring in CELSS. Respiration and metabolism of the hamster and photosynthesis of the Spirulina were measured in a combination system consisting of a hamster chamber and a Spirulina cultivator. They are connected through a membrane gas exchanger. Some technical problems were examined. In the mass spectrometric gas monitoring, a simultaneous multi-sample measurement was developed by employing a rotating exchange valve. Long term precise measurement was obtained by employing an automatic calibration system. The membrane gas sampling probe proved to be useful for long term measurement. The cultivation rate of the Spirulina was effectively changed by controlling CO2 and light supply. The experimental results are helpful for improving the hamster-spirulina system.

  5. Fundamental study on gas monitoring in CELSS

    NASA Technical Reports Server (NTRS)

    Nishi, I.; Tateishi, T.; Tomizawa, G.; Nitta, K.; Oguchi, M.

    1987-01-01

    A mass spectrometer and computer system was developed for conducting a fundamental study on gas monitoring in a Controlled Ecological Life Support System. Respiration and metabolism of the hamster and photosynthesis of the Spirulina were measured in a combination system consisting of a hamster chamber and a Spirulina cultivator. They are connected through a membrane gas exchanger. Some technical problems were examined. In the mass spectrometric gas monitoring, a simultaneous multisample measurement was developed by employing a rotating exchange valve. Long term precise measurement was obtained by employing an automatic calibration system. The membrane gas sampling probe proved to be useful for long term measurement. The cultivation rate of the Spirulina was effectively changed by controlling CO2 and light supply. The experimental results are helpful for improving the hamster-spirulina system.

  6. Noble gas adsorption in two-dimensional zeolites: a combined experimental and density functional theory study

    NASA Astrophysics Data System (ADS)

    Wang, Mengen; Zhong, Jianqiang; Boscoboinik, Jorge Anibal; Lu, Deyu

    Zeolites are important industrial catalysts with porous three-dimensional structures. The catalytically active sites are located inside the pores, thus rendering them inaccessible for surface science measurements. We synthesized a two-dimensional (2D) zeolite model system, consisting of an (alumino)silicate bilayer weakly bound to a Ru (0001) surface. The 2D zeolite is suitable for surface science studies; it allows a detailed characterization of the atomic structure of the active site and interrogation of the model system during the catalytic reaction. As an initial step, we use Ar adsorption to obtain a better understanding of the atomic structure of the 2D zeolite. In addition, atomic level studies of rare gas adsorption and separation by zeolite are important for its potential application in nuclear waste sequestration. Experimental studies found that Ar atoms can be trapped inside the 2D-zeolite, raising an interesting question on whether Ar atoms are trapped inside the hexagonal prism nano-cages or at the interface between the (alumino)silicate bilayer and Ru(0001), or both. DFT calculations using van der Waals density functionals were carried out to determine the preferred Ar adsorption sites and the corresponding adsorption energies. This research used resources of the Center for Functional Nanomaterials, which is a U.S. DOE Office of Science Facility, at Brookhaven National Laboratory under Contract No. DE-SC0012704.

  7. Magma Dynamics at Mid-Ocean Ridges by Noble Gas Kinetic Fractionation: Assessment of Magmatic Ascent Rates and Mantle Composition

    NASA Astrophysics Data System (ADS)

    Paonita, A.; Martelli, M.

    2007-12-01

    Topical scientific literature on magma degassing at mid-ocean ridges more and more focuses on exsolution processes occurring under conditions that are far from thermodynamic equilibrium between bubbles and silicate melt. Indeed, the dynamics of magma ascent and decompression can be faster than that of CO2 diffusion into bubbles, in which case the diffusivity ratios among volatiles are the main control of the composition of the exsolving gas phase. We have developed a model of bubble growth in silicate melts that calculates the extent of both CO2 supersaturation and kinetic fractionation among noble gases in vesicles in relation to the decompressive rate of basaltic melts. The model predicts that, due to comparable Ar and CO2 diffusivity, magma degassing at low pressure fractionates both He/Ar and He/CO2 ratios by a similar extent, while the slower CO2 diffusion at high pressure causes early kinetic effects on Ar/CO2 ratio and dramatically changes the degassing paths. By using this tool, we have reviewed the global He-Ar-CO2 dataset of fluid inclusions in mid-ocean-ridge glasses. We display that non-equilibrium fractionations among He, Ar and CO2, driven by their different diffusivities in silicate melts, are common in most of the natural conditions of magma decompression and their signature strongly depends on pressure of degassing. The different geochemical signatures among suites of data coming from different ridge segments mainly depend on the depth of the magma chamber where the melt was stored. Moreover, variations inside a single suite emerge due to the interplay between variable ascent speed of magma and cooling rate of the emplaced lava. As a result, two data groups coming from the Pito Seamount suite (Easter Microplate East ridge), showing different degree of CO2 supersaturation and He/Ar fractionation, provide ascent rates which differ by ten folds or even more. The large variations in both the He/CO2 and Ar/CO2 ratios at almost constant He/Ar, displayed

  8. Explaining the Noble Gas Content of the Planets: Theoretical Models for Argon-Trapping by Amorphous Ices in the Solar Nebula

    NASA Astrophysics Data System (ADS)

    Sanders, C. B.; Ciesla, F.

    2014-12-01

    The composition of planets in the modern solar system can be traced to the chemistry and physics of the solar nebula, the diffuse disk of gas and dust that surrounded the young sun immediately after its formation. Materials such as the noble gases were too volatile to be chemically incorporated by planetary embryos. Instead, it is likely that they were trapped physically and transported to the inner planets by migrating comets and planetesimals. One trapping mechanism under consideration is the capture of noble gas atoms in amorphous ices on the surface of cold grains. We created a simple numerical model to explore this mechanism, using argon as a representative volatile gas. We have demonstrated that our model reproduces experimental trapping efficiencies (ratio of the volatile atoms to water molecules in the deposited ice) when we constrain the binding energy of our representative volatile to 3500-5500K and the sticking efficiency of volatile atoms to 0.004x gas phase water pressure. Binding energy and sticking efficiency are poorly understood for most volatile substances, but this study finds that they are among the most critical when predicting the trapping of volatiles in the physical world. Constraining these parameters under nebular conditions will allow us to evaluate how much argon could have been trapped in nebular ices and ultimately assess the role of amorphous ice trapping in the origin of planetary volatiles.

  9. Continuous blood gas monitoring in femoral arteries

    NASA Astrophysics Data System (ADS)

    Schlain, Les A.; Spar, Steven M.; Dellinger, Bart

    1995-05-01

    Continuous intra-arterial blood gas monitoring is a potentially valuable tool in the surgical and intensive care arenas. Patient oxygenation and acid base status can change rapidly and without warning. The ability to monitor pHa, PaCO2 and PaO2 in arterial blood will be a major medical advance for the anesthesiologist and intensivist. Intra-arterial blood gas sensors are typically placed in radial arteries. In certain patient populations accurate monitoring is not possible in radial arteries due to arterial environmental factors such as hypotension, vasoconstriction and atherosclerotic disease. These same factors can make radial cannulation difficult resulting in traumatic catheter insertion, thereby further compromising flow conditions. In situations where radial artery flow is expected to be compromised, selecting a large vessel for sensor placement is desirable. We report an initial feasibility study of our blood gas monitoring system using the femoral artery as the sensing site. Clinical results are presented as well as potential advantages and disadvantages associated with monitoring in the femoral artery.

  10. Mineralogy and noble-gas signatures of the carbonate-rich lithology of the Tagish Lake carbonaceous chondrite: evidence for an accretionary breccia

    NASA Astrophysics Data System (ADS)

    Nakamura, Tomoki; Noguchi, Takaaki; Zolensky, Michael E.; Tanaka, Masahiko

    2003-02-01

    The carbonate-rich lithology of the Tagish Lake carbonaceous chondrite was characterized by noble-gas mass spectrometry, synchrotron X-ray diffraction analysis, and transmission and scanning electron microscopy. Noble-gas analysis was performed on two samples and the results showed that primordial noble gases are abundant and solar noble gases are absent in the samples of carbonate-rich lithology. The concentrations of Ne-A2 and -E in both samples are at the maximum level observed for CI and CM chondrites, suggesting high abundances of presolar diamonds and SiC/graphite, respectively. The cosmic-ray exposure age cannot be determined precisely, because the shielding depth of our Tagish Lake samples is unknown, but the minimum exposure age was determined to be 5.5±0.7 Myr on the basis of cosmogenic 21Ne concentrations and the highest 21Ne production rate. X-ray and electron-microscopic study showed that the carbonate-rich lithology is dominated by loosely packed porous matrix that consists mainly of fine-grained saponite and ferromagenesian carbonate. The matrix contains very few chondrules, but many fine-grained clasts having angular shape with longest dimensions up to 1 mm. The clasts differ from host matrix in both texture and mineralogy. They are massive, compacted material with porosity much lower than matrix and contain abundant magnetite and a coherent intergrowth of serpentine and saponite that is rare in matrix. The presence of texturally and mineralogically distinct clasts indicates that the carbonate-rich lithology is a breccia, but the absence of solar noble gases and impact-induced deformational features in host matrix distinguish it from an asteroid regolith breccia. Our results instead indicate that it is an accretionary breccia formed by simultaneous accretion of diverse objects in a massive dust cloud. The clasts often enclose chondrules and anhydrous silicate fragments such as low-iron-manganese-enriched olivines. This observation and their highly

  11. Prediction of neutral noble gas insertion compounds with heavier pnictides: FNgY (Ng = Kr and Xe; Y = As, Sb and Bi).

    PubMed

    Ghosh, Ayan; Manna, Debashree; Ghanty, Tapan K

    2016-04-28

    A novel class of interesting insertion compounds obtained through the insertion of a noble gas atom into the heavier pnictides have been explored by various ab initio quantum chemical techniques. Recently, the first neutral noble gas insertion compounds, FXeY (Y = P, N), were theoretically predicted to be stable; the triplet state was found to be the most stable state, with a high triplet-singlet energy gap, by our group. In this study, we investigated another noble gas inserted compound, FNgY (Ng = Kr and Xe; Y = As, Sb and Bi), with a triplet ground state. Density functional theory (DFT), second order Møller-Plesset perturbation theory (MP2), coupled-cluster theory (CCSD(T)) and multi-reference configuration interaction (MRCI) based techniques have been utilized to investigate the structures, stabilities, harmonic vibrational frequencies, charge distributions and topological properties of these compounds. These predicted species, FNgY (Ng = Kr and Xe; Y = As, Sb and Bi) are found to be energetically stable with respect to all the probable 2-body and 3-body dissociation pathways, except for the 2-body channel leading to the global minimum products (FY + Ng). Nevertheless, the finite barrier height corresponding to the saddle points of the compounds connected to their respective global minima products indicates that these compounds are kinetically stable. The structural parameters, energetics, and charge distribution results as well as atoms-in-molecules (AIM) analysis suggest that these predicted molecules can be best represented as F(-)[(3)NgY](+). Thus, all the aforementioned computed results clearly indicate that it may be possible to experimentally prepare the most stable triplet state of FNgY molecules under cryogenic conditions through a matrix isolation technique.

  12. Structure and stability of noble gas bound EX3+ compounds (E = C, Ge, Sn, Pb; X = H, F, Cl, Br).

    PubMed

    Pan, Sudip; Moreno, Diego; Ghosh, Sreyan; Chattaraj, Pratim K; Merino, Gabriel

    2016-01-15

    It has been analyzed at the MP2/def2-QZVPPD level whether EX3+ (E = C-Pb; X = H, F-Br) can bind noble gas atoms. Geometrical and electronic structures, dissociation energy values, thermochemical parameters, natural bond order, electron density, and energy decomposition analyses highlight the possibility of such noble gas bound EX3+ compounds. Except He and Ne, the other heavier congeners of this family make quite strong bonds with E. In fact, the dissociations of Ar-Rn bound analogues turn out to be endergonic in nature at 298 K, except in the cases of ArGe Cl3+, Ar/KrGeBr3+, and ArSnBr3+. GeH3+ and EF3+ (E = Ge-Pb) can even bind two Ng atoms with reasonably high dissociation energy. As the pz orbital of the E center in EX3+ plays a crucial role in its binding with the noble gas atoms, the effect of the π back-bonding causing X → E electron transfer ought to be properly understood. Due to the larger back-donation, the Ng binding ability of EX3+ gradually decreases along F to Br. EH2+ and the global minimum HE(+…) H2 (E = Sn, Pb) complexes are also able to bind Ar-Rn atoms quite effectively. The NgE bonds in Ar-Rn bound CH3+, GeH3+, and EF3+ (E = Ge-Pb) and Xe/RnE bonds in NgECl3+ and NgEBr3+ (E = Ge, Sn) are mainly of covalent type.

  13. Calculation of Collisional Cross Sections for the 2P3/2 - 2P1/2 Transition in Alkali-Noble Gas Systems

    DTIC Science & Technology

    2010-03-01

    collisional cross sections given input potentials of a system may provide a partial answer to this question in systems where collisions play a major...CALCULATION OF COLLISIONAL CROSS SECTIONS FOR THE 2P3/2 → 2P1/2 TRANSITION IN ALKALI-NOBLE GAS SYSTEMS THESIS Sam Butler, Captain, USAF AFIT/GAP/ENP...States Air Force, Department of Defense, or the United States Government. AFIT/GAP/ENP/10-M04 CALCULATION OF COLLISIONAL CROSS SECTIONS FOR THE 2P3/2

  14. Dual Species Noble Gas Nuclear Spin Polarizer for a New Search for the Atomic EDM of Xe-129 at FRM-II (Munich Research Reactor)

    NASA Astrophysics Data System (ADS)

    Cohn, Jared; Coulter, Daniel; Frisbie, Dustin; Fromm, Steven; Huneau, Jake; Rabga, Tenzin; Underwood, Walter; Singh, Jaideep; Fierlinger, Peter; Kraegeloh, Eva; Kuchler, Florian; Lins, Tobias; Marino, Mike; Meinel, Jonas; Neissen, Benjamin; Stuiber, Stefan; Fan, Isaac; Kilian, Wolfgang; Knappe-Gruenberg, Silvia; Trahms, Lutz; Chupp, Tim; Degenkolb, Skyler; Sachdeva, Natasha; Gong, Fei; Babcock, Earl; Fierlinger Group Team; Chupp Laboratory Team; Physikalisch-Technische Bundesanstalt Collaboration; Juelich CenterNeutron Science Collaboration

    2015-10-01

    Electric dipole moments are believed to be very sensitive probes of CP violation beyond the Standard Model. A new search for the atomic electric dipole moment of Xe-129 is currently underway at FRM-II in Munich. Our technique takes advantage of a state of the art magnetically shielded room, ultra-sensitive magnetometry using SQUIDs, and control of systematics using a He-3 co-magnetometer. Our goal is an order of magnitude improvement over the previous Xe-129 atomic EDM limit. We will describe the design and construction of a noble gas polarizer using spectrally-narrow diode lasers. Technische Universitaet Muenchen.

  15. Origin and Processes Highlighted By Noble Gases Geochemistry of Submarine Gas Emissions from Seeps at the Aquitaine Shelf (Bay of Biscay):

    NASA Astrophysics Data System (ADS)

    Battani, A.; Ruffine, L.; Donval, J. P.; Bignon, L.; Pujol, M.; Levaché, D.

    2014-12-01

    Noble gases are widely used as tracers to both determine fluid origin and identify transfer processes governing fluid flow in natural systems. This work presents the preliminary results and interpretations from submarine gas samples collected during the GAZCOGNE2 cruise (2013). The seepage activity and the spatial distribution of the widespread emission sites encountered at this area are described by (Dupré et al. 2014). Gas composition shows that methane is the dominant species compared to the C2+. The associated δ13C and δD signatures point to a biogenic origin- through CO2 reduction- of the gas. Helium concentrations are very low, ranging from 0.1 and 2.3 ppm, indicating a low residence time of the fluids in the subsurface. However, the resulting helium isotopic ratios are mostly crustal fingerprinted (around 0.02). The R/Ra values sometimes exhibit higher value of 0.2, indicative either an ASW (air saturated water) value, or the fingerprint of ancient mantle helium, the later in agreement with the geological structural context of the Parentis Basin. Most of the samples exhibit a mixing between ASW and air, probably by excess air addition to the initial ASW concentration. The elemental Ne/Ar ratio is remarkably constant for the totality of the samples, with a value typical of ASW (0.2). This result implies that the migrating gas phase is "stripping" the original water matrix from its noble gas content, as described by Gillfillian et al., 2008. This further indicates that an intermediate reservoir of biogenic gas should be present at depth. The GAZCOGNE study is co-funded by TOTAL and IFREMER as part of the PAMELA (Passive Margin Exploration Laboratories) scientific project. References: Dupré, S., L. Berger, N. Le Bouffant, C. Scalabrin, and J. F. Bourillet (2014), Fluid emissions at the Aquitaine Shelf (Bay of Biscay, France): a biogenic origin or the expression of hydrocarbon leakage?, Continental Shelf Research, doi:10.1016/j.csr.2014.07.004. Gilfillan S

  16. Origin and age of thermal waters in Cieplice Spa, Sudeten, Poland, inferred from isotope, chemical and noble gas data

    NASA Astrophysics Data System (ADS)

    Ciȩżkowski, W.; Gröning, M.; Leśniak, P. M.; Weise, S. M.; Zuber, A.

    1992-12-01

    Isotope and hydrochemical data of the thermal water system in Cieplice Ṡlaskie Zdrój (Spa) indicate the existence of two subsystems that greatly differ in volume and which meet at the fault zones of a granitic horst, where they discharge at an altitude of about 340m. One of the subsystems is very small (about 4 × 10 3 m 3) as indicated by the tritium age of the order of 10 years and a low outflow rate. Its recharge area found from the δ18O and δD values, is about 200m above the springs, most probably on the slopes of the foothills of the Karkonosze Mountains south-southwest of the spa. The large subsystem contains water which is free of tritium and whose 14C content is from 1 to 8 pmc with δ13C = -8.0 to -9.2‰. The isotopic composition of this water reflects either the climatic effect (low-altitude recharge during a cooler pre-Holocene climate) or the altitude effect (recharge in the early Holocene period at about 1000m at the heights of the Karkonosze assuming that the 14C concentration is strongly reduced by exchange with calcite in veins). For the former hypothesis, the recharge area of this water is probably either at the foot of the southeastern slopes of the Kaczawa Mountains or/and at the foot of the Rudawy Janowickie Mountains, to the east of Cieplice. The noble gas temperatures are more consistent with the pre-Holocene recharge. Similarly, the 4He excess and {40Ar}/{36Ar} ratio support the hypothesis of a pre-Holecene age. The constant {3He}/{4He} ratio of 26 × 10 -8 for highly different helium contents indicates crustal origin of helium. For the pre-Holocene age of water its volume is calculated at >- 10 9m 3 (stagnant water in micropores and mobile water in fractures) and the hydraulic conductivity of the host granite massif is estimated at about 7 × 10 -8 ms -1. Two outflows from this subsystem have different and variable fractions of a modern water component (bomb age), most probably originating from the bank infiltration of a nearby stream.

  17. Magmatic gas scrubbing: Implications for volcano monitoring

    USGS Publications Warehouse

    Symonds, R.B.; Gerlach, T.M.; Reed, M.H.

    2001-01-01

    Despite the abundance of SO2(g) in magmatic gases, precursory increases in magmatic SO2(g) are not always observed prior to volcanic eruption, probably because many terrestrial volcanoes contain abundant groundwater or surface water that scrubs magmatic gases until a dry pathway to the atmosphere is established. To better understand scrubbing and its implications for volcano monitoring, we model thermochemically the reaction of magmatic gases with water. First, we inject a 915??C magmatic gas from Merapi volcano into 25??C air-saturated water (ASW) over a wide range of gas/water mass ratios from 0.0002 to 100 and at a total pressure of 0.1 MPa. Then we model closed-system cooling of the magmatic gas, magmatic gas-ASW mixing at 5.0 MPa, runs with varied temperature and composition of the ASW, a case with a wide range of magmatic-gas compositions, and a reaction of a magmatic gas-ASW mixture with rock. The modeling predicts gas and water compositions, and, in one case, alteration assemblages for a wide range of scrubbing conditions; these results can be compared directly with samples from degassing volcanoes. The modeling suggests that CO2(g) is the main species to monitor when scrubbing exists; another candidate is H2S(g), but it can be affected by reactions with aqueous ferrous iron. In contrast, scrubbing by water will prevent significant SO2(g) and most HCl(g) emissions until dry pathways are established, except for moderate HCl(g) degassing from pH 100 t/d (tons per day) of SO2(g) in addition to CO2(g) and H2S(g) should be taken as a criterion of magma intrusion. Finally, the modeling suggests that the interpretation of gas-ratio data requires a case-by-case evaluation since ratio changes can often be produced by several mechanisms; nevertheless, several gas ratios may provide useful indices for monitoring the drying out of gas pathways. Published by Elsevier Science B.V.

  18. Integrated Microfluidic Gas Sensors for Water Monitoring

    NASA Technical Reports Server (NTRS)

    Zhu, L.; Sniadecki, N.; DeVoe, D. L.; Beamesderfer, M.; Semancik, S.; DeVoe, D. L.

    2003-01-01

    A silicon-based microhotplate tin oxide (SnO2) gas sensor integrated into a polymer-based microfluidic system for monitoring of contaminants in water systems is presented. This device is designed to sample a water source, control the sample vapor pressure within a microchannel using integrated resistive heaters, and direct the vapor past the integrated gas sensor for analysis. The sensor platform takes advantage of novel technology allowing direct integration of discrete silicon chips into a larger polymer microfluidic substrate, including seamless fluidic and electrical interconnects between the substrate and silicon chip.

  19. Using noble gas tracers to estimate residual CO2 saturation in the field: results from the CO2CRC Otway residual saturation and dissolution test

    NASA Astrophysics Data System (ADS)

    LaForce, T.; Ennis-King, J.; Paterson, L.

    2013-12-01

    Residual CO2 saturation is a critically important parameter in CO2 storage as it can have a large impact on the available secure storage volume and post-injection CO2 migration. A suite of single-well tests to measure residual trapping was conducted at the Otway test site in Victoria, Australia during 2011. One or more of these tests could be conducted at a prospective CO2 storage site before large-scale injection. The test involved injection of 150 tonnes of pure carbon dioxide followed by 454 tonnes of CO2-saturated formation water to drive the carbon dioxide to residual saturation. This work presents a brief overview of the full test sequence, followed by the analysis and interpretation of the tests using noble gas tracers. Prior to CO2 injection krypton (Kr) and xenon (Xe) tracers were injected and back-produced to characterise the aquifer under single-phase conditions. After CO2 had been driven to residual the two tracers were injected and produced again. The noble gases act as non-partitioning aqueous-phase tracers in the undisturbed aquifer and as partitioning tracers in the presence of residual CO2. To estimate residual saturation from the tracer test data a one-dimensional radial model of the near-well region is used. In the model there are only two independent parameters: the apparent dispersivity of each tracer and the residual CO2 saturation. Independent analysis of the Kr and Xe tracer production curves gives the same estimate of residual saturation to within the accuracy of the method. Furthermore the residual from the noble gas tracer tests is consistent with other measurements in the sequence of tests.

  20. Monitoring gas reservoirs by seismic interferometry

    NASA Astrophysics Data System (ADS)

    Grigoli, Francesco; Cesca, Simone; Sens-Schoenfelder, Christoph; Priolo, Enrico

    2014-05-01

    Ambient seismic noise can be used to image spatial anomalies in the subsurface, without the need of recordings from seismic sources, such as earthquakes or explosions. Furthermore, the temporal variation of ambient seismic noise's can be used to infer temporal changes of the seismic velocities in the investigated medium. Such temporal variations can reflect changes of several physical properties/conditions in the medium. For example, they may be consequence of stress changes, variation of hydrogeological parameters, pore pressure and saturation changes due to fluid injection or extraction. Passive image interferometry allows to continuously monitor small temporal changes of seismic velocities in the subsurface, making it a suitable tool to monitor time-variant systems such as oil and gas reservoirs or volcanic environments. The technique does not require recordings from seismic sources in the classical sense, but is based on the processing of noise records. Moreover, it requires only data from one or two seismic stations, their locations constraining the sampled target area. Here we apply passive image interferometry to monitor a gas storage reservoir in northern Italy. The Collalto field (Northern Italy) is a depleted gas reservoir located at 1500 m depth, now used as a gas storage facility. The reservoir experience a significant temporal variation in the amount of stored gas: the injection phases mainly occur in the summer, while the extraction take place mostly in winter. In order to monitor induced seismicity related to gas storage operations, a seismic network (the Collalto Seismic Network) has been deployed in 2011. The Collalto Seismic Network is composed by 10 broadband stations, deployed within an area of about 20 km x 20 km, and provides high-quality continuous data since January 1st, 2012. In this work we present preliminary results from ambient noise interferometry using a two-months sample of continuous seismic data, i.e. from October 1st, 2012, to the

  1. Using dissolved noble gas and isotopic tracers to evaluate the vulnerability of groundwater resources in a small, high elevation catchment to predicted climate changes

    SciTech Connect

    Singleton, M J; Moran, J E

    2009-10-02

    We use noble gas concentrations and multiple isotopic tracers in groundwater and stream water in a small high elevation catchment to provide a snapshot of temperature, altitude, and physical processes at the time of recharge; and to determine subsurface residence times of different groundwater components. They identify three sources that contribute to groundwater flow: (1) seasonal groundwater recharge with short travel times, (2) water from bedrock aquifers that have elevated radiogenic {sup 4}He, and (3) upwelling of deep fluids that have 'mantle' helium and hydrothermal carbon isotope signatures. Although a bimodal distribution in apparent groundwater age indicates that groundwater storage times range from less than a year to several decades, water that recharges seasonally is the largest likely contributor to stream baseflow. Under climate change scnearios with earlier snowmelt, the groundwater that moves through the alluvial aquifer seasonally will be depleted earlier, providing less baseflow and possible extreme low flows in the creek during summer and fall. Dissolved noble gas measurements indciate recharge temperatures are 5 to 11 degrees higher than would be expected for direct influx of snowmelt, and that excess air concentrations are lower than would be expected for recharge through bedrock fractures. Instead, recharge likely occurs over diffuse vegetated areas, as indicated by {delta}{sup 13}C-DIC values that are consistent with incorporation of CO{sub 2} from soil respiration. Recharge temperatures are close to or slightly higher than mean annual air temperature, and are consistent with recharge during May and June, when snowpack melting occurs.

  2. Periodic input of primitive magmas in a complex plumbing system revealed by noble gas geochemistry: the case of Mt Etna (Italy)

    NASA Astrophysics Data System (ADS)

    Paonita, Antonio; Caracausi, Antonio; Martelli, Mauro; Rizzo, Andrea

    2015-04-01

    A long-term series of noble gas compositions (He and Ar isotope abundances plus elemental Ne) coming from geochemical monitoring of five peripheral gas emissions at the base of Mt Etna, integrated by some fumaroles located in the rim of the summit crater, have allowed to put constraints on the magmatic system feeding the volcano. The peripheral gas emissions seem to be released by magmatic degassing occurring at depths of 200-400 MPa, while the crater fumaroles receive contributes coming from magmas residing at shallower levels (up to 130 MPa), which mix to the fluids from the deep levels. These estimations are in good agreement with the depth of the two main magma ponding zones (i.e., 5-12 km and 2-3 km b.s.l.) inferred by petrological and geophysical studies. The long-term monitoring of 3He/4He ratios from both peripheral and crater gases has allowed us to recognize phases of increase of the isotope ratios, occurred at all the sampled emissions some months before the onset of eruptive activities. This behaviour has been systematic for all the main eruptive phases occurred at Mt Etna since 2001 (i.e., 2001, 2002-2003, 2006, 2008-2009, 2011-2012, 2013, and 2014, except for the 2004-2005 eruption), making this parameter a very powerful tool in evaluating the activity level of the volcano and in eruption forecast. A detailed investigation of the 3He/4He time series displays that there is no defined time gap between the isotope ratio increase and the onset of the eruptive activity, this interval ranging from one to several months. After examination of shape and duration of the isotope increases versus main features of the eruptive events (e.g. duration, amount of erupted material, eruption rate), no systematic relationships emerge. It seems only that the rate of 3He/4He increase was anomalously high (by almost 10 times) during the only two eccentric eruptions since 2001 (i.e., 2001 and 2002-2003). The differences among He isotopic composition between the peripheral

  3. The evolution of Devonian hydrocarbon gases in shallow aquifers of the northern Appalachian Basin: Insights from integrating noble gas and hydrocarbon geochemistry

    NASA Astrophysics Data System (ADS)

    Darrah, Thomas H.; Jackson, Robert B.; Vengosh, Avner; Warner, Nathaniel R.; Whyte, Colin J.; Walsh, Talor B.; Kondash, Andrew J.; Poreda, Robert J.

    2015-12-01

    The last decade has seen a dramatic increase in domestic energy production from unconventional reservoirs. This energy boom has generated marked economic benefits, but simultaneously evoked significant concerns regarding the potential for drinking-water contamination in shallow aquifers. Presently, efforts to evaluate the environmental impacts of shale gas development in the northern Appalachian Basin (NAB), located in the northeastern US, are limited by: (1) a lack of comprehensive "pre-drill" data for groundwater composition (water and gas); (2) uncertainty in the hydrogeological factors that control the occurrence of naturally present CH4 and brines in shallow Upper Devonian (UD) aquifers; and (3) limited geochemical techniques to quantify the sources and migration of crustal fluids (specifically methane) at various time scales. To address these questions, we analyzed the noble gas, dissolved ion, and hydrocarbon gas geochemistry of 72 drinking-water wells and one natural methane seep all located ≫1 km from shale gas drill sites in the NAB. In the present study, we consciously avoided groundwater wells from areas near active or recent drilling to ensure shale gas development would not bias the results. We also intentionally targeted areas with naturally occurring CH4 to characterize the geochemical signature and geological context of gas-phase hydrocarbons in shallow aquifers of the NAB. Our data display a positive relationship between elevated [CH4], [C2H6], [Cl], and [Ba] that co-occur with high [4He]. Although four groundwater samples show mantle contributions ranging from 1.2% to 11.6%, the majority of samples have [He] ranging from solubility levels (∼45 × 10-6 cm3 STP/L) with below-detectable [CH4] and minor amounts of tritiogenic 3He in low [Cl] and [Ba] waters, up to high [4He] = 0.4 cm3 STP/L with a purely crustal helium isotopic end-member (3He/4He = ∼0.02 times the atmospheric ratio (R/Ra)) in samples with CH4 near saturation for shallow

  4. Apparatus and method for monitoring of gas having stable isotopes

    DOEpatents

    Clegg, Samuel M; Fessenden-Rahn, Julianna E

    2013-03-05

    Gas having stable isotopes is monitored continuously by using a system that sends a modulated laser beam to the gas and collects and transmits the light not absorbed by the gas to a detector. Gas from geological storage, or from the atmosphere can be monitored continuously without collecting samples and transporting them to a lab.

  5. Characterization of gas chemistry and noble-gas isotope ratios of inclusion fluids in magmatic-hydrothermal and magmatic-steam alunite

    USGS Publications Warehouse

    Landis, G.P.; Rye, R.O.

    2005-01-01

    Chemical and isotope data were obtained for the active gas and noble gas of inclusion fluids in coarse-grained samples of magmatic-hydrothermal and magmatic-steam alunite from well-studied deposits (Marysvale, Utah; Tambo, Chile; Tapajo??s, Brazil; Cactus, California; Pierina, Peru), most of which are discussed in this Volume. Primary fluid inclusions in the alunite typically are less than 0.2 ??m but range up to several micrometers. Analyses of the active-gas composition of these alunite-hosted inclusion fluids released in vacuo by both crushing and heating indicate consistent differences in the compositions of magmatic-hydrothermal and magmatic-steam fluids. The compositions of fluids released by crushing were influenced by contributions from significant populations of secondary inclusions that trapped largely postdepositional hydrothermal fluids. Thermally released fluids gave the best representation of the fluids that formed primary alunite. The data are consistent with current models for the evolution of magmatic-hydrothermal and magmatic-steam fluids. Magmatic-steam fluids are vapor-dominant, average about 49 mol% H2O, and contain N2, H2, CH4, CO, Ar, He, HF, and HCl, with SO2 the dominant sulfur gas (average SO2/ H2S=202). In contrast, magmatic-hydrothermal fluids are liquid-dominant, average about 88 mol% H2O, and N2, H2, CO2, and HF, with H2S about as abundant as SO2 (average SO2/H2 S=0.7). The low SO2/H2S and N2/Ar ratios, and the near-absence of He in magmatic-hydrothermal fluids, are consistent with their derivation from degassed condensed magmatic fluids whose evolution from reduced-to-oxidized aqueous sulfur species was governed first by rock and then by fluid buffers. The high SO2/H2S and N2/Ar with significant concentrations of He in magmatic-steam fluids are consistent with derivation directly from a magma. None of the data supports the entrainment of atmospheric gases or mixing of air-saturated gases in meteoric water in either magmatic

  6. Using Noble Gas Tracers to Estimate CO2 Saturation in the Field: Results from the 2014 CO2CRC Otway Repeat Residual Saturation Test

    NASA Astrophysics Data System (ADS)

    LaForce, T.; Ennis-King, J.; Boreham, C.; Serno, S.; Cook, P. J.; Freifeld, B. M.; Gilfillan, S.; Jarrett, A.; Johnson, G.; Myers, M.; Paterson, L.

    2015-12-01

    Residual trapping efficiency is a critical parameter in the design of secure subsurface CO2 storage. Residual saturation is also a key parameter in oil and gas production when a field is under consideration for enhanced oil recovery. Tracers are an important tool that can be used to estimate saturation in field tests. A series of measurements of CO2 saturation in an aquifer were undertaken as part of the Otway stage 2B extension field project in Dec. 2014. These tests were a repeat of similar tests in the same well in 2011 with improvements to the data collection and handling method. Two single-well tracer tests using noble gas tracers were conducted. In the first test krypton and xenon are injected into the water-saturated formation to establish dispersivity of the tracers in single-phase flow. Near-residual CO2 saturation is then established near the well. In the second test krypton and xenon are injected with CO2-saturated water to measure the final CO2 saturation. The recovery rate of the tracers is similar to predicted rates using recently published partitioning coefficients. Due to technical difficulties, there was mobile CO2 in the reservoir throughout the second tracer test in 2014. As a consequence, it is necessary to use a variation of the previous simulation procedure to interpret the second tracer test. One-dimensional, radial simulations are used to estimate average saturation of CO2 near the well. Estimates of final average CO2 saturation are computed using two relative permeability models, thermal and isothermal simulations, and three sets of coefficients for the partitioning of the tracers between phases. Four of the partitioning coefficients used were not previously available in the literature. The noble gas tracer field test and analysis of the 2011 and 2014 data both give an average CO2 saturation that is consistent with other field measurements. This study has demonstrated the repeatability of the methodology for noble gas tracer tests in the

  7. Air Monitoring for Hazardous Gas Detection

    NASA Technical Reports Server (NTRS)

    Arkin, C. Richard; Griffin, Timothy P.; Adams, Frederick W.; Naylor, Guy; Haskell, William; Floyd, David; Curley, Charles; Follistein, Duke W.

    2004-01-01

    The Hazardous Gas Detection Lab (HGDL) at Kennedy Space Center is involved in the design and development of instrumentation that can detect and quantify various hazardous gases. Traditionally these systems are designed for leak detection of the cryogenic gases used for the propulsion of the Shuttle and other vehicles. Mass spectrometers are the basis of these systems, which provide excellent quantitation, sensitivity, selectivity, response times and detection limits. A Table lists common gases monitored for aerospace applications. The first five gases, hydrogen, helium, nitrogen, oxygen, and argon are historically the focus of the HGDL.

  8. Inherently safe passive gas monitoring system

    SciTech Connect

    Cordaro, Joseph V.; Bellamy, John Stephen; Shuler, James M.; Shull, Davis J.; Leduc, Daniel R.

    2016-09-06

    Generally, the present disclosure is directed to gas monitoring systems that use inductive power transfer to safely power an electrically passive device included within a nuclear material storage container. In particular, the electrically passive device can include an inductive power receiver for receiving inductive power transfer through a wall of the nuclear material storage container. The power received by the inductive power receiver can be used to power one or more sensors included in the device. Thus, the device is not required to include active power generation components such as, for example, a battery, that increase the risk of a spark igniting flammable gases within the container.

  9. Absorption spectroscopy of xenon and ethylene-noble gas mixtures at high pressure: towards Bose-Einstein condensation of vacuum ultraviolet photons

    NASA Astrophysics Data System (ADS)

    Wahl, Christian; Brausemann, Rudolf; Schmitt, Julian; Vewinger, Frank; Christopoulos, Stavros; Weitz, Martin

    2016-12-01

    Bose-Einstein condensation is a phenomenon well known for material particles as cold atomic gases, and this concept has in recent years been extended to photons confined in microscopic optical cavities. Essential for the operation of such a photon condensate is a thermalization mechanism that conserves the average particle number, as in the visible spectral regime can be realized by subsequent absorption re-emission processes in dye molecules. Here we report on the status of an experimental effort aiming at the extension of the concept of Bose-Einstein condensation of photons towards the vacuum ultraviolet spectral regime, with gases at high-pressure conditions serving as a thermalization medium for the photon gas. We have recorded absorption spectra of xenon gas at up to 30 bar gas pressure of the 5p^6-5p^56s transition with a wavelength close to 147 nm. Moreover, spectra of ethylene noble gas mixtures between 158 and 180 nm wavelength are reported.

  10. Online drilling mud gas monitoring and sampling during drilling the Scandinavian Caledonides (COSC)

    NASA Astrophysics Data System (ADS)

    Wiersberg, Thomas; Almqvist, Bjarne; Klonowska, Iwona; Lorenz, Henning

    2015-04-01

    The COSC project (Collisional Orogeny in the Scandinavian Caledonides) drilled a 2496 m deep hole in Åre (Sweden) to deliver insights into mid-Palaeozoic mountain building processes from continent-continent collision, to improve our understanding of the hydrogeological-hydrochemical state and geothermal gradient of the mountain belt and to study the deep biosphere in the metamorphic rocks and crystalline basement. COSC was the first slimhole drilling project where online gasmonitoring of drilling mud was conducted during continuous wireline coring. Gas was continuously extracted at the surface from the circulating drilling mud with a gas-water separator, pumped in a nearby laboratory container and analysed in real-time with a quadrupole mass spectrometer for argon, methane, helium, carbon dioxide, nitrogen, oxygen, hydrogen, and krypton. Gas samples were taken from the gas line for laboratory studies on chemical composition of hydrocarbons, noble gas isotopes and stable isotopes. Every drill core created a gas peak identified in the drilling mud ~20-30 min after core arrival at the surface. With known core depth and surface arrival time, these gas peaks could be attributed to depth. As a result, nearly complete gas depth profiles at three meter intervals were obtained from 662 m (installation of the gas-water separator) to 2490 m depth. Maximum concentrations of non-atmospheric gasses in drilling mud were ~200 ppmv helium, ~300 ppmv methane and ~2 vol-% hydrogen. Helium peaks between ~900 m and 1000 m and correlates with enhanced concentrations of methane. Methane and hydrogen exhibit maximum concentrations below 1630 m depth where helium concentrations remain low. Integration of the drilling mud gas monitoring dataset with data from geophysical downhole logging and core analysis is ongoing to help clarifying provenances and origin of gasses.

  11. Photosensitive dopants for liquid noble gases

    DOEpatents

    Anderson, David F.

    1988-01-01

    In an ionization type detector for high energy radiation wherein the energy of incident radiation is absorbed through the ionization of a liquid noble gas and resulting free charge is collected to form a signal indicative of the energy of the incident radiation, an improvement comprising doping the liquid noble gas with photosensitive molecules to convert scintillation light due to recombination of ions, to additional free charge.

  12. Oxygen sensor for monitoring gas mixtures containing hydrocarbons

    DOEpatents

    Ruka, R.J.; Basel, R.A.

    1996-03-12

    A gas sensor measures O{sub 2} content of a reformable monitored gas containing hydrocarbons, H{sub 2}O and/or CO{sub 2}, preferably in association with an electrochemical power generation system. The gas sensor has a housing communicating with the monitored gas environment and carries the monitored gas through an integral catalytic hydrocarbon reforming chamber containing a reforming catalyst, and over a solid electrolyte electrochemical cell used for sensing purposes. The electrochemical cell includes a solid electrolyte between a sensor electrode that is exposed to the monitored gas, and a reference electrode that is isolated in the housing from the monitored gas and is exposed to a reference gas environment. A heating element is also provided in heat transfer communication with the gas sensor. A circuit that can include controls operable to adjust operations via valves or the like is connected between the sensor electrode and the reference electrode to process the electrical signal developed by the electrochemical cell. The electrical signal varies as a measure of the equilibrium oxygen partial pressure of the monitored gas. Signal noise is effectively reduced by maintaining a constant temperature in the area of the electrochemical cell and providing a monitored gas at chemical equilibria when contacting the electrochemical cell. The output gas from the electrochemical cell of the sensor is fed back into the conduits of the power generating system. 4 figs.

  13. Oxygen sensor for monitoring gas mixtures containing hydrocarbons

    DOEpatents

    Ruka, Roswell J.; Basel, Richard A.

    1996-01-01

    A gas sensor measures O.sub.2 content of a reformable monitored gas containing hydrocarbons H.sub.2 O and/or CO.sub.2, preferably in association with an electrochemical power generation system. The gas sensor has a housing communicating with the monitored gas environment and carries the monitored gas through an integral catalytic hydrocarbon reforming chamber containing a reforming catalyst, and over a solid electrolyte electrochemical cell used for sensing purposes. The electrochemical cell includes a solid electrolyte between a sensor electrode that is exposed to the monitored gas, and a reference electrode that is isolated in the housing from the monitored gas and is exposed to a reference gas environment. A heating element is also provided in heat transfer communication with the gas sensor. A circuit that can include controls operable to adjust operations via valves or the like is connected between the sensor electrode and the reference electrode to process the electrical signal developed by the electrochemical cell. The electrical signal varies as a measure of the equilibrium oxygen partial pressure of the monitored gas. Signal noise is effectively reduced by maintaining a constant temperature in the area of the electrochemical cell and providing a monitored gas at chemical equilibria when contacting the electrochemical cell. The output gas from the electrochemical cell of the sensor is fed back into the conduits of the power generating system.

  14. Portable spectrometer monitors inert gas shield in welding process

    NASA Technical Reports Server (NTRS)

    Grove, E. L.

    1967-01-01

    Portable spectrometer using photosensitive readouts, monitors the amount of oxygen and hydrogen in the inert gas shield of a tungsten-inert gas welding process. A fiber optic bundle transmits the light from the welding arc to the spectrometer.

  15. Air Monitoring for Hazardous Gas Detection

    NASA Technical Reports Server (NTRS)

    Arkin, C. Richard; Naylor, Guy; Haskell, William; Floyd, David; Curley, Charles; Griffin, Timothy P.; Adams, Frederick; Follistein, Duke

    2003-01-01

    The Hazardous Gas Detection Lab is involved in the design and development of instrumentation that can detect and quantify various hazardous gases. Traditionally these systems are designed for leak detection of the cryogenic gases used for the propulsion of the Shuttle and other vehicles. Mass spectrometers are the basis of these systems, which provide excellent quantitation, sensitivity, selectivity, response and limits of detection. Unfortunately, these systems are large, heavy and expensive. This feature limits the ability to perform gas analysis in certain applications. Smaller and lighter mass spectrometer systems could be used in many more applications primarily due to the portability of the system. Such applications would include air analysis in confined spaces, in-situ environmental analysis and emergency response. In general, system cost is lowered as size is reduced. With a low cost air analysis system, several systems could be utilized for monitoring large areas. These networked systems could be deployed at job-sites for worker safety, throughout a community for pollution warnings, or dispersed in a battlefield for early warning of chemical or biological threats. Presented will be information on the first prototype of this type of system. Included will be field trial data, with this prototype performing air analysis autonomously from an aircraft.

  16. Ageing studies of TPB in noble gas detectors for dark matter and neutrinoless ββ decay searches.

    PubMed

    Yahlali, N; Garcia, J M; Díaz, J; Soriano, A; Fernandes, L M P

    2017-02-05

    Noble gases (Xe, Ar, Kr) are very attractive as detector media in Dark Matter search and neutrinoless double-beta decay experiments. However, the detection of their scintillation light (in the VUV spectral region) requires shifting the VUV light to visible light, where standard photosensors are more efficient. Tetraphenyl butadiene (TPB) is widely used as wavelength shifter, absorbing the VUV light and re-emitting in the blue region (~430nm). TPB is an organic molecule that may degrade due to exposure to environmental agents and also to ultraviolet light. In this work, we present TPB ageing studies due to exposure to VUV light, aiming at quantifying the reduction of the absolute fluorescence yield of TPB coatings of several thicknesses (130nm, 260nm, 390nm, 1600nm), exposed to various doses of VUV light at 170nm (similar to the Xe scintillation). In our setup, the VUV light is produced from a vacuum monochromator coupled to a deuterium lamp. The VUV exposure in our setup is compared to the exposure obtained in the electroluminescent gaseous Xe TPC of the NEXT-100 experiment for neutrinoless double-beta decay search.

  17. Ageing studies of TPB in noble gas detectors for dark matter and neutrinoless ββ decay searches

    NASA Astrophysics Data System (ADS)

    Yahlali, N.; Garcia, J. M.; Díaz, J.; Soriano, A.; Fernandes, L. M. P.

    2017-02-01

    Noble gases (Xe, Ar, Kr) are very attractive as detector media in Dark Matter search and neutrinoless double-beta decay experiments. However, the detection of their scintillation light (in the VUV spectral region) requires shifting the VUV light to visible light, where standard photosensors are more efficient. Tetraphenyl butadiene (TPB) is widely used as wavelength shifter, absorbing the VUV light and re-emitting in the blue region ( 430 nm). TPB is an organic molecule that may degrade due to exposure to environmental agents and also to ultraviolet light. In this work, we present TPB ageing studies due to exposure to VUV light, aiming at quantifying the reduction of the absolute fluorescence yield of TPB coatings of several thicknesses (130 nm, 260 nm, 390 nm, 1600 nm), exposed to various doses of VUV light at 170 nm (similar to the Xe scintillation). In our setup, the VUV light is produced from a vacuum monochromator coupled to a deuterium lamp. The VUV exposure in our setup is compared to the exposure obtained in the electroluminescent gaseous Xe TPC of the NEXT-100 experiment for neutrinoless double-beta decay search.

  18. 77 FR 38790 - Noble Americas Gas & Power Corp., LNG Development Company, LLC, LNG Development Company, LLC (d/b...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-29

    ... Americas Gas & Power Corp., LNG Development Company, LLC, LNG Development Company, LLC (d/b/a Oregon LNG... Corp. authority to import/ export natural gas from/ to Canada/Mexico, and to import LNG from various international sources by vessel. 3099 05/31/12 12-43-NG LNG Development Order granting blanket Company,...

  19. Basin scale natural gas source, migration and trapping traced by noble gases and major elements: the Pakistan Indus basin

    NASA Astrophysics Data System (ADS)

    Battani, Anne; Sarda, Philippe; Prinzhofer, Alain

    2000-08-01

    He, Ne and Ar concentrations, He and Ar isotopic ratios, carbon isotopic ratios and chemical compositions of hydrocarbon gases were measured in natural gas samples from gas-producing wells in the Indus basin, Pakistan, where no oil has ever been found. 3He/ 4He ratios are in the range 0.01-0.06 Ra (Ra is the atmospheric value of 1.38×10 -6) indicating the absence of mantle-derived helium despite the Trias extension. 40Ar/ 36Ar ratios range from 296 to 800, consistent with variable additions of radiogenic argon to atmospheric, groundwater-derived argon. Rare gas concentrations show large variations, from 6×10 -5 to 1×10 -3 mol/mol for 4He and from 3×10 -7 to 3×10 -5 mol/mol for 36Ar. In general, 36Ar concentrations are high compared to literature data for natural gas. CO 2 and N 2 concentrations are variable, ranging up to 70 and 20%, respectively. Mantle-derived He is not observed, therefore CO 2 and N 2 are not mantle-derived either. Hydrocarbon gas maturity is high, but accumulation efficiency is small, suggesting that early-produced hydrocarbons, including oil, were lost as well as mantle helium. This is consistent with the generally late, Pliocene, trap formation, and explains the high N 2 concentrations, since N 2 is the final species generated at the end of organic matter maturation. Based on δ 13C data, CO 2 originates from carbonate decomposition. Very elevated 20Ne/ 36Ar ratios are found, reaching a maximum of 1.3 (compared to 0.1-0.2 for air-saturated water and 0.5 for air), and these high values are related to the lowest rare gas concentrations. We suggest that this highly fractionated signature is the trace of the past presence of oil in the basin and appeared in groundwater. We propose a model where oil-water contact is followed by gas-water contact, both with Rayleigh distillation for rare gas abundance ratios, thereby generating the fractionated 20Ne/ 36Ar signature in groundwater first and transferring it to gas later. Assuming the gas

  20. Transport of methane and noble gases during gas push-pull tests in variably saturated porous media.

    PubMed

    Gómez, Katherine; Gonzalez-Gil, Graciela; Schroth, Martin H; Zeyer, Josef

    2008-04-01

    The gas push-pull test (GPPT) is a single-well gas-tracer method to quantify in situ rates of CH4 oxidation in soils. To improve the design and interpretation of GPPT field experiments, gas component transport during GPPTs was examined in abiotic porous media over a range of water saturations (0.0 < or = Sw < or = 0.61). A series of GPPTs using He, Ne, and Ar as tracers for CH4 were performed at two injection/extraction gas flow rates (approximately 200 and approximately 700 mL min(-1)) in a laboratory tank. Extraction phase breakthrough curves and mass recovery curves of the gaseous components became more similar at higher Sw as water in the pore space restricted diffusive gas-phase transport. Diffusional fractionation of the stable carbon isotopes of CH4 during the extraction period of GPPTs also decreased with increasing Sw (particularly when Sw > 0.42). Gas-component transport during GPPTs was numerically simulated using estimated hydraulic parameters for the porous media and no fitting of data for the GPPTs. Numerical simulations accurately predicted the relative decline of the gaseous components in the breakthrough curves, but slightly overestimated recoveries at low Sw (< or = 0.35) and underestimated recoveries at high Sw (> or = 0.49). Comparison of numerical simulations considering and not considering air-water partitioning indicated that removal of gaseous components through dissolution in pore water was not significant during GPPTs, even at Sw = 0.61. These data indicate that Ar is a good tracer for CH4 physical transport over the full range of Sw studied, whereas, at Sw > 0.61, any of the tracers could be used. Greater mass recovery at higher Sw raises the possibility to reduce gas flow rates, thereby extending GPPT times in environments such as tundra soils where low activity due to low temperatures may require longer test times to establish a quantifiable difference between reactant and tracer breakthrough curves.

  1. The Effects of Added Hydrogen on Noble Gas Discharges Used as Ambient Desorption/Ionization Sources for Mass Spectrometry.

    PubMed

    Ellis, Wade C; Lewis, Charlotte R; Openshaw, Anna P; Farnsworth, Paul B

    2016-09-01

    We demonstrate the effectiveness of using hydrogen-doped argon as the support gas for the dielectric barrier discharge (DBD) ambient desorption/ionization (ADI) source in mass spectrometry. Also, we explore the chemistry responsible for the signal enhancement observed when using both hydrogen-doped argon and hydrogen-doped helium. The hydrogen-doped argon was tested for five analytes representing different classes of molecules. Addition of hydrogen to the argon plasma gas enhanced signals for gas-phase analytes and for analytes coated onto glass slides in positive and negative ion mode. The enhancements ranged from factors of 4 to 5 for gas-phase analytes and factors of 2 to 40 for coated slides. There was no significant increase in the background. The limit of detection for caffeine was lowered by a factor of 79 using H2/Ar and 2 using H2/He. Results are shown that help explain the fundamental differences between the pure-gas discharges and those that are hydrogen-doped for both argon and helium. Experiments with different discharge geometries and grounding schemes indicate that observed signal enhancements are strongly dependent on discharge configuration. Graphical Abstract ᅟ.

  2. The Effects of Added Hydrogen on Noble Gas Discharges Used as Ambient Desorption/Ionization Sources for Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Ellis, Wade C.; Lewis, Charlotte R.; Openshaw, Anna P.; Farnsworth, Paul B.

    2016-09-01

    We demonstrate the effectiveness of using hydrogen-doped argon as the support gas for the dielectric barrier discharge (DBD) ambient desorption/ionization (ADI) source in mass spectrometry. Also, we explore the chemistry responsible for the signal enhancement observed when using both hydrogen-doped argon and hydrogen-doped helium. The hydrogen-doped argon was tested for five analytes representing different classes of molecules. Addition of hydrogen to the argon plasma gas enhanced signals for gas-phase analytes and for analytes coated onto glass slides in positive and negative ion mode. The enhancements ranged from factors of 4 to 5 for gas-phase analytes and factors of 2 to 40 for coated slides. There was no significant increase in the background. The limit of detection for caffeine was lowered by a factor of 79 using H2/Ar and 2 using H2/He. Results are shown that help explain the fundamental differences between the pure-gas discharges and those that are hydrogen-doped for both argon and helium. Experiments with different discharge geometries and grounding schemes indicate that observed signal enhancements are strongly dependent on discharge configuration.

  3. Release of radiogenic noble gases as a new signal of rock deformation

    NASA Astrophysics Data System (ADS)

    Bauer, Stephen J.; Gardner, W. Payton; Lee, Hyunwoo

    2016-10-01

    In this study we investigate the release of radiogenic noble gas isotopes during mechanical deformation. We developed an analytical system for dynamic mass spectrometry of noble gas composition and helium release rate of gas produced during mechanical deformation of rocks. Our results indicate that rocks release accumulated radiogenic helium and argon from mineral grains as they undergo deformation. We found that the release of accumulated 4He and 40Ar from rocks follows a reproducible pattern and can provide insight into the deformation process. Increased gas release can be observed before dilation, and macroscopic failure is observed during high-pressure triaxial rock deformation experiments. Accumulated radiogenic noble gases can be released due to fracturing of mineral grains during small-scale strain in Earth materials. Helium and argon are highly mobile, conservative species and could be used to provide information on changes in the state of stress and strain in Earth materials, and as an early warning signal of macroscopic failure. These results pave the way for the use of noble gases to trace and monitor rock deformation for earthquake prediction and a variety of other subsurface engineering projects.

  4. Band-structure calculations of noble-gas and alkali halide solids using accurate Kohn-Sham potentials with self-interaction correction

    SciTech Connect

    Li, Y.; Krieger, J.B. ); Norman, M.R. ); Iafrate, G.J. )

    1991-11-15

    The optimized-effective-potential (OEP) method and a method developed recently by Krieger, Li, and Iafrate (KLI) are applied to the band-structure calculations of noble-gas and alkali halide solids employing the self-interaction-corrected (SIC) local-spin-density (LSD) approximation for the exchange-correlation energy functional. The resulting band gaps from both calculations are found to be in fair agreement with the experimental values. The discrepancies are typically within a few percent with results that are nearly the same as those of previously published orbital-dependent multipotential SIC calculations, whereas the LSD results underestimate the band gaps by as much as 40%. As in the LSD---and it is believed to be the case even for the exact Kohn-Sham potential---both the OEP and KLI predict valence-band widths which are narrower than those of experiment. In all cases, the KLI method yields essentially the same results as the OEP.

  5. A coupled-cluster study on the noble gas binding ability of metal cyanides versus metal halides (metal = Cu, Ag, Au).

    PubMed

    Pan, Sudip; Gupta, Ashutosh; Saha, Ranajit; Merino, Gabriel; Chattaraj, Pratim K

    2015-11-05

    A coupled-cluster study is carried out to investigate the efficacy of metal(I) cyanide (MCN; M = Cu, Ag, Au) compounds to bind with noble gas (Ng) atoms. The M-Ng bond dissociation energy, enthalpy change, and Gibbs free energy change for the dissociation processes producing Ng and MCN are computed to assess the stability of NgMCN compounds. The Ng binding ability of MCN is then compared with the experimentally detected NgMX (X = F, Cl, Br) compounds. While CuCN and AgCN have larger Ng binding ability than those of MCl and MBr (M = Cu, Ag), AuCN shows larger efficacy toward bond formation with Ng than that of AuBr. Natural bond orbital analysis, energy decomposition analysis in conjunction with the natural orbital for chemical valence theory, and the topological analysis of the electron density are performed to understand the nature of interaction occurring in between Ng and MCN. The Ng-M bonds in NgMCN are found comprise an almost equal contribution from covalent and electrostatic types of interactions. The different electron density descriptors also reveal the partial covalent character in the concerned bonds.

  6. Noble Gas (Argon and Xenon)-Saturated Cold Storage Solutions Reduce Ischemia-Reperfusion Injury in a Rat Model of Renal Transplantation

    PubMed Central

    Irani, Y.; Pype, J.L.; Martin, A.R.; Chong, C.F.; Daniel, L.; Gaudart, J.; Ibrahim, Z.; Magalon, G.; Lemaire, M.; Hardwigsen, J.

    2011-01-01

    Background Following kidney transplantation, ischemia-reperfusion injury contributes to adverse outcomes. The purpose of this study was to determine whether a cold-storage solution saturated with noble gas (xenon or argon) could limit ischemia-reperfusion injury following cold ischemia. Methods Sixty Wistar rats were randomly allocated to 4 experimental groups. Kidneys were harvested and then stored for 6 h before transplantation in cold-storage solution (Celsior®) saturated with either air, nitrogen, xenon or argon. A syngenic orthotopic transplantation was performed. Renal function was determined on days 7 and 14 after transplantation. Transplanted kidneys were removed on day 14 for histological and immunohistochemical analyses. Results Creatinine clearance was significantly higher and urinary albumin significantly lower in the argon and xenon groups than in the other groups at days 7 and 14. These effects were considerably more pronounced for argon than for xenon. In addition, kidneys stored with argon, and to a lesser extent those stored with xenon, displayed preserved renal architecture as well as higher CD-10 and little active caspase-3 expression compared to other groups. Conclusion Argon- or xenon-satured cold-storage solution preserved renal architecture and function following transplantation by reducing ischemia-reperfusion injury. PMID:22470401

  7. Evidence for prolonged El Nino-like conditions in the Pacific during the Late Pleistocene: a 43 ka noble gas record from California groundwaters

    USGS Publications Warehouse

    Kulongoski, J.T.; Hilton, David R.; Izbicki, J.A.; Belitz, K.

    2009-01-01

    Information on the ocean/atmosphere state over the period spanning the Last Glacial Maximum - from the Late Pleistocene to the Holocene - provides crucial constraints on the relationship between orbital forcing and global climate change. The Pacific Ocean is particularly important in this respect because of its dominant role in exporting heat and moisture from the tropics to higher latitudes. Through targeting groundwaters in the Mojave Desert, California, we show that noble gas derived temperatures in California averaged 4.2 ?? 1.1 ??C cooler in the Late Pleistocene (from ???43 to ???12 ka) compared to the Holocene (from ???10 to ???5 ka). Furthermore, the older groundwaters contain higher concentrations of excess air (entrained air bubbles) and have elevated oxygen-18/oxygen-16 ratios (??18O) - indicators of vigorous aquifer recharge, and greater rainfall amounts and/or more intense precipitation events, respectively. Together, these paleoclimate indicators reveal that cooler and wetter conditions prevailed in the Mojave Desert from ???43 to ???12 ka. We suggest that during the Late Pleistocene, the Pacific ocean/atmosphere state was similar to present-day El Nino-like patterns, and was characterized by prolonged periods of weak trade winds, weak upwelling along the eastern Pacific margin, and increased precipitation in the southwestern U.S.

  8. Effect of hydration on the organo-noble gas molecule HKrCCH: role of krypton in the stabilization of hydrated HKrCCH complexes.

    PubMed

    Biswas, Biswajit; Singh, Prashant Chandra

    2015-11-11

    The effect of hydration on the fluorine free organo-noble gas compound HKrCCH and the role of krypton in the stabilization of the hydrated HKrCCH complexes have been investigated using the quantum chemical calculations on the HKrCCH-(H2O)n=1-6 clusters. Structure and energetics calculations show that water stabilizes HKrCCH through the π hydrogen bond in which the OH group of water interacts with the C[triple bond, length as m-dash]C group of HKrCCH. A maximum of four water molecules can directly interact with the C[triple bond, length as m-dash]C of HKrCCH and after that only inter-hydrogen bonding takes place between the water molecules indicating that the primary hydration shell contains four water molecules. Atom in molecule analysis depicts that π hydrogen bonded complexes of the hydrated HKrCCH are cyclic structures in which the OKr interaction cooperates in the formation of strong O-HC[triple bond, length as m-dash]C interaction. Structure, energetics and charge analysis clearly established that krypton plays an important role in the stabilization as well as the formation of the primary hydration shell of hydrated HKrCCH complexes.

  9. Solute transport in formations of very low permeability: profiles of stable isotope and dissolved noble gas contents of pore water in the Opalinus Clay, Mont Terri, Switzerland

    NASA Astrophysics Data System (ADS)

    Rübel, André P.; Sonntag, Christian; Lippmann, Johanna; Pearson, F. J.; Gautschi, Andreas

    2002-04-01

    Pore water profiles of water, stable isotope, and dissolved noble gas content have been determined across the Opalinus Clay and adjacent formations at the rock laboratory at Mont Terri. We have found enhanced helium contents (up to [ 4He] = 1 × 10 -4 cubic centimeters at standard pressure and temperature per gram of pore water) and argon isotope ratios ( 40Ar/ 36Ar ratios up to 334) due to accumulation of 4He and 40Ar produced in situ. The helium profile was found to be in steady state with respect to in situ production and diffusive loss into the adjacent limestones where groundwater circulates. From this profile a representative mean value of the apparent diffusion coefficient for helium in the pore water of the whole formation was derived for the first time to be D a = 3.5 × 10 -11 m 2 · s -1, which is more than two orders of magnitude lower than the diffusion coefficient D 0 in free water. The stable isotope profile, however, indicates a component of fossil marine pore water, which has not yet been replaced by molecular diffusion of meteoric water from the adjacent limestone and shale formations over the past 10 million years.

  10. Hydrogen and Oxygen Gas Monitoring System Design and Operation

    SciTech Connect

    Lee C. Cadwallader; Kevin G. DeWall; J. Stephen Herring

    2007-06-01

    This paper describes pertinent design practices of selecting types of monitors, monitor unit placement, setpoint selection, and maintenance considerations for gas monitors. While hydrogen gas monitors and enriched oxygen atmosphere monitors as they would be needed for hydrogen production experiments are the primary focus of this paper, monitors for carbon monoxide and carbon dioxide are also discussed. The experiences of designing, installing, and calibrating gas monitors for a laboratory where experiments in support of the DOE Nuclear Hydrogen Initiative (NHI) are described along with codes, standards, and regulations for these monitors. Information from the literature about best operating practices is also presented. The NHI program has two types of activities. The first, near-term activity is laboratory and pilot-plant experimentation with different processes in the kilogram per day scale to select the most promising types of processes for future applications of hydrogen production. Prudent design calls for indoor gas monitors to sense any hydrogen leaks within these laboratory rooms. The second, longer-term activity is the prototype, or large-scale plants to produce tons of hydrogen per day. These large, outdoor production plants will require area (or “fencepost”) monitoring of hydrogen gas leaks. Some processes will have oxygen production with hydrogen production, and any oxygen releases are also safety concerns since oxygen gas is the strongest oxidizer. Monitoring of these gases is important for personnel safety of both indoor and outdoor experiments. There is some guidance available about proper placement of monitors. The fixed point, stationary monitor can only function if the intruding gas contacts the monitor. Therefore, monitor placement is vital to proper monitoring of the room or area. Factors in sensor location selection include: indoor or outdoor site, the location and nature of potential vapor/gas sources, chemical and physical data of the

  11. Noble metal alloy clusters in the gas phase derived from protein templates: unusual recognition of palladium by gold

    NASA Astrophysics Data System (ADS)

    Baksi, Ananya; Pradeep, T.

    2013-11-01

    Matrix assisted laser desorption ionization of a mixture of gold and palladium adducts of the protein lysozyme (Lyz) produces naked alloy clusters of the type Au24Pd+ in the gas phase. While a lysozyme-Au adduct forms Au18+, Au25+, Au38+ and Au102+ ions in the gas phase, lysozyme-Pd alone does not form any analogous cluster. Addition of various transition metal ions (Ag+, Pt2+, Pd2+, Cu2+, Fe2+, Ni2+ and Cr3+) in the adducts contributes to drastic changes in the mass spectrum, but only palladium forms alloys in the gas phase. Besides alloy formation, palladium enhances the formation of specific single component clusters such as Au38+. While other metal ions like Cu2+ help forming Au25+ selectively, Fe2+ catalyzes the formation of Au25+ over all other clusters. Gas phase cluster formation occurs from protein adducts where Au is in the 1+ state while Pd is in the 2+ state. The creation of alloys in the gas phase is not affected whether a physical mixture of Au and Pd adducts or a Au and Pd co-adduct is used as the precursor. The formation of Au cores and AuPd alloy cores of the kind comparable to monolayer protected clusters implies that naked clusters themselves may be nucleated in solution.Matrix assisted laser desorption ionization of a mixture of gold and palladium adducts of the protein lysozyme (Lyz) produces naked alloy clusters of the type Au24Pd+ in the gas phase. While a lysozyme-Au adduct forms Au18+, Au25+, Au38+ and Au102+ ions in the gas phase, lysozyme-Pd alone does not form any analogous cluster. Addition of various transition metal ions (Ag+, Pt2+, Pd2+, Cu2+, Fe2+, Ni2+ and Cr3+) in the adducts contributes to drastic changes in the mass spectrum, but only palladium forms alloys in the gas phase. Besides alloy formation, palladium enhances the formation of specific single component clusters such as Au38+. While other metal ions like Cu2+ help forming Au25+ selectively, Fe2+ catalyzes the formation of Au25+ over all other clusters. Gas phase cluster

  12. Operating Experience Review of the INL HTE Gas Monitoring System

    SciTech Connect

    L. C. Cadwallader; K. G. DeWall

    2010-06-01

    This paper describes the operations of several types of gas monitors in use at the Idaho National Laboratory (INL) High Temperature Electrolysis Experiment (HTE) laboratory. The gases monitored at hydrogen, carbon monoxide, carbon dioxide, and oxygen. The operating time, calibration, and unwanted alarms are described. The calibration session time durations are described. Some simple statistics are given for the reliability of these monitors and the results are compared to operating experiences of other types of monitors.

  13. The physical nature of the phenomenon of positive column plasma constriction in low-pressure noble gas direct current discharges

    SciTech Connect

    Kurbatov, P. F.

    2014-02-15

    The essence of the positive-column plasma constriction for static (the diffusion mode) and dynamic ionization equilibrium (the stratificated and constricted modes) is analyzed. Two physical parameters, namely, the effective ionization rate of gas atoms and the ambipolar diffusion coefficient of electrons and ions, determine the transverse distribution of discharge species and affect the current states of plasma. Transverse constriction of the positive column takes place as the gas ionization level (discharge current) and pressure increase. The stratified mode (including the constricted one) is observed between the two adjacent types of self-sustained discharge phases when they coexist together at the same time or in the same place as a coherent binary mixture. In the case, a occurrence of the discharge phase with more high electron density presently involve a great decrease in the cross-section of the current channel for d.c. discharges. Additional physical factors, such as cataphoresis and electrophoresis phenomena and spatial gas density inhomogeneity correlated with a circulatory flow in d.c. discharges, are mainly responsible for the current hysteresis and partially constricted discharge.

  14. Indirect Gas Species Monitoring Using Tunable Diode Lasers

    DOEpatents

    Von Drasek, William A.; Saucedo, Victor M.

    2005-02-22

    A method for indirect gas species monitoring based on measurements of selected gas species is disclosed. In situ absorption measurements of combustion species are used for process control and optimization. The gas species accessible by near or mid-IR techniques are limited to species that absorb in this spectral region. The absorption strength is selected to be strong enough for the required sensitivity and is selected to be isolated from neighboring absorption transitions. By coupling the gas measurement with a software sensor gas, species not accessible from the near or mid-IR absorption measurement can be predicted.

  15. Fast Plasma Shutdowns Obtained With Massive Hydrogenic, Noble and Mixed-Gas Injection in DIII-D

    SciTech Connect

    Wesley, J; Hollmann, E; Jernigan, T; Van Zeeland, M; Baylor, L; Boedo, J; Combs, S; Evans, T; Groth, M; Humphreys, D; Hyatt, A; Izzo, V; James, A; Moyer, R; Parks, P; Rudakov, D; Strait, E; Wu, W; Yu, J

    2008-10-14

    Massive gas injection (MGI) experiments with H{sub 2}, D{sub 2}, He, Ne and Ar and 'mixed' (H{sub 2} + Ar and D{sub 2} + Ne) gases injected into 'ITER-similar' 1.3-MA H-mode plasmas are described. Gas species, injected quantity Q, delivery time, t{sub inj}, rate-of-rise and intrinsic and added impurities are found to affect the attributes and 'disruption mitigation' efficacies of the resulting fast plasma shutdowns. With sufficient Q and t{sub inj} < {approx}2 ms, all species provide fast (within {le} {approx}3 ms), more-or-less uniform radiative dissipation of the 0.7-MJ plasma thermal energy and fast but benign current decays with reduced vacuum vessel vertical force impulse. With pure and mixed low-Z gases, free-electron densities up to 2 x 10{sup 21} m{sup -3} are obtained. While these densities are high relative to normal tokamak densities, they are still an order of magnitude smaller than the densities required for unconditional mitigation of the runaway electron avalanche process. Key information relevant to the design of effective MGI systems for larger tokamaks and ITER has been obtained and the collective species and Q-variation data provides a rich basis for validation of emerging 2D + t MHD/transport/radiation models.

  16. Project W-030 flammable gas verification monitoring test

    SciTech Connect

    BARKER, S.A.

    1999-02-24

    This document describes the verification monitoring campaign used to document the ability of the new ventilation system to mitigate flammable gas accumulation under steady state tank conditions. This document reports the results of the monitoring campaign. The ventilation system configuration, process data, and data analysis are presented.

  17. The Gas Monitoring of the Besiii Drift Chamber

    NASA Astrophysics Data System (ADS)

    Wang, Xianggao; Chen, Chang; Chen, Yuanbo; Wu, Zhi; Gu, Yunting; Ma, Xiaoyan; Jin, Yan; Liu, Rongguang; Tang, Xiao; Wang, Lan; Zhu, Qiming

    Two monitoring proportional counters (MPCs), installed at the inlet and outlet of the gas system of BESIII drift chamber (DC), were used to monitor the operation of the BESIII DC successfully and effectively as reported in this paper. The ratio of Gout/Gin (full energy photoelectron peak position of 55Fe 5.9 keV X-ray in inlet MPC as Gin and outlet MPC as Gout) is used as the main monitoring parameter. The MPC method is very useful for the gas detector system.

  18. "Elastic" property of mesoporous silica shell: for dynamic surface enhanced Raman scattering ability monitoring of growing noble metal nanostructures via a simplified spatially confined growth method.

    PubMed

    Lin, Min; Wang, Yunqing; Sun, Xiuyan; Wang, Wenhai; Chen, Lingxin

    2015-04-15

    The Raman enhancing ability of noble metal nanoparticles (NPs) is an important factor for surface enhanced Raman scattering (SERS) substrate screening, which is generally evaluated by simply mixing as-prepared NPs with Raman reporters for Raman signal measurements. This method usually leads to incredible results because of the NP surface coverage nonuniformity and reporter-induced NP aggregation. Moreover, it cannot realize in situ, continuous SERS characterization. Herein, we proposed a dynamic SERS monitoring strategy for NPs with precisely tuned structures based on a simplified spatially confined NP growth method. Gold nanorod (AuNR) seed NPs were coated with a mesoporous silica (mSiO2) shell. The permeability of mSiO2 for both reactive species and Raman reporters rendered the silver overcoating reaction and SERS indication of NP growth. Additionally, the mSiO2 coating ensured monodisperse NP growth in a Raman reporter-rich reaction system. Moreover, "elastic" features of mSiO2 were observed for the first time, which is crucial for holding the growing NP without breakage. This feature makes the mSiO2 coating adhere to metal NPs throughout the growing process, providing a stable Raman reporter distribution microenvironment near the NPs and ensuring that the substrate's SERS ability comparison is accurate. Three types of NPs, i.e., core-shell Au@AgNR@mSiO2, Au@AuNR@mSiO2, and yolk-shell Au@void@AuNR@mSiO2 NPs, were synthesized via core-shell overgrowth and galvanic replacement methods, showing the versatility of the approach. The living cell SERS labeling ability of Au@AgNR@mSiO2-based tags was also demonstrated. This strategy addresses the problems of multiple batch NP preparation, aggregation, and surface adsorption differentiation, which is a breakthrough for the dynamic comparison of SERS ability of metal NPs with precisely tuned structures and optical properties.

  19. Production of Mg and Al Auger electrons by noble gas ion bombardment of Mg and Al surfaces

    NASA Technical Reports Server (NTRS)

    Ferrante, J.; Pepper, S. V.

    1976-01-01

    Relative production efficiencies of Mg and Al Auger electrons by He, Ne, Ar, Kr, and Xe ion bombardment are reported as a function of ion energy for energies not exceeding 3 keV. The experimental apparatus employed consisted of a LEED-Auger system equipped with an ion gun and a four-grid retarding-potential analyzer. It is found that: (1) the shape of the ion-excited Auger signal was independent of the rare gas and quite symmetric; (2) the Al signal was about an order of magnitude smaller than the Mg signal for a given bombarding species and ion-gun voltage; (3) no signal was observed for He(+) bombardment under any of the experimental conditions; (4) signal strengths were independent of temperature and ion dose; (5) the Auger production efficiencies differed by no more than a factor of two among the different gases - except for He(+) - on a given metal; (6) all the signal strengths increased with increasing ion-gun voltage, with no maximum exhibited; and (7) the apparent threshold energy for the Al signal was higher than that for the Mg signal. The differences between the results for the two metals are attributed to the fact that the Al 2p orbital lies deeper in energy and closer to the nucleus than the corresponding Mg orbital.

  20. On-line ultrasonic gas entrainment monitor

    DOEpatents

    Day, Clifford K.; Pedersen, Herbert N.

    1978-01-01

    Apparatus employing ultrasonic energy for detecting and measuring the quantity of gas bubbles present in liquids being transported through pipes. An ultrasonic transducer is positioned along the longitudinal axis of a fluid duct, oriented to transmit acoustic energy radially of the duct around the circumference of the enclosure walls. The back-reflected energy is received centrally of the duct and interpreted as a measure of gas entrainment. One specific embodiment employs a conical reflector to direct the transmitted acoustic energy radially of the duct and redirect the reflected energy back to the transducer for reception. A modified embodiment employs a cylindrical ultrasonic transducer for this purpose.

  1. Fluid clathrate system for continuous removal of heavy noble gases from mixtures of lighter gases

    DOEpatents

    Gross, Kenneth C.; Markun, Francis; Zawadzki, Mary T.

    1998-01-01

    An apparatus and method for separation of heavy noble gas in a gas volume. An apparatus and method have been devised which includes a reservoir containing an oil exhibiting a clathrate effect for heavy noble gases with a reservoir input port and the reservoir is designed to enable the input gas volume to bubble through the oil with the heavy noble gas being absorbed by the oil exhibiting a clathrate effect. The gas having reduced amounts of heavy noble gas is output from the oil reservoir, and the oil having absorbed heavy noble gas can be treated by mechanical agitation and/or heating to desorb the heavy noble gas for analysis and/or containment and allow recycling of the oil to the reservoir.

  2. Fluid clathrate system for continuous removal of heavy noble gases from mixtures of lighter gases

    DOEpatents

    Gross, K.C.; Markun, F.; Zawadzki, M.T.

    1998-04-28

    An apparatus and method are disclosed for separation of heavy noble gas in a gas volume. An apparatus and method have been devised which includes a reservoir containing an oil exhibiting a clathrate effect for heavy noble gases with a reservoir input port and the reservoir is designed to enable the input gas volume to bubble through the oil with the heavy noble gas being absorbed by the oil exhibiting a clathrate effect. The gas having reduced amounts of heavy noble gas is output from the oil reservoir, and the oil having absorbed heavy noble gas can be treated by mechanical agitation and/or heating to desorb the heavy noble gas for analysis and/or containment and allow recycling of the oil to the reservoir. 6 figs.

  3. High-rangeability ultrasonic gas flowmeter for monitoring flare gas.

    PubMed

    Mylvaganam, K S

    1989-01-01

    A transit-time ultrasonic gas flowmeter for high-rangeability requirements, such as those encountered in flare-gas flow-metering, is presented. The concept of ray rescue angle for the orientation of the ultrasonic transducers in single-beam transit-time ultrasonic flowmeters is introduced to overcome the problem of ultrasonic beam drift in high-velocity flows. To overcome problems associated with noise at high velocities, a chirp signal is used. To preserve the accuracy of the meter at low velocities near zero flow, a combination of chirp and continuous-wave signals is used to interrogate the flow. Overall system performance is presented, based on results from extensive wind-tunnel tests.

  4. New mud gas monitoring system aboard D/V Chikyu

    NASA Astrophysics Data System (ADS)

    Kubo, Yusuke; Inagaki, Fumio; Eguchi, Nobuhisa; Igarashi, Chiaki

    2013-04-01

    Mud gas logging has been commonly used in oil industry and continental scientific drilling to detect mainly hydrocarbon gases from the reservoir formation. Quick analysis of the gas provides almost real-time information which is critical to evaluate the formation and, in particular, safety of drilling operation. Furthermore, mud gas monitoring complements the lack of core or fluid samples particularly in a deep hole, and strengthen interpretations of geophysical logs. In scientific ocean drilling, on the other hand, mud gas monitoring was unavailable in riserless drilling through the history of DSDP and ODP, until riser drilling was first carried out in 2009 by D/V Chikyu. In IODP Exp 319, GFZ installed the same system with that used in continental drilling aboard Chikyu. High methane concentrations are clearly correlated with increased wood content in the cuttings. The system installation was, however, temporary and gas separator was moved during the expedition for a technical reason. In 2011, new mud gas monitoring system was installed aboard Chikyu and was used for the first time in Exp 337. The gas separator was placed on a newly branched bypass mud flow line, and the gas sample was sent to analysis unit equipped with methane carbon isotope analyzer in addition to mass spectrometer and gas chromatograph. The data from the analytical instruments is converted to depth profiles by calculating the lag effects due to mud circulation. Exp 337 was carried out from July 26 to Sep 30, 2011, at offshore Shimokita peninsula, northeast Japan, targeting deep sub-seafloor biosphere in and around coal bed. Data from the hole C0020A, which was drilled to 2466 mbsf with riser drilling, provided insights into bio-geochemical process through the depth of the hole. In this presentation, we show the design of Chikyu's new mud gas monitoring system, with preliminary data from Exp 337.

  5. The Noble Gases in A-Level Chemistry.

    ERIC Educational Resources Information Center

    Marchant, G. W.

    1983-01-01

    Suggests two methods of developing the study of the noble gases: first, the discovery of the elements and recent discovery of xenon show the human face of chemistry (historical development); second, the properties of noble gas compounds (particularly xenon) can be used to test the framework of conventional chemistry. (Author/JM)

  6. Noble gas isotopic ratios from historical lavas and fumaroles at Mount Vesuvius (southern Italy): constraints for current and future volcanic activity

    NASA Astrophysics Data System (ADS)

    Tedesco, Dario; Nagao, Keisuke; Scarsi, Paolo

    1998-12-01

    Helium, neon and argon isotope ratios have been analysed from phenocrysts of eleven lava samples belonging to the last eruptive cycle of Mount Vesuvius (1631 until 1944). The phenocrysts separates include pyroxene ( N=10) and olivine ( N=1). All phenocryst samples show similarly low gas contents (He, Ne and Ar ˜10 -10 cm 3/g). 3He/ 4He ratios, 5.3-2.11 Ra, are generally low if compared to those typical of the MORB and those of the European Subcontinental Mantle (ESCM), respectively R/ Ra 8.5±1 and 6.0-6.5. A decreasing trend is found from 1631 to 1796, while a more homogeneous set of data is obtained for more recent eruptions, as evidenced by an average R/ Ra value of 2.85. Neon ratios ( 21Ne/ 22Ne and 20Ne/ 22Ne) strongly differ from those typically found on volcanoes and suggest that a crustal component has been added in the source region to Mt. Vesuvius magmas. Argon ratios ( 40Ar/ 36Ar and 38Ar/ 36Ar) have values similar to the atmosphere and are well correlated. The low 40Ar/ 36Ar ratio (max. 302) is, however, in the range of the 40Ar/ 36Ar ratios obtained from several lava samples at other Italian volcanoes and might be considered to have a deep origin. Two hypothesis have been discussed: (1) a deep argon-like-air source, due to subduction of air-rich sediments and/or (2) a preferential loss of Ar, in comparison to lighter noble gases, from silicic melts. Helium isotopic analysis of gas samples recently collected from crater and submarine fumaroles are similar to those of lavas belonging to the final part of this eruptive cycle. This result supports the idea that no new juvenile fluids from the source region have been injected into the magmatic reservoir during the 1631-1944 eruptive cycle and, more importantly, until 1993. Both sets of data help to understand the genesis of these fluids and to constrain the current activity of the volcano.

  7. Selective Growth of Noble Gases at Metal/Oxide Interface.

    PubMed

    Takahashi, Keisuke; Oka, Hiroshi; Ohnuki, Somei

    2016-02-17

    The locations and roles of noble gases at an oxide/metal interface in oxide dispersed metal are theoretically and experimentally investigated. Oxide dispersed metal consisting of FCC Fe and Y2Hf2O7 (Y2Ti2O7) is synthesized by mechanical alloying under a saturated Ar gas environment. Transmission electron microscopy and density functional theory observes the strain field at the interface of FCC Fe {111} and Y2Hf2O7 {111} whose physical origin emerges from surface reconstruction due to charge transfer. Noble gases are experimentally observed at the oxide (Y2Ti2O7) site and calculations reveal that the noble gases segregate the interface and grow toward the oxide site. In general, the interface is defined as the trapping site for noble gases; however, transmission electron microscopy and density functional theory found evidence which shows that noble gases grow toward the oxide, contrary to the generally held idea that the interface is the final trapping site for noble gases. Furthermore, calculations show that the inclusion of He/Ar hardens the oxide, suggesting that material fractures could begin from the noble gas bubble within the oxides. Thus, experimental and theoretical results demonstrate that noble gases grow from the interface toward the oxide and that oxides behave as a trapping site for noble gases.

  8. Operating experience review of an INL gas monitoring system

    SciTech Connect

    Cadwallader, Lee C.; DeWall, K. G.; Herring, J. S.

    2015-03-12

    This article describes the operations of several types of gas monitors in use at the Idaho National Laboratory (INL) High Temperature Electrolysis Experiment (HTE) laboratory. The gases monitored in the lab room are hydrogen, carbon monoxide, carbon dioxide, and oxygen. The operating time, calibration, and both actual and unwanted alarms are described. The calibration session time durations are described. In addition, some simple calculations are given to estimate the reliability of these monitors and the results are compared to operating experiences of other types of monitors.

  9. Software to Control and Monitor Gas Streams

    NASA Technical Reports Server (NTRS)

    Arkin, C.; Curley, Charles; Gore, Eric; Floyd, David; Lucas, Damion

    2012-01-01

    This software package interfaces with various gas stream devices such as pressure transducers, flow meters, flow controllers, valves, and analyzers such as a mass spectrometer. The software provides excellent user interfacing with various windows that provide time-domain graphs, valve state buttons, priority- colored messages, and warning icons. The user can configure the software to save as much or as little data as needed to a comma-delimited file. The software also includes an intuitive scripting language for automated processing. The configuration allows for the assignment of measured values or calibration so that raw signals can be viewed as usable pressures, flows, or concentrations in real time. The software is based on those used in two safety systems for shuttle processing and one volcanic gas analysis system. Mass analyzers typically have very unique applications and vary from job to job. As such, software available on the market is usually inadequate or targeted on a specific application (such as EPA methods). The goal was to develop powerful software that could be used with prototype systems. The key problem was to generalize the software to be easily and quickly reconfigurable. At Kennedy Space Center (KSC), the prior art consists of two primary methods. The first method was to utilize Lab- VIEW and a commercial data acquisition system. This method required rewriting code for each different application and only provided raw data. To obtain data in engineering units, manual calculations were required. The second method was to utilize one of the embedded computer systems developed for another system. This second method had the benefit of providing data in engineering units, but was limited in the number of control parameters.

  10. Growth of β-FeSi2 films via noble-gas ion-beam mixing of Fe/Si bilayers

    NASA Astrophysics Data System (ADS)

    Milosavljević, M.; Dhar, S.; Schaaf, P.; Bibić, N.; Huang, Y.-L.; Seibt, M.; Lieb, K. P.

    2001-11-01

    A detailed study of the formation of β-FeSi2 films by ion-beam mixing of Fe/Si bilayers with noble gas ions is presented. Fe films of 35-50 nm deposited on Si (100) were irradiated with 80-700 keV Ar, Kr, or Xe ions in a wide temperature interval, from room temperature to 600 °C. The structures were analyzed by Rutherford backscattering spectroscopy, x-ray diffraction, conversion electron Mössbauer spectroscopy, elastic recoil detection analysis, cross-section high resolution transmission electron microscopy, and energy dispersive x-ray spectroscopy. Already after Xe irradiation at 300 °C the whole Fe layer is transformed to a mixture of Fe3Si, ɛ-FeSi, and β-FeSi2 phases. At 400-450 °C, a unique, layer by layer growth of β-FeSi2 starting from the surface was found. A full transformation of 35 nm Fe on Si to a 105 nm β-FeSi2 layer was achieved by irradiation with 205 keV Xe to 2×1016 ions/cm2, at a temperature of 600 °C. The fully ion-beam grown layers exhibit a pronounced surface roughness, but a sharp interface to Si. This structure is assigned to a growth of β-FeSi2 grains in a local surrounding of interdiffused silicon. Rapid diffusion of silicon to the surface was observed during all ion irradiations. Single-phase β-FeSi2 layers were also synthesized by vacuum annealing for 2 h at 600 °C of 35 nm Fe/Si bilayers premixed with Xe at 450 °C. In this case, the layers form with a smoother surface topography. It is concluded that ion-beam mixing can be used successfully for growth of β-FeSi2 layers at moderate temperatures, either directly or combined with postirradiation annealing.

  11. Noble-Gas Atomic Interferometer

    DTIC Science & Technology

    2011-01-19

    Awards W. E. Lamb Medal for Laser Science and Quantum Optics (2008). Lewiner Distinguished Lecturer, Technion, Israel (2009). Graduate Students...effort to explain Maxwell’s demon in terms of information entropy . Single-photon cooling was demonstrated experimentally on magnetically trapped

  12. Angular correlation studies in noble gases

    NASA Technical Reports Server (NTRS)

    Coleman, P. G.

    1990-01-01

    There has been a recent revival of interest in the measurement of angular correlation of annihilation photons from the decay of positrons and positronium in gases. This revival has been stimulated by the possibility offered by the technique to shed new light on the apparently low positronium formation fraction in the heavier noble gases and to provide information on positronium quenching processes in gases such as oxygen. There is also the potential for learning about positronium slowing down in gases. This review focuses on experimental noble gas work and considers what new information has been, and may be, gained from these studies.

  13. Remote Real-Time Monitoring of Subsurface Landfill Gas Migration

    PubMed Central

    Fay, Cormac; Doherty, Aiden R.; Beirne, Stephen; Collins, Fiachra; Foley, Colum; Healy, John; Kiernan, Breda M.; Lee, Hyowon; Maher, Damien; Orpen, Dylan; Phelan, Thomas; Qiu, Zhengwei; Zhang, Kirk; Gurrin, Cathal; Corcoran, Brian; O’Connor, Noel E.; Smeaton, Alan F.; Diamond, Dermot

    2011-01-01

    The cost of monitoring greenhouse gas emissions from landfill sites is of major concern for regulatory authorities. The current monitoring procedure is recognised as labour intensive, requiring agency inspectors to physically travel to perimeter borehole wells in rough terrain and manually measure gas concentration levels with expensive hand-held instrumentation. In this article we present a cost-effective and efficient system for remotely monitoring landfill subsurface migration of methane and carbon dioxide concentration levels. Based purely on an autonomous sensing architecture, the proposed sensing platform was capable of performing complex analytical measurements in situ and successfully communicating the data remotely to a cloud database. A web tool was developed to present the sensed data to relevant stakeholders. We report our experiences in deploying such an approach in the field over a period of approximately 16 months. PMID:22163975

  14. 21 CFR 870.4330 - Cardiopulmonary bypass on-line blood gas monitor.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Cardiopulmonary bypass on-line blood gas monitor... Cardiopulmonary bypass on-line blood gas monitor. (a) Identification. A cardiopulmonary bypass on-line blood gas monitor is a device used in conjunction with a blood gas sensor to measure the level of gases in the...

  15. 21 CFR 870.4330 - Cardiopulmonary bypass on-line blood gas monitor.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Cardiopulmonary bypass on-line blood gas monitor... Cardiopulmonary bypass on-line blood gas monitor. (a) Identification. A cardiopulmonary bypass on-line blood gas monitor is a device used in conjunction with a blood gas sensor to measure the level of gases in the...

  16. 21 CFR 870.4330 - Cardiopulmonary bypass on-line blood gas monitor.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Cardiopulmonary bypass on-line blood gas monitor... Cardiopulmonary bypass on-line blood gas monitor. (a) Identification. A cardiopulmonary bypass on-line blood gas monitor is a device used in conjunction with a blood gas sensor to measure the level of gases in the...

  17. 21 CFR 870.4330 - Cardiopulmonary bypass on-line blood gas monitor.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Cardiopulmonary bypass on-line blood gas monitor... Cardiopulmonary bypass on-line blood gas monitor. (a) Identification. A cardiopulmonary bypass on-line blood gas monitor is a device used in conjunction with a blood gas sensor to measure the level of gases in the...

  18. 21 CFR 870.4330 - Cardiopulmonary bypass on-line blood gas monitor.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cardiopulmonary bypass on-line blood gas monitor... Cardiopulmonary bypass on-line blood gas monitor. (a) Identification. A cardiopulmonary bypass on-line blood gas monitor is a device used in conjunction with a blood gas sensor to measure the level of gases in the...

  19. Development of an Exhaled Breath Monitoring System with Semiconductive Gas Sensors, a Gas Condenser Unit, and Gas Chromatograph Columns

    PubMed Central

    Itoh, Toshio; Miwa, Toshio; Tsuruta, Akihiro; Akamatsu, Takafumi; Izu, Noriya; Shin, Woosuck; Park, Jangchul; Hida, Toyoaki; Eda, Takeshi; Setoguchi, Yasuhiro

    2016-01-01

    Various volatile organic compounds (VOCs) in breath exhaled by patients with lung cancer, healthy controls, and patients with lung cancer who underwent surgery for resection of cancer were analyzed by gas condenser-equipped gas chromatography-mass spectrometry (GC/MS) for development of an exhaled breath monitoring prototype system involving metal oxide gas sensors, a gas condenser, and gas chromatography columns. The gas condenser-GC/MS analysis identified concentrations of 56 VOCs in the breath exhaled by the test population of 136 volunteers (107 patients with lung cancer and 29 controls), and selected four target VOCs, nonanal, acetoin, acetic acid, and propanoic acid, for use with the condenser, GC, and sensor-type prototype system. The prototype system analyzed exhaled breath samples from 101 volunteers (74 patients with lung cancer and 27 controls). The prototype system exhibited a level of performance similar to that of the gas condenser-GC/MS system for breath analysis. PMID:27834896

  20. Development of an Exhaled Breath Monitoring System with Semiconductive Gas Sensors, a Gas Condenser Unit, and Gas Chromatograph Columns.

    PubMed

    Itoh, Toshio; Miwa, Toshio; Tsuruta, Akihiro; Akamatsu, Takafumi; Izu, Noriya; Shin, Woosuck; Park, Jangchul; Hida, Toyoaki; Eda, Takeshi; Setoguchi, Yasuhiro

    2016-11-10

    Various volatile organic compounds (VOCs) in breath exhaled by patients with lung cancer, healthy controls, and patients with lung cancer who underwent surgery for resection of cancer were analyzed by gas condenser-equipped gas chromatography-mass spectrometry (GC/MS) for development of an exhaled breath monitoring prototype system involving metal oxide gas sensors, a gas condenser, and gas chromatography columns. The gas condenser-GC/MS analysis identified concentrations of 56 VOCs in the breath exhaled by the test population of 136 volunteers (107 patients with lung cancer and 29 controls), and selected four target VOCs, nonanal, acetoin, acetic acid, and propanoic acid, for use with the condenser, GC, and sensor-type prototype system. The prototype system analyzed exhaled breath samples from 101 volunteers (74 patients with lung cancer and 27 controls). The prototype system exhibited a level of performance similar to that of the gas condenser-GC/MS system for breath analysis.

  1. New generation enrichment monitoring technology for gas centrifuge enrichment plants

    SciTech Connect

    Ianakiev, Kiril D; Alexandrov, Boian S.; Boyer, Brian D.; Hill, Thomas R.; Macarthur, Duncan W.; Marks, Thomas; Moss, Calvin E.; Sheppard, Gregory A.; Swinhoe, Martyn T.

    2008-06-13

    The continuous enrichment monitor, developed and fielded in the 1990s by the International Atomic Energy Agency, provided a go-no-go capability to distinguish between UF{sub 6} containing low enriched (approximately 4% {sup 235}U) and highly enriched (above 20% {sup 235}U) uranium. This instrument used the 22-keV line from a {sup 109}Cd source as a transmission source to achieve a high sensitivity to the UF{sub 6} gas absorption. The 1.27-yr half-life required that the source be periodically replaced and the instrument recalibrated. The instrument's functionality and accuracy were limited by the fact that measured gas density and gas pressure were treated as confidential facility information. The modern safeguarding of a gas centrifuge enrichment plant producing low-enriched UF{sub 6} product aims toward a more quantitative flow and enrichment monitoring concept that sets new standards for accuracy stability, and confidence. An instrument must be accurate enough to detect the diversion of a significant quantity of material, have virtually zero false alarms, and protect the operator's proprietary process information. We discuss a new concept for advanced gas enrichment assay measurement technology. This design concept eliminates the need for the periodic replacement of a radioactive source as well as the need for maintenance by experts. Some initial experimental results will be presented.

  2. Commercial anesthetic-respiratory gas monitor utilizing Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Gregonis, Donald E.; Van Wagenen, Richard A.; Coleman, D.; Mitchell, John R.

    1990-11-01

    A commercial gas monitor which utilizes Raman Spectroscopy has been developed to monitor anesthetic and respiratory gases in the hospital operating room. The instrument measures all molecular gases administered by the anesthesiologist in real time with fast response of breath waveform. These gases include carbon dioxide, nitrous oxide, oxygen, nitrogen and various volatile halogenated organic anesthetics, e.g. halothane, isoflurane, enflurane, sevoflurane and desflurane. The key feature of this instrument which allows it to produce adequate Raman signals with a low cost argon ion laser is measuring these gases inside the laser resonant cavity.

  3. Consent Decree for Noble Energy

    EPA Pesticide Factsheets

    Noble Energy, Inc. (Noble) that comprehensively identifies and addresses issues with vapor control systems at Noble’s condensate storage tank batteries in the Denver-area 8-hour ozone marginal nonattainment area (nonattainment area).

  4. Flammable gas tank safety program: Technical basis for gas analysis and monitoring

    SciTech Connect

    Sherwood, D.J.

    1995-09-08

    Flammable gases generated in radioactive liquids. Twenty-five high level radioactive liquid waste storage tanks located underground at the Hanford Site are on a Flammable Gas Watch List because they contain waste which tends to retain the gases generated in it until rather large quantities are available for sudden release to the tank head space; if a tank is full it has little dome space, and a flammable concentration of gases could be produced--even if the tank is ventilated. If the waste has no tendency to retain gas generated in it then a continual flammable gas concentration in the tank dome space is established by the gas production rate and the tank ventilation rate (or breathing rate for unventilated tanks); this is also a potential problem for Flammable Gas Watch List tanks, and perhaps other Hanford tanks too. All Flammable Gas Watch List tanks will be fitted with Standard Hydorgen Monitoring Systems so that their behavior can be observed. In some cases, such as tank 241-SY-101, the data gathered from such observations will indicate that tank conditions need to be mitigated so that gas release events are either eliminated or rendered harmless. For example, a mixer pump was installed in tank 241-SY-101; operating the pump stirs the waste, replacing the large gas release events with small releases of gas that are kept below twenty-five percent of the lower flammability limit by the ventilation system. The concentration of hydrogen measured in Hanford waste tanks is greater than that of any other flammable gas. Hydrogen levels measured with a Standard Hydrogen Monitoring System in excess of 0.6 volume percent will cause Westinghouse Hanford Company to consider actions which will decrease the amount of flammable gas in the tank

  5. Sensor validation and fusion for gas turbine vibration monitoring

    NASA Astrophysics Data System (ADS)

    Yan, Weizhong; Goebel, Kai F.

    2003-08-01

    Vibration monitoring is an important practice throughout regular operation of gas turbine power systems and, even more so, during characterization tests. Vibration monitoring relies on accurate and reliable sensor readings. To obtain accurate readings, sensors are placed such that the signal is maximized. In the case of characterization tests, strain gauges are placed at the location of vibration modes on blades inside the gas turbine. Due to the prevailing harsh environment, these sensors have a limited life and decaying accuracy, both of which impair vibration assessment. At the same time bandwidth limitations may restrict data transmission, which in turn limits the number of sensors that can be used for assessment. Knowing the sensor status (normal or faulty), and more importantly, knowing the true vibration level of the system all the time is essential for successful gas turbine vibration monitoring. This paper investigates a dynamic sensor validation and system health reasoning scheme that addresses the issues outlined above by considering only the information required to reliably assess system health status. In particular, if abnormal system health is suspected or if the primary sensor is determined to be faulted, information from available "sibling" sensors is dynamically integrated. A confidence expresses the complex interactions of sensor health and system health, their reliabilities, conflicting information, and what the health assessment is. Effectiveness of the scheme in achieving accurate and reliable vibration evaluation is then demonstrated using a combination of simulated data and a small sample of a real-world application data where the vibration of compressor blades during a real time characterization test of a new gas turbine power system is monitored.

  6. Microfabricated BTU monitoring device for system-wide natural gas monitoring.

    SciTech Connect

    Einfeld, Wayne; Manginell, Ronald Paul; Robinson, Alex Lockwood; Moorman, Matthew Wallace

    2005-11-01

    The natural gas industry seeks inexpensive sensors and instrumentation to rapidly measure gas heating value in widely distributed locations. For gas pipelines, this will improve gas quality during transfer and blending, and will expedite accurate financial accounting. Industrial endusers will benefit through continuous feedback of physical gas properties to improve combustion efficiency during use. To meet this need, Sandia has developed a natural gas heating value monitoring instrument using existing and modified microfabricated components. The instrument consists of a silicon micro-fabricated gas chromatography column in conjunction with a catalytic micro-calorimeter sensor. A reference thermal conductivity sensor provides diagnostics and surety. This combination allows for continuous calorimetric determination with a 1 minute analysis time and 1.5 minute cycle time using air as a carrier gas. This system will find application at remote natural gas mining stations, pipeline switching and metering stations, turbine generators, and other industrial user sites. Microfabrication techniques will allow the analytical components to be manufactured in production quantities at a low per-unit cost.

  7. Clinical assessment of intraarterial blood gas monitor accuracy

    NASA Astrophysics Data System (ADS)

    Aziz, Salim; Spiess, R.; Roby, Paul; Kenny, Margaret

    1993-08-01

    The accuracy of intraarterial blood gas monitoring (IABGM) devices is challenging to assess under routine clinical conditions. When comparing discrete measurements by blood gas analyzer (BGA) to IABGM values, it is important that the BGA determinations (reference method) be as accurate as possible. In vitro decay of gas tensions caused by delay in BGA analysis is particularly problematic for specimens with high arterial oxygen tension (PaO2) values. Clinical instability of blood gases in the acutely ill patient may cause disagreement between BGA and IABGM values because of IABGM response time lag, particularly in the measurement of arterial blood carbon dioxide tension (PaCO2). We recommend that clinical assessments of IABGM accuracy by comparison with BGA use multiple bedside BGA instruments, and that blood sampling only occur during periods when IABGM values appear stable.

  8. Long-term monitoring of marine gas leakage

    NASA Astrophysics Data System (ADS)

    Spickenbom, Kai; Faber, Eckhard; Poggenburg, Jürgen; Seeger, Christian; Furche, Markus

    2010-05-01

    The sequestration of CO2 in sub-seabed geological formations is one of the Carbon Capture and Storage (CCS) strategies currently under study. Although offshore operations are significantly more expensive than comparable onshore operations, the growing public resistance against onshore CCS projects makes sub-seabed storage a promising option. Even after a thorough review of the geological setting, there is always the possibility of leakage from the reservoir. As part of the EU-financed project CO2ReMoVe (Research, Monitoring, Verification), which aims to develop innovative research and technologies for monitoring and verification of carbon dioxide geological storage, we are working on the development of submarine long-term gas flow monitoring systems. The basic design of the monitoring system builds on our experience in volcano monitoring. Early prototypes were composed of a raft floating on the surface of a mud volcano, carrying sensors for CO2 flux and concentration, data storage and transmission, and power supply by battery-buffered solar panels. The system was modified for installation in open sea by using a buoy instead of a raft and a funnel on the seafloor to collect the gas, connected by a flexible tube. This setup provides a cost-effective solution for shallow waters. However, a buoy interferes with ship traffic, and it is also difficult to adapt this design to greater water depths. These requirements can best be complied by a completely submersed system. A system for unattended long-term monitoring in a marine environment has to be extremely durable. Therefore, we focussed on developing a mechanically and electrically as simple setup as possible, which has the additional advantage of low cost. The system consists of a funnel-shaped gas collector, a sensor head and pressure housings for electronics and power supply. Since this setup is inexpensive, it can be deployed in numbers to cover larger areas. By addition of multi-channel data loggers, data

  9. Long-term flow monitoring of submarine gas emanations

    NASA Astrophysics Data System (ADS)

    Spickenbom, K.; Faber, E.; Poggenburg, J.; Seeger, C.

    2009-04-01

    One of the Carbon Capture and Storage (CCS) strategies currently under study is the sequestration of CO2 in sub-seabed geological formations. Even after a thorough review of the geological setting, there is the possibility of leaks from the reservoirs. As part of the EU-financed project CO2ReMoVe (Research, Monitoring, Verification), which aims to develop innovative research and technologies for monitoring and verification of carbon dioxide geological storage, we are working on the development of submarine long-term gas flow monitoring systems. Technically, however, these systems are not limited to CO2 but can be used for monitoring of any free gas emission (bubbles) on the seafloor. The basic design of the gas flow sensor system was derived from former prototypes developed for monitoring CO2 and CH4 on mud volcanoes in Azerbaijan. This design was composed of a raft floating on the surface above the gas vent to collect the bubbles. Sensors for CO2 flux and concentration and electronics for data storage and transmission were mounted on the raft, together with battery-buffered solar panels for power supply. The system was modified for installation in open sea by using a buoy instead of a raft and a funnel on the seafloor to collect the gas, which is then guided above water level through a flexible tube. Besides some technical problems (condensed water in the tube, movement of the buoys due to waves leading to biased measurement of flow rates), this setup provides a cost-effective solution for shallow waters. However, a buoy interferes with ship traffic, and it is also difficult to adapt this design to greater water depths. These requirements can best be complied by a completely submersed system. To allow unattended long-term monitoring in a submarine environment, such a system has to be extremely durable. Therefore, we focussed on developing a mechanically and electrically as simple setup as possible, which has the additional advantage of low cost. The system

  10. 78 FR 19605 - Greenhouse Gas Reporting Rule: Revision to Best Available Monitoring Method Request Submission...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-02

    ... AGENCY 40 CFR Part 98 Greenhouse Gas Reporting Rule: Revision to Best Available Monitoring Method Request... published a direct final rule, Greenhouse Gas Reporting Rule: Revision to Best Available Monitoring Method... petroleum and natural gas systems source category of the Greenhouse Gas Reporting Rule are required...

  11. On baseline determination and gas saturation derivation from downhole electrical monitoring of shallow biogenic gas production

    NASA Astrophysics Data System (ADS)

    Pezard, P. A.; Celerier, B. P.

    2015-12-01

    Adequate hydrogeophysical monitoring of CO2 geological storage remains a challenge as different parameters might be modified during storage. That implies to compare real-time measurements to an adequate baseline. At the Maguelone shallow experimental site a representative baseline for electrical resistivity was built from a large number of downhole geophysical measurements recorded over time. At this coastal site this issue is particularly important due to the production of biogenic gas at shallow depth (< 200 m) from the subsurface sediments.For this, a modified petrophysical model based on the Waxman-Smits model is proposed to estimate gas saturation found to vary up to 7% within shallow sand layers, indicating that natural gas production within the sedimentary pile from biological activity cannot be neglected during gas injection experiments. In the two main reservoirs located at shallow depth (R1 and R2), a variable gas content of 7% and 4% was obtained over short periods of time in the TLL6 and DSO1 boreholes, respectively. The difference might be due to the gentle stratigraphic slope identified from cross hole log and core analyses, TLL6 being located upslope from DSO1. This study also revealed a rapid dynamic mechanism resulting in transfer of biogenic gas from the bottom reservoir (R1) to the top one (R2), possibly due to gas leaking along some of the monitoring boreholes. These sand-rich layers constitute buffer reservoirs for biogenic gases before being released to the atmosphere. Future studies at Maguelone will first focus on biogenic gas sampling from a downhole multi-packer completion in order to identify and quantify the different gas phases produced over time by the sedimentary pile.

  12. Preserving noble gases in a convecting mantle.

    PubMed

    Gonnermann, Helge M; Mukhopadhyay, Sujoy

    2009-05-28

    High (3)He/(4)He ratios sampled at many ocean islands are usually attributed to an essentially undegassed lower-mantle reservoir with high (3)He concentrations. A large and mostly undegassed mantle reservoir is also required to balance the Earth's (40)Ar budget, because only half of the (40)Ar produced from the radioactive decay of (40)K is accounted for by the atmosphere and upper mantle. However, geophysical and geochemical observations suggest slab subduction into the lower mantle, implying that most or all of Earth's mantle should have been processed by partial melting beneath mid-ocean ridges and hotspot volcanoes. This should have left noble gases in both the upper and the lower mantle extensively outgassed, contrary to expectations from (3)He/(4)He ratios and the Earth's (40)Ar budget. Here we suggest a simple solution: recycling and mixing of noble-gas-depleted slabs dilutes the concentrations of noble gases in the mantle, thereby decreasing the rate of mantle degassing and leaving significant amounts of noble gases in the processed mantle. As a result, even when the mass flux across the 660-km seismic discontinuity is equivalent to approximately one lower-mantle mass over the Earth's history, high (3)He contents, high (3)He/(4)He ratios and (40)Ar concentrations high enough to satisfy the (40)Ar mass balance of the Earth can be preserved in the lower mantle. The differences in (3)He/(4)He ratios between mid-ocean-ridge basalts and ocean island basalts, as well as high concentrations of (3)He and (40)Ar in the mantle source of ocean island basalts, can be explained within the framework of different processing rates for the upper and the lower mantle. Hence, to preserve primitive noble gas signatures, we find no need for hidden reservoirs or convective isolation of the lower mantle for any length of time.

  13. Thermal conductivity of graphene nanoribbons in noble gaseous environments

    SciTech Connect

    Zhong, Wei-Rong Xu, Zhi-Cheng; Zheng, Dong-Qin; Ai, Bao-Quan

    2014-02-24

    We investigate the thermal conductivity of suspended graphene nanoribbons in noble gaseous environments using molecular dynamics simulations. It is reported that the thermal conductivity of perfect graphene nanoribbons decreases with the gaseous pressure. The decreasing is more obvious for the noble gas with large atomic number. However, the gaseous pressure cannot change the thermal conductivity of defective graphene nanoribbons apparently. The phonon spectra of graphene nanoribbons are also provided to give corresponding supports.

  14. A gas scintillation monitor for tritium gas in argon or in nitrogen.

    PubMed

    Campi, F; Mascherpa, C; Sterlini, C; Pacenti, P; Terrani, S

    1996-09-01

    For civilian purposes tritium is presently used in quantities of tens of PBq (MCi) in laboratories for the studies of tritium technology, at the Joint European Torus plant (Abingdon, Oxon, OX143A, UK) as fuel for the process of nuclear fusion, and in the manufacture of radio-luminescent items. Given the extreme mobility of tritium in most materials, it is necessary to use systems for double containment, such as glove boxes or spaces between primary and secondary containers, in which inert gas like argon or nitrogen flows. With these systems it is possible to recover tritium that escapes from the primary containment. Presently the gas flow is monitored continuously by means of ionization chambers which may present problems in particular applications ("memory effect" with high activity, strong dependence of the response on the presence of impurity, etc.). The aim of the work here presented is to determine the prospects for the realization of a new type of monitor mainly dedicated to the measurement of gas activity in isolation space of the containing systems of the high activity tritium plants. This monitor should have sufficient sensitivity, quick response, and should be easily decontaminated. As a detection technique we chose the scintillation produced in the inert gas by radioactive decay. With the first prototype, designed in cylindrical form, it was possible to observe gaseous scintillation events in mixture of tritium and argon or nitrogen. Following that, a spherical prototype was designed, of which we studied the performances and the dependence of the response varying the pressure, the concentration of tritium, the percentage of the impurity, and the gas flow rate. The results are satisfactory and suggest that the monitor could be used in glove boxes and double containment systems. The future research program will include tests involving large quantities of tritium and a study of the ideal dimensions and geometry of the detection chamber in order to optimize

  15. Active Geophysical Monitoring in Oil and Gas Industry

    NASA Astrophysics Data System (ADS)

    Bakulin, A.; Calvert, R.

    2005-12-01

    Effective reservoir management is a Holy Grail of the oil and gas industry. Quest for new technologies is never ending but most often they increase effectiveness and decrease the costs. None of the newcomers proved to be a silver bullet in such a key metric of the industry as average oil recovery factor. This factor is still around 30 %, meaning that 70 % of hydrocarbon reserves are left in the ground in places where we already have expensive infrastructure (platforms, wells) to extract them. Main reason for this inefficiency is our inability to address realistic reservoir complexity. Most of the time we fail to properly characterize our reservoirs before production. As a matter of fact, one of the most important parameters -- permeability -- can not be mapped from remote geophysical methods. Therefore we always start production blind even though reservoir state before production is the simplest one. Once first oil is produced, we greatly complicate the things and quickly become unable to estimate the state and condition of the reservoir (fluid, pressures, faults etc) or oilfield hardware (wells, platforms, pumps) to make a sound next decision in the chain of reservoir management. Our modeling capabilities are such that if we know true state of the things - we can make incredibly accurate predictions and make extremely efficient decisions. Thus the bottleneck is our inability to properly describe the state of the reservoirs in real time. Industry is starting to recognize active monitoring as an answer to this critical issue. We will highlight industry strides in active geophysical monitoring from well to reservoir scale. It is worth noting that when one says ``monitoring" production technologists think of measuring pressures at the wellhead or at the pump, reservoir engineers think of measuring extracted volumes and pressures, while geophysicist may think of change in elastic properties. We prefer to think of monitoring as to measuring those parameters of the

  16. TIGER TM : Intelligent continuous monitoring of gas turbines

    SciTech Connect

    McKay, I.; Hibbert, J.; Milne, R.; Nicol, C.

    1998-07-01

    The field of condition monitoring has been an area of rapid growth, with many specialized techniques being developed to measure or predict the health of a particular item of plant. Much of the most recent work has gone into the diagnosis of problems on rotating machines through the application of vibration analysis techniques. These techniques though useful can have a number of limiting factors, such as the need to install specialized sensors and measurement equipment, or the limited scope of the type of data measured. It was recognized in 1992, that the surveillance and condition monitoring procedures available for critical plant, such as gas turbines, were not as comprehensive as they might be and that a novel approach was required to give the operator the necessary holistic view of the health of the plant. This would naturally provide an assessment of the maintenance practices required to yield the highest possible availability without the need to install extensive new instrumentation. From the above objective, the TIGER system was designed which utilizes available data from the gas turbine control system or additionally the plant DCS to measure the behavior of the gas turbine and its associated sub systems. These measured parameters are then compared with an internal model of the turbine system and used to diagnose incorrect responses and therefore the item that is at fault, allowing the operator to quickly restart the turbine after a trip or perform condition based maintenance at the next scheduled outage. This philosophy has been built into the TIGER system and the purpose of this paper is to illustrate its functionality and some of the innovative techniques used in the diagnosis of real gas turbine problems. This is achieved by discussing three case studies where TIGER was integral in returning the plant to operation more quickly than can normally be expected.

  17. Residual-gas-ionization beam profile monitors in RHIC

    SciTech Connect

    Connolly, R.; Fite, J.; Jao, S.; Trabocchi, C.

    2010-05-02

    Four ionization profile monitors (IPMs) are in RHIC to measure vertical and horizontal beam profiles in the two rings. These work by measuring the distribution of electrons produced by beam ionization of residual gas. During the last two years both the collection accuracy and signal/noise ratio have been improved. An electron source is mounted across the beam pipe from the collector to monitor microchannel plate (MCP) aging and the signal electrons are gated to reduce MCP aging and to allow charge replenishment between single-turn measurements. Software changes permit simultaneous measurements of any number of individual bunches in the ring. This has been used to measure emittance growth rates on six bunches of varying intensities in a single store. Also the software supports FFT analysis of turn-by-turn profiles of a single bunch at injection to detect dipole and quadrupole oscillations.

  18. Continuous monitoring of a changing sample by multiplex gas chromatography

    NASA Technical Reports Server (NTRS)

    Valentin, Jose R.; Hall, Kirsten W.; Becker, Joseph F.

    1990-01-01

    Results are presented from a study in which a continuously changed gaseous sample was monitored by multiplex gas chromatography (MGC), using the exponential dilution (ED) technique of Ritter and Adams (1976) to change the composition and concentration of a gaseous mixture in such a way as to imitate changes in the atmospheric gases sampled by a descending aircraft. A calibration of the MGC system was performed with four different rates of sample dilution, and the errors resulting from various degrees of change in the sample concentration were determined.

  19. Where do noble gases hide in space?

    NASA Astrophysics Data System (ADS)

    Pauzat, F.; Ellinger, Y.

    Observations showing anomalous amounts of noble gas, especially in planetary atmospheres, are at the origin of a series of controversial interpretations from 1990 to nowadays (Hersant et al. (2004)). If, in a first step, we adopt a chemical point of view, we have to consider the possibility of associations of such elements (though usually considered as non reactive), with other molecules or atoms. Such complexes could trap the noble gases in some astrophysical objects at one time of their evolution, for example, in the early step of formation of protoplanetary disks. But two questions have to be answered to assert this type of hypothesis: which stable compounds could exist taking into account the environnement and which reactions could lead to such compounds? Hydrogen being by far the most abundant element in space, and neutral systems whose cohesion is driven by weak Van der Waals forces being unable to resist turbulence in space, the first and simplest association to consider is the one between the noble gas and the H3+ ion. Thus, DFT in the B3LYP, PW91 and BHandHLYP formalisms together with ab-initio methods of Coupled Cluster type have been employed to determine the equilibrium geometries, the spectroscopic constants and the bonding energies of the possible complexes between noble gases and hydrogen. We have first performed an extensive study of the associations ArnH3+ possible with Argon (the first noble gas which rose questions in the area of Jupiter's poles). We have found that several Argon atoms can be stabilized around the H3+ ion, the first complexation being in the plane of the ion. The spectroscopic data (rotational constants, dipole moments and IR signatures) were calculated (Pauzat & Ellinger (2005)) so that the laboratory experiments and spatial observations of these species could then be carried out. From our results and previous observations on this complex (Bogey et al. (1987)) we can say that the ArH3+ ion is certainly a good candidate for

  20. Development of monitoring and control technology based on trace gas monitoring. Final report

    SciTech Connect

    Liebowitz, B.

    1997-07-01

    Trace gases are generated by many biological reactions. During anaerobic decomposition, trace levels of hydrogen (H{sub 2}) and carbon monoxide (CO) gases are produced. It was shown previously that these trace gases are intrinsically related to the biochemical reactions occurring and, therefore, offer promise for on-line process monitoring and control. This work was designed to test how effectively hydrogen and CO could be to monitor high-rate anaerobic systems that has significant mass transfer and complex hydraulics. An experimental program was designed to examine the behavior of an upflow anaerobic sludge blanket (UASB) reactor system under steady state and in response to organic loading perturbations. The responses of trace gases CO and H{sub 2} were tracked using an on-line, real-time gas-monitoring system linked to a computer-controlled data acquisition package. Data on conventional process parameters such as pH, chemical oxygen demand (COD), volatile fatty acids (VFAs) were concurrently collected. Monitoring of conventional process indicators (i.e., pH, VFA, gas production) and trace gas (H{sub 2} and CO) indicators was conducted using a matrix of nine different steady-state OLRs (4-23 kg COD/m{sup 3} -d) and system HRTs (0.5 to 2.5 days) was performed to determine any correlation among the indicators. Of OLR, HRT, and influent COD, only OLR had any significant influence on the process indicators examined. All parameters except methane increased with increases in OLR; methane decreased with increased OLR. The OLR and gas production rate (GP) were observed to be linearly correlated.

  1. Widespread distribution of ascending fluids transporting mantle helium in the fore-arc region and their upwelling processes: Noble gas and major element composition of deep groundwater in the Kii Peninsula, southwest Japan

    NASA Astrophysics Data System (ADS)

    Morikawa, Noritoshi; Kazahaya, Kohei; Takahashi, Masaaki; Inamura, Akihiko; Takahashi, Hiroshi A.; Yasuhara, Masaya; Ohwada, Michiko; Sato, Tsutomu; Nakama, Atsuko; Handa, Hiroko; Sumino, Hirochika; Nagao, Keisuke

    2016-06-01

    Chemical and isotopic studies including analyses of noble gases were comprehensively conducted on the groundwater of the entire Kii Peninsula, which is located in the fore-arc region of southwest Japan. Groundwater of Na-Cl-HCO3, Na-HCO3-Cl, and Na-Cl types was shown to be distributed across the whole area. Groundwater in the inland central part of the peninsula shows relatively low salinity, whereas groundwater from the area along the ENE-trending Median Tectonic Line (MTL), on the north side of the peninsula, shows high salinity (up to 18,800 mg/L of Cl-) and the presence of unusual heavy oxygen isotopes. This trend is similar to that documented in saline waters from the Arima region (the so-called "Arima-type thermal water"). High 3He/4He ratios relative to the atmospheric value (up to 6.7 Ra) were recorded throughout the Kii Peninsula, covering a wider area than documented previously. The saline groundwater is also strongly depleted in 20Ne and heavy noble gases. From the wide distribution of high 3He/4He values and the associated 20Ne and Cl- concentrations, we infer that aqueous fluids derived from dehydration of the subducting slab are present at depth beneath almost the entire Kii Peninsula. These aqueous fluids may ascend along the major north-dipping boundary faults. The isotopic composition of groundwater from the southern part of the peninsula suggests that the contribution from these dehydration-derived fluids is relatively small in this region. However, volatile components (e.g., noble gases and CO2) in the groundwater of this area may originate from the dehydration-derived fluids. Upwelling of Arima-type thermal water of the Na-Cl-HCO3 type is expected to undergo a phase separation of volatile species due to decompression as the fluid ascends. The variety of water types documented may be due to this water-gas separation and the subsequent incorporation of gaseous species into shallow meteoric groundwater. The observed high 3He/4He ratios in the

  2. Metal Oxide Semi-Conductor Gas Sensors in Environmental Monitoring

    PubMed Central

    Fine, George F.; Cavanagh, Leon M.; Afonja, Ayo; Binions, Russell

    2010-01-01

    Metal oxide semiconductor gas sensors are utilised in a variety of different roles and industries. They are relatively inexpensive compared to other sensing technologies, robust, lightweight, long lasting and benefit from high material sensitivity and quick response times. They have been used extensively to measure and monitor trace amounts of environmentally important gases such as carbon monoxide and nitrogen dioxide. In this review the nature of the gas response and how it is fundamentally linked to surface structure is explored. Synthetic routes to metal oxide semiconductor gas sensors are also discussed and related to their affect on surface structure. An overview of important contributions and recent advances are discussed for the use of metal oxide semiconductor sensors for the detection of a variety of gases—CO, NOx, NH3 and the particularly challenging case of CO2. Finally a description of recent advances in work completed at University College London is presented including the use of selective zeolites layers, new perovskite type materials and an innovative chemical vapour deposition approach to film deposition. PMID:22219672

  3. Condition Based Monitoring of Gas Turbine Combustion Components

    SciTech Connect

    Ulerich, Nancy; Kidane, Getnet; Spiegelberg, Christine; Tevs, Nikolai

    2012-09-30

    The objective of this program is to develop sensors that allow condition based monitoring of critical combustion parts of gas turbines. Siemens teamed with innovative, small companies that were developing sensor concepts that could monitor wearing and cracking of hot turbine parts. A magnetic crack monitoring sensor concept developed by JENTEK Sensors, Inc. was evaluated in laboratory tests. Designs for engine application were evaluated. The inability to develop a robust lead wire to transmit the signal long distances resulted in a discontinuation of this concept. An optical wear sensor concept proposed by K Sciences GP, LLC was tested in proof-of concept testing. The sensor concept depended, however, on optical fiber tips wearing with the loaded part. The fiber tip wear resulted in too much optical input variability; the sensor could not provide adequate stability for measurement. Siemens developed an alternative optical wear sensor approach that used a commercial PHILTEC, Inc. optical gap sensor with an optical spacer to remove fibers from the wearing surface. The gap sensor measured the length of the wearing spacer to follow loaded part wear. This optical wear sensor was developed to a Technology Readiness Level (TRL) of 5. It was validated in lab tests and installed on a floating transition seal in an F-Class gas turbine. Laboratory tests indicate that the concept can measure wear on loaded parts at temperatures up to 800{degrees}C with uncertainty of < 0.3 mm. Testing in an F-Class engine installation showed that the optical spacer wore with the wearing part. The electro-optics box located outside the engine enclosure survived the engine enclosure environment. The fiber optic cable and the optical spacer, however, both degraded after about 100 operating hours, impacting the signal analysis.

  4. A lattice Boltzmann model for noble gas diffusion in solids: The importance of domain shape and diffusive anisotropy and implications for thermochronometry

    NASA Astrophysics Data System (ADS)

    Huber, Christian; Cassata, William S.; Renne, Paul R.

    2011-04-01

    Thermochronometry based on radiogenic noble gases is critically dependent upon accurate knowledge of the kinetics of diffusion. With few exceptions, complex natural crystals are represented by ideal geometries such as infinite sheets, infinite cylinders, or spheres, and diffusivity is assumed to be isotropic. However, the physical boundaries of crystals generally do not conform to ideal geometries and diffusion within some crystals is known to be anisotropic. Our failure to incorporate such complexities into diffusive models leads to inaccuracies in both thermal histories and diffusion parameters calculated from fractional release data. To address these shortcomings we developed a code based on the lattice Boltzmann (LB) method to model diffusion from complex 3D geometries having isotropic, temperature-independent anisotropic, and temperature-dependent anisotropic diffusivity. In this paper we outline the theoretical basis for the LB code and highlight several advantages of this model relative to more traditional finite difference approaches. The LB code, along with existing analytical solutions for diffusion from simple geometries, is used to investigate the affect of intrinsic crystallographic features (e.g., crystal topology and diffusion anisotropy) on calculated diffusion parameters and a novel method for approximating thermal histories from crystals with complex topologies and diffusive anisotropy is presented.

  5. Method and apparatus for measuring purity of noble gases

    SciTech Connect

    Austin, Robert

    2008-04-01

    A device for detecting impurities in a noble gas includes a detection chamber and a source of pulsed ultraviolet light. The pulse of the ultraviolet light is transferred into the detection chamber and onto a photocathode, thereby emitting a cloud of free electrons into the noble gas within the detection chamber. The cloud of electrons is attracted to the opposite end of the detection chamber by a high positive voltage potential at that end and focused onto a sensing anode. If there are impurities in the noble gas, some or all of the electrons within the cloud will bond with the impurity molecules and not reach the sensing anode. Therefore, measuring a lower signal at the sensing anode indicates a higher level of impurities while sensing a higher signal indicates fewer impurities. Impurities in the range of one part per billion can be measured by this device.

  6. Trace gas detection and monitoring with the Digital Array Gas-correlation Radiometer (DAGR)

    NASA Astrophysics Data System (ADS)

    Gordley, Larry L.; Hervig, Mark E.; Fish, Chad; McHugh, Martin J.

    2011-05-01

    We present the first results from a Digital Array Gas-correlation Radiometer (DAGR) prototype sensor, and discuss applications in remote sensing of trace gases. The sensor concept is based on traditional and reliable Gas Filter Correlation Radiometry (GFCR), but overcomes the limitations in solar backscatter applications. The DAGR sensor design can be scaled to the size of a digital camera and is ideal for downlooking detection of gases in the boundary layer, where solar backscatter measurements are needed to overcome the lack of thermal contrast in the IR. Ground-based portable DAGR sensors can monitor carbon sequestration sites or industrial facilities. Aircraft or UAV deployment can quickly survey large areas and are particularly well suited for gas leak detection or carbon monitoring. From space-based platforms, Doppler modulation can be exploited to produce an extremely fine spectral resolution with effective resolving power exceeding 100,000. Such space-based DAGR observations could provide near-global sensing of climatically important species such as such as CO2, CO, CH4, O3 and N2O. Planetary science applications include detection and mapping of biomarkers in the Martian atmosphere.

  7. [Noninvasive monitoring of gas exchange: methodologic prerequisites and clinical use].

    PubMed

    Kreymann, G; Gottschall, C; Grosser, S; Matthaei, S; Raedler, A; Schubmann, R; Beck, H

    1989-02-01

    The noninvasive determination of the respiratory gas exchange (measurement of oxygen uptake and carbon dioxide delivery) permits the calculation of cardiac output by Fick principle and of the actual energy requirement of the patient (indirect calorimetry). A system is presented for the continuous measurement of oxygen uptake and carbon dioxide delivery, that bases on simple components, which are available on most intensive care units. The methodical problems are discussed and the improvement of the signal of the oxygen sensor by digital signal processing is described. Clinical measurements on 16 patients are presented, whose metabolic rate early after extracorporal circulation was measured. The results reveal, that 4.4 hours after ECC the metabolic rate is close to the calculated basic metabolic rate. They demonstrate the importance of indirect calorimetry as a future bedside monitoring routine.

  8. Similarities and differences between the solar wind light noble gas compositions determined on Apollo 15 SWC foils and on NASA Genesis targets

    NASA Astrophysics Data System (ADS)

    Vogel, N.; Bochsler, P.; Bühler, F.; Heber, V. S.; Grimberg, A.; Baur, H.; Horstmann, M.; Bischoff, A.; Wieler, R.

    2015-10-01

    We compare the solar wind (SW) He, Ne, and Ar compositions collected during the Apollo Solar Wind Composition (SWC) experiments (1969-1972; Al- & Pt-foils) and the Genesis mission (2002-2004; so-called DOS targets considered here). While published SW 20Ne/22Ne and 36Ar/38Ar ratios of both data sets agree, differences exist in the 4He/3He, 4He/20Ne, and 20Ne/36Ar ratios. However, 20Ne/36Ar ratios from Apollo-16 Pt-foils, exclusively adopted as SW values by the SWC team, are consistent with the Genesis results. We investigate if the differences indicate a variability of the SW over the course of about 30 yr, or systematic biases of the two data sets, which were collected in different environments and measured several decades apart in different laboratories (University of Bern; ETH Zurich). New measurements of Apollo-15 SWC aluminum foils in Zurich generally agree with the original measurements performed in Bern. Zurich samples show slightly lower 4He concentrations suggesting a few percent of diffusive loss of 4He during storage of the foils. A 3% difference between the He isotopic ratios measured in Bern and in Zurich possibly represents an analytical bias between the laboratories. The low SW 4He/20Ne and 20Ne/36Ar ratios in Apollo-15 Al-foils compared to Genesis data are consistent with a mixture of Genesis-like SW and noble gases from small amounts of lunar dust. Our data suggest that the mean SW He, Ne, and Ar isotopic and elemental compositions have not significantly changed between the overall Apollo and Genesis mission collection periods.

  9. Upgrade to the Cryogenic Hydrogen Gas Target Monitoring System

    NASA Astrophysics Data System (ADS)

    Slater, Michael; Tribble, Robert

    2013-10-01

    The cryogenic hydrogen gas target at Texas A&M is a vital component for creating a secondary radioactive beam that is then used in experiments in the Momentum Achromat Recoil Spectrometer (MARS). A stable beam from the K500 superconducting cyclotron enters the gas cell and some incident particles are transmuted by a nuclear reaction into a radioactive beam, which are separated from the primary beam and used in MARS experiments. The pressure in the target chamber is monitored so that a predictable isotope production rate can be assured. A ``black box'' received the analog pressure data and sent RS232 serial data through an outdated serial connection to an outdated Visual Basic 6 (VB6) program, which plotted the chamber pressure continuously. The black box has been upgraded to an Arduino UNO microcontroller [Atmel Inc.], which can receive the pressure data and output via USB to a computer. It has been programmed to also accept temperature data for future upgrade. A new computer program, with updated capabilities, has been written in Python. The software can send email alerts, create audible alarms through the Arduino, and plot pressure and temperature. The program has been designed to better fit the needs of the users. Funded by DOE and NSF-REU Program.

  10. Optical methods for monitoring harmful gas in animal facilities

    NASA Astrophysics Data System (ADS)

    Zhang, Shirui; Dong, Daming; Zheng, Wengang; Wang, Jihua

    2014-06-01

    Animal facilities produce large amounts of harmful gases such as ammonia, hydrogen sulfide, and methane, many of which have a pungent odor. The harmful gases produced by animal housing not only affect the health of people and livestock but also pollute the air. The detection of the harmful gases can effectively improve efficiency of livestock production and reduce environmental pollution. More and more optical detection methods are applied to the detection of the harmful gases produced by animal housing. This summarizes optical detection methods for monitoring the harmful gases in animal housing recently, including nondispersive infrared gas analyzer, ultraviolet differential optical absorption spectroscopy, Fourier transform infrared spectroscopy, and tunable diode laser absorption spectroscopy. The basic principle and the characteristics of these methods are illustrated and the applications on the detection of harmful gases in animal housing are described. Meanwhile, the research of harmful gases monitoring for livestock production based on these methods were listed. The current situation and future development of the detection methods for harmful gases generated by animal housing were summarized by comparing the advantages and disadvantages of each method.

  11. Using integrated noble gas and hydrocarbon geochemistry to constrain the source of hydrocarbon gases in shallow aquifers in the northern Appalachian Basin

    EPA Pesticide Factsheets

    Rising demands for domestic energy sources, mandates for cleaner burning fuels for electricity generation, and the approach of peak global hydrocarbon production are driving the transformation from coal to natural gas from unconventional energy resources.

  12. Howardite Noble Gases as Indicators of Asteroid Surface Processing

    NASA Technical Reports Server (NTRS)

    Cartwright, J. A.; Mittlefehldt, D. W.; Herrin, J. S.; Ott, U.

    2011-01-01

    The HED (Howardite, Eucrite and Diogenite) group meteorites likely or iginate from the Asteroid 4 Vesta - one of two asteroid targets of NA SA's Dawn mission. Whilst Howardites are polymict breccias of eucriti c and diogenitic material that often contain "regolithic" petrologica l features, neither their exact regolithic nature nor their formation processes are well defined. As the Solar Wind (SW) noble gas compon ent is implanted onto surfaces of solar system bodies, noble gas anal yses of Howardites provides a key indicator of regolithic origin. In addition to SW, previous work by suggested that restricted Ni (300-12 00 micro g/g) and Al2O3 (8-9 wt%) contents may indicate an ancient we ll-mixed regolith. Our research combines petrological, compositional and noble gas analyses to help improve understanding of asteroid reg olith formation processes, which will play an intergral part in the i nterpretation of Dawn mission data. Following compositional and petrological analyses, we developed a regolith grading scheme for our sampl e set of 30 Howardites and polymict Eucrites. In order to test the r egolith indicators suggested by, our 8 selected samples exhibited a r ange of Ni, Al2O3 contents and regolithic grades. Noble gas analyses were performed using furnace stepheating on our MAP 215-50 noble gas mass spectrometer. Of our 8 howardites, only 3 showed evidence of SW noble gases (e.g approaching Ne-20/Ne-22 approximately equals 13.75, Ne-21/Ne-22 approximately equals 0.033). As these samples display low regolithic grades and a range of Ni and Al2O3 contents, so far we are unable to find any correlation between these indicators and "regolit hic" origin. These results have a number of implications for both Ho wardite and Vesta formation, and may suggest complex surface stratigr aphies and surface-gardening processes.

  13. 77 FR 70159 - Marble River, LLC v. Noble Clinton Windpark I, LLC, Noble Ellenburg Windpark, LLC, Noble...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-23

    ... Energy Regulatory Commission Marble River, LLC v. Noble Clinton Windpark I, LLC, Noble Ellenburg Windpark..., Marble River, LLC (Marble River or Complainant) filed a formal complaint against Noble Clinton Windpark I... pay Marble River for headroom created by common system upgrade facilities that benefit Noble and...

  14. Noble metals in oncology

    PubMed Central

    Markowska, Anna; Jaszczyńska-Nowinka, Karolina; Lubin, Jolanta; Markowska, Janina

    2015-01-01

    Worldwide research groups are searching for anticancer compounds, many of them are organometalic complexes having platinum group metals as their active centers. Most commonly used cytostatics from this group are cisplatin, carboplatin and oxaliplatin. Cisplatin was used fot the first time in 1978, from this time many platinum derivatives were created. In this review we present biological properties and probable future clinical use of platinum, gold, silver, iridium and ruthenium derivatives. Gold derivative Auranofin has been studied extensively. Action of silver nanoparticles on different cell lines was analysed. Iridium isotopes are commonly used in brachyterapy. Ruthenium compound new anti-tumour metastasis inhibitor (NAMI-A) is used in managing lung cancer metastases. Electroporation of another ruthenium based compound KP1339 was also studied. Most of described complexes have antiproliferative and proapoptotic properties. Further studies need to be made. Nevertheless noble metal based chemotherapheutics and compounds seem to be an interesting direction of research. PMID:26557773

  15. Contiuous gas monitoring at the volcano Galeras, Colombia

    NASA Astrophysics Data System (ADS)

    Faber, E.; Morán, C.; Poggenburg, J.; Garzón, G.; Teschner, M.; Weinlich, F. H.

    2003-04-01

    (1) Federal Institute for Geosciences and Natural Resources, Hannover, Germany (e.faber@bgr.de), (2) Instituto de Investigación en Geocientifica, Mineroambiental y Nuclear - INGEOMINAS, San Juan de Pasto, Colombia (3) Instituto de Investigación en Geocientifica, Mineroambiental y Nuclear - INGEOMINAS, Manizales, Colombia A gas monitoring system has been installed on the volcano Galeras in Colombia as part of a multi-parameter station. Gases are extracted from the fumarolic vapour through a short pipe. After the water has been condensed the gas passes over sensors for carbon dioxide, sulphur dioxide and radon. Other parameters measured are temperature of the fumarolic vapour, fumarolic pressure, temperature of the ambient air and the ambient atmospheric pressure. The signals of the sensors are digitised in the electronics. The digital data are transmitted every 6 seconds by a telemetry system to the observatory down in the city of Pasto via a repeater station at the rim of the Galeras. The system at the volcano is powered by batteries connected to solar panels. Data are stored in the observatory, they are plotted and compared with all the other information of the multi-parameter station. Although the various compounds of the gas system are well preserved for the very aggressive environment close to the fumarole some problems still remain: Sulphur often plugs the pipe to the sensors and requires maintenance more often than desired. As the volcano is most of the time in clouds the installed solar power system (about 400 Watts maximum power) does not enable to run the system at the fumarole (consumption about 15 Watts) continuously during all nights. Despite these still existing problems some results have been obtained encouraging us to continue the operation of the system, to further develop the technical quality and to increase the number of fumaroles included into a growing monitoring network. In March 2000 seismic activity in the crater increased accompanied by a

  16. Noble gases in the moon

    NASA Technical Reports Server (NTRS)

    Manuel, O. K.; Srinivasan, B.; Hennecke, E. W.; Sinclair, D. E.

    1972-01-01

    The abundance and isotopic composition of helium, neon, argon, krypton, and xenon which were released by stepwise heating of lunar fines (15601.64) and (15271.65) were measured spectrometrically. The results of a composition of noble gases released from the lunar fines with noble gases in meteorites and in the earth are presented along with the isotopic composition of noble gases in lunar fines, in meteorites, and in the atmosphere. A study of two isotopically distinct components of trapped xenon in carbonaceous chondrites is also included.

  17. Results of Vapor Space Monitoring of Flammable Gas Watch List Tanks

    SciTech Connect

    MCCAIN, D.J.

    2000-09-27

    This report documents the measurement of headspace gas concentrations and monitoring results from the Hanford tanks that have continuous flammable gas monitoring. The systems used to monitor the tanks are Standard Hydrogen Monitoring Systems. Further characterization of the tank off-gases was done with Gas Characterization systems and vapor grab samples. The background concentrations of all tanks are below the action level of 6250 ppm. Other information which can be derived from the measurements (such as generation rate, released rate, and ventilation rate) is also discussed.

  18. Results of vapor space monitoring of flammable gas Watch List tanks

    SciTech Connect

    Wilkins, N.E.

    1997-09-18

    This report documents the measurement of headspace gas concentrations and monitoring results from the Hanford tanks that have continuous flammable gas monitoring. The systems used to monitor the tanks are Standard Hydrogen Monitoring Systems. Further characterization of the tank off-gases was done with Gas Characterization Systems and vapor grab samples. The background concentrations of all tanks are below the action level of 6250 ppm. Other information which can be derived from the measurements (such as generation rate, release rate, and ventilation rate) is also discussed.

  19. A mathematical model for the release of noble gas and Cs from porous nuclear fuel based on VEGA 1&2 experiments

    NASA Astrophysics Data System (ADS)

    Simones, M. P.; Reinig, M. L.; Loyalka, S. K.

    2014-05-01

    Release of fission products from nuclear fuel in accidents is an issue of major concern in nuclear reactor safety, and there is considerable room for development of improved models, supported by experiments, as one needs to understand and elucidate role of various phenomena and parameters. The VEGA (Verification Experiments of radionuclides Gas/Aerosol release) program on several irradiated nuclear fuels investigated the release rates of radionuclides and results demonstrated that the release rates of radionuclides from all nuclear fuels tested decreased with increasing external gas pressure surrounding the fuel. Hidaka et al. (2004-2011) accounted for this pressure effect by developing a 2-stage diffusion model describing the transport of radionuclides in porous nuclear fuel. We have extended this 2-stage diffusion model to account for mutual binary gas diffusion in the open pores as well as to introduce the appropriate parameters to cover the slip flow regime (0.01 ⩽ Kn ⩽ 0.1). While we have directed our numerical efforts toward the simulation of the VEGA experiments and assessments of differences from the results of Hidaka et al., the model and the techniques reported here are of larger interest as these would aid in modeling of diffusion in general (e.g. in graphite and other nuclear materials of interest).

  20. On the origin of noble gases in mantle plumes.

    PubMed

    Coltice, Nicolas; Ricard, Yanick

    2002-11-15

    The chemical differences between deep- and shallow-mantle sources of oceanic basalts provide evidence that several distinct components coexist within the Earth's mantle. Most of these components have been identified as recycled in origin. However, the noble-gas signature is still a matter of debate and questions the preservation of primitive regions in the convective mantle. We show that a model where the noble-gas signature observed in Hawaii and Iceland comes from a pristine homogeneous deep layer would imply a primitive (3)He content and (3)He/(22)Ne ratio that are very unlikely. On the contrary, mass balances show that the partly degassed peridotite of a marble-cake mantle can be the noble-gas end-member with an apparent 'primitive'-like composition. This component is mixed with recycled oceanic crust in different proportions in the plume sources and in the shallow mantle. A recycling model of the mantle, involving gravitational segregation of the oceanic crust at the bottom of the mantle, potentially satisfies trace-element as well as noble-gas constraints.

  1. Leakage detection of Marcellus Shale natural gas at an Upper Devonian gas monitoring well: a 3-d numerical modeling approach.

    PubMed

    Zhang, Liwei; Anderson, Nicole; Dilmore, Robert; Soeder, Daniel J; Bromhal, Grant

    2014-09-16

    Potential natural gas leakage into shallow, overlying formations and aquifers from Marcellus Shale gas drilling operations is a public concern. However, before natural gas could reach underground sources of drinking water (USDW), it must pass through several geologic formations. Tracer and pressure monitoring in formations overlying the Marcellus could help detect natural gas leakage at hydraulic fracturing sites before it reaches USDW. In this study, a numerical simulation code (TOUGH 2) was used to investigate the potential for detecting leaking natural gas in such an overlying geologic formation. The modeled zone was based on a gas field in Greene County, Pennsylvania, undergoing production activities. The model assumed, hypothetically, that methane (CH4), the primary component of natural gas, with some tracer, was leaking around an existing well between the Marcellus Shale and the shallower and lower-pressure Bradford Formation. The leaky well was located 170 m away from a monitoring well, in the Bradford Formation. A simulation study was performed to determine how quickly the tracer monitoring could detect a leak of a known size. Using some typical parameters for the Bradford Formation, model results showed that a detectable tracer volume fraction of 2.0 × 10(-15) would be noted at the monitoring well in 9.8 years. The most rapid detection of tracer for the leak rates simulated was 81 days, but this scenario required that the leakage release point was at the same depth as the perforation zone of the monitoring well and the zones above and below the perforation zone had low permeability, which created a preferred tracer migration pathway along the perforation zone. Sensitivity analysis indicated that the time needed to detect CH4 leakage at the monitoring well was very sensitive to changes in the thickness of the high-permeability zone, CH4 leaking rate, and production rate of the monitoring well.

  2. On the vibrational linear and nonlinear optical properties of compounds involving noble gas atoms: HXeOXeH, HXeOXeF, and FXeOXeF.

    PubMed

    Avramopoulos, Aggelos; Reis, Heribert; Luis, Josep M; Papadopoulos, Manthos G

    2013-06-30

    The vibrational (hyper)polarizabilities of some selected Xe derivatives are studied in the context of Bishop-Kirtman perturbation theory (BKPT) and numerical finite field methodology. It was found that for this set of rare gas compounds, the static vibrational properties are quite large, in comparison to the corresponding electronic ones, especially those of the second hyperpolarizability. This also holds for the dc-Pockels β(-ω;ω,0), Kerr γ(-ω;ω,0,0) and electric field second harmonic generation γ (-2ω;ω,ω,0) effects, although the computed nuclear relaxation (nr) vibrational contributions are smaller in magnitude than the static ones. HXeOXeH was used to study the effects of electron correlation, basis set, and geometry. Geometry effects were found to lead to noticeable changes of the vibrational and electronic second hyperpolarizability. A limited study of the effect of Xe insertion to the nr vibrational properties is also reported. Assessment of the results revealed that Xe insertion has a remarkable effect on the nr (hyper)polarizabilities. In terms of the BKPT, this is associated with a remarkable increase of the electrical and mechanical anharmonicity terms. The latter is consistent with the anharmonic character of several vibrational modes reported for rare gas compounds.

  3. Methane activation using noble gases in a dielectric barrier discharge reactor

    SciTech Connect

    Jo, Sungkwon; Hoon Lee, Dae; Seok Kang, Woo; Song, Young-Hoon

    2013-08-15

    The conversion of methane is measured in a planar-type dielectric barrier discharge reactor using three different noble gases—He, Ne, and Ar—as additives. The empirical results obtained clearly indicate that methane activation is considerably affected by thy type of noble gas used. Through 0-D calculations, the discharge parameters inside the reactor, i.e., electron temperature and electron density, are estimated using experiment results. A comparison of the discharge characteristics and experimental results shows that the electron temperature is an important factor in achieving high methane activation and the mixture with Ar gas shows the highest methane conversion. These results are constructed using the mechanisms of energy and charge transfer from excited and ionized noble gas atoms to methane molecules, considering the number density of active atoms of noble gases. Finally, electron temperatures obtained for gas mixtures having different reactant compositions and concentrations are analyzed to estimate methane activation.

  4. Spectroscopy of low-energy atoms released from a solid noble-gas matrix: Proposal for a trap-loading technique

    SciTech Connect

    Lambo, R.; Rodegheri, C. C.; Silveira, D. M.; Cesar, C. L.

    2007-12-15

    We have studied the velocity distribution of chromium atoms released from a solid neon matrix at cryogenic temperatures via Doppler spectroscopy. The Ne matrix is grown by directing a small flux of gas onto a cold substrate, while Cr atoms are simultaneously implanted by laser ablation, with the resultant plume directed toward the growing matrix. The atoms are then released by a heat pulse. We have observed neutral Cr atoms at temperatures around 13 K with densities close to 10{sup 12} cm{sup -3}. The released atoms have a large initial drift velocity, explained by simple kinetic theory arguments, due to the light species' drag force. The scheme could be adapted to produce cryogenic beams of atoms, molecules, and possibly ions, for collisional studies and spectroscopy. However, our main motivation was the construction of a hydrogen trap, and here we discuss the prospects and problems of using this technique for this purpose.

  5. Long-term autonomous volcanic gas monitoring with Multi-GAS at Mount St. Helens, Washington, and Augustine Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Kelly, P. J.; Ketner, D. M.; Kern, C.; Lahusen, R. G.; Lockett, C.; Parker, T.; Paskievitch, J.; Pauk, B.; Rinehart, A.; Werner, C. A.

    2015-12-01

    In recent years, the USGS Volcano Hazards Program has worked to implement continuous real-time in situ volcanic gas monitoring at volcanoes in the Cascade Range and Alaska. The main goal of this ongoing effort is to better link the compositions of volcanic gases to other real-time monitoring data, such as seismicity and deformation, in order to improve baseline monitoring and early detection of volcanic unrest. Due to the remote and difficult-to-access nature of volcanic-gas monitoring sites in the Cascades and Alaska, we developed Multi-GAS instruments that can operate unattended for long periods of time with minimal direct maintenance from field personnel. Our Multi-GAS stations measure H2O, CO2, SO2, and H2S gas concentrations, are comprised entirely of commercial off-the-shelf components, and are powered by small solar energy systems. One notable feature of our Multi-GAS stations is that they include a unique capability to perform automated CO2, SO2, and H2S sensor verifications using portable gas standards while deployed in the field, thereby allowing for rigorous tracking of sensor performances. In addition, we have developed novel onboard data-processing routines that allow diagnostic and monitoring data - including gas ratios (e.g. CO2/SO2) - to be streamed in real time to internal observatory and public web pages without user input. Here we present over one year of continuous data from a permanent Multi-GAS station installed in August 2014 in the crater of Mount St. Helens, Washington, and several months of data from a station installed near the summit of Augustine Volcano, Alaska in June 2015. Data from the Mount St. Helens Multi-GAS station has been streaming to a public USGS site since early 2015, a first for a permanent Multi-GAS site. Neither station has detected significant changes in gas concentrations or compositions since they were installed, consistent with low levels of seismicity and deformation.

  6. New insight from noble gas and stable isotopes of geothermal/hydrothermal fluids at Caviahue-Copahue Volcanic Complex: Boiling steam separation and water-rock interaction at shallow depth

    NASA Astrophysics Data System (ADS)

    Roulleau, Emilie; Tardani, Daniele; Sano, Yuji; Takahata, Naoto; Vinet, Nicolas; Bravo, Francisco; Muñoz, Carlos; Sanchez, Juan

    2016-12-01

    We measured noble gas and stable isotopes of the geothermal and hydrothermal fluids of the Caviahue-Copahue Volcanic Complex (CCVC), one of the most important geothermal systems in Argentina/Chile, in order to provide new insights into fluid circulation and origin. With the exception of Anfiteatro and Chancho-co geothermal systems, mantle-derived helium dominates in the CCVC fluids, with measured 3He/4He ratios up to 7.86Ra in 2015. Their positive δ15N is an evidence for subducted sediment-derived nitrogen, which is commonly observed in subduction settings. Both He-N2-Ar composition and positive correlation between δD-H2O and δ18O-H2O suggest that the fluids from Anfiteatro and Chancho-co (and partly from Pucon-Mahuida as well, on the southern flank of Copahue volcano) represent a meteoric water composition with a minor magmatic contribution. The Ne, Kr and Xe isotopic compositions are entirely of atmospheric origin, but processes of boiling and steam separation have led to fractionation of their elemental abundances. We modeled the CCVC fluid evolution using Rayleigh distillation curves, considering an initial air saturated geothermal water (ASGW) end-member at 250 and 300 °C, followed by boiling and steam separation at lower temperatures (from 200 °C to 150 °C). Between 2014 and 2015, the CCVC hydrogen and oxygen isotopes shifted from local meteoric water-dominated to andesitic water-dominated signature. This shift is associated with an increase of δ13C values and Stotal, HCl and He contents. These characteristics are consistent with a change in the gas ascent pathway between 2014 and 2015, which in turn induced higher magmatic-hydrothermal contribution in the fluid signature. The composition of the magmatic source of the CCVC fluids is: 3He/4He = 7.7Ra, δ15N = + 6‰, and δ13C = - 6.5‰. Mixing models between air-corrected He and N suggest the involvement of 0.5% to 5% of subducted sediments in the magmatic source. The magmatic sulfur isotopic

  7. Portable Mass Spectrometer System for in-situ Environmental Gas Monitoring

    NASA Technical Reports Server (NTRS)

    Conejo, E.; Griffin, T. P.; Diaz, J. A.; Arkin, C. R.; Soto, C.; Naylor, G. R.; Curley, C.; Floyd, D.

    2005-01-01

    A system developed by NASA has been used for monitoring air quality around different locations. The system was designed for aircraft applications but has proven to be very useful as a portable gas analyzer. The system has been used to monitor air quality around volcanoes, cities, and the surrounding areas. The transport of the system has been via aircraft, car, and hand carried.

  8. Development and testing of a prototype on-line radioiodine monitor for nuclear power stations

    SciTech Connect

    Tseng, T.T.; Jester, W.A.; Baratta, A.J.; McMaster, I.B.; Miller, D.W.

    1986-01-01

    A prototype on-line monitor has been developed which is capable of detecting radioiodine in the presence of as much as 1 X 10(6) higher concentration of noble gases. The system contains two identical radiation monitoring chambers through which the monitored air and a purging gas alternately cycle. Each chamber contains a silver zeolite filter which has a high retention of the various forms of airborne radioiodine but low retention of noble gases. During the purging cycle the radioactive noble gases are quickly purged from the filter and chamber and the lower levels of radioiodine accumulated on the filter are detected. This system has been successfully tested using short-lived radionuclides simulating vented reactor gases resulting from an abnormal condition.

  9. Review of Monitoring Plans for Gas Bubble Disease Signs and Gas Supersaturation Levels on the Columbia and Snake Rivers.

    SciTech Connect

    Fidler, Larry; Elston, Ralph; Colt, John

    1994-07-01

    Montgomery Watson was retained by the Bonneville Power Administration to evaluate the monitoring program for gas bubble disease signs and dissolved gas supersaturation levels on the Columbia and Snake rivers. The results of this evaluation will provide the basis for improving protocols and procedures for future monitoring efforts. Key study team members were Dr. John Colt, Dr. Larry Fidler, and Dr. Ralph Elston. On the week of June 6 through 10, 1994 the study team visited eight monitoring sites (smolt, adult, and resident fish) on the Columbia and Snake rivers. Additional protocol evaluations were conducted at the Willard Field Station (National Biological Survey) and Pacific Northwest Laboratories at Richland (Battelle). On June 13 and 14, 1994, the study team visited the North Pacific Division office of the U.S. Corps of Engineers and the Fish Passage Center to collect additional information and data on the monitoring programs. Considering the speed at which the Gas Bubble Trauma Monitoring Program was implemented this year, the Fish Passage Center and cooperating Federal, State, and Tribal Agencies have been doing an incredible job. Thirty-one specific recommendations are presented in this report and are summarized in Section 14.

  10. Satellite monitoring of trace gas and aerosol emissions during wildfires in Russia

    NASA Astrophysics Data System (ADS)

    Bondur, V. G.

    2016-12-01

    Peculiarities of the formation of carbon gas and fine aerosol emissions into the atmosphere during wildfires are analyzed. A prompt satellite monitoring system and technique for the assessment of burnt areas and volumes of CO2, CO, and PM2.5 emissions from wildfires are described. The results of satellite monitoring of the Russian Federation and some Russian regions for different months over 2010-2014 are given; burnt areas and volumes of carbon gas and aerosol emissions throughout the entire territory are assessed. The peculiarities of seasonal frequencies of wildfires and volumes of hazardous gas and fine aerosol emissions in the regions under study are identified.

  11. Sensitivity of Mach-Zehnder interferometer for dissolved gas monitoring

    NASA Astrophysics Data System (ADS)

    Lindecrantz, Susan; Dullo, Firehun T.; Ahluwalia, Balpreet S.; Hellesø, Olav G.

    2014-03-01

    An integrated optical sensor is developed for measuring gas concentration for subsea and atmospheric applications. The optical sensor is based on a waveguide Mach-Zehnder interferometer (MZI). In MZI, the light is spilt into a sensing and a reference arm and after a certain distance the branches are recombined. The sensing branch is covered with a sensitive layer that has high affinity towards a specified gas. The presence of the gas gives a change in the refractive index of the sensing arm, which is translated into a change in the output signal. With a prior calibration, the change in the output signal is correlated to the gas concentration. The waveguide should be single-mode and it is desirable to have high intensity in the evanescent field. By using a high refractive index material and a thin waveguide core, the intensity of the evanescent field can be enhanced. Simulations are performed to obtain waveguide parameters with low losses and high sensitivity. The maximum sensitivity at wavelength 785 nm was obtained for a waveguide of core thickness 150 nm, rib height 5 nm and width 1 m for TM polarization. The first measurements of phase sensitivity of 12456π rad/RIU was obtain by the Hydrogen Chlorine (HCl) measurement. This is comparable to the phase sensitivity of 14268π rad/RIU obtained by the simulation.μ

  12. Confinement induced binding of noble gas atoms

    NASA Astrophysics Data System (ADS)

    Khatua, Munmun; Pan, Sudip; Chattaraj, Pratim K.

    2014-04-01

    The stability of Ngn@B12N12 and Ngn@B16N16 systems is assessed through a density functional study and ab initio simulation. Although they are found to be thermodynamically unstable with respect to the dissociation of individual Ng atoms and parent cages, ab initio simulation reveals that except Ne2@B12N12 they are kinetically stable to retain their structures intact throughout the simulation time (500 fs) at 298 K. The Ne2@B12N12 cage dissociates and the Ne atoms get separated as the simulation proceeds at this temperature but at a lower temperature (77 K) it is also found to be kinetically stable. He-He unit undergoes translation, rotation and vibration inside the cavity of B12N12 and B16N16 cages. Electron density analysis shows that the He-He interaction in He2@B16N16 is of closed-shell type whereas for the same in He2@B12N12 there may have some degree of covalent character. In few cases, especially for the heavier Ng atoms, the Ng-N/B bonds are also found to have some degree of covalent character. But the Wiberg bond indices show zero bond order in He-He bond and very low bond order in cases of Ng-N/B bonds. The energy decomposition analysis further shows that the ΔEorb term contributes 40.9% and 37.3% towards the total attraction in the He2 dimers having the same distances as in He2@B12N12 and He2@B16N16, respectively. Therefore, confinement causes some type of orbital interaction between two He atoms, which akins to some degree of covalent character.

  13. Complementary optical diagnostics of noble gas plasmas

    NASA Astrophysics Data System (ADS)

    Smith, D. J.; Stewart, R. S.

    2001-10-01

    In this talk we will discuss our theoretical modeling and application of an array of four complementary optical diagnostic techniques for low-temperature plasmas. These are cw laser collisionally induced fluorescence (LCIF), cw optogalvanic effect (OGE), optical emission spectroscopy (OES) and optical absorption spectroscopy (OAS). We will briefly present an overview of our investigation of neon positive column plasmas for reduced axial electrical fields ranging from 3x10-17 Vcm^2 to 2x10-16 Vcm^2 (3-20 Td), detailing our determination of five sets of important collisional rate coefficients involving the fifteen lowest levels, the ^1S0 ground state and the 1s and 2p excited states (in Paschen notation), hence information on several energy regions of the electron distribution function (EDF). The discussion will be extended to show the new results obtained from analysis of the argon positive column over similar reduced fields. Future work includes application of our multi-diagnostic technique to move complex systems, including the addition of molecules for EDF determination.

  14. Biomedical Magnetic Resonance Imaging and Spectroscopy with Laser Polarized Noble Gases

    NASA Astrophysics Data System (ADS)

    Welsh, R. C.; Rosen, M. S.; Coulter, K. P.; Chupp, T. E.; Swanson, S. D.; Agranoff, B. W.; Prince, M. R.

    1996-05-01

    In the past year, a great deal of attention has been drawn to the use of laser polarized noble gases to produce magnetic resonance images of rodent and human lungs. Initial demonstrations proved the principle that air space images can be produced with noble gases polarized to several percent. (The noble gas density is thousands of times smaller, but the noble gas polarization is thousands of times greater than the proton polarization of order 10-5 at 2 Tesla.) The manifold motivations include improvement of pulmonary and circulatory diagnostic radiology techniques as well as study of physiological function including neurological response. We have undertaken a program of development and application of MR imaging and spectroscopy using laser polarized gases with several goals including development of techniques and technologies to facilitate research and eventual medical applications. This talk will describe this multi-disciplinary program combining laser and optical physics, magnetic resonance tomography, neurophysiology and medical science.

  15. Ionization and positronium formation in noble gases

    SciTech Connect

    Marler, J.P.; Sullivan, J.P.; Surko, C.M.

    2005-02-01

    Absolute measurements are presented for the positron-impact cross sections for direct ionization and positronium formation of noble gas atoms in the range of energies from threshold to 90 eV. The experiment uses a cold, trap-based positron beam and the technique of studying positron scattering in a strong magnetic field. The current data show generally good, quantitative agreement with previous measurements taken using a qualitatively different method. However, significant differences in the cross sections for both direct ionization and positronium formation are also observed. An analysis is presented that yields another, independent measurement of the direct ionization and positronium formation cross sections that is in agreement with the present, direct measurements to within {+-}10% for argon, krypton, and xenon. Comparison with available theoretical predictions yields good quantitative agreement for direct ionization cross sections, and qualitative agreement in the case of positronium formation.

  16. Biomedical imaging with hyperpolarized noble gases

    NASA Astrophysics Data System (ADS)

    Ruppert, Kai

    2014-11-01

    Hyperpolarized noble gases (HNGs), polarized to approximately 50% or higher, have led to major advances in magnetic resonance (MR) imaging of porous structures and air-filled cavities in human subjects, particularly the lung. By boosting the available signal to a level about 100 000 times higher than that at thermal equilibrium, air spaces that would otherwise appear as signal voids in an MR image can be revealed for structural and functional assessments. This review discusses how HNG MR imaging differs from conventional proton MR imaging, how MR pulse sequence design is affected and how the properties of gas imaging can be exploited to obtain hitherto inaccessible information in humans and animals. Current and possible future imaging techniques, and their application in the assessment of normal lung function as well as certain lung diseases, are described.

  17. A new online exhaust gas monitoring system in hydrochloric acid regeneration of cold rolling mills.

    PubMed

    Tuo, Long; Zheng, Xiang; Chen, Xiong

    2015-07-07

    Measuring the content of hydrogen chloride (HCl) in exhaust gas used to take time and energy. In this paper, we introduce a new online monitoring system which can output real-time data to the monitoring center. The system samples and cools exhaust gas, and after a series of processing, it will be analyzed by a specific instrument. The core part of this system is remote terminal unit (RTU) which is designed on Cortex-A8 embedded architecture. RTU runs a scaled-down version of Linux which is a good choice of OS for embedded applications. It controls the whole processes, does data acquisition and data analysis, and communicates with monitoring center through Ethernet. In addition, through a software developed for windows, the monitoring process can be remotely controlled. The new system is quite beneficial for steel industry to do environment monitoring.

  18. Recent Experimental Advances to Determine (noble) Gases in Waters

    NASA Astrophysics Data System (ADS)

    Kipfer, R.; Brennwald, M. S.; Huxol, S.; Mächler, L.; Maden, C.; Vogel, N.; Tomonaga, Y.

    2013-12-01

    In aquatic systems noble gases, radon, and bio-geochemically conservative transient trace gases (SF6, CFCs) are frequently applied to determine water residence times and to reconstruct past environmental and climatic conditions. Recent experimental breakthroughs now enable ● to apply the well-established concepts of terrestrial noble gas geochemistry in waters to the minute water amounts stored in sediment pore space and in fluid inclusions (A), ● to determine gas exchange processes on the bio-geochemical relevant time scales of minutes - hours (B), and ● to separate diffusive and advective gas transport in soil air (C). A. Noble-gas analysis in water samples (< 1 g) facilitates determining the solute transport in the pore space and identifying the origin of bio- and geogenic fluids in (un) consolidated sediments [1]. Advanced techniques that combine crushing and sieving speleothem samples in ultra-high-vacuum to a specific grain size allow to separate air and water-bearing fluid inclusions and thus enables noble-gas-based reconstruction of environmental conditions from water masses as small as 1mg [2]. B. The coupling of noble gas analysis with approaches of gas chromatography permits combined analysis of noble gases and other gases species (e.g., SF6, CFCs, O2, N2) from a single water sample. The new method substantially improves ground water dating by SF6 and CFCs as excess air is quantified from the same sample and hence can adequately be corrected for [3]. Portable membrane-inlet mass spectrometers enable the quasi-continuous and real-time analysis of noble gases and other dissolved gases directly in the field, allowing, for instance, quantification of O2 turnover rates on small time scales [4]. C. New technical developments perfect 222Rn analysis in water by the synchronous the determination of the short-lived 220Rn. The combined 220,222Rn analysis sheds light on the emanation behaviour of radon by identifying soil water content to be the crucial

  19. Environmental Monitoring and the Gas Industry: Program Manager Handbook

    SciTech Connect

    Gregory D. Gillispie

    1997-12-01

    This document has been developed for the nontechnical gas industry manager who has the responsibility for the development of waste or potentially contaminated soil and groundwater data or must make decisions based on such data for the management or remediation of these materials. It explores the pse of common analytical chemistry instrumentation and associated techniques for identification of environmentally hazardous materials. Sufficient detail is given to familiarize the nontechnical reader with the principles behind the operation of each technique. The scope and realm of the techniques and their constituent variations are portrayed through a discussion of crucial details and, where appropriate, the depiction of real-life data. It is the author's intention to provide an easily understood handbook for gas industry management. Techniques which determine the presence, composition, and quantification of gas industry wastes are discussed. Greater focus is given to traditional techniques which have been the mainstay of modem analytical benchwork. However, with the continual advancement of instrumental principles and design, several techniques have been included which are likely to receive greater attention in fiture considerations for waste-related detection. Definitions and concepts inherent to a thorough understanding of the principles common to analytical chemistry are discussed. It is also crucial that gas industry managers understand the effects of the various actions which take place before, during, and after the actual sampling step. When a series of sample collection, storage, and transport activities occur, new or inexperienced project managers may overlook or misunderstand the importance of the sequence. Each step has an impact on the final results of the measurement process; errors in judgment or decision making can be costly. Specific techniques and methodologies for the collection, storage, and transport of environmental media samples are not described or

  20. Assessment and Design of Water Quality Monitoring Networks with respect to Shale Gas Activities in Pennsylvania

    NASA Astrophysics Data System (ADS)

    Arjmand, S.; Abad, J. D.; Brantley, S. L.

    2013-12-01

    Over the past few years, hydraulic fracturing and horizontal drilling techniques have been extensively used to extract shale gas from the Marcellus Shale. Likewise, several environmental violations that have been repeatedly reported in drilling sites have created greater awareness on potentially adverse environmental impacts of shale gas. Long-term monitoring in the Marcellus Shale is the key to maintain and improve the quality of water supplies in future. Currently, the absence of an efficient water quality monitoring network prevents the detection and source identification of contaminants associated with shale gas activities. Evaluation and re-design of monitoring networks from time to time is a major step towards efficient water resources planning and management. In this study, we assessed the performance of the current water quality monitoring network with respect to the shale gas development in Pennsylvania. For better evaluation, the Oil and Gas Compliance Report by the Pennsylvania Department of Environmental Protection between January 2005 and May 2013 was compiled. Using statistical and GIS methods each violation item was examined against the number and location of sensors in the current monitoring network. The results helped identify the adequacy of the number of sensors to detect the potential contamination. Moreover, to improve the performance and to lower the long-term monitoring costs, we re-designed the network using optimization methods. This optimal system maximizes the understanding of the aquifer condition and investigates the shale gas industry impacts on shallow aquifers, and it is applicable to other watersheds with shale oil and gas drilling activities.

  1. The future of gas turbine compliance monitoring: The integration of PEMS and CEMS for regulatory compliance

    SciTech Connect

    Macak, J.J. III

    1999-07-01

    When the New Source Performance Standards (NSPS) for Stationary Gas Turbines were first promulgated in 1979 (40 CFR 60, Subpart GG), continuous compliance monitoring for gas turbines was simply a parametric monitoring approach where a unit was tested at four load conditions. For those units where water or steam injection was used for NO{sub x} control, testing consisted of establishing a water (or steam injection) versus fuel flow curve to achieve permitted NO{sub x} emission levels across the load range. Since 1979, the growth in gas turbine popularity has encouraged the development of Predictive Emissions Monitoring Systems (PEMS) where gas turbine operating parameters and ambient conditions are fed into a prediction algorithm to predict, rather than monitor, emissions. However, permitting requirements and technological advances now have gas turbines emitting NO{sub x} in the single digits while the overall combined-cycle thermal efficiency has improved dramatically. The combination of supplemental duct-firing in heat recovery steam generators, pollution prevention technology, post-combustion emission controls, and EPA Continuous Emissions Monitoring System (CEMS) regulations for the power industry, resulted in a shift towards CEMS due to the complexity of the overall process. Yet, CEMS are often considered to be a maintenance nightmare with significant amounts of downtime. CEMS and PEMS have their own advantages and disadvantages. Thus evolved the need to find the optimum balance between CEMS and PEMS for gas turbine projects. To justify the cost of both PEMS and CEMS in the same installation, there must be an economic incentive to do so. This paper presents the application of a PEMS/CEMS monitoring system that integrates both PEMS and CEMS in order to meet, and exceed, all emissions monitoring requirements.

  2. An in situ method for real-time monitoring of soil gas diffusivity

    NASA Astrophysics Data System (ADS)

    Laemmel, Thomas; Maier, Martin; Schack-Kirchner, Helmer; Lang, Friederike

    2016-04-01

    Soil aeration is an important factor for the biogeochemistry of soils. Generally, gas exchange between soil and atmosphere is assumed to be governed by molecular diffusion and by this way fluxes can be calculated using by Fick's Law. The soil gas diffusion coefficient DS represents the proportional factor between the gas flux and the gas concentration gradient in the soil and reflects the ability of the soil to "transport passively" gas through the soil. One common way to determine DS is taking core samples in the field and measuring DS in the lab. Unfortunately this method is destructive and laborious and it can only reflect a small fraction of the whole soil. As a consequence, uncertainty about the resulting effective diffusivity on the profile scale, i.e. the real aeration status remains. We developed a method to measure and monitor DS in situ. The set-up consists of a custom made gas sampling device, the continuous injection of an inert tracer gas and inverse gas transport modelling in the soil. The gas sampling device has seven sampling depths (from 0 to -43 cm of depth) and can be easily installed into vertical holes drilled by an auger, which allows for fast installation of the system. Helium (He) as inert tracer gas was injected continuously at the lower end of the device. The resulting steady state distribution of He was used to deduce the DS depth distribution of the soil. For Finite Element Modeling of the gas-sampling-device/soil system the program COMSOL was used. We tested our new method both in the lab and in a field study and compared the results with a reference lab method using soil cores. DS profiles obtained by our in-situ method were consistent with DS profiles determined based on soil core analyses. Soil gas profiles could be measured with a temporal resolution of 30 minutes. During the field study, there was an important rain event and we could monitor the decrease in soil gas diffusivity in the top soil due to water infiltration. The effect

  3. Oxygen adsorption at noble metal/TiO2 junctions

    NASA Astrophysics Data System (ADS)

    Hossein-Babaei, F.; Alaei-Sheini, Navid; Lajvardi, Mehdi M.

    2016-03-01

    Electric conduction in titanium dioxide is known to be oxygen sensitive and the conductivity of a TiO2 ceramic body is determined mainly by the concentration of its naturally occurring oxygen vacancy. Recently, fabrications and electronic features of a number of noble metal/TiO2-based electronic devices, such as solar cells, UV detectors, gas sensors and memristive devices have been demonstrated. Here, we investigate the effect of oxygen adsorption at the noble metal/TiO2 junction in such devices, and show the potentials of these junctions in chemical sensor fabrication. The polycrystalline, poly-phase TiO2 layers are grown by the selective and controlled oxidation of titanium thin films vacuum deposited on silica substrates. Noble metal thin films are deposited on the oxide layers by physical vapor deposition. Current-voltage (I-V) diagrams of the fabricated devices are studied for Ag/, Au/, and Pt/TiO2 samples. The raw samples show no junction energy barrier. After a thermal annealing in air at 250° C, I-V diagrams change drastically. The annealed samples demonstrate highly non-linear I-V indicating the formation of high Schottky energy barriers at the noble metal/TiO2 junctions. The phenomenon is described based on the effect of the oxygen atoms adsorbed at the junction.

  4. Laboratory Connections--Gas Monitoring Transducers Part III: Combustible Gas Sensors.

    ERIC Educational Resources Information Center

    Powers, Michael H.; Dahman, Doug

    1989-01-01

    Describes an interface that uses semiconductor metal oxides to detect low gas concentrations. Notes the detector has long life, high stability, good reproducibility, low cost, and is able to convert the gas concentration to an electrical signal with a simple circuit. Theory, schematic, and applications are provided. (MVL)

  5. Stellar condensates in meteorites - Isotopic evidence from noble gases

    NASA Technical Reports Server (NTRS)

    Lewis, R. S.; Alaerts, L.; Matsuda, J.-I.; Anders, E.

    1979-01-01

    The Murchison carbonaceous chondrite contains three isotopically anomalous noble-gas components of apparently presolar origin: two kinds of Ne-E, (Ne-20)/(Ne-22) less than 0.6, and s-process Kr + Xe (enriched in the even isotopes 82, 84, 86, 128, 130, 132). Their carriers are tentatively identified as spinel and two carbonaceous phases, the principal high-temperature stellar condensates at low and high C/O ratios, respectively.

  6. Realization of administration unit for 3He with gas recycling

    NASA Astrophysics Data System (ADS)

    Güldner, M.; Becker, S.; Friesenecker, A.; Gast, K. K.; Heil, W.; Karpuk, S.; Otten, E. W.; Rivoire, J.; Salhi, Z.; Scholz, A.; Schreiber, L. M.; Terekhov, M.; Weiss, P.; Wolf, U.; Zentel, J.

    2011-06-01

    Hyperpolarized (HP) noble gases (3He,129Xe) are used for MR-imaging of the lung. In the majority of case the HP gas is filled in Tedlarbags and directly inhaled by the patients. Starting from an earlier pilot device, an administration unit was built respectively to the Medical Devices Law to administer patients HP noble gas boli in defined quantities and at a predefined time during inspiration with high reproducibility and reliability without reducing MR-quality. The patient's airflows are monitored and recorded. It is possible to use gas admixtures, measure the polarization on-line and collect the exhaled gas for later recycling. The first images with healthy volunteers were taken with this setup in a clinical study. Current results will be presented.

  7. Method For Enhanced Gas Monitoring In High Density Flow Streams

    DOEpatents

    Von Drasek, William A.; Mulderink, Kenneth A.; Marin, Ovidiu

    2005-09-13

    A method for conducting laser absorption measurements in high temperature process streams having high levels of particulate matter is disclosed. An impinger is positioned substantially parallel to a laser beam propagation path and at upstream position relative to the laser beam. Beam shielding pipes shield the beam from the surrounding environment. Measurement is conducted only in the gap between the two shielding pipes where the beam propagates through the process gas. The impinger facilitates reduced particle presence in the measurement beam, resulting in improved SNR (signal-to-noise) and improved sensitivity and dynamic range of the measurement.

  8. Monitoring of nitropolycyclic aromatic hydrocarbons in food using gas chromatography.

    PubMed

    Schlemitz, S; Pfannhauser, W

    1996-07-01

    Nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) were determined in different kinds of food. The investigation of food matrices necessitates the development of appropriate analytical procedures for sensitive monitoring and determination of these compounds. The analysis of the nitro-PAHs was carried out by GC/MSD, GC plus mass spectrometry, and GC/NPD (nitrogen-phosphorus detection) GC plus nitrogen-phosphorus detection. Seven nitro-PAHs were positively identified and quantified in vegetables, smoked and grilled foods, oil, tea, coffee and spices.

  9. Electrochemical amperometric gas sensors for environmental monitoring and control

    NASA Technical Reports Server (NTRS)

    Venkatasetty, H. V.

    1990-01-01

    Theoretical considerations and experimental results regarding a unique class of vapor sensors are presented, and the sensors are compared to semiconductor-based sensors. The electrochemical sensors are based on nonaquaeous electrolytes, and gas-detection selectivity achieved by applying a known potential to the sensing electrode using a reference electrode and a counter electrode. Results are given regarding the detection of oxygen and carbon dioxide using one cell, the detection of 3-percent carbon dioxide in nitrogen, and the detection of carbon dioxide in air at percentages ranging from 3 to 6. The sensors are found to be effective in the detection of toxic chemical species including CO, NO2, and formaldehyde; the sensors are further found to require minimal power, operate over long periods of time, and function over a wide temperature range.

  10. Monitoring temperature for gas turbine blade: correction of reflection model

    NASA Astrophysics Data System (ADS)

    Gao, Shan; Wang, Lixin; Feng, Chi; Xiao, Yihan; Daniel, Ketui

    2015-06-01

    For a gas turbine blade working in a narrow space, the accuracy of blade temperature measurements is greatly impacted by environmental irradiation. A reflection model is established by using discrete irregular surfaces to calculate the angle factor between the blade surface and the hot adjacent parts. The model is based on the rotational angles and positions of the blades, and can correct for measurement error caused by background radiation when the blade is located at different rotational positions. This method reduces the impact of reflected radiation on the basis of the turbine's known geometry and the physical properties of the material. The experimental results show that when the blade temperature is 911.2±5 K and the vane temperature ranges from 1011.3 to 1065.8 K, the error decreases from 4.21 to 0.75%.

  11. Statistical methods to monitor the West Valley off-gas system

    SciTech Connect

    Eggett, D.L.

    1990-10-01

    The off-gas system for the ceramic melter operated at the West Valley Demonstration Project at West Valley, NY, is monitored during melter operation. A one-at-a-time method of monitoring the parameters of the off-gas system is not statistically sound. Therefore, multivariate statistical methods appropriate for the monitoring of many correlated parameters will be used. Monitoring a large number of parameters increases the probability of a false out-of-control signal. If the parameters being monitored are statistically independent, the control limits can be easily adjusted to obtain the desired probability of a false out-of-control signal. However, a high degree of correlation generally exists among the parameters being monitored in the off-gas system. This makes it very difficult to control the probability of false calls (saying the system is out-of-control when it is in-control or saying the system is in-control when it is actually out-of-control). The interpretation of the individual control charts is difficult in the presence of correlation among the variables. When a high degree of correlation exists, variable reduction techniques can be used to reduce the number of parameters. Principal components have been used as a variable reduction technique. The principal component (PC) scores have desirable statistical properties when the original variables are distributed as multivariate normals. Two statistics derived from the PC scores and used to form multivariate control charts are outlined and their distributional properties reviewed. 2 refs., 2 figs.

  12. Novel method for online monitoring of dissolved N2O concentrations through a gas stripping device.

    PubMed

    Mampaey, Kris E; van Dongen, Udo G J M; van Loosdrecht, Mark C M; Volcke, Eveline I P

    2015-01-01

    Nitrous oxide emissions from wastewater treatment plants are currently measured by online gas phase analysis or grab sampling from the liquid phase. In this study, a novel method is presented to monitor the liquid phase N2O concentration for aerated as well as non-aerated conditions/reactors, following variations both in time and in space. The monitoring method consists of a gas stripping device, of which the measurement principle is based on a continuous flow of reactor liquid through a stripping flask and subsequent analysis of the N2O concentration in the stripped gas phase. The method was theoretically and experimentally evaluated for its fit for use in the wastewater treatment context. Besides, the influence of design and operating variables on the performance of the gas stripping device was addressed. This method can easily be integrated with online off-gas measurements and allows to better investigate the origin of the gas emissions from the treatment plant. Liquid phase measurements of N2O are of use in mitigation of these emissions. The method can also be applied to measure other dissolved gasses, such as methane, being another important greenhouse gas.

  13. High-Resolution Gas Metering and Nonintrusive Appliance Load Monitoring System

    NASA Astrophysics Data System (ADS)

    Tewolde, Mahder

    This thesis deals with design and implementation of a high-resolution metering system for residential natural gas meters. Detailed experimental measurements are performed on the meter to characterize and understand its measurement properties. Results from these experiments are used to develop a simple, fast and accurate technique to non-intrusively monitor the gas consumption of individual appliances in homes by resolving small amounts of gas usage. The technique is applied on an existing meter retrofitted with a module that includes a high-resolution encoder to collect gas flow data and a microprocessor to analyze and identify appliance load profiles. This approach provides a number of appealing features including low cost, easy installation and integration with automated meter reading (AMR) systems. The application of this method to residential gas meters currently deployed is also given. This is done by performing a load simulation on realistic gas loads with the aim of identifying the necessary parameters that minimize the cost and complexity of the mechanical encoder module. The primary benefits of the system are efficiency analysis, appliance health monitoring and real-time customer feedback of gas usage. Additional benefits of include the ability to detect very small leaks and theft. This system has the potential for wide scale market adoption.

  14. A gas filter correlation monitor for CO, CH4, and HCl

    NASA Technical Reports Server (NTRS)

    Sebacher, D. I.

    1977-01-01

    A fast response instrument for monitoring the atmospheric constituents CO, CH4, and HCl, using a modified nondispersive infrared technique, was designed, assembled, and tested. This gas filter correlation method uses a sample of gas to provide a selective filter for radiation absorbed in a gas mixture containing the specified gas. Depending on the spectral line broadening, temperature, and optical depth of the gas selected, exceptionally high spectral resolution may be attained. A description of the single beam rotating cell system and its specific application is presented along with the signal processing circuit. Calibrations of the instrument show that the technique can be used to measure CO, CH4, and HCl concentrations as small as 5 ppm-m. A field version was employed to measure diurnal variations of CO and CH4 and the interfering effects of other atmospheric gases were analyzed.

  15. Estimates of in situ gas hydrate concentration from resistivity monitoring of gas hydrate bearing sediments during temperature equilibration

    USGS Publications Warehouse

    Riedel, M.; Long, P.E.; Collett, T.S.

    2006-01-01

    As part of Ocean Drilling Program Leg 204 at southern Hydrate Ridge off Oregon we have monitored changes in sediment electrical resistivity during controlled gas hydrate dissociation experiments. Two cores were used, each filled with gas hydrate bearing sediments (predominantly mud/silty mud). One core was from Site 1249 (1249F-9H3), 42.1 m below seafloor (mbsf) and the other from Site 1248 (1248C-4X1), 28.8 mbsf. At Site 1247, a third experiment was conducted on a core without gas hydrate (1247B-2H1, 3.6 mbsf). First, the cores were imaged using an infra-red (IR) camera upon recovery to map the gas hydrate occurrence through dissociation cooling. Over a period of several hours, successive runs on the multi-sensor track (includes sensors for P-wave velocity, resistivity, magnetic susceptibility and gamma-ray density) were carried out complemented by X-ray imaging on core 1249F-9H3. After complete equilibration to room temperature (17-18??C) and complete gas hydrate dissociation, the final measurement of electrical resistivity was used to calculate pore-water resistivity and salinities. The calculated pore-water freshening after dissociation is equivalent to a gas hydrate concentration in situ of 35-70% along core 1249F-9H3 and 20-35% for core 1248C-4X1 assuming seawater salinity of in situ pore fluid. Detailed analysis of the IR scan, X-ray images and split-core photographs showed the hydrate mainly occurred disseminated throughout the core. Additionally, in core 1249F-9H3, a single hydrate filled vein, approximately 10 cm long and dipping at about 65??, was identified. Analyses of the logging-while-drilling (LWD) resistivity data revealed a structural dip of 40-80?? in the interval between 40 and 44 mbsf. We further analyzed all resistivity data measured on the recovered core during Leg 204. Generally poor data quality due to gas cracks allowed analyses to be carried out only at selected intervals at Sites 1244, 1245, 1246, 1247, 1248, 1249, and 1252. With a few

  16. Isotope Ratio Monitoring Gas Chromatography Mass Spectrometry (IRM-GCMS)

    NASA Technical Reports Server (NTRS)

    Freeman, K. H.; Ricci, S. A.; Studley, A.; Hayes, J. M.

    1989-01-01

    On Earth, the C-13 content of organic compounds is depleted by roughly 13 to 23 permil from atmospheric carbon dioxide. This difference is largely due to isotope effects associated with the fixation of inorganic carbon by photosynthetic organisms. If life once existed on Mars, then it is reasonable to expect to observe a similar fractionation. Although the strongly oxidizing conditions on the surface of Mars make preservation of ancient organic material unlikely, carbon-isotope evidence for the existence of life on Mars may still be preserved. Carbon depleted in C-13 could be preserved either in organic compounds within buried sediments, or in carbonate minerals produced by the oxidation of organic material. A technique is introduced for rapid and precise measurement of the C-13 contents of individual organic compounds. A gas chromatograph is coupled to an isotope-ratio mass spectrometer through a combustion interface, enabling on-line isotopic analysis of isolated compounds. The isotope ratios are determined by integration of ion currents over the course of each chromatographic peak. Software incorporates automatic peak determination, corrections for background, and deconvolution of overlapped peaks. Overall performance of the instrument was evaluated by the analysis of a mixture of high purity n-alkanes of know isotopic composition. Isotopic values measured via IRM-GCMS averaged withing 0.55 permil of their conventionally measured values.

  17. Large-Scale Wireless Temperature Monitoring System for Liquefied Petroleum Gas Storage Tanks

    PubMed Central

    Fan, Guangwen; Shen, Yu; Hao, Xiaowei; Yuan, Zongming; Zhou, Zhi

    2015-01-01

    Temperature distribution is a critical indicator of the health condition for Liquefied Petroleum Gas (LPG) storage tanks. In this paper, we present a large-scale wireless temperature monitoring system to evaluate the safety of LPG storage tanks. The system includes wireless sensors networks, high temperature fiber-optic sensors, and monitoring software. Finally, a case study on real-world LPG storage tanks proves the feasibility of the system. The unique features of wireless transmission, automatic data acquisition and management, local and remote access make the developed system a good alternative for temperature monitoring of LPG storage tanks in practical applications. PMID:26393596

  18. Large-Scale Wireless Temperature Monitoring System for Liquefied Petroleum Gas Storage Tanks.

    PubMed

    Fan, Guangwen; Shen, Yu; Hao, Xiaowei; Yuan, Zongming; Zhou, Zhi

    2015-09-18

    Temperature distribution is a critical indicator of the health condition for Liquefied Petroleum Gas (LPG) storage tanks. In this paper, we present a large-scale wireless temperature monitoring system to evaluate the safety of LPG storage tanks. The system includes wireless sensors networks, high temperature fiber-optic sensors, and monitoring software. Finally, a case study on real-world LPG storage tanks proves the feasibility of the system. The unique features of wireless transmission, automatic data acquisition and management, local and remote access make the developed system a good alternative for temperature monitoring of LPG storage tanks in practical applications.

  19. Comparison of photoacoustic radiometry to gas chromatography/mass spectrometry methods for monitoring chlorinated hydrocarbons

    SciTech Connect

    Sollid, J.E.; Trujillo, V.L.; Limback, S.P.; Woloshun, K.A.

    1996-03-01

    A comparison of two methods of gas chromatography mass spectrometry (GCMS) and a nondispersive infrared technique, photoacoustic radiometry (PAR), is presented in the context of field monitoring a disposal site. First is presented an historical account describing the site and early monitoring to provide an overview. The intent and nature of the monitoring program changed when it was proposed to expand the Radiological Waste Site close to the Hazardous Waste Site. Both the sampling methods and analysis techniques were refined in the course of this exercise.

  20. Designing optimal greenhouse gas monitoring networks for Australia

    NASA Astrophysics Data System (ADS)

    Ziehn, T.; Law, R. M.; Rayner, P. J.; Roff, G.

    2016-01-01

    Atmospheric transport inversion is commonly used to infer greenhouse gas (GHG) flux estimates from concentration measurements. The optimal location of ground-based observing stations that supply these measurements can be determined by network design. Here, we use a Lagrangian particle dispersion model (LPDM) in reverse mode together with a Bayesian inverse modelling framework to derive optimal GHG observing networks for Australia. This extends the network design for carbon dioxide (CO2) performed by Ziehn et al. (2014) to also minimise the uncertainty on the flux estimates for methane (CH4) and nitrous oxide (N2O), both individually and in a combined network using multiple objectives. Optimal networks are generated by adding up to five new stations to the base network, which is defined as two existing stations, Cape Grim and Gunn Point, in southern and northern Australia respectively. The individual networks for CO2, CH4 and N2O and the combined observing network show large similarities because the flux uncertainties for each GHG are dominated by regions of biologically productive land. There is little penalty, in terms of flux uncertainty reduction, for the combined network compared to individually designed networks. The location of the stations in the combined network is sensitive to variations in the assumed data uncertainty across locations. A simple assessment of economic costs has been included in our network design approach, considering both establishment and maintenance costs. Our results suggest that, while site logistics change the optimal network, there is only a small impact on the flux uncertainty reductions achieved with increasing network size.

  1. Ocean observatory networks monitor gas hydrates systems - Updates from Cascadia

    NASA Astrophysics Data System (ADS)

    Scherwath, M.; Kelley, D. S.; Moran, K.; Philip, B. T.; Roemer, M.; Riedel, M.; Solomon, E. A.; Spence, G.; Heesemann, M.

    2015-12-01

    Seafloor observatories have been installed at the Cascadia margin with a long-term (>20 year) lifespan. These observatories consist of a variety of node locations cabled back to shore for continuous power and communication to instruments via high bandwidth internet access. Ocean Networks Canada (ONC) maintains two hydrate sites at Barkley Canyon and Clayoquot Slope off Vancouver Island, and the Ocean Observatories Initiative (OOI) Cabled Array connects to Hydrate Ridge off the Oregon coast. Together, these installations comprise a diverse suite of different experiments. For example, a seafloor crawler, operated by Jacobs University in Bremen, travels around the Barkley hydrate mounds on a daily basis and carries out a suite of measurements such as determining the rate of change of the benthic community composition. Another example is from several years of hourly sonar data showing gas bubbles rising from the seafloor near the Bullseye Vent with varying intensities, allowing statistically sound correlations with other seafloor parameters such as ground shaking, temperature and pressure variations and currents, where tidal pressure appearing as the main driver. The Southern Hydrate Ridge is now equipped with the world's first long-term seafloor mass spectrometer, co-located with a camera and lights, hydrophone, current meters, pressure sensor, autonomous dissolved oxygen and fluid samplers, and is surrounded by a seismometer array for local seismicity. In the future, long-term data will be continuously captured and made available throughout the year covering the full range of variations of the dynamic hydrate system, and expect additional experiments to be connected to the observatories from the broader research community.

  2. Feasibility of monitoring gas hydrate production with time-lapse VSP

    SciTech Connect

    Kowalsky, M.B.; Nakagawa, S.; Moridis, G.J.

    2009-11-01

    In this work we begin to examine the feasibility of using time-lapse seismic methods-specifically the vertical seismic profiling (VSP) method-for monitoring changes in hydrate accumulations that are predicted to occur during production of natural gas.

  3. GREENHOUSE GAS (GHG) MITIGATION AND MONITORING TECHNOLOGY PERFORMANCE: ACTIVITIES OF THE GHG TECHNOLOGY VERIFICATION CENTER

    EPA Science Inventory

    The paper discusses greenhouse gas (GHG) mitigation and monitoring technology performance activities of the GHG Technology Verification Center. The Center is a public/private partnership between Southern Research Institute and the U.S. EPA's Office of Research and Development. It...

  4. A Three Dimensional Beam Profile Monitor Based on Residual Gas Ionization

    SciTech Connect

    Lewis, T.A.; Shapira, D.

    1998-11-04

    A three-dimensional beam profile monitor based on tracking the ionization of the residual gas molecules in the evacuated beam pipe is described. Tracking in position and time of the ions and electrons produced in the ionization enables simultaneous position sampling in three dimensions. Special features which make it possible to sample very low beam currents were employed.

  5. Limitations of a residual gas ionization beam profile monitor for the SSC Collider

    SciTech Connect

    Meinke, R.; Nexsen, W.; Tsyganov, E.; Zinchenko, A.

    1992-11-01

    A residual gas ionization beam profile monitor for the superconducting Super Collider is considered in detail using the Monte Carlo simulation code. It is shown that a good spatial resolution could be obtained using a combination of strong electrical and magnetic fields.

  6. New Hadron Monitor By Using A Gas-Filled RF Resonator

    SciTech Connect

    Yonehara, Katsuya; Fasce, Giorgio; Flanagan, Gene; Johnson, Rolland; Tollestrup, Alvin; Zwaska, Robert

    2015-05-01

    It is trend to build an intense neutrino beam facility for the fundamental physics research, e.g. LBNF at Fermilab, T2K at KEK, and CNGS at CERN. They have investigated a hadron monitor to diagnose the primary/secondary beam quality. The existing hadron monitor based on an ionization chamber is not robust in the high-radiation environment vicinity of MW-class secondary particle production targets. We propose a gas-filled RF resonator to use as the hadron monitor since it is simple and hence radiation robust in this environment. When charged particles pass through the resonator they produce ionized plasma via the Coulomb interaction with the inert gas. The beam-induced plasma changes the permittivity of inert gas. As a result, a resonant frequency in the resonator shifts with the amount of ionized electrons. The radiation sensitivity is adjustable by the inert gas pressure and the RF amplitude. The hadron profile will be reconstructed with a tomography technique in the hodoscope which consists of X, Y, and theta layers by using a strip-shaped gas resonator. The sensitivity and possible system design will be shown in this presentation.

  7. Monitoring for methane gas in Carbon and Emery Counties, Utah, 1995-2003

    USGS Publications Warehouse

    Burr, Andrew L.; Stolp, Bernard J.; Johnson, Kevin K.; Hunt, Gilbert L.

    2006-01-01

    The release of methane gas from coal beds creates the potential for it to move into near-surface environments through natural and human-made pathways. To help ensure the safety of communities and determine the potential effects of development of coal-bed resources, methane gas concentrations in soils and ground water in Carbon and Emery Counties, Utah, were monitored from 1995 to 2003. A total of 420 samples were collected, which contained an average methane concentration of 2,740 parts per million by volume (ppmv) and a median concentration of less than 10 ppmv. On the basis of spatial and temporal methane concentration data collected during the monitoring period, there does not appear to be an obvious, widespread, or consistent migration of methane gas to the near-surface environment.

  8. Gas hydrate environmental monitoring program in the Ulleung Basin, East Sea of Korea

    NASA Astrophysics Data System (ADS)

    Ryu, Byong-Jae; Chun, Jong-Hwa; McLean, Scott

    2013-04-01

    As a part of the Korean National Gas Hydrate Program, the Korea Institute of Geoscience and Mineral Resources (KIGAM) has been planned and conducted the environmental monitoring program for the gas hydrate production test in the Ulleung Basin, East Sea of Korea in 2014. This program includes a baseline survey using a KIGAM Seafloor Observation System (KISOS) and R/V TAMHAE II of KIGAM, development of a KIGAM Seafloor Monitoring System (KIMOS), and seafloor monitoring on various potential hazards associated with the dissociated gas from gas hydrates during the production test. The KIGAM also plans to conduct the geophysical survey for determining the change of gas hydrate reservoirs and production-efficiency around the production well before and after the production test. During production test, release of gas dissociated from the gas hydrate to the water column, seafloor deformation, changes in chemical characteristics of bottom water, changes in seafloor turbidity, etc. will be monitored by using the various monitoring instruments. The KIMOS consists of a near-field observation array and a far-field array. The near-field array is constructed with four remote sensor platforms each, and cabled to the primary node. The far-field sensor array will consists of four autonomous instrument pods. A scientific Remotely Operated Vehicle (ROV) will be used to deploy the sensor arrays, and to connect the cables to each field instrument package and a primary node. A ROV will also be tasked to collect the water and/or gas samples, and to identify any gas (bubble) plumes from the seafloor using a high-frequency sector scanning sonar. Power to the near-field instrument packages will be supplied by battery units located on the seafloor near the primary node. Data obtained from the instruments on the near-field array will be logged and downloaded in-situ at the primary node, and transmitted real-time to the support vessel using a ROV. These data will also be transmitted real-time to

  9. Gas Filled RF Resonator Hadron Beam Monitor for Intense Neutrino Beam Experiments

    SciTech Connect

    Yonehara, Katsuya; Abrams, Robert; Dinkel, Holly; Freemire, Ben; Johnson, Rolland; Kazakevich, Grigory; Tollestrup, Alvin; Zwaska, Robert

    2016-06-01

    MW-class beam facilities are being considered all over the world to produce an intense neutrino beam for fundamental particle physics experiments. A radiation-robust beam monitor system is required to diagnose the primary and secondary beam qualities in high-radiation environments. We have proposed a novel gas-filled RF-resonator hadron beam monitor in which charged particles passing through the resonator produce ionized plasma that changes the permittivity of the gas. The sensitivity of the monitor has been evaluated in numerical simulation. A signal manipulation algorithm has been designed. A prototype system will be constructed and tested by using a proton beam at the MuCool Test Area at Fermilab.

  10. Noble metal reforming of naphtha

    SciTech Connect

    Bonacci, J.C.; Patterson, J.R.

    1981-09-29

    Conventional noble metal reforming to upgrade the octane number of petroleum naphtha is an endothermic reaction which is carried out in a series of reactors with intermediate furnace heating of the petroleum fraction being upgraded. This specification discloses a process and apparatus configuration to increase the octane number of the reformate at a minimum liquid yield loss by cooling the first reforming stage effluent and then contacting the cooled effluent with a zsm-5 type zeolite catalyst prior to the first intermediate furnace heating.

  11. The record of cosmogenic, radiogenic, fissiogenic, and trapped noble gases in recently recovered Chinese and other chondrites

    NASA Astrophysics Data System (ADS)

    Eugster, O.; Michel, Th.; Niedermann, S.; Wang, D.; Yi, W.

    1993-03-01

    Noble-gas isotopic abundances were determined in 36 recently recovered chondrites including 27 chondrites recovered in China. The comparison of the release patterns of trapped noble gases from ordinary and from carbonaceous chondrites showed that the planetary trapped noble gases in ordinary chondrites were released mainly above 1200 C, whereas more than 85 percent of noble gases trapped in carbonaceous chondrites were released at or below 1200 C, indicating that the carrier phases of the trapped noble gases in ordinary and in carbonaceous chondrites may not be the same. It is suggested that the ordinary chondrites started to retain fission Xe about 48 +/- 30 Ma earlier than Angra dos Reis. No systematic differences were observed between H, L, and LL or type 5 and 6 chondrites with respect to the time of fission Xe retention. Eight chondrites displayed neutron capture effects due to secondary cosmic-ray-produced neutrons.

  12. Ground gas monitoring: implications for hydraulic fracturing and CO2 storage.

    PubMed

    Teasdale, Christopher J; Hall, Jean A; Martin, John P; Manning, David A C

    2014-12-02

    Understanding the exchange of carbon dioxide (CO2) and methane (CH4) between the geosphere and atmosphere is essential for the management of anthropogenic emissions. Human activities such as carbon capture and storage and hydraulic fracturing ("fracking") affect the natural system and pose risks to future global warming and to human health and safety if not engineered to a high standard. In this paper an innovative approach of expressing ground gas compositions is presented, using data derived from regulatory monitoring of boreholes in the unsaturated zone at infrequent intervals (typically 3 months) with data from a high frequency monitoring instrument deployed over periods of weeks. Similar highly variable trends are observed for time scales ranging from decades to hourly for boreholes located close to sanitary landfill sites. Additionally, high frequency monitoring data confirm the effect of meteorological controls on ground gas emissions; the maximum observed CH4 and CO2 concentrations in a borehole monitored over two weeks were 40.1% v/v and 8.5% v/v respectively, but for 70% of the monitoring period only air was present. There is a clear weakness in current point monitoring strategies that may miss emission events and this needs to be considered along with obtaining baseline data prior to starting any engineering activity.

  13. Enabling Technology for Monitoring & Predicting Gas Turbine Health & Performance in IGCC Powerplants

    SciTech Connect

    Kenneth A. Yackly

    2005-12-01

    The ''Enabling & Information Technology To Increase RAM for Advanced Powerplants'' program, by DOE request, was re-directed, de-scoped to two tasks, shortened to a 2-year period of performance, and refocused to develop, validate and accelerate the commercial use of enabling materials technologies and sensors for coal/IGCC powerplants. The new program was re-titled ''Enabling Technology for Monitoring & Predicting Gas Turbine Health & Performance in IGCC Powerplants''. This final report summarizes the work accomplished from March 1, 2003 to March 31, 2004 on the four original tasks, and the work accomplished from April 1, 2004 to July 30, 2005 on the two re-directed tasks. The program Tasks are summarized below: Task 1--IGCC Environmental Impact on high Temperature Materials: The first task was refocused to address IGCC environmental impacts on high temperature materials used in gas turbines. This task screened material performance and quantified the effects of high temperature erosion and corrosion of hot gas path materials in coal/IGCC applications. The materials of interest included those in current service as well as advanced, high-performance alloys and coatings. Task 2--Material In-Service Health Monitoring: The second task was reduced in scope to demonstrate new technologies to determine the inservice health of advanced technology coal/IGCC powerplants. The task focused on two critical sensing needs for advanced coal/IGCC gas turbines: (1) Fuel Quality Sensor to rapidly determine the fuel heating value for more precise control of the gas turbine, and detection of fuel impurities that could lead to rapid component degradation. (2) Infra-Red Pyrometer to continuously measure the temperature of gas turbine buckets, nozzles, and combustor hardware. Task 3--Advanced Methods for Combustion Monitoring and Control: The third task was originally to develop and validate advanced monitoring and control methods for coal/IGCC gas turbine combustion systems. This task was

  14. Research on coal-mine gas monitoring system controlled by annealing simulating algorithm

    NASA Astrophysics Data System (ADS)

    Zhou, Mengran; Li, Zhenbi

    2007-12-01

    This paper introduces the principle and schematic diagram of gas monitoring system by means of infrared method. Annealing simulating algorithm is adopted to find the whole optimum solution and the Metroplis criterion is used to make iterative algorithm combination optimization by control parameter decreasing aiming at solving large-scale combination optimization problem. Experiment result obtained by the performing scheme of realizing algorithm training and flow of realizing algorithm training indicates that annealing simulating algorithm applied to identify gas is better than traditional linear local search method. It makes the algorithm iterate to the optimum value rapidly so that the quality of the solution is improved efficiently. The CPU time is shortened and the identifying rate of gas is increased. For the mines with much-gas gushing fatalness the regional danger and disaster advanced forecast can be realized. The reliability of coal-mine safety is improved.

  15. Gas Bubble Disease Monitoring and Research of Juvenile Salmonids : Annual Report 1996.

    SciTech Connect

    Maule, Alec G.; Beeman, John W.; Hans, Karen M.; Mesa, M.G.; Haner, P.; Warren, J.J.

    1997-10-01

    This document describes the project activities 1996--1997 contract year. This report is composed of three chapters which contain data and analyses of the three main elements of the project: field research to determine the vertical distribution of migrating juvenile salmonids, monitoring of juvenile migrants at dams on the Snake and Columbia rivers, and laboratory experiments to describe the progression of gas bubble disease signs leading to mortality. The major findings described in this report are: A miniature pressure-sensitive radio transmitter was found to be accurate and precise and, after compensation for water temperature, can be used to determine the depth of tagged-fish to within 0.32 m of the true depth (Chapter 1). Preliminary data from very few fish suggest that depth protects migrating juvenile steelhead from total dissolved gas supersaturation (Chapter 1). As in 1995, few fish had any signs of gas bubble disease, but it appeared that prevalence and severity increased as fish migrated downstream and in response to changing gas supersaturation (Chapter 2). It appeared to gas bubble disease was not a threat to migrating juvenile salmonids when total dissolved gas supersaturation was < 120% (Chapter 2). Laboratory studies suggest that external examinations are appropriate for determining the severity of gas bubble disease in juvenile salmonids (Chapter 3). The authors developed a new method for examining gill arches for intravascular bubbles by clamping the ventral aorta to reduce bleeding when arches were removed (Chapter 3). Despite an outbreak of bacterial kidney disease in the experimental fish, the data indicate that gas bubble disease is a progressive trauma that can be monitored (Chapter 3).

  16. Dynamics of strong-field laser-induced microplasma formation in noble gases

    SciTech Connect

    Romanov, D. A.; Compton, R.; Filin, A.; Levis, R. J.

    2010-03-15

    The ultrafast dynamics of microplasmas generated by femtosecond laser pulses in noble gases has been investigated using four-wave mixing (FWM). The time dependence of the FWM signal is observed to reach higher intensity levels faster for Xe, with progressively lower scattering intensity and longer time dynamics for the noble gas series Xe, Kr, Ar, Ne, and He. The temporal dynamics is interpreted in terms of a tunnel ionization and impact cooling mechanism. A formalism to interpret the observed phenomena is presented here with comparison to the measured laser intensity and gas pressure trends.

  17. Integrated gas analyzer for complete monitoring of turbine engine test cells.

    PubMed

    Markham, James R; Bush, Patrick M; Bonzani, Peter J; Scire, James J; Zaccardi, Vincent A; Jalbert, Paul A; Bryant, M Denise; Gardner, Donald G

    2004-01-01

    Fourier transform infrared (FT-IR) spectroscopy is proving to be reliable and economical for the quantification of many gas-phase species during testing and development of gas turbine engines in ground-based facilities such as sea-level test cells and altitude test cells. FT-IR measurement applications include engine-generated exhaust gases, facility air provided as input to engines, and ambient air in and around test cells. Potentially, the traditionally used assembly of many gas-specific single gas analyzers will be eliminated. However, the quest for a single instrument capable of complete gas-phase monitoring at turbine engine test cells has previously suffered since the FT-IR method cannot measure infrared-inactive oxygen molecules, a key operational gas to both air-breathing propulsion systems and test cell personnel. To further the quest, the FT-IR sensor used for the measurements presented in this article was modified by integration of a miniature, solid-state electrochemical oxygen sensor. Embedded in the FT-IR unit at a location near the long-effective-optical-path-length gas sampling cell, the amperometric oxygen sensor provides simultaneous, complementary information to the wealth of spectroscopic data provided by the FT-IR method.

  18. Continued Development of Compact Multi-Gas Monitor for Life Support Systems Control in Space

    NASA Technical Reports Server (NTRS)

    Delgado, Jesus; Phillips, Straun; Chullen, Cinda

    2015-01-01

    Miniature optic gas sensors (MOGS) based on luminescent materials have shown great potential as alternatives to NIR-based gas sensor systems for the Portable Life Support System (PLSS). The unique capability of MOGS for carbon dioxide and oxygen monitoring under wet conditions has been reported, as has the fast recovery of MOGS humidity sensors after long periods of being wet. Lower volume and power requirements are also potential advantages of MOGS over both traditional and advanced Non-Dispersive Infrared (NDIR) gas sensors, which have shown so far longer life than luminescent sensors. In this paper we present the most recent results in the development and analytical validation of a compact multi-gas sensor unit based on luminescent sensors for the PLSS. Results of extensive testing are presented, including studies conducted at Intelligent Optical Systems laboratories, a United Technology Corporation Aerospace Systems (UTAS) laboratory, and a Johnson Space Center laboratory. The potential of this sensor technology for gas monitoring in PLSSs and other life support systems and the advantages and limitations found through detailed sensor validation are discussed.

  19. Continued Development of Compact Multi-gas Monitor for Life Support Systems Control in Space

    NASA Technical Reports Server (NTRS)

    Delgado-Alonso, Jesús; Phillips, Straun; Chullen, Cinda; Quinn, Gregory

    2016-01-01

    Miniature optic gas sensors (MOGS) based on luminescent materials have shown great potential as alternatives to Near-Infrared-based gas sensor systems for the advanced space suit portable life support system (PLSS). The unique capability of MOGS for carbon dioxide and oxygen monitoring under wet conditions has been reported, as has the fast recovery of MOGS humidity sensors after long periods of being wet. Lower volume and power requirements are also potential advantages of MOGS over both traditional and advanced Non-Dispersive Infrared (NDIR) gas sensors, which have shown so far longer life than luminescent sensors. This paper presents the most recent results in the development and analytical validation of a compact multi-gas sensor unit based on luminescent sensors for the PLSS. Results of extensive testing are presented, including studies conducted at Intelligent Optical Systems laboratories, a United Technology Corporation Aerospace Systems (UTAS) laboratory, and a Johnson Space Center laboratory. The potential of this sensor technology for gas monitoring in PLSSs and other life support systems and the advantages and limitations found through detailed sensor validation are discussed.

  20. Preconcentration modeling for the optimization of a micro gas preconcentrator applied to environmental monitoring.

    PubMed

    Camara, Malick; Breuil, Philippe; Briand, Danick; Viricelle, Jean-Paul; Pijolat, Christophe; de Rooij, Nico F

    2015-04-21

    This paper presents the optimization of a micro gas preconcentrator (μ-GP) system applied to atmospheric pollution monitoring, with the help of a complete modeling of the preconcentration cycle. Two different approaches based on kinetic equations are used to illustrate the behavior of the micro gas preconcentrator for given experimental conditions. The need for high adsorption flow and heating rate and for low desorption flow and detection volume is demonstrated in this paper. Preliminary to this optimization, the preconcentration factor is discussed and a definition is proposed.

  1. Underground Fiber-Optic Differential Absorption Instrument for Monitoring Carbon Dioxide Soil Gas Concentrations for Carbon Sequestration Site Monitoring

    NASA Astrophysics Data System (ADS)

    Nehrir, A. R.; Humphries, S. D.; Repasky, K. S.; Carlsten, J. L.; Spangler, L. H.; Dobeck, L. M.

    2007-12-01

    The burning of fossil fuels has resulted in higher carbon dioxide (CO2) concentrations in the atmosphere with potential impacts on the Earth's climate. The use of fossil fuels is predicted to grow over the next several decades with the potential for further increasing the atmospheric concentration of CO2. A proposed method of diminishing the impacts of increased CO2 on the Earth's climate is to capture and store the CO2 in geologic storage sites. One issue with underground sequestration of CO2 is the ability to monitor sequestration sites to verify the integrity of the storage of the CO2. An underground fiber optic differential absorption instrument based on a tunable distributed feedback (DFB) diode laser is being developed at Montana State University to detect small changes in CO2 soil gas concentration in an effort to monitor the overall integrity of the sequestration storage site. The fiber optic instrument exploits the 2003-2006 nm region of the spectrum which contains four CO2 absorption lines. Light from the DFB laser is delivered to an underground absorption cell one meter in length via a single mode optical fiber. The normalized transmission is measured by tuning the DFB diode laser across these four absorption lines and the results are used to determine the CO2 soil gas concentration. A description of this instrument will be presented including the instrument design, operation, and performance characteristics. A field site for testing the performance of CO2 detection instruments and techniques has been developed by the Zero Emissions Research Technology (ZERT) group at Montana State University. The field site allows a controlled flow rate of CO2 to be released underground through a 100 m long horizontal pipe placed below the water table. Two release experiments were performed this past summer with flow rates of 0.1 and 0.3 tons CO2/day. The first release experiment lasted ten days while the second release lasted seven days. Measurements taken with the

  2. Unraveling fabrication and calibration of wearable gas monitor for use under free-living conditions.

    PubMed

    Yue Deng; Cheng Chen; Tsow, Francis; Xiaojun Xian; Forzani, Erica

    2016-08-01

    Volatile organic compounds (VOC) are organic chemicals that have high vapor pressure at regular conditions. Some VOC could be dangerous to human health, therefore it is important to determine real-time indoor and outdoor personal exposures to VOC. To achieve this goal, our group has developed a wearable gas monitor with a complete sensor fabrication and calibration protocol for free-living conditions. Correction factors for calibrating the sensors, including sensitivity, aging effect, and temperature effect are implemented into a Quick Response Code (QR code), so that the pre-calibrated quartz tuning fork (QTF) sensor can be used with the wearable monitor under free-living conditions.

  3. Novel industrial application: flammable and toxic gas monitoring in the printing industry

    NASA Astrophysics Data System (ADS)

    Jacobson, Esther; Spector, Yechiel

    1999-12-01

    The present paper describes an Open Path Electro-Optical Gas Monitoring System specifically designed for in-situ on-line monitoring of flammable and toxic atmospheres in the Printing Industry in general, and for air-duct applications in particular. The printing industry posies unique fire hazards due to the variety of toxic and flammable chemical employed in the various printing process. Flammable material such as paper, ink, solvents, thinners, metal powders, cornstarch powders, cloth, synthetic materials are frequently used in the printing industry in several processes such as letter-pressing, lithography, screen printing etc.

  4. Monitoring Requirements and Methods for Greenhouse Gas Management and Climate Change Detection

    NASA Astrophysics Data System (ADS)

    Birdsey, R.; Pan, Y.; Clark, K.; Hom, J.

    2007-12-01

    Climate change policy and management require monitoring data to support decision making. Availability of good data about past trends, and projections based on reasonable assumptions and models, can support debate about response options and avoid the pitfall of arguing about information quality. A hierarchical or multi-tier approach to environmental monitoring has been used efficiently for many decades, and can be linked with experiments and process modeling to improve natural resource assessments. Consideration of spatial and temporal scale can align data requirements with the information needed to facilitate separation of causal factors, e.g., factoring out natural effects from human-induced effects on the carbon cycle. Here we describe a 3-tier integrated monitoring hierarchy: intensive process-level monitoring, landscape-scale monitoring, and regional monitoring. Information at each tier may be used independently or integrated across tiers. Methods to integrate information include statistical techniques for diagnostic analysis, and ecosystem models for prognostic analysis. We illustrate the methods and results for each tier using data and analyses for the Pinelands Management Area of New Jersey, a reserved area of 360,000 ha. A cluster of flux towers and associated intensive-site measurements comprises the process monitoring. A network of biometric monitoring sites represents the landscape conditions, and forest inventory with remote sensing is used to characterize the region. This approach is capable of closing the regional carbon budget, i.e., accounting for all exchanges of carbon between the land, atmosphere, and ocean. It is also an excellent platform for monitoring the effects of climate change and factoring out different effects -- the system was designed to provide information about dangerous fire weather and identify needs to manage wildfire fuels. The New Jersey Pinelands site is part of a national network of multi-scale monitoring sites that can meet

  5. DWPF Hydrogen Generation Study-Form of Noble Metal SRAT Testing

    SciTech Connect

    Bannochie, C

    2005-09-01

    The Defense Waste Processing Facility, DWPF, has requested that the Savannah River National Laboratory, SRNL, investigate the factors that contribute to hydrogen generation to determine if current conservatism in setting the DWPF processing window can be reduced. A phased program has been undertaken to increase understanding of the factors that influence hydrogen generation in the DWPF Chemical Process Cell, CPC. The hydrogen generation in the CPC is primarily due to noble metal catalyzed decomposition of formic acid with a minor contribution from radiolytic processes. Noble metals have historically been added as trim chemicals to process simulations. The present study investigated the potential conservatism that might be present from adding the catalytic species as trim chemicals to the final sludge simulant versus co-precipitating the noble metals into the insoluble sludge solids matrix. Two sludge simulants were obtained, one with co-precipitated noble metals and one without noble metals. Co-precipitated noble metals were expected to better match real waste behavior than using trimmed noble metals during CPC simulations. Portions of both sludge simulants were held at 97 C for about eight hours to qualitatively simulate the effects of long term storage on particle morphology and speciation. The two original and two heat-treated sludge simulants were then used as feeds to Sludge Receipt and Adjustment Tank, SRAT, process simulations. Testing was done at relatively high acid stoichiometries, {approx}175%, and without mercury in order to ensure significant hydrogen generation. Hydrogen generation rates were monitored during processing to assess the impact of the form of noble metals. The following observations were made on the data: (1) Co-precipitated noble metal simulant processed similarly to trimmed noble metal simulant in most respects, such as nitrite to nitrate conversion, formate destruction, and pH, but differently with respect to hydrogen generation: (A

  6. Platinum-coated non-noble metal-noble metal core-shell electrocatalysts

    DOEpatents

    Adzic, Radoslav; Zhang, Junliang; Mo, Yibo; Vukmirovic, Miomir

    2015-04-14

    Core-shell particles encapsulated by a thin film of a catalytically active metal are described. The particles are preferably nanoparticles comprising a non-noble core with a noble metal shell which preferably do not include Pt. The non-noble metal-noble metal core-shell nanoparticles are encapsulated by a catalytically active metal which is preferably Pt. The core-shell nanoparticles are preferably formed by prolonged elevated-temperature annealing of nanoparticle alloys in an inert environment. This causes the noble metal component to surface segregate and form an atomically thin shell. The Pt overlayer is formed by a process involving the underpotential deposition of a monolayer of a non-noble metal followed by immersion in a solution comprising a Pt salt. A thin Pt layer forms via the galvanic displacement of non-noble surface atoms by more noble Pt atoms in the salt. The overall process is a robust and cost-efficient method for forming Pt-coated non-noble metal-noble metal core-shell nanoparticles.

  7. CANCELLED Molecular dynamics simulations of noble gases in liquidwater: Solvati on structure, self-diffusion, and kinetic isotopeeffect

    SciTech Connect

    Bourg, I.C.; Sposito, G.

    2007-05-25

    Despite their great importance in low-temperaturegeochemistry, self-diffusion coefficients of noble gas isotopes in liquidwater (D) have been measured only for the major isotopes of helium, neon,krypton and xenon. Data on the self-diffusion coefficients of minor noblegas isotopes are essentially non-existent and so typically are estimatedby a kinetic theory model in which D varies as the inverse square root ofthe isotopic mass (m): D proportional to m-0.5. To examine the validityof the kinetic theory model, we performed molecular dynamics (MD)simulations of the diffusion of noble gases in ambient liquid water withan accurate set of noble gas-water interaction potentials. Our simulationresults agree with available experimental data on the solvation structureand self-diffusion coefficients of the major noble gas isotopes in liquidwater and reveal for the first time that the isotopic mass-dependence ofall noble gas self-diffusion coefficients has the power-law form Dproportional to m-beta with 0noble gasisotopes caused by diffusion in ambient liquid water.

  8. The quest for regolithic howardites. Part 2: Surface origins highlighted by noble gases

    NASA Astrophysics Data System (ADS)

    Cartwright, J. A.; Ott, U.; Mittlefehldt, D. W.

    2014-09-01

    We report noble gas data of helium (He), neon (Ne), argon (Ar), krypton (Kr) and xenon (Xe), cosmic ray exposure (CRE) ages and nominal gas retention (K-Ar, U-Th-He) ages for seven howardites (CRE 01400, EET 87513, EET 87518, EET 99400, GRO 95535, GRO 95602, SAN 03472), in continuing research to identify regolithic samples, and better understand the vestan regolith. In our previous work, we found little correlation between suggested regolith parameters of Ni > 300 μg/g, Al2O3 8-9 wt% and eucrite/diogenite (E:D) ratio of 2:1 (Warren et al., 2009), and trapped solar wind (SW), fractionated solar wind (FSW) or planetary noble gas components (from impacted material) - noble gas indicators of a regolithic origin. Here, we have expanded our data set to include samples outside of these parameters to further explore composition, and the differences in Ni content as indicators for the presence of non-Vesta material. In addition, our sample set includes two potentially paired meteorites from the GRO suite. Finally, in our petrographic studies, the samples selected showed no evidence for carbonaceous chondrite fragments, which should reduce the effect of "contamination" by planetary noble gas components, and will allow us to better identify SW/FSW components, where present. Of the samples studied here, three howardites GRO 95535, GRO 95602 and EET 87513 show evidence for a regolithic origin, with both isotopic and element noble gas ratios clearly pointing to the presence of trapped components similar to SW/FSW or planetary. The two GRO howardites, GRO 95535 and GRO 95602, show similar noble gas ratios to our previously defined SW/FSW dominated regolithic group (LEW 85313 and MET 00423), suggesting a surface origin for these samples. However, interestingly, the GRO samples show vastly different cosmogenic noble gas abundances, and thus different CRE ages, which suggests that they are not paired. For howardite EET 87513, the data hint to the presence of CM-material, with a

  9. Optical Multi-Gas Monitor Technology Demonstration on the International Space Station

    NASA Technical Reports Server (NTRS)

    Pilgrim, Jeffrey S.; Wood, William R.; Casias, Miguel E.; Vakhtin, Andrei B,; Johnson, Michael D.; Mudgett, Paul D.

    2014-01-01

    There are a variety of both portable and fixed gas monitors onboard the International Space Station (ISS). Devices range from rack-mounted mass spectrometers to hand-held electrochemical sensors. An optical Multi-Gas Monitor has been developed as an ISS Technology Demonstration to evaluate long-term continuous measurement of 4 gases. Based on tunable diode laser spectroscopy, this technology offers unprecedented selectivity, concentration range, precision, and calibration stability. The monitor utilizes the combination of high performance laser absorption spectroscopy with a rugged optical path length enhancement cell that is nearly impossible to misalign. The enhancement cell serves simultaneously as the measurement sampling cell for multiple laser channels operating within a common measurement volume. Four laser diode based detection channels allow quantitative determination of ISS cabin concentrations of water vapor (humidity), carbon dioxide, ammonia and oxygen. Each channel utilizes a separate vertical cavity surface emitting laser (VCSEL) at a different wavelength. In addition to measuring major air constituents in their relevant ranges, the multiple gas monitor provides real time quantitative gaseous ammonia measurements between 5 and 20,000 parts-per-million (ppm). A small ventilation fan draws air with no pumps or valves into the enclosure in which analysis occurs. Power draw is only about 3 W from USB sources when installed in Nanoracks or when connected to 28V source from any EXPRESS rack interface. Internal battery power can run the sensor for over 20 hours during portable operation. The sensor is controlled digitally with an FPGA/microcontroller architecture that stores data internally while displaying running average measurements on an LCD screen and interfacing with the rack or laptop via USB. Design, construction and certification of the Multi-Gas Monitor were a joint effort between Vista Photonics, Nanoracks and NASA-Johnson Space Center (JSC

  10. Continuous Seafloor Gas Hydrate Monitoring on the Ocean Networks Canada NEPTUNE Cabled Observatory

    NASA Astrophysics Data System (ADS)

    Scherwath, M.; Heesemann, M.; Moran, K.; Insua, T. L.; Roemer, M.; Riedel, M.; Spence, G.; Thomsen, L.; Purser, A.

    2014-12-01

    Long-term seafloor experiments provide high-resolution data that allow new kinds of observations on the dynamics and variability of gas hydrates. In the north-east Pacific, Canadian as well as US efforts on building cabled seafloor observatories enable the scientific community to study the Cascadia margin gas hydrates at various locations independent of dedicated ship cruises and unstable weather, without power saving restrictions and with near realtime access to the data and the ability to influence the in-situ data acquisition in reaction to events. We show scientific highlights from Barkley Canyon and Clayoquot Slope off Vancouver Island on of the gas hydrate stability and variability on and below the seafloor as well as gas release into the water column, using some standard measurements from core instruments such as temperature, salinity, bottom pressure, currents, as well as sonar, seismometer and camera image data. Correlations of these various data sets shed light on the dependence of the observed gas hydrate dynamics on various environmental factors, some still subject to debate and longer-term monitoring requirements. Global efforts on cabling the seafloor elsewhere are underway and an exciting future on gas hydrate research lies ahead. Ocean Networks Canada invites the research community to participate, propose experiments, download data and collaborate (www.oceannetworks.ca).

  11. Nonequilibrium electron dynamics in noble metals

    NASA Astrophysics Data System (ADS)

    del Fatti, N.; Voisin, C.; Achermann, M.; Tzortzakis, S.; Christofilos, D.; Vallée, F.

    2000-06-01

    Electron-electron and electron-lattice interactions in noble metals are discussed in the light of two-color femtosecond pump-probe measurements in silver films. The internal thermalization of a nonequilibrium electron distribution created by intraband absorption of a pump pulse is followed by probing the induced optical property changes in the vicinity of the frequency threshold for the d band to Fermi surface transitions. This is shown to take place with a characteristic time constant of 350 fs, significantly shorter than previously reported in gold. This difference is ascribed to a weaker screening of the electron-electron interaction by the d-band electrons in silver than in gold. These results are in quantitative agreement with numerical simulations of the electron relaxation dynamics using a reduced static screening of the electron-electron Coulomb interaction, and including bound electron screening. Electron-lattice thermalization has been studied using a probe frequency out of resonance with the interband transitions. In both materials, the transient nonthermal nature of the electron distribution leads to the observation of a short-time delay reduction of the energy-loss rate of the electron gas to the lattice, in very good agreement with our theoretical model.

  12. Laser Spectroscopy Multi-Gas Monitor: Results of Technology Demonstration on ISS

    NASA Technical Reports Server (NTRS)

    Mudgett, Paul D.; Pilgrim, Jeffrey S.

    2015-01-01

    Tunable diode laser spectroscopy (TDLS) is an up and coming trace and major gas monitoring technology with unmatched selectivity, range and stability. The technology demonstration of the 4 gas Multi-Gas Monitor (MGM), reported at the 2014 ICES conference, operated continuously on the International Space Station (ISS) for nearly a year. The MGM is designed to measure oxygen, carbon dioxide, ammonia and water vapor in ambient cabin air in a low power, relatively compact device. While on board, the MGM experienced a number of challenges, unplanned and planned, including a test of the ammonia channel using a commercial medical ammonia inhalant. Data from the unit was downlinked once per week and compared with other analytical resources on board, notably the Major Constituent Analyzer (MCA), a magnetic sector mass spectrometer. MGM spent the majority of the time installed in the Nanoracks Frame 2 payload facility in front breathing mode (sampling the ambient environment of the Japanese Experiment Module), but was also used to analyze recirculated rack air. The capability of the MGM to be operated in portable mode (via internal rechargeable lithium ion polymer batteries or by plugging into any Express Rack 28VDC connector) was a part of the usability demonstration. Results to date show unprecedented stability and accuracy of the MGM vs. the MCA for oxygen and carbon dioxide. The ammonia challenge (approx. 75 ppm) was successful as well, showing very rapid response time in both directions. Work on an expansion of capability in a next generation MGM has just begun. Combustion products and hydrazine are being added to the measurable target analytes. An 8 to 10 gas monitor (aka Gas Tricorder 1.0) is envisioned for use on ISS, Orion and Exploration missions.

  13. Polynomials and Neural Networks for Gas Turbine Monitoring: a Comparative Study

    NASA Astrophysics Data System (ADS)

    Loboda, Igor; Feldshteyn, Yakov

    2011-09-01

    Gas turbine health monitoring includes the common stages of problem detection, fault identification, and prognostics. To extract useful diagnostic information from raw recorded data, these stages require a preliminary operation of computing differences between measurements and an engine baseline, which is a function of engine operating conditions. These deviations of measured values from the baseline data can be good indicators of engine health. However, their quality and the success of all diagnostic stages strongly depend on the adequacy of the baseline model employed and, in particular, on the mathematical techniques applied to create it. To create a baseline model, we have applied polynomials and the least squares method for computing the coefficients over a long period of time. Methods were proposed to enhance such a polynomial-based model. The resulting accuracy was sufficient for reliable monitoring of gas turbine deterioration effects. The polynomials previously investigated thus far are used in the present study as a standard for evaluating artificial neural networks, a very popular technique in gas turbine diagnostics. The focus of this comparative study is to verify whether the use of networks results in a better description of the engine baseline. Extensive field data for two different industrial gas turbines were used to compare these two techniques under various conditions. The deviations were computed for all available data, and the quality of the resulting deviation plots was compared visually. The mean error of the baseline model was used as an additional criterion for comparing the techniques. To find the best network configurations, many network variations were realised and compared with the polynomials. Although the neural networks studied were found to be close to the polynomials in accuracy, they did not exceed the polynomials in any variation. In this way, it seems that polynomials can be successfully used for engine monitoring, at least for

  14. Alpha-beta monitoring system based on pair of simultaneous Multi-Wire Proportional Counters

    NASA Astrophysics Data System (ADS)

    Wengrowicz, U.; Amidan, D.; Orion, I.

    2016-08-01

    A new approach for a simultaneous alpha-beta Multi-wire Proportional Counter (MWPC) is presented. The popular approach for alpha-beta monitoring systems consists of a large area MWPC using noble gas flow such as Argon Methane. This method of measurement is effective but requires large-scale and expensive maintenance due to the needs of gas flow control and periodic replacements. In this work, a pair of simultaneous MWPCs for alpha-beta measuring is presented. The developed detector consists of a sealed gas MWPC sensor for beta particles, behind a free air alpha sensor. This approach allows effective simultaneous detection and discrimination of both alpha and beta radiation without the maintenance cost noble gas flow required for unsealed detectors.

  15. Optical Multi-Gas Monitor Technology Demonstration on the International Space Station

    NASA Technical Reports Server (NTRS)

    Pilgrim, Jeffrey S.; Wood, William R.; Casias, Miguel E.; Vakhtin, Andrei B.; Johnson, Michael D.; Mudgett, Paul D.

    2014-01-01

    The International Space Station (ISS) employs a suite of portable and permanently located gas monitors to insure crew health and safety. These sensors are tasked with functions ranging from fixed mass spectrometer based major constituents analysis to portable electrochemical sensor based combustion product monitoring. An all optical multigas sensor is being developed that can provide the specificity of a mass spectrometer with the portability of an electrochemical cell. The technology, developed under the Small Business Innovation Research program, allows for an architecture that is rugged, compact and low power. A four gas version called the Multi-Gas Monitor was launched to ISS in November 2013 aboard Soyuz and activated in February 2014. The portable instrument is comprised of a major constituents analyzer (water vapor, carbon dioxide, oxygen) and high dynamic range real-time ammonia sensor. All species are sensed inside the same enhanced path length optical cell with a separate vertical cavity surface emitting laser (VCSEL) targeted at each species. The prototype is controlled digitally with a field-programmable gate array/microcontroller architecture. The optical and electronic approaches are designed for scalability and future versions could add three important acid gases and carbon monoxide combustion product gases to the four species already sensed. Results obtained to date from the technology demonstration on ISS are presented and discussed.

  16. Air Monitoring System in Elders' Apartment with QCM Type Gas Sensors

    NASA Astrophysics Data System (ADS)

    Kikuchi, Masashi; Ito, Tsukasa; Shiratori, Seimei

    The gas monitoring system for elders' apartment using QCM sensors was newly developed. The QCM sensors for sulfide gas and ammonia gas were used for this system. The system for bodily wastes was fabricated and applied to nursing care system in elders' apartment. This system is composed by the sensor unit, communication unit and data server. Care person can see whether the linen should be changed or not without seeing over each room. The QCM sensors have some problems such as the interference of humidity and temperature, therefore these influences were dissolved using humidity sensor and temperature sensor as feedback source. The sensors were placed in several points of elders' apartment for 2 weeks. This system can be used in elders' apartment successfully.

  17. Metal oxide nanowire gas sensors for indoor and outdoor environmental monitoring

    NASA Astrophysics Data System (ADS)

    Köck, Anton; Brunet, Elise; Freudenberg, Oliver; Gamauf, Christoph; Kraft, Jochen; Mutinati, Giorgio C.; Maier, Thomas; Nemecek, Alexander; Schrank, Franz; Schrems, Martin; Siegele, Martin; Siegert, Jörg; Steinhauer, Stephan; Teva, Jordi

    2013-05-01

    We present performance results of SnO2 and CuO nanowire gas sensor devices, where single and multi-nanowire device configurations have been employed in order to optimize sensor design. In particular the response to the target gases CO, H2, and H2S has been measured in dry and humid air; both the SnO2 and CuO nanowire sensors are able to detect CO in the low ppm concentration range, which is important for environmental monitoring. The CuO multi-nanowire devices show an extraordinary high response to H2S with sensitivity in the low ppb concentration. We present our developments of CMOS technology based micro-hotplates, which are employed as platform for gas sensitive thin films and nanowires. Potential heterogeneous integration of nanowires on the micro-hotplate chips as well as an approach towards gas sensor arrays is discussed. We conclude that CMOS integrated multi-nanowire gas sensors are highly promising candidates for the practical realization of multi-parameter sensor devices for indoor and outdoor environmental monitoring.

  18. The noble gases: how their electronegativity and hardness determines their chemistry.

    PubMed

    Furtado, Jonathan; De Proft, Frank; Geerlings, Paul

    2015-02-26

    The establishment of an internally consistent scale of noble gas electronegativities is a long-standing problem. In the present study, the problem is attacked via the Mulliken definition, which in recent years gained widespread use to its natural appearance in the context of conceptual density functional theory. Basic ingredients of this scale are the electron affinity and the ionization potential. Whereas the latter can be computed routinely, the instability of the anion makes the judicious choice of computational technique for evaluating electron affinities much more tricky. We opted for Puiatti's approach, extrapolating the energy of high ε solvent stabilized anions to the ε = 1 (gas phase) case. The results give negative electron affinity values, monotonically increasing (except for helium which is an outlier in most of the story) to almost zero at eka-radon in agreement with high level calculations. The stability of the B3LYP results is successfully tested both via improving the level of theory (CCSD(T)) and expanding the basis set. Combined with the ionization energies (in good agreement with experiment), an electronegativity scale is obtained displaying (1) a monotonic decrease of χ when going down the periodic table, (2) top values not for the noble gases but for the halogens, as opposed to most (extrapolation) procedures of existing scales, invariably placing the noble gases on top, and (3) noble gases having electronegativities close to the chalcogens. In the accompanying hardness scale (hardly, if ever, discussed in the literature) the noble gases turn out to be by far the farthest the hardest elements, again with a continuous decrease with increasing Z. Combining χ value of the halogens and the noble gases the Ng(δ+)F(δ-) bond polarity emerging from ab initio calculations naturally emerges. In conclusion, the chemistry of the noble gases is for a large part determined by their extreme hardness, equivalent to a high resistance to change in its

  19. Effect of noble gases on oxygen and glucose deprived injury in human tubular kidney cells.

    PubMed

    Rizvi, Maleeha; Jawad, Noorulhuda; Li, Yuantao; Vizcaychipi, Marcela P; Maze, Mervyn; Ma, Daqing

    2010-07-01

    The noble gas xenon has been shown to be protective in preconditioning settings against renal ischemic injury. The aims of this study were to determine the protective effects of the other noble gases, helium, neon, argon, krypton and xenon, on human tubular kidney HK2 cells in vitro. Cultured human renal tubular cells (HK2) were exposed to noble gas preconditioning (75% noble gas; 20% O(2); 5% CO(2)) for three hours or mock preconditioning. Twenty-four hours after gas exposure, cell injury was provoked with oxygen-glucose deprived (OGD) culture medium for three hours. Cell viability was assessed 24 h post-OGD by a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. Other cohorts of cultured cells were incubated in the absence of OGD in 75% noble gas, 20% O(2) and 5% CO(2) and cellular signals phospho-Akt (p-Akt), hypoxia-inducible factor-1alpha (HIF-1alpha) and Bcl-2 were assessed by Western blotting. OGD caused a reduction in cell viability to 0.382 +/- 0.1 from 1.0 +/- 0.15 at control (P < 0.01). Neon, argon and krypton showed no protection from injury (0.404 +/- 0.03; 0.428 +/- 0.02; 0.452 +/- 0.02; P > 0.05). Helium by comparison significantly enhanced cell injury (0.191 +/- 0.05; P < 0.01). Xenon alone exerted a protective effect (0.678 +/- 0.07; P < 0.001). In the absence of OGD, helium was also detrimental (0.909 +/- 0.07; P < 0.01). Xenon caused an increased expression of p-Akt, HIF-1alpha and Bcl-2, while the other noble gases did not modify protein expression. These results suggest that unlike other noble gases, preconditioning with the anesthetic noble gas xenon may have a role in protection against renal ischemic injury.

  20. Incorporation of noble metals into aerogels

    DOEpatents

    Hair, L.M.; Sanner, R.D.; Coronado, P.R.

    1998-12-22

    Aerogels or xerogels containing atomically dispersed noble metals for applications such as environmental remediation are disclosed. New noble metal precursors, such as Pt--Si or Pd(Si--P){sub 2}, have been created to bridge the incompatibility between noble metals and oxygen, followed by their incorporation into the aerogel or xerogel through sol-gel chemistry and processing. Applications include oxidation of hydrocarbons and reduction of nitrogen oxide species, complete oxidation of volatile organic carbon species, oxidative membranes for photocatalysis and partial oxidation for synthetic applications.

  1. Incorporation of noble metals into aerogels

    DOEpatents

    Hair, Lucy M.; Sanner, Robert D.; Coronado, Paul R.

    1998-01-01

    Aerogels or xerogels containing atomically dispersed noble metals for applications such environmental remediation. New noble metal precursors, such as Pt--Si or Pd(Si--P).sub.2, have been created to bridge the incompatibility between noble metals and oxygen, followed by their incorporation into the aerogel or xerogel through sol-gel chemistry and processing. Applications include oxidation of hydrocarbons and reduction of nitrogen oxide species, complete oxidation of volatile organic carbon species, oxidative membranes for photocatalysis and partial oxidation for synthetic applications.

  2. Enabling Technology for Monitoring & Predicting Gas Turbine Health & Performance in COAL IGCC Powerplants

    SciTech Connect

    Kenneth A. Yackly

    2004-09-30

    The ''Enabling & Information Technology To Increase RAM for Advanced Powerplants'' program, by DOE request, has been re-directed, de-scoped to two tasks, shortened to a 2-year period of performance, and refocused to develop, validate and accelerate the commercial use of enabling materials technologies and sensors for Coal IGCC powerplants. The new program has been re-titled as ''Enabling Technology for Monitoring & Predicting Gas Turbine Health & Performance in IGCC Powerplants'' to better match the new scope. This technical progress report summarizes the work accomplished in the reporting period April 1, 2004 to August 31, 2004 on the revised Re-Directed and De-Scoped program activity. The program Tasks are: Task 1--IGCC Environmental Impact on high Temperature Materials: This first materials task has been refocused to address Coal IGCC environmental impacts on high temperature materials use in gas turbines and remains in the program. This task will screen material performance and quantify the effects of high temperature erosion and corrosion of hot gas path materials in Coal IGCC applications. The materials of interest will include those in current service as well as advanced, high-performance alloys and coatings. Task 2--Material In-Service Health Monitoring: This second task develops and demonstrates new sensor technologies to determine the in-service health of advanced technology Coal IGCC powerplants, and remains in the program with a reduced scope. Its focus is now on only two critical sensor need areas for advanced Coal IGCC gas turbines: (1) Fuel Quality Sensor for detection of fuel impurities that could lead to rapid component degradation, and a Fuel Heating Value Sensor to rapidly determine the fuel heating value for more precise control of the gas turbine, and (2) Infra-Red Pyrometer to continuously measure the temperature of gas turbine buckets, nozzles, and combustor hardware.

  3. Recovery and use of fission product noble metals

    SciTech Connect

    Jensen, G.A.; Rohmann, C.A.; Perrigo, L.D.

    1980-06-01

    Noble metals in fission products are of strategic value. Market prices for noble metals are rising more rapidly than recovery costs. A promising concept has been developed for recovery of noble metals from fission product waste. Although the assessment was made only for the three noble metal fission products (Rh, Pd, Ru), there are other fission products and actinides which have potential value. (DLC)

  4. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Noble metal alloy. 872.3060 Section 872.3060 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification. A noble metal alloy is a device composed primarily of noble metals, such as gold, palladium, platinum, or silver,...

  5. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Noble metal alloy. 872.3060 Section 872.3060 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification. A noble metal alloy is a device composed primarily of noble metals, such as gold, palladium, platinum, or silver,...

  6. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Noble metal alloy. 872.3060 Section 872.3060 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification. A noble metal alloy is a device composed primarily of noble metals, such as gold, palladium, platinum, or silver,...

  7. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Noble metal alloy. 872.3060 Section 872.3060 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification. A noble metal alloy is a device composed primarily of noble metals, such as gold, palladium, platinum, or silver,...

  8. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Noble metal alloy. 872.3060 Section 872.3060 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification. A noble metal alloy is a device composed primarily of noble metals, such as gold, palladium, platinum, or silver,...

  9. NDIR Gas Sensor for Spatial Monitoring of Carbon Dioxide Concentrations in Naturally Ventilated Livestock Buildings

    PubMed Central

    Mendes, Luciano B.; Ogink, Nico W. M.; Edouard, Nadège; van Dooren, Hendrik Jan C.; Tinôco, Ilda de Fátima F.; Mosquera, Julio

    2015-01-01

    The tracer gas ratio method, using CO2 as natural tracer, has been suggested as a pragmatic option to measure emissions from naturally ventilated (NV) barns without the need to directly estimate the ventilation rate. The aim of this research was to assess the performance of a low-cost Non-Dispersive Infra-Red (NDIR) sensor for intensive spatial field monitoring of CO2 concentrations in a NV dairy cow house. This was achieved by comparing NDIR sensors with two commonly applied methods, a Photo-Acoustic Spectroscope (PAS) Gas Monitor and an Open-Path laser (OP-laser). First, calibrations for the NDIR sensors were obtained in the laboratory. Then, the NDIR sensors were placed in a dairy cow barn for comparison with the PAS and OP-laser methods. The main conclusions were: (a) in order to represent the overall barn CO2 concentration of the dairy cow barn, the number of NDIR sensors to be accounted for average concentration calculation was dependent on barn length and on barn area occupation; and (b) the NDIR CO2 sensors are suitable for multi-point monitoring of CO2 concentrations in NV livestock barns, being a feasible alternative for the PAS and the OP-laser methods to monitor single-point or averaged spatial CO2 concentrations in livestock barns. PMID:25985166

  10. NDIR Gas Sensor for Spatial Monitoring of Carbon Dioxide Concentrations in Naturally Ventilated Livestock Buildings.

    PubMed

    Mendes, Luciano B; Ogink, Nico W M; Edouard, Nadège; van Dooren, Hendrik Jan C; Tinôco, Ilda de Fátima F; Mosquera, Julio

    2015-05-13

    The tracer gas ratio method, using CO2 as natural tracer, has been suggested as a pragmatic option to measure emissions from naturally ventilated (NV) barns without the need to directly estimate the ventilation rate. The aim of this research was to assess the performance of a low-cost Non-Dispersive Infra-Red (NDIR) sensor for intensive spatial field monitoring of CO2 concentrations in a NV dairy cow house. This was achieved by comparing NDIR sensors with two commonly applied methods, a Photo-Acoustic Spectroscope (PAS) Gas Monitor and an Open-Path laser (OP-laser). First, calibrations for the NDIR sensors were obtained in the laboratory. Then, the NDIR sensors were placed in a dairy cow barn for comparison with the PAS and OP-laser methods. The main conclusions were: (a) in order to represent the overall barn CO2 concentration of the dairy cow barn, the number of NDIR sensors to be accounted for average concentration calculation was dependent on barn length and on barn area occupation; and (b) the NDIR CO2 sensors are suitable for multi-point monitoring of CO2 concentrations in NV livestock barns, being a feasible alternative for the PAS and the OP-laser methods to monitor single-point or averaged spatial CO2 concentrations in livestock barns.

  11. Idaho National Laboratory (INL) Site Greenhouse Gas (GHG) Monitoring Plan - 40 CFR 98

    SciTech Connect

    Deborah L. Layton; Kimberly Frerichs

    2010-07-01

    The purpose of this Greenhouse Gas (GHG) Monitoring Plan is to meet the monitoring plan requirements of Title 40 of the Code of Federal Regulations Part 98.3(g)(5). This GHG Monitoring Plan identifies procedures and methodologies used at the Idaho National Laboratory Site (INL Site) to collect data used for GHG emissions calculations and reporting requirements from stationary combustion and other regulated sources in accordance with 40 CFR 98, Subparts A and other applicable subparts. INL Site Contractors determined subpart applicability through the use of a checklist (Appendix A). Each facility/contractor reviews operations to determine which subparts are applicable and the results are compiled to determine which subparts are applicable to the INL Site. This plan is applicable to the 40 CFR 98-regulated activities managed by the INL Site contractors: Idaho National Laboratory (INL), Idaho Cleanup Project (ICP), Advanced Mixed Waste Treatment Project (AMWTP), and Naval Reactors Facilities (NRF).

  12. Idaho National Laboratory (INL) Site Greenhouse Gas (GHG) Monitoring Plan - 40 CFR 98

    SciTech Connect

    Deborah L. Layton; Kimberly Frerichs

    2011-12-01

    The purpose of this Greenhouse Gas (GHG) Monitoring Plan is to meet the monitoring plan requirements of Title 40 of the Code of Federal Regulations Part 98.3(g)(5). This GHG Monitoring Plan identifies procedures and methodologies used at the Idaho National Laboratory Site (INL Site) to collect data used for GHG emissions calculations and reporting requirements from stationary combustion and other regulated sources in accordance with 40 CFR 98, Subparts A and other applicable subparts. INL Site Contractors determined subpart applicability through the use of a checklist (Appendix A). Each facility/contractor reviews operations to determine which subparts are applicable and the results are compiled to determine which subparts are applicable to the INL Site. This plan is applicable to the 40 CFR 98-regulated activities managed by the INL Site contractors: Idaho National Laboratory (INL), Idaho Cleanup Project (ICP), Advanced Mixed Waste Treatment Project (AMWTP), and Naval Reactors Facilities (NRF).

  13. A New Automatic Subsurface Gas Monitoring System for Seismogeochemical Studies, Installed in Haruno Borehole, Shizuoka Prefecture, Central Japan

    NASA Astrophysics Data System (ADS)

    Miyakawa, Kazuya; Takama, Ruka; Kawabe, Iwao; Kariya, Shinnichi; Yamauchi, Tsuneo

    2010-12-01

    The results of subsurface gas monitoring by application of gas chromatography (GC) to the gas composition of bubbles associated with groundwater for seismogeochemical studies are reported. An automated gas monitoring system was used to determine gas compositions in a 500-m borehole at the Haruno Crustal Movement Observation Site (HOS), central Japan during period 1, from December 1999 to December 2000. The average ± two standard deviation (2SD) compositions of gases in this period were He = 82 ± 29 ppmV, H2 = 170 ± 62 ppmV, Ar = 0.05 ± 0.07%, N2 = 50 ± 8%, and CH4 = 45 ± 6%. A new automated gas monitoring system equipped with a micro-GC was installed in the borehole at the HOS, and gas bubbles from the borehole were monitored during period 2, from December 2006 to March 2007. The average ± two standard deviation (2SD) compositions of gases in this period were He = 8 ± 7 ppmV, H2 = 13 ± 15 ppmV, Ar = 0.6 ± 0.3%, N2 = 66 ± 7%, and CH4 = 14 ± 14%. The gas concentration ratios (He/Ar, H2/Ar, N2/Ar, and CH4/Ar) fluctuated significantly over time and repeatedly showed abrupt spike-like increases during period 2. The gas compositions obtained in period 1 and 2 were markedly different. Over the period from 2006 to 2007, the gas bubbles were depleted in He, H2, and CH4 of deep origin, but enriched in Ar and N2 of atmospheric origin. This difference can be interpreted as being due to an irreversible change of the aquifer/gas system. The present deep component in the HOS gas is estimated to have composition He = 63 ppmV, H2 = 37 ppmV, Ar = 0.17%, N2 = 63%, and CH4 = 37%. The new monitoring system is able to analyze the gas composition using a smaller volume of sample gas and with greater precision than the previous system. During the 3-month monitoring period 2, the separation capacity of the capillary column of the micro-GC was sufficiently maintained to determine gas-chromatographic peak areas for the five gaseous species examined. This study confirms that the

  14. One year continuous soil gas monitoring above an EGR test site

    NASA Astrophysics Data System (ADS)

    Furche, Markus; Schlömer, Stefan; Faber, Eckhard; Dumke, Ingolf

    2010-05-01

    Setup and first results of an ongoing research activity are presented, which is funded by the German Geotechnologien program within in the joint project CLEAN (CO2 Large Scale Enhanced Gas Recovery in the Altmark Natural Gas Field). The task is to establish several soil gas monitoring stations above a partly exhausted gas field in the Altmark which will be used for an enhanced gas recovery (EGR) test by injecting CO2 into the reservoir. The aim is to optimize the monitoring technique including automatic data transfer and data exploitation and to understand mechanisms of natural variations of soil gas concentrations in the specific area. Furthermore the suitability of these measurements as a contribution to leakage detection shall be evaluated. A network of 13 gauging stations for the measurement of CO2 is working continuously for about one year. They are spread