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Sample records for krypton isotopic anomalies

  1. Discovery of the krypton isotopes

    SciTech Connect

    Heim, M.; Fritsch, A.; Schuh, A.; Shore, A.; Thoennessen, M.

    2010-07-15

    Thirty-two krypton isotopes have been observed so far and the discovery of these isotopes is discussed here. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  2. Atom trap trace analysis of krypton isotopes

    SciTech Connect

    Bailey, K.; Chen, C. Y.; Du, X.; Li, Y. M.; Lu, Z.-T.; O'Connor, T. P.; Young, L.

    1999-11-17

    A new method of ultrasensitive isotope trace analysis has been developed. This method, based on the technique of laser manipulation of neutral atoms, has been used to count individual {sup 85}Kr and {sup 81}Kr atoms present in a natural krypton gas sample with isotopic abundances in the range of 10{sup {minus}11} and 10{sup {minus}13}, respectively. This method is free of contamination from other isotopes and elements and can be applied to several different isotope tracers for a wide range of applications. The demonstrated detection efficiency is 1 x 10{sup {minus}7}. System improvements could increase the efficiency by many orders of magnitude.

  3. Physicochemical isotope anomalies

    SciTech Connect

    Esat, T.M.

    1988-06-01

    Isotopic composition of refractory elements can be modified, by physical processes such as distillation and sputtering, in unexpected patterns. Distillation enriches the heavy isotopes in the residue and the light isotopes in the vapor. However, current models appear to be inadequate to describe the detailed mass dependence, in particular for large fractionations. Coarse- and fine-grained inclusions from the Allende meteorite exhibit correlated isotope effects in Mg both as mass-dependent fractionation and residual anomalies. This isotope pattern can be duplicated by high temperature distillation in the laboratory. A ubiquitous property of meteoritic inclusions for Mg as well as for most of the other elements, where measurements exist, is mass-dependent fractionation. In contrast, terrestrial materials such as microtektites, tektite buttons as well as lunar orange and green glass spheres have normal Mg isotopic composition. A subset of interplanetary dust particles labelled as chondritic aggregates exhibit excesses in {sup 26}Mg and deuterium anomalies. Sputtering is expected to be a dominant mechanism in the destruction of grains within interstellar dust clouds. An active proto-sun as well as the present solar-wind and solar-flare flux are of sufficient intensity to sputter significant amounts of material. Laboratory experiments in Mg show widespread isotope effects including residual {sup 26}Mg excesses and mass dependent fractionation. It is possible that the {sup 26}Mg excesses in interplanetary dust is related to sputtering by energetic solar-wind particles. The implication if the laboratory distillation and sputtering effects are discussed and contrasted with the anomalies in meteoritic inclusions the other extraterrestrial materials the authors have access to.

  4. Krypton isotope analysis using near-resonant stimulated Raman spectroscopy

    SciTech Connect

    Whitehead, C.A.; Cannon, B.D.; Wacker, J.F.

    1994-12-01

    A method for measuring low relative abundances of {sup 85}Kr in one liter or less samples of air has been under development here at Pacific Northwest Laboratory. The goal of the Krypton Isotope Laser Analysis (KILA) method is to measure ratios of 10{sup {minus}10} or less of {sup 85}Kr to more abundant stable krypton. Mass spectrometry and beta counting are the main competing technologies used in rare-gas trace analysis and are limited in application by such factors as sample size, counting times, and selectivity. The use of high-resolution lasers to probe hyperfine levels to determine isotopic abundance has received much attention recently. In this study, we report our progress on identifying and implementing techniques for trace {sup 85}Kr analysis on small gas samples in a static cell as well as limitations on sensitivity and selectivity for the technique. High-resolution pulsed and cw lasers are employed in a laser-induced fluorescence technique that preserves the original sample. This technique, is based on resonant isotopic depletion spectroscopy (RIDS) in which one isotope is optically depleted while preserving the population of a less abundant isotope. The KILA method consists of three steps. In the first step, the 1s{sub 5} metastable level of krypton is populated via radiative cascade following two-photon excitation of the 2p{sub 6} energy level. Next, using RBDS, the stable krypton isotopes are optically depleted to the ground state through the 1s{sub 4} level with the bulk of the {sup 85}Kr population being preserved. Finally, the remaining metastable population is probed to determine {sup 85}Kr concentration. The experimental requirements for each of these steps are outlined below.

  5. s-process studies - Xenon and krypton isotopic abundances

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.; Ward, R. A.

    1978-01-01

    We propose an analysis of the s-process contributions to the isotopes of xenon and krypton. The object is to aid studies of the possibility that meteorites may contain gas that was carried in presolar grains that were grown in stellar ejecta and that were not degassed prior to incorporation into parent bodies. That model suggests routine interstellar fractionation of s-isotopes from r-isotopes owing to differential incorporation into dust. We show that a deficiency of s-process nuclei cannot yield details of Xe-X, but the gross similarities are strong enough to lead one to think that such a deficiency may play a role in a more complicated explanation. We predict the existence of an s-rich complement somewhere if fractional separation of this type has played a role in Xe-X. We show that the analogous decomposition of krypton is more uncertain, and we call for measurements of neutron-capture cross sections to alleviate these uncertainties.

  6. Isotopic anomalies in extraterrestrial grains.

    PubMed

    Ireland, T R

    1996-03-01

    Isotopic compositions are referred to as anomalous if the isotopic ratios measured cannot be related to the terrestrial (solar) composition of a given element. While small effects close to the resolution of mass spectrometric techniques can have ambiguous origins, the discovery of large isotopic anomalies in inclusions and grains from primitive meteorites suggests that material from distinct sites of stellar nucleosynthesis has been preserved. Refractory inclusions, which are predominantly composed of the refractory oxides of Al, Ca, Ti, and Mg, in chondritic meteorites commonly have excesses in the heaviest isotopes of Ca, Ti, and Cr which are inferred to have been produced in a supernova. Refractory inclusions also contain excess 26Mg from short lived 26Al decay. However, despite the isotopic anomalies indicating the preservation of distinct nucleosynthetic sites, refractory inclusions have been processed in the solar system and are not interstellar grains. Carbon (graphite and diamond) and silicon carbide grains from the same meteorites also have large isotopic anomalies but these phases are not stable in the oxidized solar nebula which suggests that they are presolar and formed in the circumstellar atmospheres of carbon-rich stars. Diamond has a characteristic signature enriched in the lightest and heaviest isotopes of Xe, and graphite shows a wide range in C isotopic compositions. SiC commonly has C and N isotopic signatures which are characteristic of H-burning in the C-N-O cycle in low-mass stars. Heavier elements such as Si, Ti, Xe, Ba, and Nd, carry an isotopic signature of the s-process. A minor population of SiC (known as Grains X, ca. 1%) are distinct in having decay products of short lived isotopes 26Al (now 26Mg), 44Ti (now 44Ca), and 49V (now 49Ti), as well as 28Si excesses which are characteristic of supernova nucleosynthesis. The preservation of these isotopic anomalies allows the examination of detailed nucleosynthetic pathways in stars. PMID

  7. Titanium isotopic anomalies in meteorites

    NASA Technical Reports Server (NTRS)

    Niemeyer, S.; Lugmair, G. W.

    1984-01-01

    Studies of Ti isotopic compositions have shown that virtually every Ca-Al-rich Allende inclusion contains anomalous Ti. The present investigation is concerned with the results of a study of Ti isotopic compositions in meteorites. One objective of the study is to evaluate the possibility of a relation between oxygen and Ti anomalies, while another objective is to explore questions regarding the origin of the Ti anomalies. A summary of the major experimental findings of the study of Ti isotopic compositions is also presented. It is noted that an assessment of the implications of the Ti results favors a chemical memory type of model in which products from various nucleosynthetic sources survive in mineral grains. Isotopic heterogeneities are then preserved due to incomplete mixing and/or equilibriation with the bulk of solar system matter. Strong arguments are found to exist against a pure late supernova injection model.

  8. Titanium isotopic anomalies in meteorites

    NASA Astrophysics Data System (ADS)

    Neimeyer, S.; Lugmair, G. W.

    1984-07-01

    Studies of Ti isotopic compositions have shown that virtually every Ca-Al-rich Allende inclusion contains anomalous Ti. The present investigation is concerned with the results of a study of Ti isotopic compositions in meteorites. One objective of the study is to evaluate the possibility of a relation between oxygen and Ti anomalies, while another objective is to explore questions regarding the origin of the Ti anomalies. A summary of the major experimental findings of the study of Ti isotopic compositions is also presented. It is noted that an assessment of the implications of the Ti results favors a chemical memory type of model in which products from various nucleosynthetic sources survive in mineral grains. Isotopic heterogeneities are then preserved due to incomplete mixing and/or equilibriation with the bulk of solar system matter. Strong arguments are found to exist against a pure late supernova injection model.

  9. Chromium isotopic anomalies in the Murchison meteorite

    NASA Astrophysics Data System (ADS)

    Esat, T. M.; Ireland, T. R.

    1989-02-01

    The abundances of chromium isotopes, in refractory inclusions from the Allende meteorite, show wide-spread anomalies. The chromium isotope anomalies are similar in pattern to the anomalies discovered in Ca and Ti. The largest effects occur at the neutron-rich isotopes Ca-48, Ti-50 and Cr-54. Individual Cr-rich pink spinels, from the Murchison meteorite, exhibit large and variable excesses in Cr-53 and Cr-54 including the largest Cr-53 anomaly so far reported. Magnesium isotopes, in Murchison Cr-poor blue spinels, also show variable anomalies in Mg-26 including mass-dependent fractionation favoring the lighter isotopes. The Cr-53, Cr-54 and Mg-26 anomalies in Murchison spinels are indicative of a heterogeneous distribution of magnesium and chromium isotopes in the early solar nebula and require a contribution from several nucleosynthetic components in addition to physicochemical processing.

  10. Zinc Isotope Anomalies in bulk Chondrites

    NASA Astrophysics Data System (ADS)

    Savage, P. S.; Boyet, M.; Moynier, F.

    2014-09-01

    This study is the first to demonstrate that Zn isotope anomalies are present in bulk primitive meteorites, consistent with the injection of material derived from a neutron-rich supernova source into the solar nebula.

  11. Chromium isotopic anomalies in the Allende meteorite

    NASA Technical Reports Server (NTRS)

    Papanastassiou, D. A.

    1986-01-01

    Abundances of the chromium isotopes in terrestrial and bulk meteorite samples are identical to 0.01 percent. However, Ca-Al-rich inclusions from the Allende meteorite show endemic isotopic anomalies in chromium which require at least three nucleosynthetic components. Large anomalies at Cr-54 in a special class of inclusions are correlated with large anomalies at Ca-48 and Ti-50 and provide strong support for a component reflecting neutron-rich nucleosynthesis at nuclear statistical equilibrium. This correlation suggests that materials from very near the core of an exploding massive star may be injected into the interstellar medium.

  12. S-process krypton of variable isotopic composition in the Murchison meteorite

    NASA Technical Reports Server (NTRS)

    Ott, Urlich; Begemann, Friedrich; Yang, Yongmann; Epstein, Samuel

    1988-01-01

    Data are reported which, for the first time, permit the derivation of the full isotopic spectrum of s-process krypton with reasonable precision. It is shown that this s-Kr in a residue from the Murchison meteorite did not originate in one single s-process but rather is a mixture of contributions from stellar environments where the density of free neutrons was not the same. The astrophysical conditions under which this krypton was produced were distinct from those that have been invoked to explain the solar system s-process abundance. Similar to the C-13-rich carbon component in an aliquot of the same residue, the s-process Kr from different astrophysical sites has retained its identity during the accumulation and subsequent history of the meteorite.

  13. Isotopic anomalies - Chemical memory of Galactic evolution

    NASA Technical Reports Server (NTRS)

    Clayton, Donald D.

    1988-01-01

    New mechanisms for the chemical memory of isotopic anomalies are proposed which are based on the temporal change during the chemical evolution of the Galaxy of the isotopic composition of the mean ejecta from stars. Because of the differing temporal evolution of primary and secondary products of nucleosynthesis, the isotopic composition of the bulk interstellar medium changes approximately linearly with time, and thus any dust component having an age different from that of average dust will be isotopically anomalous. Special attention is given to C, O, Mg, Si, and isotopically heavy average-stellar condensates of SiC.

  14. Mass Spectrometric Measurement of Martian Krypton and Xenon Isotopic Abundance

    NASA Technical Reports Server (NTRS)

    Mahaffy, P.; Mauersberger, K.

    1993-01-01

    The Viking gas chromatograph mass spectrometer experiment provided significant data on the atmospheric composition at the surface of Mars, including measurements of several isotope ratios. However, the limited dynamic range of this mass spectrometer resulted in marginal measurements for the important Kr and Xe isotopic abundance. The Xe-129 to Xe-132 ratio was measured with an uncertainty of 70%, but none of the other isotope ratios for these species were obtained. Accurate measurement of the Xe and Kr isotopic abundance in this atmosphere provides an important data point in testing theories of planetary formation and atmospheric evolution. The measurement is also essential for a stringent test for the Martian origin of the SNC meteorites, since the Kr and Xe fractionation pattern seen in gas trapped in glassy nodules of an SNC (EETA 79001) is unlike any other known solar system resevoir. Current flight mass spectrometer designs combined with the new technology of a high-performance vacuum pumping system show promise for a substantial increase in gas throughput and the dynamic range required to accurately measure these trace species. Various aspects of this new technology are discussed.

  15. Development of an improved detector for krypton-81 and other noble-gas isotopes

    SciTech Connect

    Hurst, G.S.

    1988-08-25

    Phase 1 studies focused on the annealing (transient melting) of silicon and germanium targets with a krypton-fluoride (KrF) excimer laser. A suitable target of a semiconducting material--as a means of storing noble gas atoms--is a key component of a device called the RISTRON for counting isotopes of a noble gas. A means for isotopic selective counting of atoms such as 39Ar for ocean water circulation studies and 81Kr for groundwater and ice-cap dating would be of considerable interest to earth scientists. In the RISTRON, ions are created by resonance ionization of neutral krypton atoms released from one of the targets by pulsed laser melting, and these ions are implanted in a second target after isotopic enrichment. The studies evaluated the space charge or plasma effects created as an undesirable by-product of the annealing of a semiconductor with a pulsed excimer laser. The studies showed that the space charge produced when either silicon or germanium is annealed with a KrF laser can be removed with modest electric fields in less than one microsecond.

  16. Use of a krypton isotope for rapid ion changeover at the Lawrence Berkeley Laboratory 88-inch cyclotron

    NASA Technical Reports Server (NTRS)

    Soli, George A.; Nichols, Donald K.

    1989-01-01

    An isotope of krypton, Kr86, has been combined with a mix of Ar, Ne, and N ions at the electron cyclotron resonance (ECR) source, at the Lawrence Berkeley Laboratory cyclotron, to provide rapid ion changeover in Single Event Phenomena (SEP) testing. The new technique has been proved out successfully by a recent Jet Propulsion Laboratory (JPL) test in which it was found that there was no measurable contamination from other isotopes.

  17. Isotopic anomalies from neutron reactions during explosive carbon burning

    NASA Technical Reports Server (NTRS)

    Lee, T.; Schramm, D. N.; Wefel, J. P.; Blake, J. B.

    1979-01-01

    The heavy isotopic anomalies observed recently in the fractionation and unknown nuclear inclusions from the Allende meteorite are explained by neutron reactions during the explosive carbon burning (ECB). This model produces heavy anomalies in the same zone where Al-26 and O-16 are produced, thus reducing the number of source zones required for the isotopic anomalies. Unlike the classical r-process, the ECB n-process avoids the problem with the Sr anomaly and may resolve the problem of conflicting time scales between Al-26 and the r-process isotopes I-129 and Pu-244. Experimental studies of Zr and Ce isotopic composition are proposed to test this model.

  18. The Role of Triaxiality in Shape-Coexistence in Light Krypton Isotopes

    NASA Astrophysics Data System (ADS)

    Fischer, S. M.; Lister

    2008-04-01

    Shape co-existence in lead^1 and krypton^2-4 isotopes has become a cutting-edge topic in understanding the structure of heavier nuclei. Prediction of the relative binding energies of different shapes, and understanding the mixing between configurations presents a discriminating challenge to nuclear theory. In ^72,74,76Kr the occurrence of two well bound shapes has been demonstrated through the observation of low-lying J^π = 0^+ isomers and through radioactive beam Coulomb excitation. Roughly speaking, the shapes correspond to oblate-like and prolate-like configurations. However, the exact shapes, and the role of triaxiality has yet to be fully explored. We present new results from ``in-beam'' heavy-ion spectroscopy on ^74Kr which shows that the population of the isomer is mainly through a gamma vibrational band and that considerable mixing is involved between the states built on the isomer and the gamma band. This research was supported by the DOE Office of Nuclear Physics under contract DE-AC02-06CH11357. ^1A. N. Andreyev et al., Nature 405, 430 (2000) ^2E. Clement et al., Phys. Rev. C 75, 054313 (2007) ^3E. Bouchez et al., Phys. Rev. Lett. 90, 082502 (2003) ^4M. Bender et al., Phys. Rev. C 74, 024312 (2006)

  19. The identification of meteorite inclusions with isotope anomalies

    NASA Astrophysics Data System (ADS)

    Papanastassiou, D. A.; Brigham, C. A.

    1989-03-01

    Ca-Al refractory inclusions with characteristic chemical and mineralogical compositions show an enhanced occurrence of 20 pct of isotope anomalies reflecting unknown nucleosynthetic effects for O and Mg. The anomalies are characterized by large isotope fractionation in Mg, apparent deficits in Mg-26/Mg-24, and large correlated effects for isotopes of Ca, Ti, and Cr. These isotope patterns define exotic components depleted in the most neutron-rich isotopes of Ca, Ti, and Cr, or components depleted in isotopes produced in explosive O and Si burning. An opaque assemblage within one of the inclusions yields isotope anomalies in Cr similar to the bulk inclusion and must be intrinsically part of the inclusion and not a trapped, foreign grain aggregate.

  20. Nucleosynthetic strontium isotope anomalies in carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Yokoyama, Tetsuya; Fukami, Yusuke; Okui, Wataru; Ito, Nobuaki; Yamazaki, Hiroshi

    2015-04-01

    Precise Sr isotopic compositions in samples from sequential acid leaching experiments have been determined for three carbonaceous chondrites, Allende, Murchison, and Tagish Lake, together with those in the bulk aliquots of these meteorites. The chondritic acid leachates and residues were characterized by Sr isotope anomalies with variable μ84Sr values (106 relative deviation from a standard material) ranging from +120 to - 4700 ppm, documenting multiple nucleosynthetic sources within a single meteorite. In addition, the μ84Sr patterns across leaching samples for individual chondrites differed from one another. The highest μ84Sr values were observed for leaching Step 3 (HCl+H2O, 75 °C) for Allende and Murchison likely because of the incorporation of calcium and aluminum-rich inclusions (CAIs). In contrast, extremely low μ84Sr values were observed in the later fractions (Steps 6 and 7) for Murchison and Tagish Lake, suggesting the existence of s-process-enriched presolar SiC grains derived from AGB stars. A μ84Sr-ɛ54Cr diagram was prepared with the CAIs and bulk aliquots of carbonaceous chondrites and other meteorites (noncarbonaceous) that were plotted separately; however, they still formed a global positive correlation. CAIs presented the highest μ84Sr and ɛ54Cr values, whereas carbonaceous chondrites and noncarbonaceous meteorites had intermediate and the lowest μ84Sr and ɛ54Cr values, respectively. The positive trend was interpreted as resulting from global thermal processing in which sublimation of high μ84Sr and ɛ54Cr carriers generated the excess μ84Sr and ɛ54Cr signatures in CAIs, while noncarbonaceous planetesimals accreted from materials that underwent significant thermal processing and thus had relatively low μ84Sr and ɛ54Cr values. Apart from the global trend, the carbonaceous chondrites and noncarbonaceous meteorites both exhibited intrinsic variations that highlight an isotopic dichotomy similar to that observed in other isotope

  1. Titanium isotopic anomalies in chondrules from carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Niemeyer, S.

    1988-02-01

    Isotopic analyses of Ti from a suite of eight Allende chondrules were conducted to determine whether any relationship exists between the composition and structure of a chondrule and the Ti isotopic patterns. Four of the eight chondrules displayed well-resolved anomalies with respect to Ti-50/Ti-46 ratio, which ranged from a Ti-50 deficit of two epsilon-units to a T-50 excess of nine epsilon-units. No clear link was found between the structure of the chondrules and the Ti anomalies (although the chondrule with by far the largest Ti isotopic anomaly was also Al-rich, suggesting that there might exist a complicated relationship between the degree of refractory enrichment and the magnitude of Ti isotopic anomalies.

  2. Some key issues in isotopic anomalies - Astrophysical history and aggregation

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.

    1982-01-01

    Astrophysical history, particularly that period extending from stellar nucleosynthesis events to the formation of meteorites, is discussed as the key element for the understanding of isotopic anomalies in meteorites. The bulk homogeneity of the interstellar medium is considered, and it is argued that, despite the presence of spatial inhomogeneities due to different nucleosynthesis rates in different parts of the galaxy and supernova ejecta, a cosmic chemical memory of nucleosynthesis patterns, rather than an inhomogeneous injection, is the source of isotopic anomalies. According to this view, volatility patterns and some isotopic patterns are mapped onto a grain-size spectrum, and the FUN systematics may be explained by interstellar sputtering. Furthermore, meteoritic He and Ne abundances are inferred to be presolar, and the ubiquitous titanium isotopic anomalies are explained by processes of chemical fixation and condensation in varying environments.

  3. Barium and neodymium isotopic anomalies in the Allende meteorite

    NASA Technical Reports Server (NTRS)

    Mcculloch, M. T.; Wasserburg, G. J.

    1978-01-01

    The discovery of Ba and Nd isotopic anomalies in two inclusions from the Allende meteorite is reported. The inclusions are Ca-Al-rich objects typical of the type considered as high-temperature condensation products in the solar nebula and contain distinctive Mg and O isotopic anomalies of the FUN (mass Fractionation, Unknown Nuclear processes) type. Mass-spectrometry results are discussed which show that inclusion C1 has anomalies in Ba at masses 134 and 136, while inclusion EK1-4-1 exhibits large marked negative anomalies at 130, 132, 134, and 136, as well as a positive anomaly at 137. It is also found that inclusion EK1-4-1 shows marked negative anomalies in Nd at masses 142, 146, 148, and 150, in addition to a positive anomaly at 145. These isotopic shifts are attributed to addition of r-process nuclei rather than mass fractionation. It is suggested that an onion-shell supernova explosion followed by injection into the solar nebula is the most likely generic model that may explain the observations.

  4. Zinc isotope anomalies. [in Allende meteorite

    NASA Technical Reports Server (NTRS)

    Volkening, J.; Papanastassiou, D. A.

    1990-01-01

    The Zn isotope composition in refractory-element-rich inclusions of the Allende meteorite are determined. Typical inclusions contain normal Zn. A unique inclusion of the Allende meteorite shows an excess for Zn-66 of 16.7 + or - 3.7 eu (1 eu = 0.01 percent) and a deficit for Zn-70 of 21 + or - 13 eu. These results indicate the preservation of exotic components even for volatile elements in this inclusion. The observed excess Zn-66 correlates with excesses for the neutron-rich isotopes of Ca-48, Ti-50, Cr-54, and Fe-58 in the same inclusion.

  5. Zinc isotope anomalies in Allende meteorite inclusions

    NASA Technical Reports Server (NTRS)

    Loss, R. D.; Lugmair, G. W.

    1990-01-01

    The isotopic compositions of Zn, Cr, Ti, and Ca have been measured in a number of CAIs from the Allende meteorite. The aim was to test astrophysical models which predict large excesses of Zn-66 to accompany excesses in the neutron-rich isotopes of Ca, Ti, Cr, and Ni. Some of the CAIs show clearly resolved but small excesses for Zn-66 which are at least an order of magnitude smaller than predicted. This result may simply reflect the volatility and chemical behavior of Zn as compared to the other (more refractory) anomalous elements found in these samples. Alternatively, revision of parameters and assumptions used for the model calculations may be required.

  6. Endemic Mo Isotopic Anomalies in Iron and Carbonaceous Meteorites

    NASA Technical Reports Server (NTRS)

    Chen, J. H.; Papanastassiou, D. A.; Wasserburg, G. J.; Ngo, H. H.

    2004-01-01

    Mo in refractory interstellar grains shows large isotope anomalies. Recent Mo studies showed isotope effects in Allende and Murchison, and in iron meteorites, mesosiderites, and pallasites. Excesses of p- and r-process isotopes (or depletion of sprocess isotopes) of up to 3.5 epsilon units (epsilon u=parts in 10(exp 4)) were reported. We have reported on endemic isotope anomalies in Ru. Other workers have resolved no isotope anomalies for Mo or Ru and have claimed that the work by others is incorrect. Because Ru isotopes can interfere at Mo-96, Mo-98, Mo-100, we improved the chemical separations and eliminated interferences. For Mo work, we used the same solutions from which we separated and analyzed Ru. Three of the iron meteorites (Coahuila, Cape York, and Cape of Good Hope) were chosen for their large Mo isotopic effects. Mo was loaded on outgassed Re filaments, and then reduced; we used Ba(OH)2-NaOH as emitter, and measured Mo in static mode, as MoO3(-). We used Mo-98/Mo-96 for the mass fractionation correction (exponential law). No interferences from Ru or Zr isotopes were detected using the electron multiplier and no corrections were needed. For results on Mo standards we show 2 sigma(not 2 sigma mean) external precision better than: 0.7 epsilon u for Mo-94/Mo-96 and Mo-95/Mo-96; 1.0 epsilon u for Mo-92/Mo-96 and Mo-97/Mo-96; 1.4 epsilon u for Mo-100/Mo-96. Reproducibility for Mo standards is shown as contours (blue lines).

  7. The longevity of the South Pacific isotopic and thermal anomaly

    USGS Publications Warehouse

    Staudigel, H.; Park, K.-H.; Pringle, M.; Rubenstone, J.L.; Smith, W.H.F.; Zindler, A.

    1991-01-01

    The South Pacific is anomalous in terms of the Sr, Nd, and Pb isotope ratios of its hot spot basalts, a thermally enhanced lithosphere, and possibly a hotter mantle. We have studied the Sr, Nd, and Pb isotope characteristics of 12 Cretaceous seamounts in the Magellans, Marshall and Wake seamount groups (western Pacific Ocean) that originated in this South Pacific Isotopic and Thermal Anomaly (SOPITA). The range and values of isotope ratios of the Cretaceous seamount data are similar to those of the island chains of Samoa, Tahiti, Marquesas and Cook/Austral in the SOPITA. These define two major mantle components suggesting that isotopically extreme lavas have been produced at SOPITA for at least 120 Ma. Shallow bathymetry, and weakened lithosphere beneath some of the seamounts studied suggests that at least some of the thermal effects prevailed during the Cretaceous as well. These data, in the context of published data, suggest: 1. (1)|SOPITA is a long-lived feature, and enhanced heat transfer into the lithosphere and isotopically anomalous mantle appear to be an intrinsic characteristic of the anomaly. 2. (2)|The less pronounced depth anomaly during northwesterly plate motion suggests that some of the expressions of SOPITA may be controlled by the direction of plate motion. Motion parallel to the alignment of SOPITA hot spots focusses the heat (and chemical input into the lithosphere) on a smaller cross section than oblique motion. 3. (3)|The lithosphere in the eastern and central SOPITA appears to have lost its original depleted mantle characteristics, probably due to enhanced plume/lithosphere interaction, and it is dominated by isotopic compositions derived from plume materials. 4. (4)|We speculate (following D.L. Anderson) that the origin of the SOPITA, and possibly the DUPAL anomaly is largely due to focussed subduction through long periods of the geological history of the earth, creating a heterogeneous distribution of recycled components in the lower mantle

  8. A spectacular nitrogen isotope anomaly in Bencubbin

    NASA Technical Reports Server (NTRS)

    Prombo, C. A.; Clayton, R. N.

    1985-01-01

    Results of isotopic measurements on an unusual stony-iron meteorite named Bencubbin, which was found in Western Australia in 1930, are reported. Nitrogen from both the metallic and stony parts of the Bencubbin meteorite was analyzed, and in both materials large excesses of (15)N were found, resulting in values of the (14)N/(15)N abundance ratios as low as 137. That is, (15)N is enriched in Bencubbin by about a factor of two relative to terrestrial nitrogen. This is the largest (15)N enrichment of any known natural material. The effect is so large that chemical processes are probably inadequate to account for it. Nuclear processes which may be responsible for the anomalous isotope abundance are discussed.

  9. Isotopic anomalies from neutron reactions during explosive carbon burning

    NASA Technical Reports Server (NTRS)

    Lee, T.; Schramm, D. N.; Wefel, J. P.; Blake, J. B.

    1978-01-01

    The possibility that the newly discovered correlated isotopic anomalies for heavy elements in the Allende meteorite were synthesized in the secondary neutron capture episode during the explosive carbon burning, the possible source of the O-16 and Al-26 anomalies, is examined. Explosive carbon burning calculations under typical conditions were first performed to generate time profiles of temperature, density, and free particle concentrations. These quantities were inputted into a general neutron capture code which calculates the resulting isotopic pattern from exposing the preexisting heavy seed nuclei to these free particles during the explosive carbon burning conditions. The interpretation avoids the problem of the Sr isotopic data and may resolve the conflict between the time scales inferred from 1-129, Pu-244, and Al-26.

  10. Palladium Isotopic Evidence for Nucleosynthetic and Cosmogenic Isotope Anomalies in IVB Iron Meteorites

    NASA Astrophysics Data System (ADS)

    Mayer, Bernhard; Wittig, Nadine; Humayun, Munir; Leya, Ingo

    2015-08-01

    The origin of ubiquitous nucleosynthetic isotope anomalies in meteorites may represent spatial and/or temporal heterogeneity in the sources that supplied material to the nascent solar nebula, or enhancement by chemical processing. For elements beyond the Fe peak, deficits in s-process isotopes have been reported in some (e.g., Mo, Ru, W) but not all refractory elements studied (e.g., Os) that, among the iron meteorites, are most pronounced in IVB iron meteorites. Palladium is a non-refractory element in the same mass region as Mo and Ru. In this study, we report the first precise Pd isotopic abundances from IVB irons to test the mechanisms proposed for the origin of isotope anomalies. First, this study determined the existence of a cosmogenic neutron dosimeter from the reaction 103Rh(n, β-)104Pd in the form of excess 104Pd, correlated with excess 192Pt, in IVB irons. Second, all IVB irons show a deficit of the s-process only isotope 104Pd (\\varepsilon 104Pd = -0.48 ± 0.24), an excess of the r-only isotope 110Pd (\\varepsilon 110Pd = +0.46 ± 0.12), and no resolvable anomaly in the p-process 102Pd (\\varepsilon 102Pd = +1 ± 1). The magnitude of the Pd isotope anomaly is about half that predicted from a uniform depletion of the s-process yields from the correlated isotope anomalies of refractory Mo and Ru. The discrepancy is best understood as the result of nebular processing of the less refractory Pd, implying that all the observed nucleosynthetic anomalies in meteorites are likely to be isotopic relicts. The Mo-Ru-Pd isotope systematics do not support enhanced rates of the 22Ne(α,n)25Mg neutron source for the solar system s-process.

  11. Iron isotope anomalies. [in carbonaceous meteorites

    NASA Technical Reports Server (NTRS)

    Voelkening, J.; Papanastassiou, D. A.

    1989-01-01

    Precise determinations of the Fe isotope abundances yield identical results for a terrestrial standard and for samples of carbonaceous meteorites. Fe-54/Fe-56 = 0.062669; Fe-57/Fe-56 = 0.023261 + or - 0.000002; and Fe-58/Fe-56 = 0.0031132 + or - 0.0000011 are found. Refractory element-rich inclusions from the Allende carbonaceous meteorite yield hints of deficits in Fe-57/Fe-56 of up to -3.9 + or - 2.6 parts in 10,000 and a hint of excess in Fe-58/Fe-56 of up to 27 + or - 11 parts in 10,000. One special (FUN) inclusion shows a large excess of 2.9 percent, uniquely attributable to Fe-58. This excess correlates with large excesses in the same inclusion in the neutron-rich isotopes Ca-48, Ti-50 and Cr-54. These results strengthen the evidence for an exotic nucleosynthetic component produced by neutron-rich, statistical equilibrium burning, and injected into the interstellar medium.

  12. NEUTRON-RICH CHROMIUM ISOTOPE ANOMALIES IN SUPERNOVA NANOPARTICLES

    SciTech Connect

    Dauphas, N.; Remusat, L.; Papanastassiou, D. A.; Guan, Y.; Ma, C.; Eiler, J. M.; Chen, J. H.; Roskosz, M.; Stodolna, J.

    2010-09-10

    Neutron-rich isotopes with masses near that of iron are produced in Type Ia and II supernovae (SNeIa and SNeII). Traces of such nucleosynthesis are found in primitive meteorites in the form of variations in the isotopic abundance of {sup 54}Cr, the most neutron-rich stable isotope of chromium. The hosts of these isotopic anomalies must be presolar grains that condensed in the outflows of SNe, offering the opportunity to study the nucleosynthesis of iron-peak nuclei in ways that complement spectroscopic observations and can inform models of stellar evolution. However, despite almost two decades of extensive search, the carrier of {sup 54}Cr anomalies is still unknown, presumably because it is fine grained and is chemically labile. Here, we identify in the primitive meteorite Orgueil the carrier of {sup 54}Cr anomalies as nanoparticles (<100 nm), most likely spinels that show large enrichments in {sup 54}Cr relative to solar composition ({sup 54}Cr/{sup 52}Cr ratio >3.6 x solar). Such large enrichments in {sup 54}Cr can only be produced in SNe. The mineralogy of the grains supports condensation in the O/Ne-O/C zones of an SNII, although a Type Ia origin cannot be excluded. We suggest that planetary materials incorporated different amounts of these nanoparticles, possibly due to late injection by a nearby SN that also delivered {sup 26}Al and {sup 60}Fe to the solar system. This idea explains why the relative abundance of {sup 54}Cr and other neutron-rich isotopes vary between planets and meteorites. We anticipate that future isotopic studies of the grains identified here will shed new light on the birth of the solar system and the conditions in SNe.

  13. More on Ru Endemic Isotope Anomalies in Meteorites

    NASA Technical Reports Server (NTRS)

    Papanastassiou, D. A.; Chen, J. H.; Wasserburg, G. J.

    2004-01-01

    We reported last year on endemic isotope anomalies for Ru in iron meteorites, pallasites, ordinary chondrites, and on a whole-rock sample of Allende. We have extended the Ru measurements to more meteorites, to refractory Ca-Al-rich inclusions (CAI) from Allende, and to a whole rock sample of Murchison (CM2). In a companion abstract we report on new measurements for the Mo isotopes, in some of the same samples. There has been a renewed interest in searching for isotope anomalies in this nuclide region, as Ru and Mo include many isotopes from r-, s-, and p-process nucleosynhesis. Furthermore, the Ru and Mo p-process isotopes show atypically high abundances, which have been hard to explain through the standard nucleosynthetic processes. Effects are possible in Ru-98 and Ru-99 from Tc-98 (with a poorly known t(sub 1/2)=4.2 to 10Ma) and from Tc-99 (t(sub 1/2)=0.21Ma). Natural Tc is now extinct on Earth due to the short half-lives, but may have been present in the early solar system. Both radiogenic and general isotope anomalies are important in understanding the processes for the formation of the early solar system. The current emphasis on Ru and Mo is also the result of the development of Negative-ion Thermal Ionization Mass Spectrometry and of Multiple-Collector, Inductively-Coupled-Mass-Spectrometry. We have also developed specific chemical siparation techniques for Ru, which eliminated mass interference effects.

  14. Neutron-poor Nickel Isotope Anomalies in Meteorites

    NASA Astrophysics Data System (ADS)

    Steele, Robert C. J.; Coath, Christopher D.; Regelous, Marcel; Russell, Sara; Elliott, Tim

    2012-10-01

    We present new, mass-independent, Ni isotope data for a range of bulk chondritic meteorites. The data are reported as ɛ60Ni58/61, ɛ62Ni58/61, and ɛ64Ni58/61, or the parts per ten thousand deviations from a terrestrial reference, the NIST SRM 986 standard, of the 58Ni/61Ni internally normalized 60Ni/61Ni, 62Ni/61Ni, and 64Ni/61Ni ratios. The chondrites show a range of 0.15, 0.29, and 0.84 in ɛ60Ni58/61, ɛ62Ni58/61, and ɛ64Ni58/61 relative to a typical sample precision of 0.03, 0.05, and 0.08 (2 s.e.), respectively. The carbonaceous chondrites show the largest positive anomalies, enstatite chondrites have approximately terrestrial ratios, though only EH match Earth's composition within uncertainty, and ordinary chondrites show negative anomalies. The meteorite data show a strong positive correlation between ɛ62Ni58/61 and ɛ64Ni58/61, an extrapolation of which is within the error of the average of previous measurements of calcium-, aluminium-rich inclusions. Moreover, the slope of this bulk meteorite array is 3.003 ± 0.166 which is within the error of that expected for an anomaly solely on 58Ni. We also determined to high precision (~10 ppm per AMU) the mass-dependent fractionation of two meteorite samples which span the range of ɛ62Ni58/61 and ɛ64Ni58/61. These analyses show that "absolute" ratios of 58Ni/61Ni vary between these two samples whereas those of 62Ni/61Ni and 64Ni/61Ni do not. Thus, Ni isotopic differences seem most likely explained by variability in the neutron-poor 58Ni, and not correlated anomalies in the neutron-rich isotopes, 62Ni and 64Ni. This contrasts with previous inferences from mass-independent measurements of Ni and other transition elements which invoked variable contributions of a neutron-rich component. We have examined different nucleosynthetic environments to determine the possible source of the anomalous material responsible for the isotopic variations observed in Ni and other transition elements within bulk samples. We find

  15. NEUTRON-POOR NICKEL ISOTOPE ANOMALIES IN METEORITES

    SciTech Connect

    Steele, Robert C. J.; Coath, Christopher D.; Regelous, Marcel; Elliott, Tim; Russell, Sara

    2012-10-10

    We present new, mass-independent, Ni isotope data for a range of bulk chondritic meteorites. The data are reported as {epsilon}{sup 60}Ni{sub 58/61}, {epsilon}{sup 62}Ni{sub 58/61}, and {epsilon}{sup 64}Ni{sub 58/61}, or the parts per ten thousand deviations from a terrestrial reference, the NIST SRM 986 standard, of the {sup 58}Ni/{sup 61}Ni internally normalized {sup 60}Ni/{sup 61}Ni, {sup 62}Ni/{sup 61}Ni, and {sup 64}Ni/{sup 61}Ni ratios. The chondrites show a range of 0.15, 0.29, and 0.84 in {epsilon}{sup 60}Ni{sub 58/61}, {epsilon}{sup 62}Ni{sub 58/61}, and {epsilon}{sup 64}Ni{sub 58/61} relative to a typical sample precision of 0.03, 0.05, and 0.08 (2 s.e.), respectively. The carbonaceous chondrites show the largest positive anomalies, enstatite chondrites have approximately terrestrial ratios, though only EH match Earth's composition within uncertainty, and ordinary chondrites show negative anomalies. The meteorite data show a strong positive correlation between {epsilon}{sup 62}Ni{sub 58/61} and {epsilon}{sup 64}Ni{sub 58/61}, an extrapolation of which is within the error of the average of previous measurements of calcium-, aluminium-rich inclusions. Moreover, the slope of this bulk meteorite array is 3.003 {+-} 0.166 which is within the error of that expected for an anomaly solely on {sup 58}Ni. We also determined to high precision ({approx}10 ppm per AMU) the mass-dependent fractionation of two meteorite samples which span the range of {epsilon}{sup 62}Ni{sub 58/61} and {epsilon}{sup 64}Ni{sub 58/61}. These analyses show that 'absolute' ratios of {sup 58}Ni/{sup 61}Ni vary between these two samples whereas those of {sup 62}Ni/{sup 61}Ni and {sup 64}Ni/{sup 61}Ni do not. Thus, Ni isotopic differences seem most likely explained by variability in the neutron-poor {sup 58}Ni, and not correlated anomalies in the neutron-rich isotopes, {sup 62}Ni and {sup 64}Ni. This contrasts with previous inferences from mass-independent measurements of Ni and other

  16. On isotopic anomalies in samarium. [in Allende meteorite

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.

    1979-01-01

    The solar isotopic composition of Sm is decomposed into s, r, and p components. The anomaly pattern discovered by Lugmair et al. (1978) in EK1-04 Allende inclusion can be presented as a fractionation of the average s-pattern from the average r-pattern. This representation requires a fractionation of 0.029%/(amu) and either (1) a 0.42% deficiency of s relative to r and a 0.15% deficiency of p relative to r, or (2) a 0.42% excess of r relative to s and a 0.27% excess of p relative to s. The nature of this anomaly suggest a systematic physical fractionation of r, s, and p nuclei from each other in the initial condition leading to EK1-04. A neighboring supernova injection would not be expected to produce this anomaly.

  17. On krypton isotopic abundances in the sun and in the solar wind

    NASA Technical Reports Server (NTRS)

    Marti, K.

    1980-01-01

    The Kr isotopic systematics in the meteorite Pesyanoe which is known to contain solar-type gases, are reported. Discrepancies in the isotopic data of fractions released at stepwise increasing temperatures cannot be reconciled with spallation Kr components, although spallation effects are significant. Fractionation mechanisms on the parent body and in the solar wind source region are considered and the implications for solar abundances discussed.

  18. Wolf-Rayet Stars and the Isotopic Anomaly Connection

    NASA Astrophysics Data System (ADS)

    Arnould, M.; Paulus, G.; Meynet, G.

    1993-07-01

    Isotopic anomalies are now known to be carried by high-temperature inclusions of primitive meteorites that formed from solar reservoirs out of equilibrium with the rest of the solar nebula, as well as by various types of grains (diamond, graphite, SiC) that are considered to be of circumstellar origin, and have survived the process of incorporation into the solar system (see e.g. [1] for a recent review). Such anomalies provide new clues to many important astrophysical problems, and raise the question of their nucleosynthetic origin. In fact, they offer the exciting perspective of confronting abundance observations with nucleosynthesis models for a very limited number of events, even possibly a single one. This situation is in marked contrast with the one encountered when trying to understand the bulk solar system composition. Up to now, Red Giant stars, massive mass loosing objects (of the Wolf-Rayet type), novae or supernovae have been proposed as possible contributors to the observed anomalies. In this paper, we revisit the role that could possibly be played in that respect by Wolf-Rayet (WR) stars. Wolf-Rayet stars are appealing isotopic anomaly contributors for many reasons. In particular (1) they are observed to loose mass at very large rates that can exceed 10^-5M solar masses yr^-l, the ejected material being contaminated with the products of hydrogen and helium burning, and (2) certain WR stars are known to make dust episodically in their winds [e.g., 2]. In addition, the role of WR stars would be well in line with the "bing-bang" model for the isotopic anomalies promoted by Reeves [3]. The aim of this contribution is to extent and update previous calculations [4,5] of the isotopic anomalies that could be carried by the wind of WR stars of various masses and initial compositions during different phases of their evolution, those anomalies possibly loading circumstellar WR grains. The calculation of the WR wind composition is performed on grounds of detailed

  19. Mass Fractionation Laws, Mass-Independent Effects, and Isotopic Anomalies

    NASA Astrophysics Data System (ADS)

    Dauphas, Nicolas; Schauble, Edwin A.

    2016-06-01

    Isotopic variations usually follow mass-dependent fractionation, meaning that the relative variations in isotopic ratios scale with the difference in mass of the isotopes involved (e.g., δ17O ≈ 0.5×δ18O). In detail, however, the mass dependence of isotopic variations is not always the same, and different natural processes can define distinct slopes in three-isotope diagrams. These variations are subtle, but improvements in analytical capabilities now allow precise measurement of these effects and make it possible to draw inferences about the natural processes that caused them (e.g., reaction kinetics versus equilibrium isotope exchange). Some elements, in some sample types, do not conform to the regularities of mass-dependent fractionation. Oxygen and sulfur display a rich phenomenology of mass-independent fractionation, documented in the laboratory, in the rock record, and in the modern atmosphere. Oxygen in meteorites shows isotopic variations that follow a slope-one line (δ17O ≈ δ18O) whose origin may be associated with CO photodissociation. Sulfur mass-independent fractionation in ancient sediments provides the tightest constraint on the oxygen partial pressure in the Archean and the timing of Earth's surface oxygenation. Heavier elements also show departures from mass fractionation that can be ascribed to exotic effects associated with chemical reactions such as magnetic effects (e.g., Hg) or the nuclear field shift effect (e.g., U or Tl). Some isotopic variations in meteorites and their constituents cannot be related to the terrestrial composition by any known process, including radiogenic, nucleogenic, and cosmogenic effects. Those variations have a nucleosynthetic origin, reflecting the fact that the products of stellar nucleosynthesis were not fully homogenized when the Solar System formed. Those anomalies are found at all scales, from nanometer-sized presolar grains to bulk terrestrial planets. They can be used to learn about stellar

  20. Investigation of cold collision in a two isotope magneto-optical trap for Krypton atoms

    NASA Astrophysics Data System (ADS)

    Singh, S.; Tiwari, V. B.; Kale, Y. B.; Mishra, S. R.; Rawat, H. S.

    2015-09-01

    We report simultaneous cooling and trapping of metastable 84Kr (84Kr*) and metastable 86Kr (86Kr*) atoms by overlapping the cooling laser beams for these different isotopes in the same region of a magneto-optical trap (MOT). Approximately 2 × 105 atoms of each isotope were trapped in this two isotope-MOT (TIMOT). We have investigated the heteronuclear collision trap loss rates for each isotope due to the presence of cold atoms of other isotope using the TIMOT loading curves. The two body heteronuclear loss rate coefficient {β }{84Kr*-{}86Kr*} (i.e. for the loss of 84Kr* due to presence of 86Kr*) and the reciprocal loss rate coefficient {β }{86Kr*-{}84Kr*} (i.e. for the loss of 86Kr* due to presence of 84Kr*) are measured to be (8.7 ± 0.8) × 10-10 cm3 s-1 and (8.8 ± 0.8) × 10-10 cm3 s-1 respectively for laser beam intensity values of 21 mW cm-2 (for cooling of 84Kr*) and 64 mW cm-2 (for cooling of 86Kr*). The dependence of heteronuclear cold collision loss rate on cooling laser beams intensity has also been studied and compared with homonuclear cold collision loss rate.

  1. MULTIPLE ORIGINS OF NITROGEN ISOTOPIC ANOMALIES IN METEORITES AND COMETS

    SciTech Connect

    Aleon, Jerome

    2010-10-20

    Isotopic fractionation and mixing calculations compared with coupled hydrogen and nitrogen isotopic composition of organic molecules from primitive chondrites, interplanetary dust particles (IDPs), and comets C/1995 O1 (Hale-Bopp) and 81P/Wild2 reveal that meteoritic and cometary organic matter contains three different isotopic components of different origins. (1) A major component of carbonaceous chondrites, IDPs, and comets Hale-Bopp and Wild2 shows correlated H and N isotopic compositions attributable to isotope exchange between an organic matter of solar composition and a reservoir formed by ion-molecule reactions at T < 25 K under conditions where competing reactions are strongly inhibited, possibly in the final evolutionary stages of the presolar cloud core, or more likely in the coldest outer regions of the solar protoplanetary disk. (2) In carbonaceous chondrites, IDPs, and comet Wild2, this component is mixed with a {sup 15}N-rich component having identical {sup 15}N and D enrichments relative to the protosolar gas. Temperatures > 100 K deduced from the low D/H ratio and an anti-correlation between the abundance of this component and meteoritic age indicate a late origin in the solar protoplanetary disk. N{sub 2} self-shielding and the non-thermal nucleosynthesis of {sup 15}N upon irradiation are possible but unlikely sources of this component, and a chemical origin is preferred. (3) An interstellar component with highly fractionated hydrogen isotopes and unfractionated nitrogen isotopes is present in ordinary chondrites. A dominantly solar origin of D and {sup 15}N excesses in primitive solar system bodies shows that isotopic anomalies do not necessarily fingerprint an interstellar origin and implies that only a very small fraction of volatile interstellar matter survived the events of solar system formation.

  2. Isotopically distinct reservoirs in the solar nebula: Isotope anomalies in Vigarano meteorite inclusions

    NASA Technical Reports Server (NTRS)

    Loss, R. D.; Lugmair, G. W.; Davis, A. M.; Macpherson, G. J.

    1994-01-01

    The isotopic compositions of Mg, Ca, Ti, Cr, Zn, Sr, Ba, Nd, and Sm were measured in four relatively unaltered refractory inclusions from the Vigarano carbonaceous chondrite meteorite. Three of the inclusions (USNM 1623-2, 1623-3, and 1623-8) show similar Mg, Ca, Ti, and Cr isotopic compositions to those found in most inclusions in the Allende carbonaceous chondrite. This indicates that these Vigarano inclusions sampled the same isotopic reservoirs as the majority of the Allende inclusions that isotope signatures in the latter were not significantly modified by the secondary alteration that permeates most Allende inclusions. In contrast, inclusion 1623-5 has large deficits in Mg-26, Ca-48, and Ti-50 and small but distinct Cr-54, Zn-66, Sr-84, Ba-135, Ba-137, and Sm-144 anomalies. The magnitudes of these unusual anomalies in the refractory elements are within analytical uncertainty of those found in the Allende 'FUN" inclusion C1, yet 1623-5 has a very different bulk chemical composition from C1. The fact that 1623-5 and C1 have identical isotopic anomalies yet have significantly distinct major and trace element contents provide convincing evidence for the presence of isotopically distinct reservoirs in the early solar system.

  3. Titanium isotopic anomalies in hibonites from the Murchison carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Ireland, T. R.; Compston, W.; Heydegger, H. R.

    1985-09-01

    The isotopic compositions of titanium in eight grains of hibonite (CaAl12O19) from the carbonaceous chondrite Murchison have been determined by high precision secondary ion mass spectrometry using an ion microprobe. The titanium in the hibonites varies greatly in Ti-50 from about -42 to +8 permil (relative to terrestrial) with smaller (up to 4 permil), but clearly resolvable, effects in Ti-46 and Ti-48. These results confirm the presence of widespread negative anomalies suggested by the results of Hutcheon et al. (1983) on hibonites from Murchison. The magnitude of these variations seems explicable only in terms of nucleogenic processes which produced extremely variable titanium isotopic abundances in the hibonite source materials. The hibonites evidently did not participate to the same extent as most material in the mixing and homogenisation processes that accompanied the formation and later evolution of the solar system.

  4. The atmosphere of Mars - Detection of krypton and xenon

    NASA Technical Reports Server (NTRS)

    Owen, T.; Biemann, K.; Biller, J. E.; Lafleur, A. L.; Rushneck, D. R.; Howarth, D. W.

    1976-01-01

    Krypton and xenon have been discovered in the Martian atmosphere with the mass spectrometer on the second Viking lander. Krypton is more abundant than xenon. The relative abundances of the krypton isotopes appear normal, but the ratio of xenon-129 to xenon-132 is enhanced on Mars relative to the terrestrial value for this ratio. Some possible implications of these findings are discussed.

  5. The isotopic homogeneity in the early solar system: Revisiting the CAI oxygen isotopic anomaly

    NASA Astrophysics Data System (ADS)

    Ozima, M.; Yamada, A.

    2009-12-01

    Since the first discovery of the mass-independently fractionated oxygen isotopes in anhydrous, high temperature Ca-Al rich inclusion minerals in carbonaceous meteorites (CAIs) by Clayton et al. (1), their common occurrence in primitive meteorites has generally been regarded to reflect some fundamental process prevalent in the early solar nebula. The CAI oxygen isotopic composition is uniquely characterized by (i) large mass independent isotopic fractionation and (ii) their isotopic data in an oxygen three isotope plot (δ17O - δ18O (δ17O ≡ {(17O/16O)/(17O/16O)SMOW - 1} × 1000) yield nearly a straight line with a slope 1.0. In establishing these characteristics, ion microprobe analyses has played a central role, especially an isotopic mapping technique (isotopography) was crucial (e.g., 2). The extraordinary oxygen isotopic ratio in CAIs is widely attributed to the self-shielding absorption of UV radiation in CO, one of the dominant chemical compounds in the early solar nebula (3). However, the self-shielding scenario necessarily leads to the unusual prediction that a mean solar oxygen isotopic composition differs from most of planetary bodies including Earth, Moon, and Mars. If the self-shielding process were indeed responsible to the CAI oxygen isotopic anomaly, this would require a fundamental revision of the current theory of the origin of the solar system, which generally assumes the initial total vaporization of nebula material to give rise to isotopic homogenization. The GENESIS mission launched in 2001(4), which collected oxygen in the solar wind was hoped to resolve the isotopic composition of the Sun. However, because of difficulties in correcting for instrumental and more importantly for intrinsic isotopic fractionation between the SW and the Sun, a final answer is yet to be seen (5). Here, we show on the basis of the oxygen isotopic fractionation systematics that the self shielding hypothesis cannot explain the key characteristics of the CAI oxygen

  6. Large sulfur-isotope anomaly in nonvolcanic sulfate aerosol and its implications for the Archean atmosphere.

    PubMed

    Shaheen, Robina; Abaunza, Mariana M; Jackson, Teresa L; McCabe, Justin; Savarino, Joël; Thiemens, Mark H

    2014-08-19

    Sulfur-isotopic anomalies have been used to trace the evolution of oxygen in the Precambrian atmosphere and to document past volcanic eruptions. High-precision sulfur quadruple isotope measurements of sulfate aerosols extracted from a snow pit at the South Pole (1984-2001) showed the highest S-isotopic anomalies (Δ(33)S = +1.66‰ and Δ(36)S = +2‰) in a nonvolcanic (1998-1999) period, similar in magnitude to Pinatubo and Agung, the largest volcanic eruptions of the 20th century. The highest isotopic anomaly may be produced from a combination of different stratospheric sources (sulfur dioxide and carbonyl sulfide) via SOx photochemistry, including photoexcitation and photodissociation. The source of anomaly is linked to super El Niño Southern Oscillation (ENSO) (1997-1998)-induced changes in troposphere-stratosphere chemistry and dynamics. The data possess recurring negative S-isotope anomalies (Δ(36)S = -0.6 ± 0.2‰) in nonvolcanic and non-ENSO years, thus requiring a second source that may be tropospheric. The generation of nonvolcanic S-isotopic anomalies in an oxidizing atmosphere has implications for interpreting Archean sulfur deposits used to determine the redox state of the paleoatmosphere. PMID:25092338

  7. Large sulfur-isotope anomaly in nonvolcanic sulfate aerosol and its implications for the Archean atmosphere

    PubMed Central

    Shaheen, Robina; Abaunza, Mariana M.; Jackson, Teresa L.; McCabe, Justin; Savarino, Joël; Thiemens, Mark H.

    2014-01-01

    Sulfur-isotopic anomalies have been used to trace the evolution of oxygen in the Precambrian atmosphere and to document past volcanic eruptions. High-precision sulfur quadruple isotope measurements of sulfate aerosols extracted from a snow pit at the South Pole (1984–2001) showed the highest S-isotopic anomalies (Δ33S = +1.66‰ and Δ36S = +2‰) in a nonvolcanic (1998–1999) period, similar in magnitude to Pinatubo and Agung, the largest volcanic eruptions of the 20th century. The highest isotopic anomaly may be produced from a combination of different stratospheric sources (sulfur dioxide and carbonyl sulfide) via SOx photochemistry, including photoexcitation and photodissociation. The source of anomaly is linked to super El Niño Southern Oscillation (ENSO) (1997–1998)-induced changes in troposphere–stratosphere chemistry and dynamics. The data possess recurring negative S-isotope anomalies (Δ36S = −0.6 ± 0.2‰) in nonvolcanic and non-ENSO years, thus requiring a second source that may be tropospheric. The generation of nonvolcanic S-isotopic anomalies in an oxidizing atmosphere has implications for interpreting Archean sulfur deposits used to determine the redox state of the paleoatmosphere. PMID:25092338

  8. On strontium isotopic anomalies and odd-A p-process abundances. [in solar system

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.

    1978-01-01

    Several aspects of the nucleosynthesis of Sr isotopes are considered in an attempt to shed light on the problem of the Sr isotopic anomalies discovered in an inclusion of the Allende meteorite. Decomposition of the Sr isotopes into average r-, s-, and p-process nucleosynthetic classes is performed. It is suggested that the Allende inclusion most likely has an excess of s-process Sr and that the initial Sr-87/Sr-86 isotopic ratio is probably slightly more primitive than basaltic achondrites. The results also show that Sn-115 is mostly due to the r-process and that odd-A yields are very small. It is concluded that if the Sr anomaly in the inclusion is an average s enhancement, it argues somewhat in favor of a model of gas/dust fractionation of s and r isotopes during accumulation of the inclusion parent in the protosolar cloud.

  9. Endemic Ru Isotopic Anomalies in Iron Meteorites and in Allende

    NASA Technical Reports Server (NTRS)

    Chen, J. H.; Papanastassiou, D. A.; Wasserburg, G. J.

    2003-01-01

    Small variations for Mo isotopes have been observed recently in the Allende meteorite and in iron meteorites, mesosiderites, and pallasites, using ICPMS. Large effects for Mo have been reported for leaches of Orgueil and in SiC and graphite from Murchison. Variations for Mo in bulk Allende and in Murchison have also been presented by NTIMS. Effects in Ru isotopes can define further the preserved exotic r, s, and p contributions in this mass region, and possible effects in Ru-98 and Ru-99 from Tc-98 (4.2 Ma half-life) and Tc-99 (0.21 Ma half-life). Previous attempts at determination of Ru isotopes yielded no resolved effects. The present work represents a substantial improvement in precision over the earlier work. Chemical and mass spectrometric analytical techniques are presented to determine the Ru isotope compositions in terrestrial standards and in meteorites.

  10. Carbon Isotopic tests on the Origins of the Shuram Anomaly from the San Juan Fm., Peru

    NASA Astrophysics Data System (ADS)

    Hodgin, E. B.

    2015-12-01

    Carbon isotope anomalies are associated with perturbations to the carbon cycle that offer insight into the geochemical evolution of the Earth. The largest Carbon isotope anomaly in earth history is the Shuram, which remains poorly understood in spite of being linked to the oxygenation of earth, the rise of metazoans, and a complete reorganization of the carbon cycle. From a basin transect of the carbonate-dominated San Juan Formation in southern Peru, we present evidence for the first clear example of the Shuram isotope anomaly in South America. Unique to this succession are ~140 meters of organic-rich black shale within the anomaly, containing as much as 4% TOC. Preliminary data from the organic-rich black shales of the San Juan Fm. confirm that δ13Corg is relatively invariant and does not covary with δ13Ccarb. These observations are consistent with other Shuram sections and support various models: an exogenous carbon source, an enlarged dissolved organic carbon pool, as well as authigenic carbonate production in organic-rich anoxic sediments. Critical tests of these models have been complicated by a paucity of organics in Shuram facies worldwide. Further analyses of the robust organics from the Shuram facies of the San Juan Fm. therefore hold promise in shedding light on the origin of the Shuram isotope anomaly and critical earth history events to which it has been linked.

  11. Anomalies.

    ERIC Educational Resources Information Center

    Online-Offline, 1999

    1999-01-01

    This theme issue on anomalies includes Web sites, CD-ROMs and software, videos, books, and additional resources for elementary and junior high school students. Pertinent activities are suggested, and sidebars discuss UFOs, animal anomalies, and anomalies from nature; and resources covering unexplained phenonmenas like crop circles, Easter Island,…

  12. Sulfur and Hydrogen Isotope Anomalies in Meteorite Sulfonic Acids

    NASA Technical Reports Server (NTRS)

    Cooper, George W.; Thiemens, Mark H.; Jackson, Teresa L.; Chang, Sherwood

    1997-01-01

    Intramolecular carbon, hydrogen, and sulfur isotope ratios were measured on a homologous series of organic sulfonic acids discovered in the Murchison meteorite. Mass-independent sulfur isotope fractionations were observed along with high deuterium/hydrogen ratios. The deuterium enrichments indicate formation of the hydrocarbon portion of these compounds in a low-temperature environment that is consistent with that of interstellar clouds. Sulfur-33 enrichments observed in methanesulfonic acid could have resulted from gas-phase ultraviolet irradiation of a precursor, carbon disulfide. The source of the sulfonic acid precursors may have been the reactive interstellar molecule carbon monosulfide.

  13. Isotopic Anomalies in Organic Nanoglobules from Comet 81P/Wild 2: Comparison to Murchison Nanoglobules and Isotopic Anomalies Induced in Terrestrial Organics by Electron Irradiation

    SciTech Connect

    De Gregorio, B.; Stroud, R; Nittler, L; Alexander, C; Kilcoyne, A; Zega, T

    2010-01-01

    Nanoglobules are a form of organic matter found in interplanetary dust particles and primitive meteorites and are commonly associated with {sup 15}N and D isotopic anomalies that are suggestive of interstellar processes. We report the discovery of two isotopically-anomalous organic globules from the Stardust collection of particles from Comet 81P/Wild 2 and compare them with nanoglobules from the Murchison CM2 meteorite. One globule from Stardust Cometary Track 80 contains highly aromatic organic matter and a large {sup 15}N anomaly ({delta}{sup 15}N = 1120{per_thousand}). Associated, non-globular, organic matter from this track is less enriched in {sup 15}N and contains a mixture of aromatic and oxidized carbon similar to bulk insoluble organic material (IOM) from primitive meteorites. The second globule, from Cometary Track 2, contains non-aromatic organic matter with abundant nitrile ({single_bond}C{triple_bond}N) and carboxyl ({single_bond}COOH) functional groups. It is significantly enriched in D ({delta}D = 1000{per_thousand}) but has a terrestrial {sup 15}N/{sup 14}N ratio. Experiments indicate that similar D enrichments, unaccompanied by {sup 15}N fractionation, can be reproduced in the laboratory by electron irradiation of epoxy or cyanoacrylate. Thus, a terrestrial origin for this globule cannot be ruled out, and, conversely, exposure to high-energy electron irradiation in space may be an important factor in producing D anomalies in organic materials. For comparison, we report two Murchison globules: one with a large {sup 15}N enrichment and highly aromatic chemistry analogous to the Track 80 globule and the other only moderately enriched in {sup 15}N with IOM-like chemistry. The observation of organic globules in Comet 81P/Wild 2 indicates that comets likely sampled the same reservoirs of organic matter as did the chondrite parent bodies. The observed isotopic anomalies in the globules are most likely preserved signatures of low temperature (<10 K

  14. Isotopic anomalies in organic nanoglobules from Comet 81P/Wild 2: Comparison to Murchison nanoglobules and isotopic anomalies induced in terrestrial organics by electron irradiation

    NASA Astrophysics Data System (ADS)

    De Gregorio, Bradley T.; Stroud, Rhonda M.; Nittler, Larry R.; Alexander, Conel M. O.'D.; Kilcoyne, A. L. David; Zega, Thomas J.

    2010-08-01

    Nanoglobules are a form of organic matter found in interplanetary dust particles and primitive meteorites and are commonly associated with 15N and D isotopic anomalies that are suggestive of interstellar processes. We report the discovery of two isotopically-anomalous organic globules from the Stardust collection of particles from Comet 81P/Wild 2 and compare them with nanoglobules from the Murchison CM2 meteorite. One globule from Stardust Cometary Track 80 contains highly aromatic organic matter and a large 15N anomaly (δ 15N = 1120‰). Associated, non-globular, organic matter from this track is less enriched in 15N and contains a mixture of aromatic and oxidized carbon similar to bulk insoluble organic material (IOM) from primitive meteorites. The second globule, from Cometary Track 2, contains non-aromatic organic matter with abundant nitrile ( sbnd C tbnd N) and carboxyl ( sbnd COOH) functional groups. It is significantly enriched in D (δD = 1000‰) but has a terrestrial 15N/ 14N ratio. Experiments indicate that similar D enrichments, unaccompanied by 15N fractionation, can be reproduced in the laboratory by electron irradiation of epoxy or cyanoacrylate. Thus, a terrestrial origin for this globule cannot be ruled out, and, conversely, exposure to high-energy electron irradiation in space may be an important factor in producing D anomalies in organic materials. For comparison, we report two Murchison globules: one with a large 15N enrichment and highly aromatic chemistry analogous to the Track 80 globule and the other only moderately enriched in 15N with IOM-like chemistry. The observation of organic globules in Comet 81P/Wild 2 indicates that comets likely sampled the same reservoirs of organic matter as did the chondrite parent bodies. The observed isotopic anomalies in the globules are most likely preserved signatures of low temperature (<10 K) chemistry in the interstellar medium or perhaps the outer regions of the solar nebula. In other

  15. Carbon dioxide and oxygen isotope anomalies in the mesosphere and stratosphere

    SciTech Connect

    Thiemens, M.H.; Jackson, T.; Zipf, E.C.

    1995-11-10

    Isotopic ({delta}{sup 17}O and {delta}{sup 18}O) measurements of stratospheric and mesospheric carbon dioxide (CO{sub 2}) and oxygen (O{sub 2}), along with trace species concentrations (N{sub 2}O, CO, and CO{sub 2}), were made in samples collected from a rocket-borne cryogenic whole air sampler. A large mass-independent isotopic anomaly was observed in CO{sub 2}, which may in part derive from photochemical coupling to ozone (O{sub 3}). The data also require an additional isotopic fractionation process, which is presently unidentified. Mesospheric O{sub 2} isotope ratios differed from those in the troposphere and stratosphere. The cause of this isotopic variation in O{sub 2} is presently unknown. The inability to account for these observations represents a fundamental gap in the understanding of the O{sub 2} chemistry in the stratosphere and mesosphere. 28 refs., 2 figs., 1 tab.

  16. Isotopic Anomalies in a Uranium Cluster Formed by Lais

    NASA Astrophysics Data System (ADS)

    van de Walle, J.; Tarento, R. J.; Joyes, P.

    A study of a Au-U liquid alloy ion source (LAIS) where uranium is enriched in its lighter element (20% 235U, 80% 238U) has been performed by high resolution mass spectrometry. Monoatomic species Au+, Au2+, U2+, U3+ and polyatomic species Au+n, Up+n, AunU+ are observed. The monoatomic results are well explained by the Kingham postionization process. Au+n and AunU+ species present an interesting odd-even effect characteristic of monovalent elements. The main result of this preliminary letter is a heteroisotope anomaly which appears in U+2, U+3 and U4+3 emission where only homoisotopes are detected. A similar phenomenon was reported for Cu+2 and Ge+2 in a previous work and was attributed to a higher state of excitation of emitted heteroisotope aggregates which explode as they fly to the collector.1,2

  17. Oxygen Isotope Anomalies in Orgueil Corundum: Confirmation of Presolar Origin

    NASA Astrophysics Data System (ADS)

    Huss, G. R.; Hutcheon, I. D.; Fahey, A. J.; Wasserburg, G. J.

    1993-07-01

    In a study of Mg isotopes in oxide grains from an Orgueil SiC-spinel-rich residue, [1] reported a corundum grain with ^26Mg*/^27Al = 8.9 x 10^-4, a value ~18 times greater than the canonical 5 x 10^-5 value characteristic of refractory phases formed in the solar nebula. Comparable ratios had previously been found only in carbon-rich interstellar materials, SiC and graphite, [2] leading [1] to suggest that Orgueil corundum B is a pre-solar oxide grain. Subsequently, [3] discovered Murchison corundum 83-5 with a sirnilar ^26Mg*/^27Al of 8.7 x 10^-4; the very unusual oxygen isotope composition (delta^17O = 1072 +- 59 per mil, delta^18O = -244 per mil) led [3] to conclude 83-5 is an interstellar oxide grain. The Panurge ion probe was used to determine ^170/^160 and ^180/^160 ratios in 27 Orgueil oxide grains--16 corundum, 2 hibonite, and 9 spinel--and in 6 Allende spinels. Orgueil corundum B has an extreme ^17O excess (delta^17O = 1394 +- 178 per mil (2sigma(mean)) and a hint of an ^18O depletion (delta^18O = -65 +- 64 per mil) (Fig. 1). The extraordinary enrichments in ^26Mg* and ^17O identify Orgueil B as an interstellar oxide grain. Orgueil B and Murchison 83-5 have remarkably similar O- and Mg-isotope compositions. Red giant stars are enriched in ^17O with ^17O/^18O >~ 1 [4], suggesting these stars are a likely source of the interstellar corundum. Production of ^26Al during H-burning in AGB stars also appears to account for the ^26Mg* excess [5,6]. Condensation of corundum in the circumstellar envelope must occur before dredge up of processed material from the stellar interior decreases ^17O/^16O and creates a C-rich atmosphere. The oxygen isotope compositions of the remaining oxide grains fall into three groups (Fig. 1). All but six corundums and one Orgueil spinel exhibit ^16O excesses and lie along the ^16O-mixing line with compositions similar to those of corundum and spinel from Murchison LS, LU, and CFO(sub)c [7]. Data from Allende spinels cluster about a

  18. Calcium-48 isotopic anomalies in bulk chondrites and achondrites: Evidence for a uniform isotopic reservoir in the inner protoplanetary disk

    NASA Astrophysics Data System (ADS)

    Dauphas, Nicolas; Chen, James H.; Zhang, Junjun; Papanastassiou, Dimitri A.; Davis, Andrew M.; Travaglio, Claudia

    2014-12-01

    Thermal ionization mass spectrometry (TIMS) was used to measure the calcium isotopic compositions of carbonaceous, ordinary, enstatite chondrites as well as eucrites and aubrites. We find that after correction for mass-fractionation by internal normalization to a fixed 42Ca/44Ca ratio, the 43Ca/44Ca and 46Ca/44Ca ratios are indistinguishable from terrestrial ratios. In contrast, the 48Ca/44Ca ratios show significant departure from the terrestrial composition (from -2 ε in eucrites to +4 ε in CO and CV chondrites). Isotopic anomalies in ε48Ca correlate with ε50Ti: ε 48Ca=(1.09±0.11)×ε 50Ti+(0.03±0.14). Further work is needed to identify the carrier phase of 48Ca-50Ti anomalies but we suggest that it could be perovskite and that the stellar site where these anomalies were created was also responsible for the nucleosynthesis of the bulk of the solar system inventory of these nuclides. The Earth has identical 48Ca isotopic composition to enstatite chondrites (EH and EL) and aubrites. This adds to a long list of elements that display nucleosynthetic anomalies at a bulk planetary scale but show identical or very similar isotopic compositions between enstatite chondrites, aubrites, and Earth. This suggests that the inner protoplanetary disk was characterized by a uniform isotopic composition (IDUR for Inner Disk Uniform Reservoir), sampled by enstatite chondrites and aubrites, from which the Earth drew most of its constituents. The terrestrial isotopic composition for 17O, 48Ca, 50Ti, 62Ni, and 92Mo is well reproduced by a mixture of 91% enstatite, 7% ordinary, and 2% carbonaceous chondrites. The Earth was not simply made of enstatite chondrites but it formed from the same original material that was later modified by nebular and disk processes. The Moon-forming impactor probably came from the same region as the other embryos that made the Earth, explaining the strong isotopic similarity between lunar and terrestrial rocks.

  19. Oxygen isotope anomaly observed in water vapor from Alert, Canada and the implication for the stratosphere

    PubMed Central

    Lin, Ying; Clayton, Robert N.; Huang, Lin; Nakamura, Noboru; Lyons, James R.

    2013-01-01

    To identify the possible anomalous oxygen isotope signature in stratospheric water predicted by model studies, 25 water vapor samples were collected in 2003−2005 at Alert station, Canada (82°30′N), where there is downward transport of stratospheric air to the polar troposphere, and were analyzed for δ17O and δ18O relative to Chicago local precipitation (CLP). The latter was chosen as a reference because the relatively large evaporative moisture source should erase any possible oxygen isotope anomaly from the stratosphere. A mass-dependent fractionation coefficient for meteoric waters, λMDF(H2O) = 0.529 ± 0.003 [2σ standard error (SE)], was determined from 27 CLP samples collected in 2003−2005. An oxygen isotopic anomaly of Δ17O = 76 ± 16 ppm (2σ SE) was found in water vapor samples from Alert relative to CLP. We propose that the positive oxygen isotope anomalies observed at Alert originated from stratospheric ozone, were transferred to water in the stratosphere, and subsequently mixed with tropospheric water at high latitudes as the stratospheric air descended into the troposphere. On the basis of this ground signal, the average Δ17O in stratospheric water vapor predicted by a steady-state box model is ∼40‰. Seven ice core samples (1930−1991) from Dasuopu glacier (Himalayas, China) and Standard Light Antarctic Precipitation did not show an obvious oxygen isotope anomaly, and Vienna Standard Mean Ocean Water exhibited a negative Δ17O relative to CLP. Six Alert snow samples collected in March 2011 and measured at Laboratoire des Sciences du Climat et de l'Environnement, Gif sur Yvette, France, had 17Oexcess of 45 ± 5 ppm (2σ SE) relative to Vienna Standard Mean Ocean Water. PMID:24009339

  20. Oxygen isotope anomaly observed in water vapor from Alert, Canada and the implication for the stratosphere.

    PubMed

    Lin, Ying; Clayton, Robert N; Huang, Lin; Nakamura, Noboru; Lyons, James R

    2013-09-24

    To identify the possible anomalous oxygen isotope signature in stratospheric water predicted by model studies, 25 water vapor samples were collected in 2003-2005 at Alert station, Canada (82°30'N), where there is downward transport of stratospheric air to the polar troposphere, and were analyzed for δ(17)O and δ(18)O relative to Chicago local precipitation (CLP). The latter was chosen as a reference because the relatively large evaporative moisture source should erase any possible oxygen isotope anomaly from the stratosphere. A mass-dependent fractionation coefficient for meteoric waters, λMDF(H2O) = 0.529 ± 0.003 [2σ standard error (SE)], was determined from 27 CLP samples collected in 2003-2005. An oxygen isotopic anomaly of Δ(17)O = 76 ± 16 ppm (2σ SE) was found in water vapor samples from Alert relative to CLP. We propose that the positive oxygen isotope anomalies observed at Alert originated from stratospheric ozone, were transferred to water in the stratosphere, and subsequently mixed with tropospheric water at high latitudes as the stratospheric air descended into the troposphere. On the basis of this ground signal, the average Δ(17)O in stratospheric water vapor predicted by a steady-state box model is ∼40‰. Seven ice core samples (1930-1991) from Dasuopu glacier (Himalayas, China) and Standard Light Antarctic Precipitation did not show an obvious oxygen isotope anomaly, and Vienna Standard Mean Ocean Water exhibited a negative Δ(17)O relative to CLP. Six Alert snow samples collected in March 2011 and measured at Laboratoire des Sciences du Climat et de l'Environnement, Gif sur Yvette, France, had (17)Oexcess of 45 ± 5 ppm (2σ SE) relative to Vienna Standard Mean Ocean Water. PMID:24009339

  1. Krypton oxides under pressure.

    PubMed

    Zaleski-Ejgierd, Patryk; Lata, Pawel M

    2016-01-01

    Under high pressure, krypton, one of the most inert elements is predicted to become sufficiently reactive to form a new class of krypton compounds; krypton oxides. Using modern ab-initio evolutionary algorithms in combination with Density Functional Theory, we predict the existence of several thermodynamically stable Kr/O species at elevated pressures. In particular, our calculations indicate that at approx. 300 GPa the monoxide, KrO, should form spontaneously and remain thermo- and dynamically stable with respect to constituent elements and higher oxides. The monoxide is predicted to form non-molecular crystals with short Kr-O contacts, typical for genuine chemical bonds. PMID:26830129

  2. Krypton oxides under pressure

    PubMed Central

    Zaleski-Ejgierd, Patryk; Lata, Pawel M.

    2016-01-01

    Under high pressure, krypton, one of the most inert elements is predicted to become sufficiently reactive to form a new class of krypton compounds; krypton oxides. Using modern ab-initio evolutionary algorithms in combination with Density Functional Theory, we predict the existence of several thermodynamically stable Kr/O species at elevated pressures. In particular, our calculations indicate that at approx. 300 GPa the monoxide, KrO, should form spontaneously and remain thermo- and dynamically stable with respect to constituent elements and higher oxides. The monoxide is predicted to form non-molecular crystals with short Kr-O contacts, typical for genuine chemical bonds. PMID:26830129

  3. The sp-process and Allende isotope anomalies in calcium and titanium

    NASA Astrophysics Data System (ADS)

    Harris, M. J.

    1983-01-01

    The goal of the study described here is to show that partial nuclear destruction of the Ca isotopes can reproduce the EK-1-4-1 pattern and can simultaneously produce the Ti anomaly observed in that inclusion. The parameterized approach adopted here yields little information about a likely stellar site. Considerations of time scale and proton density, however, both point to a hydrostatic O burning zone, with which the required s-process-like initial composition is compatible. The temperatures involved, however, are considerably lower than those estimated by Arnett (1977) and Weaver, Zimmerman, and Woosley (1978). It is found that slow proton captures on nuclei with Z between 18 and 25 at temperatures in the range where T9 ranges from 1.25 to 1.7 can reproduce the Ca isotopic anomaly in Allende Ca-Al-rich FUN inclusion EK-1-4-1. It is noted that at T9 = 1.55, the required proton exposure approximately reproduces the Ek-1-4-1 Ti anomaly also. Under these conditions, the production of long-lived Ca-41 and Mn-53, as well as of an anomaly in Cr, is predicted.

  4. Model Calculations of Continuous-Wave Laser Ionization of Krypton

    SciTech Connect

    Bret D. Cannon

    1999-07-27

    This report describes modeling of a scheme that uses continuous-wave (CW) lasers to ionize selected isotopes of krypton with high isotopic selectivity. The models predict that combining this ionization scheme with mass spectrometric measurement of the resulting ions can be the basis for ultra-sensitive methods to measure {sup 85}Kr in the presence of a 10{sup 11} excess of the stable krypton isotopes. Two experimental setups are considered in this model: the first setup is for krypton as a static gas, the second is for krypton in an atomic beam. In the static gas experiment, for a total krypton press of 10{sup {minus}4} torr and 10 W of power in the cavity, the model predicts a total krypton ion current of 4.6 x 10{sup 8} s{sup {minus}1} and for a {sup 85}Kr/Kr of 10{sup {minus}11} a {sup 85}Kr ion current of 3.5 s{sup {minus}1} or about 10,000 per hour. The atomic beam setup allowed higher isotopic selectivity; the model predicts a {sup 85}Kr ion current of 18 s{sup {minus}1} or 65,000 per hour.

  5. Sulfur and Hydrogen Isotope Anomalies in Organic Compounds from the Murchison Meteorite

    NASA Technical Reports Server (NTRS)

    Cooper, G. W.; Thiemens, M. H.; Jackson, T.; Chang, Sherwood

    1996-01-01

    Isotopic measurements have been made on organic sulfur and phosphorus compounds recently discovered in the Murchison meteorite. Carbon, hydrogen and sulfur measurements were performed on individual members of the organic sulfur compounds, alkyl sulfonates; and carbon and hydrogen measurements were made on bulk alkyl phosphonates. Cooper and Chang reported the first carbon isotopic measurements of Murchison organic sulfonates, providing insight into the potential synthetic mechanisms of these and, possibly, other organic species. Hydrogen isotopic measurements of the sulforiates now reveal deuterium excesses ranging from +660 to +2730 %. The deuterium enrichments indicate formation of the hydrocarbon portion of these compounds in a low temperature astrophysical environment consistent with that of dense molecular clouds. Measurements of the sulfur isotopes provide further constraints on the origin and mechanism of formation of these organic molecules. Recently, there has been growing documentation of sulfur isotopic anomalies in meteoritic material. Thiemens and Jackson have shown that some bulk ureilites possess excess S-33 and Thiemens et al. have reported excess S-33 in an oldhamite separate from the Norton County meteorite. Rees and Thode reported a large S-33 excess in an Allende acid residue, however, attempts to verify this measurements have been unsuccessful, possibly due to the heterogeneous nature of the carrier phase. With the recognition that sulfur isotopes may reflect chemistry in the protosolar nebula or the precursor molecular cloud, identification of potential carriers is of considerable interest. In the present study, the stable isotopes of sulfur were measured in methane sulfonic acid extracted from the Murchison meteorite. The isotopic composition was found to be: (delta)S-33 = 2.48 %, (delta)S-34 = 2.49 % and (delta)S-36 = 6.76 %. Based upon analysis of more than 60 meteoritic and numerous terrestrial samples, the mass fractionation lines are

  6. Nucleosynthetic W isotope anomalies and the Hf-W chronometry of Ca-Al-rich inclusions

    NASA Astrophysics Data System (ADS)

    Kruijer, Thomas S.; Kleine, Thorsten; Fischer-Gödde, Mario; Burkhardt, Christoph; Wieler, Rainer

    2014-10-01

    Ca-Al-rich inclusions (CAI) are the oldest dated objects formed in the solar system and are pivotal reference points in early solar system chronology. Knowledge of their initial 182Hf/180Hf and 182W/184W is essential, not only for obtaining precise Hf-W ages relative to the start of the solar system, but also to assess the distribution of short-lived radionuclides in the early solar nebula. However, the interpretation of Hf-W data for CAI is complicated by nucleosynthetic W isotope variations. To explore their extent and nature, and to better quantify the initial Hf and W isotope compositions of the solar system, we obtained Hf-W data for several fine- and coarse-grained CAI from three CV3 chondrites. The fine-grained CAI exhibit large and variable anomalies in ε183W (εiW equals 0.01% deviation from terrestrial values), extending to much larger anomalies than previously observed in CAI, and reflecting variable abundances of s- and r-process W isotopes. Conversely, the coarse-grained (mostly type B) inclusions show only small (if any) nucleosynthetic W isotope anomalies. The investigated CAI define a precise correlation between initial ε182W and ε183W, providing a direct empirical means to correct the ε182W of any CAI for nucleosynthetic isotope anomalies using their measured ε183W. After correction for nucleosynthetic W isotope variations, the CAI data define an initial 182Hf/180Hf of (1.018±0.043)×10-4 and an initial ε182W of -3.49±0.07. The Hf-W formation intervals of the angrites D'Orbigny and Sahara 99555 relative to this CAI initial is 4.8±0.6 Ma, in good agreement with Al-Mg ages of these two angrites. This renders a grossly heterogeneous distribution of 26Al in the inner solar system unlikely, at least in the region were CAI and angrites formed.

  7. Sulfur and Hydrogen Isotope Anomalies in Organic Compounds from the Murchison Meteorite

    NASA Astrophysics Data System (ADS)

    Cooper, G. W.; Thiemens, M. H.; Jackson, T.; Chang, S.

    1995-09-01

    Carbon, hydrogen and sulfur isotopic measurements have been made on individual members of a recently discovered class of organic sulfur compounds, alkyl sulfonates, in the Murchison meteorite. Cooper and Chang (1) reported the first carbon isotopic measurements of Murchison organic sulfonates, providing insight into potential synthetic mechanisms of these, and possibly other, organic species. Hydrogen isotopic measurements of the sulfonates now reveal deuterium excesses ranging from +660 to +2730 per mil. The deuterium enrichments indicate formation of the hydrocarbon portion of these compounds in a low temperature astrophysical environment consistent with that of dense molecular clouds. Measurement of the sulfur isotopes provide further constraints on the origin and mechanism of formation of these organic molecules. Recently, there has been growing documentation of sulfur isotopic anomalies in meteoritic material. Thiemens and Jackson (2) have shown that some bulk ureilites possess excess 33S and Thiemens et al. (3) have reported excess 33S in an oldhamite separate from Norton County. Rees and Thode (4) reported a large 33S excess in an Allende acid residue, however, attempts to verify this measurement have been unsuccessful, possibly due to the heterogeneous nature of the carrier phase. With the recognition that sulfur isotopes may reflect nebular chemistry, identification of potential carriers is of considerable interest. In the present study the three stable isotopes of sulfur were measured in methane sulfonate extracted from the Murchison meteorite. The isotopic composition was found to be delta 33S=2.48, delta 34S=2.49 and delta 36S = 6.76 per mil. Based upon analysis of more than 60 meteoritic, and numerous terrestrial samples, the mass fractionation lines are defined by 33Delta = delta 33S-0.50 delta 34S and 36Delta = delta 36S -1.97 delta 34S. From these relations a 33Delta = 1.24 per mil and 36Delta = 0.89 per mil is observed. These anomalies

  8. Calcium isotopic anomalies and the lack of aluminum-26 in an unusual Allende inclusion

    NASA Technical Reports Server (NTRS)

    Lee, T.; Russell, W. A.; Wasserburg, G. J.

    1979-01-01

    This letter reports the discovery of an unusual Allende inclusion that is rich in hibonite, Ca(Al, Ti, Mg)12O19, the most refractory and possibly the most primitive major oxide mineral from the solar nebula. The Mg and Ca isotopic compositions of this hibonite-rich inclusion are studied in order to investigate the distribution of Al-26 in the solar system and to extend the search for isotopic anomalies. The Mg results indicate that no Mg isotopic anomalies are present, that the initial Al-26/Al-27 ratio for the inclusion when it crystallized was less than 200 billionths, and that the Mg mass-fractionation effect in the inclusion must be less than about 20 per mil/amu for the hibonite and 10 per mil/amu for other phases. The Ca studies reveal that large Ca mass-fractionation effects of about 7.5 per mil/amu are present and that additional small 'nonlinear' effects of presumably nuclear origin at a level of about 1 to 2 per mil are present in at least Ca-42. A plausible model for the evolution of the hibonite-rich inclusion is outlined.

  9. Oxygen Isotope Anomaly in the Carbonate Fractions of Aerosols and its Potential to Assess Urban Pollution

    NASA Astrophysics Data System (ADS)

    Shaheen, R.; Abramian, A.; Dominguez, G.; Jackson, T.; Thiemens, M. H.

    2008-12-01

    = 0.887) was observed between oxygen isotope anomaly (Δ17O) in the carbonate fraction of coarse aerosols and urban index, indicating that the isotope anomaly of carbonates can be used as a proxy for urban pollution. Additionally, controlled laboratory experiments to understand the origin of isotope anomaly in the carbonate fraction of aerosols will be discussed.

  10. Update and improvement of the global krypton-85 emission inventory.

    PubMed

    Ahlswede, Jochen; Hebel, Simon; Ross, J Ole; Schoetter, Robert; Kalinowski, Martin B

    2013-01-01

    Krypton-85 is mainly produced in nuclear reactors by fission of uranium and plutonium and released during chopping and dissolution of spent fuel rods in nuclear reprocessing facilities. As noble gas it is suited as a passive tracer for evaluation of atmospheric transport models. Furthermore, research is ongoing to assess its quality as an indicator for clandestine reprocessing activities. This paper continues previous efforts to compile a comprehensive historic emission inventory for krypton-85. Reprocessing facilities are the by far largest emitters of krypton-85. Information on sources and calculations used to derive the annual krypton-85 emission is provided for all known reprocessing facilities in the world. In addition, the emission characteristics of two plants, Tokai (Japan) and La Hague (France), are analysed in detail using emission data with high temporal resolution. Other types of krypton-85 sources are power reactors, naval reactors and isotope production facilities. These sources contribute only little or negligible amounts of krypton-85 compared to the large reprocessing facilities. Taking the decay of krypton-85 into account, the global atmospheric inventory is estimated to about 5500 PBq at the end of 2009. The correctness if the inventory has been proven by meteorological simulations and its error is assumed to be in the range of a few percent. PMID:22858641

  11. Hibonite-bearing microspherules - A new type of refractory inclusions with large isotopic anomalies

    NASA Technical Reports Server (NTRS)

    Ireland, T. R.; Fahey, A. J.; Zinner, E. K.

    1991-01-01

    This paper presents petrographic description as well as results on the major- and trace-element chemistry and on Mg, Ca, and Ti isotopic compositions of three refractory inclusions, including 3413-1/31 inclusion from Lance and Murchison 7-228 and 7-753, the mineralogy of which is dominated by the oxide minerals spinel, hibonite, and perovskite. The microspherules examined seem to constitute a separate class of refractory inclusions, characterized by a distinct morphology and mineralogy; large excesses of Ca-48 and Ti-50, and Mg-26 depletions. It is suggested that this type of inclusions must have formed early, prior to the dilution of isotopic anomalies by mixing processes, and in an area characterized by excesses of Ca-48 and Ti-50, depletions of Mg-26, and a lack of Al-26.

  12. Detection of oxygen isotopic anomaly in terrestrial atmospheric carbonates and its implications to Mars.

    PubMed

    Shaheen, R; Abramian, A; Horn, J; Dominguez, G; Sullivan, R; Thiemens, Mark H

    2010-11-23

    The debate of life on Mars centers around the source of the globular, micrometer-sized mineral carbonates in the ALH84001 meteorite; consequently, the identification of Martian processes that form carbonates is critical. This paper reports a previously undescribed carbonate formation process that occurs on Earth and, likely, on Mars. We identified micrometer-sized carbonates in terrestrial aerosols that possess excess (17)O (0.4-3.9‰). The unique O-isotopic composition mechanistically describes the atmospheric heterogeneous chemical reaction on aerosol surfaces. Concomitant laboratory experiments define the transfer of ozone isotopic anomaly to carbonates via hydrogen peroxide formation when O(3) reacts with surface adsorbed water. This previously unidentified chemical reaction scenario provides an explanation for production of the isotopically anomalous carbonates found in the SNC (shergottites, nakhlaites, chassignites) Martian meteorites and terrestrial atmospheric carbonates. The anomalous hydrogen peroxide formed on the aerosol surfaces may transfer its O-isotopic signature to the water reservoir, thus producing mass independently fractionated secondary mineral evaporites. The formation of peroxide via heterogeneous chemistry on aerosol surfaces also reveals a previously undescribed oxidative process of utility in understanding ozone and oxygen chemistry, both on Mars and Earth. PMID:21059939

  13. Detection of oxygen isotopic anomaly in terrestrial atmospheric carbonates and its implications to Mars

    PubMed Central

    Shaheen, R.; Abramian, A.; Horn, J.; Dominguez, G.; Sullivan, R.; Thiemens, Mark H.

    2010-01-01

    The debate of life on Mars centers around the source of the globular, micrometer-sized mineral carbonates in the ALH84001 meteorite; consequently, the identification of Martian processes that form carbonates is critical. This paper reports a previously undescribed carbonate formation process that occurs on Earth and, likely, on Mars. We identified micrometer-sized carbonates in terrestrial aerosols that possess excess 17O (0.4–3.9‰). The unique O-isotopic composition mechanistically describes the atmospheric heterogeneous chemical reaction on aerosol surfaces. Concomitant laboratory experiments define the transfer of ozone isotopic anomaly to carbonates via hydrogen peroxide formation when O3 reacts with surface adsorbed water. This previously unidentified chemical reaction scenario provides an explanation for production of the isotopically anomalous carbonates found in the SNC (shergottites, nakhlaites, chassignites) Martian meteorites and terrestrial atmospheric carbonates. The anomalous hydrogen peroxide formed on the aerosol surfaces may transfer its O-isotopic signature to the water reservoir, thus producing mass independently fractionated secondary mineral evaporites. The formation of peroxide via heterogeneous chemistry on aerosol surfaces also reveals a previously undescribed oxidative process of utility in understanding ozone and oxygen chemistry, both on Mars and Earth. PMID:21059939

  14. The NO+O{sub 3} reaction: A triple oxygen isotope perspective on the reaction dynamics and atmospheric implications for the transfer of the ozone isotope anomaly

    SciTech Connect

    Savarino, J.; Morin, S.; Baroni, M.; Bhattacharya, S. K.; Doussin, J.-F.

    2008-05-21

    Atmospheric nitrate shows a large oxygen isotope anomaly ({delta} {sup 17}O), characterized by an excess enrichment of {sup 17}O over {sup 18}O, similar to the ozone molecule. Modeling and observations assign this specific isotopic composition mainly to the photochemical steady state that exists in the atmosphere between ozone and nitrate precursors, namely, the nitrogen oxides (NO{sub x}=NO+NO{sub 2}). However, this transfer is poorly quantified and is built on unverified assumptions about which oxygen atoms of ozone are transferred to NO{sub x}, greatly weakening any interpretation of the nitrate oxygen isotopic composition in terms of chemical reaction pathways and the oxidation state of the atmosphere. With the aim to improve our understanding and quantify how nitrate inherits this unusual isotopic composition, we have carried out a triple isotope study of the reaction NO+O{sub 3}. Using ozone intramolecular isotope distributions available in the literature, we have found that the central atom of the ozone is abstracted by NO with a probability of (8{+-}5)%({+-}2{sigma}) at room temperature. This result is at least qualitatively supported by dynamical reaction experiments, the non-Arrhenius behavior of the kinetic rate of this reaction, and the kinetic isotope fractionation factor. Finally, we have established the transfer function of the isotope anomaly of O{sub 3} to NO{sub 2}, which is described by the linear relationship {delta} {sup 17}O(NO{sub 2})=Ax{delta} {sup 17}O(O{sub 3})+B, with A=1.18{+-}0.07({+-}1{sigma}) and B=(6.6{+-}1.5) per mille ({+-}1{sigma}). Such a relationship can be easily incorporated into models dealing with the propagation of the ozone isotope anomaly among oxygen-bearing species in the atmosphere and should help to better interpret the oxygen isotope anomaly of atmospheric nitrate in terms of its formation reaction pathways.

  15. The NO +O3 reaction: A triple oxygen isotope perspective on the reaction dynamics and atmospheric implications for the transfer of the ozone isotope anomaly

    NASA Astrophysics Data System (ADS)

    Savarino, J.; Bhattacharya, S. K.; Morin, S.; Baroni, M.; Doussin, J.-F.

    2008-05-01

    Atmospheric nitrate shows a large oxygen isotope anomaly (ΔO17), characterized by an excess enrichment of O17 over O18, similar to the ozone molecule. Modeling and observations assign this specific isotopic composition mainly to the photochemical steady state that exists in the atmosphere between ozone and nitrate precursors, namely, the nitrogen oxides (NOx=NO+NO2). However, this transfer is poorly quantified and is built on unverified assumptions about which oxygen atoms of ozone are transferred to NOx, greatly weakening any interpretation of the nitrate oxygen isotopic composition in terms of chemical reaction pathways and the oxidation state of the atmosphere. With the aim to improve our understanding and quantify how nitrate inherits this unusual isotopic composition, we have carried out a triple isotope study of the reaction NO +O3. Using ozone intramolecular isotope distributions available in the literature, we have found that the central atom of the ozone is abstracted by NO with a probability of (8±5)%(±2σ) at room temperature. This result is at least qualitatively supported by dynamical reaction experiments, the non-Arrhenius behavior of the kinetic rate of this reaction, and the kinetic isotope fractionation factor. Finally, we have established the transfer function of the isotope anomaly of O3 to NO2, which is described by the linear relationship ΔO17(NO2)=A ×ΔO17(O3)+B, with A =1.18±0.07(±1σ) and B =(6.6±1.5)‰(±1σ). Such a relationship can be easily incorporated into models dealing with the propagation of the ozone isotope anomaly among oxygen-bearing species in the atmosphere and should help to better interpret the oxygen isotope anomaly of atmospheric nitrate in terms of its formation reaction pathways.

  16. Analysis of krypton-85 and krypton-81 in a few liters of air.

    PubMed

    Tu, Le-Yi; Yang, Guo-Min; Cheng, Cun-Feng; Liu, Gu-Liang; Zhang, Xiang-Yang; Hu, Shui-Ming

    2014-04-15

    Long-lived radioactive krypton isotopes, (81)Kr (t1/2 = 229,000 year) and (85)Kr (t1/2 = 10.76 year), are ideal tracers. (81)Kr is cosmogenic and can be used for dating groundwater beyond the (14)C age. (85)Kr is a fission product and can be applied in atmospheric studies, nuclear safety inspections, and dating young groundwater. It has long been a challenge to analyze radio-krypton in small samples, in which the total number of such isotopes can be as low as 1 × 10(5). This work presents a system developed to analyze (81)Kr and (85)Kr from a few liters of air samples. A separation system based on cryogenic distillation and gas chromatographic separation is used to extract krypton gas with an efficiency of over 90% from air samples of 1-50 L. (85)Kr/Kr and (81)Kr/Kr ratios in krypton gases are determined from single-atom counting using a laser-based atom trap. In order to test the performance of the system, we have analyzed various samples collected from ambient air and extracted from groundwater, with a minimum size of 1 L. The system can be applied to analyze (81)Kr and (85)Kr in environmental samples including air, groundwater, and ices. PMID:24641193

  17. Cerium anomaly across the mid-Tournaisian carbon isotope excursion (TICE)

    NASA Astrophysics Data System (ADS)

    Jiang, G.; Morales, D. C.; Maharjan, D. K.

    2015-12-01

    The Early Mississippian (ca. 359-345 Ma) represents one of the most important greenhouse-icehouse climate transitions in Earth history. Closely associated with this critical transition is a prominent positive carbon isotope excursion (δ13C ≥ +5‰) that has been documented from numerous stratigraphic successions across the globe. This δ13C excursion, informally referred to as the TICE (mid-Tournaisian carbon isotope excursion) event, has been interpreted as resulting from enhanced organic carbon burial, with anticipated outcomes including the lowering of atmospheric CO2 and global cooling, the growth of continental ice sheets and sea-level fall, and the increase of ocean oxygenation and ocean redox changes. The casual relationship between these events has been addressed from various perspectives but not yet clearly demonstrated. To document the potential redox change associated with the perturbation of the carbon cycle, we have analyzed rare earth elements (REE) and trace elements across the TICE in two sections across a shallow-to-deep water transect in the southern Great Basin (Utah and Nevada), USA. In both sections, the REE data show a significant positive cerium (Ce) anomaly (Ce/Ce* = Ce/(0.5La+0.5Pr)). Prior to the positive δ13C shift, most Ce/Ce* values are around 0.3 (between 0.2 and 0.4). Across the δ13C peak, Ce/Ce* values increase up to 0.87, followed by a decrease back to 0.2~0.3 after the δ13C excursion (Figure 1). The positive Ce anomaly is best interpreted as recording expansion of oxygen minimum zone and anoxia resulted from increased primary production. This is consistent with a significant increase of nitrogen isotopes (δ15N) across the δ13C peak. Integration of the carbon, nitrogen, and REE data demonstrates a responsive earth systems change linked to the perturbation of the Early Mississippian carbon cycle.

  18. Heavy-ion isotopic anomalies in He-3 rich solar particle events

    NASA Astrophysics Data System (ADS)

    Mason, G. M.; Mazur, J. E.; Halmilton, D. C.

    1994-04-01

    We have measured the approximately 1 MeV/nucleon heavy-ion mass composition during a series of (3)He-rich solar particle events during 1992 July using the University of Maryland instrument on the SAMPEX spacecraft. In addition to enhancements of He-3/He-4 of approximately 103 to 104 larger than coronal values, these events also showed typical enhancements of heavy nuclei of up to a factor of approximately 10 compared with large solar particle events. Over the energy range of approximately 0.4 - 4.0 MeV/nucleon the spectra of both he isotopes as well as heavier ions C, N, O, Ne, Mg, Si, S, Ca+Ar, and Fe were found to be power laws in enegy per nucleon with nearly identical spectral indices, indicating that both the He and heavier ions were accelerated by the same mechanism. We obtain upper limits of approximately 15 for possible enrichments of neutron-rich isotopes of C, N, O, and Fe compared to large solar particle events; however, we find Ne-22/Ne-20 = 0.29 +/- 0.10, an enhancement of a factor of 3-4 compared with large solar particle event abundances. We also find evidence of enrichments of approximately 2-3 for Mg-25/Mg-24 and Mg-26/Mg-24, although the uncertainties are large. Thus while at least one of the heavy elements shows isotopic enhancements of neutron-rich isotopes, the mechanisms that produce the extremely large He-3 enrichments apparently do not produce similarly dramatic isotopic anomalies in the heavy nuclei. These observations constrain possible acceleration models and may indicate that the particles are energized in solar coronal locations enhanced in heavy ions.

  19. Krypton and xenon in the atmosphere of Venus

    NASA Technical Reports Server (NTRS)

    Donahue, T. M.; Hoffman, J. H.; Hodges, R. R., Jr.

    1981-01-01

    The paper reports a determination by the Pioneer Venus large probe neutral mass spectrometer of upper limits to the concentration of krypton and xenon along with most of their isotopes in the atmosphere of Venus. The upper limit to the krypton mixing ratio is estimated at 47 ppb, with a very conservative estimate at 69 ppb. The probable upper limit to the sum of the mixing ratios of the isotopes Xe-128, Xe-129, Xe-130, Xe-131, and Xe-132 is 40 ppb by volume, with a very conservative upper limit three times this large.

  20. Large isotopic anomalies of Si, C, N and noble gases in interstellar silicon carbide from the Murray meteorite

    NASA Astrophysics Data System (ADS)

    Zinner, E.; Ming, T.; Anders, E.

    1987-12-01

    Primitive meteorites contain several noble gas components with anomalous isotopic compositions which imply that they - and their solid 'carrier' phases - are of exotic, pre-solar origin. The authors found that minor fractions of the Murray meteorite contain two minerals not previously seen in meteorites: silicon carbide and an amorphous Si-O phase. They report ion microprobe analyses of these phases which reveal very large isotopic anomalies in silicon, nitrogen and carbon, exceeding the highest anomalies previously measured by factors of up to ≡50. It is concluded that these phases are circumstellar grains from carbon-rich stars, whose chemical inertness allowed them to survive in exceptionally well-preserved form.

  1. Strong water isotopic anomalies in the martian atmosphere: probing current and ancient reservoirs.

    PubMed

    Villanueva, G L; Mumma, M J; Novak, R E; Käufl, H U; Hartogh, P; Encrenaz, T; Tokunaga, A; Khayat, A; Smith, M D

    2015-04-10

    We measured maps of atmospheric water (H2O) and its deuterated form (HDO) across the martian globe, showing strong isotopic anomalies and a significant high deuterium/hydrogen (D/H) enrichment indicative of great water loss. The maps sample the evolution of sublimation from the north polar cap, revealing that the released water has a representative D/H value enriched by a factor of about 7 relative to Earth's ocean [Vienna standard mean ocean water (VSMOW)]. Certain basins and orographic depressions show even higher enrichment, whereas high-altitude regions show much lower values (1 to 3 VSMOW). Our atmospheric maps indicate that water ice in the polar reservoirs is enriched in deuterium to at least 8 VSMOW, which would mean that early Mars (4.5 billion years ago) had a global equivalent water layer at least 137 meters deep. PMID:25745065

  2. Strong water isotopic anomalies in the martian atmosphere: Probing current and ancient reservoirs

    NASA Astrophysics Data System (ADS)

    Villanueva, G. L.; Mumma, M. J.; Novak, R. E.; Käufl, H. U.; Hartogh, P.; Encrenaz, T.; Tokunaga, A.; Khayat, A.; Smith, M. D.

    2015-04-01

    We measured maps of atmospheric water (H2O) and its deuterated form (HDO) across the martian globe, showing strong isotopic anomalies and a significant high deuterium/hydrogen (D/H) enrichment indicative of great water loss. The maps sample the evolution of sublimation from the north polar cap, revealing that the released water has a representative D/H value enriched by a factor of about 7 relative to Earth’s ocean [Vienna standard mean ocean water (VSMOW)]. Certain basins and orographic depressions show even higher enrichment, whereas high-altitude regions show much lower values (1 to 3 VSMOW). Our atmospheric maps indicate that water ice in the polar reservoirs is enriched in deuterium to at least 8 VSMOW, which would mean that early Mars (4.5 billion years ago) had a global equivalent water layer at least 137 meters deep.

  3. Strong Water Isotopic Anomalies in the Martian Atmosphere: Probing Current and Ancient Reservoirs

    NASA Technical Reports Server (NTRS)

    Villanueva, G. L.; Mumma, M. J.; Novak, R. E.; Käufl, H. U.; Hartogh, P.; Encrenaz, T.; Tokunaga, A.; Khayat, A.; Smith, M. D.

    2015-01-01

    We measured maps of atmospheric water (H2O) and its deuterated form (HDO) across the martian globe, showing strong isotopic anomalies and a significant high deuterium/hydrogen (D/H) enrichment indicative of great water loss. The maps sample the evolution of sublimation from the north polar cap, revealing that the released water has a representative D/H value enriched by a factor of about 7 relative to Earth's ocean [Vienna standard mean ocean water (VSMOW)]. Certain basins and orographic depressions show even higher enrichment, whereas high-altitude regions show much lower values (1 to 3 VSMOW). Our atmospheric maps indicate that water ice in the polar reservoirs is enriched in deuterium to at least 8 VSMOW, which would mean that early Mars (4.5 billion years ago) had a global equivalent water layer at least 137 meters deep.

  4. Krypton Ion Thruster Performance

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J.; Williams, George J.

    1992-01-01

    Preliminary data were obtained from a 30 cm ion thruster operating on krypton propellant over the input power range of 0.4 to 5.5 kW. The data presented are compared and contrasted to the data obtained with xenon propellant over the same input power envelope. Typical krypton thruster efficiency was 70 percent at a specific impulse of approximately 5000 s, with a maximum demonstrated thrust to power ratio of approximately 42 mN/kW at 2090 s specific impulse and 1580 watts input power. Critical thruster performance and component lifetime issues were evaluated. Order of magnitude power throttling was demonstrated using a simplified power-throttling strategy.

  5. Krypton ion thruster performance

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J.; Williams, George J., Jr.

    1992-01-01

    Preliminary data were obtained from a 30 cm ion thruster operating on krypton propellant over the input power range of 0.4-5.5 kW. The data are presented, and compared and contrasted to those obtained with xenon propellant over the same input power envelope. Typical krypton thruster efficiency was 70 percent at a specific impulse of approximately 5000 s, with a maximum demonstrated thrust-to-power ratio of approximately 42 mN/kW at 2090 s specific impulse and 1580 watts input power. Critical thruster performance and component lifetime issues were evaluated. Order-of-magnitude power throttling was demonstrated using a simplified power-throttling strategy.

  6. Ca ISOTOPE EFFECTS IN ORGUEIL LEACHATES AND THE IMPLICATIONS FOR THE CARRIER PHASES OF {sup 54}Cr ANOMALIES

    SciTech Connect

    Moynier, Frederic; Podosek, Frank A.; Brannon, Joyce; Simon, Justin I.; DePaolo, Donald J.; Meyer, Bradley S. E-mail: fap@levee.wustl.ed E-mail: Justin.I.Simon@NASA.go E-mail: mbradle@clemson.ed

    2010-07-20

    Primitive meteorites contain small {sup 40}Ca excesses, in addition to rare anomalies in {sup 48}Ca. Refractory inclusions from Vigarano and Allende have larger {sup 40}Ca and resolvable {sup 48}Ca anomalies. These results imply that Ca isotopic heterogeneities were still present in the early solar system at both the mineral and whole-rock scale. The absence of correlated Ca isotope anomalies in leachates from the CI1 chondrite Orgueil containing large {sup 54}Cr anomalies has implications on the origin of the Cr anomalies. {sup 54}Cr has to be produced either in massive stars during s-process nucleosynthesis without accompanying {sup 48}Ca or in particular zones in the rare Type Ia supernovae. In the latter case, {sup 54}Cr has been produced in a zone predominantly enriched in Cr and {sup 54}Cr and not mixed with other zones, or {sup 54}Cr has been produced together with other neutron-rich nuclides and there has been subsequent decoupling of this material in the star, in the solar system, or in the laboratory.

  7. Erosion during accretion: Consequences for planetary iron-silicate ratios and tungsten isotope anomalies

    NASA Astrophysics Data System (ADS)

    Dwyer, C. A.; Nimmo, F.; Asphaug, E. I.; O'Brien, D. P.; Chambers, J.

    2011-12-01

    The late stages of planetary accretion involve stochastic, large collisions [1]. Although such collisions are usually assumed to result in perfect mergers, many of the collisions may instead result in hit-and-run events [2, 3] or erosion of existing bodies' mantles [4]. Impact-related erosion can have profound consequences for the rate and style of accretion [5] and the bulk chemistries of terrestrial planets [6]. Here we present some preliminary investigations into the occurrence of erosional collisions during late-stage accretion and consequences for the bulk chemistry and isotopic characteristics of the resulting planets. We have performed a preliminary investigation into the nature of late-stage accretion using an N-body simulation in which the different possible collision outcomes are treated in a more realistic manner than hitherto. The simulation starts with 155 planetesimals of roughly lunar mass; at the end, four bodies remain with masses of 0.83, 0.62, 0.33, and 0.02 Mearth. Collisional efficiency is parametrized based on the results of [7]. The results of the collisions, especially highly disruptive collisions, are idealized in order to be computationally tractable; in particular, bodies smaller than a minimum mass are not permitted. To track the bulk compositional evolution of the bodies, we assume all are initially chondritic. We alter the bulk chemistry after an impact according to a scheme which is based on the assumption that mantle material is much more likely to be eroded than core material. We track the tungsten isotopic evolution of each body using the method of [8] and treat the extent of core-mantle equilibration as a free parameter. The stochastic nature of planetary accretion means that even with perfect mergers, the tungsten isotope anomaly (eW) of the final bodies will vary, due to variations in the timing of the impacts which create the final bodies. Irrespective of accretion style, the extent of core re-equilibration affects e

  8. Delineating the effect of El-Nino Southern Oscillations using oxygen and sulfur isotope anomalies of sulfate aerosols

    NASA Astrophysics Data System (ADS)

    Shaheen, R.; Abaunza Quintero, M. M.; Jackson, T.; McCabe, J.; Savarino, J. P.; Thiemens, M. H.

    2013-12-01

    Sulfate aerosols, unlike greenhouse gases, contribute to global cooling by acting as cloud condensation nuclei in the troposphere and by directly reflecting solar radiation in the stratosphere. To understand the long-term effect of natural and anthropogenic sulfate aerosol on the climate cycle, it is critical to obtain a clear picture of the factors controlling the transport and transformation of sulfate aerosols. We have employed both oxygen triple isotopes and sulfur quadruple isotopes on sulfates from Antarctic ice samples to define the oxidation history, long range transport dynamics, and sources of sulfate aerosols over time. The measurements are used to deconvolve the impact of natural and anthropogenic aerosols on the stratospheric sulfate aerosol composition. Sulfate aerosols were extracted from a snow pit at the South Pole (1979-2002) with a high resolution temporal (6 month) record of the winter and summer seasons covering two largest volcanic events, Pinatubo and El-chichon and three largest ENSO events of the century. All three oxygen and four sulfur isotopes were measured on the extracted sulfate (Shaheen et al., 2013). The high temperature pyrolysis (1000oC) of silver sulfate yielded O2 and SO2. The oxygen triple isotopic composition of the O2 gas was used to determine the oxidation history of sulfate aerosol and SO2 gas obtained during this reaction was utilized to measure sulfur quadruple isotopes following appropriate reaction chemistry (Farquhar et al., 2001). The data revealed that oxygen isotope anomalies in Antarctic aerosols (Δ17O = 0.8-3.7‰) from 1990 to 2001 are strongly linked to the variation in ozone levels in the upper stratosphere/lower stratosphere. The variations in ozone levels are reflective of the intensity of the ENSO events and changes in relative humidity in the atmosphere during this time period. Sulfate concentrations and sulfur quadruple isotopic composition and associated anomalies were used to elucidate the sources of

  9. Ice Ih anomalies: Thermal contraction, anomalous volume isotope effect, and pressure-induced amorphization.

    PubMed

    Salim, Michael A; Willow, Soohaeng Yoo; Hirata, So

    2016-05-28

    Ice Ih displays several anomalous thermodynamic properties such as thermal contraction at low temperatures, an anomalous volume isotope effect (VIE) rendering the volume of D2O ice greater than that of H2O ice, and a pressure-induced transition to the high-density amorphous (HDA) phase. Furthermore, the anomalous VIE increases with temperature, despite its quantum-mechanical origin. Here, embedded-fragment ab initio second-order many-body perturbation (MP2) theory in the quasiharmonic approximation (QHA) is applied to the Gibbs energy of an infinite, proton-disordered crystal of ice Ih at wide ranges of temperatures and pressures. The quantum effect of nuclei moving in anharmonic potentials is taken into account from first principles without any empirical or nonsystematic approximation to either the electronic or vibrational Hamiltonian. MP2 predicts quantitatively correctly the thermal contraction at low temperatures, which is confirmed to originate from the volume-contracting hydrogen-bond bending modes (acoustic phonons). It qualitatively reproduces (but underestimates) the thermal expansion at higher temperatures, caused by the volume-expanding hydrogen-bond stretching (and to a lesser extent librational) modes. The anomalous VIE is found to be the result of subtle cancellations among closely competing isotope effects on volume from all modes. Consequently, even ab initio MP2 with the aug-cc-pVDZ and aug-cc-pVTZ basis sets has difficulty reproducing this anomaly, yielding qualitatively varied predictions of the sign of the VIE depending on such computational details as the choice of the embedding field. However, the temperature growth of the anomalous VIE is reproduced robustly and is ascribed to the librational modes. These solid-state MP2 calculations, as well as MP2 Born-Oppenheimer molecular dynamics, find a volume collapse and a loss of symmetry and long-range order in ice Ih upon pressure loading of 2.35 GPa or higher. Concomitantly, rapid softening of

  10. Ice Ih anomalies: Thermal contraction, anomalous volume isotope effect, and pressure-induced amorphization

    NASA Astrophysics Data System (ADS)

    Salim, Michael A.; Willow, Soohaeng Yoo; Hirata, So

    2016-05-01

    Ice Ih displays several anomalous thermodynamic properties such as thermal contraction at low temperatures, an anomalous volume isotope effect (VIE) rendering the volume of D2O ice greater than that of H2O ice, and a pressure-induced transition to the high-density amorphous (HDA) phase. Furthermore, the anomalous VIE increases with temperature, despite its quantum-mechanical origin. Here, embedded-fragment ab initio second-order many-body perturbation (MP2) theory in the quasiharmonic approximation (QHA) is applied to the Gibbs energy of an infinite, proton-disordered crystal of ice Ih at wide ranges of temperatures and pressures. The quantum effect of nuclei moving in anharmonic potentials is taken into account from first principles without any empirical or nonsystematic approximation to either the electronic or vibrational Hamiltonian. MP2 predicts quantitatively correctly the thermal contraction at low temperatures, which is confirmed to originate from the volume-contracting hydrogen-bond bending modes (acoustic phonons). It qualitatively reproduces (but underestimates) the thermal expansion at higher temperatures, caused by the volume-expanding hydrogen-bond stretching (and to a lesser extent librational) modes. The anomalous VIE is found to be the result of subtle cancellations among closely competing isotope effects on volume from all modes. Consequently, even ab initio MP2 with the aug-cc-pVDZ and aug-cc-pVTZ basis sets has difficulty reproducing this anomaly, yielding qualitatively varied predictions of the sign of the VIE depending on such computational details as the choice of the embedding field. However, the temperature growth of the anomalous VIE is reproduced robustly and is ascribed to the librational modes. These solid-state MP2 calculations, as well as MP2 Born-Oppenheimer molecular dynamics, find a volume collapse and a loss of symmetry and long-range order in ice Ih upon pressure loading of 2.35 GPa or higher. Concomitantly, rapid softening of

  11. O-16 excesses in Murchison and Murray hibonites - A case against a late supernova injection origin of isotopic anomalies in O, Mg, Ca, and Ti

    NASA Technical Reports Server (NTRS)

    Fahey, A. J.; Goswami, J. N.; Mckeegan, K. D.; Zinner, E. K.

    1987-01-01

    Ion probe measurements of the oxygen isotopic composition of seven hibonite samples from the CM chondrites Murchison and Murray are reported. All samples show large O-16 excesses relative to terrestrial oxygen. The data for all samples plot along the carbonaceous chondrite O-16-rich mixing line and show no evidence for isotopic mass fractionation effects characteristic of FUN inclusions. These hibonites have the largest Ca-48 and Ti-50 isotopic anomalies found to date; thus there is no intrinsic relationship between anomalies of a nucleosynthetic origin and isotopic mass fractionation effects. The large O-16 excess seen in the sample with the largest measured Ca-48 and Ti-50 depletions argues against a late injection of exotic material from a nearby supernova as a source for the isotopic anomalies.

  12. Developing hyperpolarized krypton-83 for nuclear magnetic resonance spectroscopy and magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Cleveland, Zackary I.

    This dissertation discusses the production of highly nonequilibrium nuclear spin polarization, referred to as hyperpolarization or hp, in the nuclear spin I = 9/2 noble gas isotope krypton-83 using spin exchange optical pumping (SEOP). This nonequilibrium polarization yields nuclear magnetic resonance (NMR) signals that are enhanced three or more orders of magnitude above those of thermally polarized krypton and enables experiments that would otherwise be impossible. Krypton-83 possesses a nuclear electric quadrupole moment that dominates the longitudinal (T1) relaxation due to coupling of the quadrupole moment to fluctuating electric field gradients generated by distortions to the spherical symmetry of the electronic environment. Relaxation slows polarization buildup and limits the maximum signal intensity but makes krypton-83 a sensitive probe of its environment. The gas-phase krypton-83 longitudinal relaxation rate increases linearly with total gas density due to binary collisions. Density independent relaxation, caused by the formation of krypton-krypton van der Waals molecules and surface adsorption, also contributes to the observed rate. Buffer gases suppress van der Waals molecule mediated relaxation by breaking apart the weakly bound krypton dimers. Surface relaxation is gas composition independent and therefore more difficult to suppress. However, this relaxation mechanism makes hp krypton-83 sensitive to important surface properties including surface-to-volume ratio, surface chemistry, and surface temperature. The presence of surfaces with high krypton adsorption affinities (i.e. hydrophobic surfaces) accelerates the relaxation times and can produce T1 contrast in hp krypton-83 magnetic resonance imaging (MRI). Tobacco smoke deposited on surfaces generates strong T1 contrast allowing the observation of smoke deposition with spatial resolution. Conversely, water adsorption on surfaces significantly lengths the T1 times due competitive surface adsorption

  13. Isotopic Anomalies in Primitive Solar System Matter: Spin-State-Dependent Fractionation of Nitrogen and Deuterium in Interstellar Clouds

    NASA Technical Reports Server (NTRS)

    Wirstrom, Eva S.; Charnley, Steven B.; Cordiner, Martin A.; Milam, Stefanie N.

    2012-01-01

    Organic material found in meteorites and interplanetary dust particles is enriched in D and N-15. This is consistent with the idea that the functional groups carrying these isotopic anomalies, nitriles and amines, were formed by ion-molecule chemistry in the protosolar nebula, Theoretical models of interstellar fractionation at low temperatures predict large enrichments in both D and N-15 and can account for the largest isotopic enrichments measured in carbonaceous meteorites. However, more recent measurements have shown that, in some primitive samples, a large N-15 enrichment does not correlate with one in D, and that some D-enriched primitive material displays little, if any, N-15 enrichment. By considering the spin-state dependence in ion-molecule reactions involving the ortho and para forms of H2, we show that ammonia and related molecules can exhibit such a wide range of fractionation for both N-15 and D in dense cloud cores. We also show that while the nitriles, HCN and HNC, contain the greatest N=15 enrichment, this is not expected to correlate with extreme D enrichment. These calculations therefore support the view that solar system N-15 and D isotopic anomalies have an interstellar heritage. We also compare our results to existing astronomical observations and briefly discuss future tests of this model.

  14. ISOTOPIC ANOMALIES IN PRIMITIVE SOLAR SYSTEM MATTER: SPIN-STATE-DEPENDENT FRACTIONATION OF NITROGEN AND DEUTERIUM IN INTERSTELLAR CLOUDS

    SciTech Connect

    Wirstroem, Eva S.; Cordiner, Martin A.; Charnley, Steven B.; Milam, Stefanie N.

    2012-09-20

    Organic material found in meteorites and interplanetary dust particles is enriched in D and {sup 15}N. This is consistent with the idea that the functional groups carrying these isotopic anomalies, nitriles and amines, were formed by ion-molecule chemistry in the protosolar nebula. Theoretical models of interstellar fractionation at low temperatures predict large enrichments in both D and {sup 15}N and can account for the largest isotopic enrichments measured in carbonaceous meteorites. However, more recent measurements have shown that, in some primitive samples, a large {sup 15}N enrichment does not correlate with one in D, and that some D-enriched primitive material displays little, if any, {sup 15}N enrichment. By considering the spin-state dependence in ion-molecule reactions involving the ortho and para forms of H{sub 2}, we show that ammonia and related molecules can exhibit such a wide range of fractionation for both {sup 15}N and D in dense cloud cores. We also show that while the nitriles, HCN and HNC, contain the greatest {sup 15}N enrichment, this is not expected to correlate with extreme D enrichment. These calculations therefore support the view that solar system {sup 15}N and D isotopic anomalies have an interstellar heritage. We also compare our results to existing astronomical observations and briefly discuss future tests of this model.

  15. Isotopic Anomalies in Primitive Solar System Matter: Spin-State Dependent Fractionation of Nitrogen and Deuterium in Interstellar Clouds

    NASA Technical Reports Server (NTRS)

    Wirstrom, Eva S.; Charnley, Steven B.; Cordiner, Martin A.; Milan, Stefanie N.

    2012-01-01

    Organic material found in meteorites and interplanetary dust particles is enriched in D and N-15, This is consistent with the idea that the functional groups carrying these isotopic anomalies, nitriles and amines, were formed by ion-molecule chemistry in the protosolar core. Theoretical models of interstellar fractionation at low temperatures predict large enrichments in both D and N-15 and can account for the largest isotop c enrichments measured in carbonaceous meteorites, However, more recent measurements have shown that, in some primitive samples, a large N-15 enrichment does not correlate with one in D, and that some D-enriched primitive material displays little, if any, N-15 enrichment. By considering the spin-state dependence in ion-molecule reactions involving the ortho and para forms of H2, we show that ammonia and related molecules can exhibit such a wide range of fractionation for both N-15 and D in dense cloud cores, We also show that while the nitriles, HCN and HNC, contain the greatest N-15 enrichment, this is not expected to correlate with extreme D emichment. These calculations therefore support the view that Solar System N-15 and D isotopic anomalies have an interstellar heritage, We also compare our results to existing astronomical observations and briefly discuss future tests of this model.

  16. Isotopic anomaly in peat nitrogen is a probable trace of acid rains caused by 1908 Tunguska bolide

    NASA Astrophysics Data System (ADS)

    Kolesnikov, E. M.; Kolesnikova, N. V.; Boettger, T.

    1998-02-01

    In peat sampled at the Tunguska Cosmic Body (TCB) explosion area, the sharp increase of the N concentration (about three-fold) and the positive N isotopic anomaly (δ 15N = + 3.5‰, see eqn) have for the first time been revealed. In contrast with the C and H effects observed earlier which were clearly limited to the epicentre area (Kolesnikov et al., 1997 in press), the same N effect has also been shown in peat sampled near the Vanavara settlement, 65 km south of the explosion epicentre. A clear connection of the observed anomalies in peat to the 1908 permafrost boundary, synchronism of the changes of δ 15N and the N concentration and also good agreement with data on the K/T boundary deposits allow us to connect the observed effects to acid rain fall-out after passage and an explosion of the TCB.

  17. Zinc isotopic composition of iron meteorites: Absence of isotopic anomalies and origin of the volatile element depletion

    NASA Astrophysics Data System (ADS)

    Chen, Heng; Nguyen, Bach Mai; Moynier, Frédéric

    2013-12-01

    High-precision Zn isotopic compositions measured by MC-ICP-MS are documented for 32 iron meteorites from various fractionally crystallized and silicate-bearing groups. The δ66Zn values range from -0.59‰ up to +5.61‰ with most samples being slightly enriched in the heavier isotopes compared with carbonaceous chondrites (0 < δ66Zn < 0.5). The δ66Zn versus δ68Zn plot of all samples defines a common linear fractionation line, which supports the hypothesis that Zn was derived from a single reservoir or from multiple reservoirs linked by mass-dependent fractionation processes. Our data for Redfields fall on a mass fractionation line and therefore refute a previous claim of it having an anomalous isotopic composition due to nonmixing of nucleosynthetic products. The negative correlation between δ66Zn and the Zn concentration of IAB and IIE is consistent with mass-dependent isotopic fractionation due to evaporation with preferential loss of lighter isotopes in the vapor phase. Data for the Zn concentrations and isotopic compositions of two IVA samples demonstrate that volatile depletion in the IVA parent body is not likely the result of evaporation. This is important evidence that favors the incomplete condensation origin for the volatile depletion of the IVA parent body.

  18. NUCLEOSYNTHETIC TUNGSTEN ISOTOPE ANOMALIES IN ACID LEACHATES OF THE MURCHISON CHONDRITE: IMPLICATIONS FOR HAFNIUM-TUNGSTEN CHRONOMETRY

    SciTech Connect

    Burkhardt, Christoph; Wieler, Rainer; Kleine, Thorsten; Dauphas, Nicolas

    2012-07-01

    Progressive dissolution of the Murchison carbonaceous chondrite with acids of increasing strengths reveals large internal W isotope variations that reflect a heterogeneous distribution of s- and r-process W isotopes among the components of primitive chondrites. At least two distinct carriers of nucleosynthetic W isotope anomalies must be present, which were produced in different nucleosynthetic environments. The co-variation of {sup 182}W/{sup 184}W and {sup 183}W/{sup 184}W in the leachates follows a linear trend that is consistent with a mixing line between terrestrial W and a presumed s-process-enriched component. The composition of the s-enriched component agrees reasonably well with that predicted by the stellar model of s-process nucleosynthesis. The co-variation of {sup 182}W/{sup 184}W and {sup 183}W/{sup 184}W in the leachates provides a means for correcting the measured {sup 182}W/{sup 184}W and {sup 182}W/{sup 183}W of Ca-Al-rich inclusions (CAI) for nucleosynthetic anomalies using the isotopic variations in {sup 183}W/{sup 184}W. This new correction procedure is different from that used previously, and results in a downward shift of the initial {epsilon}{sup 182}W of CAI to -3.51 {+-} 0.10 (where {epsilon}{sup 182}W is the variation in 0.01% of the {sup 182}W/{sup 183}W ratio relative to Earth's mantle). This revision leads to Hf-W model ages of core formation in iron meteorite parent bodies that are {approx}2 Myr younger than previously calculated. The revised Hf-W model ages are consistent with CAI being the oldest solids formed in the solar system, and indicate that core formation in some planetesimals occurred within {approx}2 Myr of the beginning of the solar system.

  19. DUPAL anomaly in the Sea of Japan: Pb, Nd, and Sr isotopic variations at the eastern Eurasian continental margin

    USGS Publications Warehouse

    Tatsumoto, M.; Nakamura, Y.

    1991-01-01

    Volcanic rocks from the eastern Eurasian plate margin (southwestern Japan, the Sea of Japan, and northeastern China) show enriched (EMI) component signatures. Volcanic rocks from the Ulreung and Dog Islands in the Sea of Japan show typical DUPAL anomaly characteristics with extremely high ??208/204 Pb (up to 143) and enriched Nd and Sr isotopic compositions (??{lunate}Nd = -3 to -5, 87Sr 86Sr = ~0.705). The ??208/204 Pb values are similar to those associated with the DUPAL anomaly (up to 140) in the southern hemisphere. Because the EMI characteristics of basalts from the Sea of Japan are more extreme than those of southwestern Japan and inland China basalts, we propose that old mantle lithosphere was metasomatized early (prior to the Proterozoic) with subduction-related fluids (not present subduction system) so that it has been slightly enriched in incompatible elements and has had a high Th/U for a long time. The results of this study support the idea that the old subcontinental mantle lithosphere is the source for EMI of oceanic basalts, and that EMI does not need to be stored at the core/ mantle boundary layer for a long time. Dredged samples from seamounts and knolls from the Yamato Basin Ridge in the Sea of Japan show similar isotopic characteristics to basalts from the Mariana arc, supporting the idea that the Yamato Basin Ridge is a spreading center causing separation of the northeast Japan Arc from Eurasia. ?? 1991.

  20. Excitation rate and background measurements during LIF studies on krypton

    SciTech Connect

    Whitehead, C.A.; Cannon, B.D.; Wacker, J.F.

    1993-04-01

    The Krypton Isotope Laser Analysis (KILA) method is being developed at the Pacific Northwest Laboratory (PNL) to measure {sup 85}Kr concentrations in small air samples. The technique uses high-resolution lasers to excite individual isotopes of krypton specifically to induce {sup 85}Kr to fluorescence for detection by optical means. Production of krypton metastables via two-photon excitation to the 2p{sub 6} state has been shown to be 0.15% efficient in 0.13 mTorr of krypton--sufficiently high to demonstrate overall feasibility of the KILA method. Since this goal was met, focus has been directed toward development of a working vacuum ultraviolet (VUV) fluorescence detection system and toward understanding the VUV background. This report describes the progress made in these two areas. The second step of the KILA process is to optically pump all except the {sup 85}Kr isotopes from the metastable state back to the ground state using laser-induced fluorescence (LIF). The rate of this process and the VUV background afterward will determine the sensitivity and selectivity of the KILA approach. De-excitation of the metastable population was accomplished via one-photon absorption of a continuous-wave (c-w) laser to the 2p{sub 8} energy level. Non-isotopically selective de-excitation rates as high as 5 {times} 10{sup 5} sec{sup {minus}1} have been measured, yielding a signal-to-background ratio of >10{sup 6}. The lifetime of the metastables is 1.2 msec in 200 mTorr of neon--much longer than the time required to de-excite krypton metastables and to detect fluorescence produced by {sup 85}Kr. After attaining these high de-excitation rates, a gated VUV detection system was built with a dynamic range large enough to measure a small background following de-excitation of large metastable populations. Future experiments will focus on reducing the background level by another 2--3 orders of magnitude and perfecting the isotopically selective de-excitation technique with known samples.

  1. Excitation rate and background measurements during LIF studies on krypton

    SciTech Connect

    Whitehead, C.A.; Cannon, B.D.; Wacker, J.F.

    1993-04-01

    The Krypton Isotope Laser Analysis (KILA) method is being developed at the Pacific Northwest Laboratory (PNL) to measure [sup 85]Kr concentrations in small air samples. The technique uses high-resolution lasers to excite individual isotopes of krypton specifically to induce [sup 85]Kr to fluorescence for detection by optical means. Production of krypton metastables via two-photon excitation to the 2p[sub 6] state has been shown to be 0.15% efficient in 0.13 mTorr of krypton--sufficiently high to demonstrate overall feasibility of the KILA method. Since this goal was met, focus has been directed toward development of a working vacuum ultraviolet (VUV) fluorescence detection system and toward understanding the VUV background. This report describes the progress made in these two areas. The second step of the KILA process is to optically pump all except the [sup 85]Kr isotopes from the metastable state back to the ground state using laser-induced fluorescence (LIF). The rate of this process and the VUV background afterward will determine the sensitivity and selectivity of the KILA approach. De-excitation of the metastable population was accomplished via one-photon absorption of a continuous-wave (c-w) laser to the 2p[sub 8] energy level. Non-isotopically selective de-excitation rates as high as 5 [times] 10[sup 5] sec[sup [minus]1] have been measured, yielding a signal-to-background ratio of >10[sup 6]. The lifetime of the metastables is 1.2 msec in 200 mTorr of neon--much longer than the time required to de-excite krypton metastables and to detect fluorescence produced by [sup 85]Kr. After attaining these high de-excitation rates, a gated VUV detection system was built with a dynamic range large enough to measure a small background following de-excitation of large metastable populations. Future experiments will focus on reducing the background level by another 2--3 orders of magnitude and perfecting the isotopically selective de-excitation technique with known samples.

  2. Excitation rate and background measurements during LIF studies on krypton

    NASA Astrophysics Data System (ADS)

    Whitehead, C. A.; Cannon, B. D.; Wacker, J. F.

    1993-04-01

    The Krypton Isotope Laser Analysis (KILA) method is being developed at the Pacific Northwest Laboratory (PNL) to measure Kr-85 concentrations in small air samples. The technique uses high-resolution lasers to excite individual isotopes of krypton specifically to induce Kr-85 to fluorescence for detection by optical means. Production of krypton metastables via two-photon excitation to the 2p(sub 6) state has been shown to be 0.15% efficient in 0.13 mTorr of krypton--sufficiently high to demonstrate overall feasibility of the KILA method. Since this goal was met, focus has been directed toward development of a working vacuum ultraviolet (VUV) fluorescence detection system and toward understanding the VUV background. This report describes the progress made in these two areas. The second step of the KILA process is to optically pump all except the Kr-85 isotopes from the metastable state back to the ground state using laser-induced fluorescence (LIF). The rate of this process and the VUV background afterward will determine the sensitivity and selectivity of the KILA approach. De-excitation of the metastable population was accomplished via one-photon absorption of a continuous-wave (c-w) laser to the 2p(sub 8) energy level. Non-isotopically selective de-excitation rates as high as 5 x 10(exp 5)/sec have been measured, yielding a signal-to-background ratio of g reater than 10(exp 6). The lifetime of the metastables is 1.2 msec in 200 mTorr of neon--much longer than the time required to de-excite krypton metastables and to detect fluorescence produced by Kr-85. After attaining these high de-excitation rates, a gated VUV detection system was built with a dynamic range large enough to measure a small background following de-excitation of large metastable populations. Future experiments will focus on reducing the background level by another 2-3 orders of magnitude and perfecting the isotopically selective de-excitation technique with known samples.

  3. Simulation of the diurnal variations of the oxygen isotope anomaly (Δ17O) of reactive atmospheric species

    NASA Astrophysics Data System (ADS)

    Morin, S.; Sander, R.; Savarino, J.

    2010-12-01

    The isotope anomaly (Δ17O) of secondary atmospheric species such as nitrate (NO3-) or hydrogen peroxyde (H2O2) has potential to provide useful constrains on their formation pathways. Indeed, the Δ17O of their precursors (NOx, HOx etc.) differs and depends on their interactions with ozone, which is the main source of non-zero Δ17O in the atmosphere. Interpreting variations of Δ17O in secondary species requires an in-depth understanding of the Δ17O of their precursors taking into account non-linear chemical regimes operating under various environmental settings. We present results from numerical simulations carried out using the atmospheric chemistry box model (CAABA/MECCA) to explicitly compute the diurnal variations of the isotope anomaly of short-lived species such as NOx and HOx. Δ17O was propagated from ozone to other species (NO, NO2, OH, HO2, RO2, NO3, N2O5, HONO, HNO3, HNO4, H2O2) according to the classical mass-balance equation, through the implementation of various sets of hypotheses pertaining to the transfer of Δ17O during chemical reactions. The model confirms that diurnal variations in Δ17O of NOx are well predicted by the photochemical steady-state relationship during the day, but that at night a different approach must be employed (i.e. "fossilization" of the Δ17O of NOx as soon as the photolytical lifetime of NOx drops below ca. 5 min). We quantify the diurnally-integrated isotopic signature (DIIS) of sources of atmospheric nitrate and H2O2 under the various environmental conditions analyzed, which is of particular relevance to larger-scale implementations of Δ17O where high computational costs cannot be afforded.

  4. Experimental Investigation of Continuous-Wave Laser Ionization of Krypton

    SciTech Connect

    Cannon, Bret D.; Shannon, Robert F.

    2001-10-30

    This report describes experimental investigations of a method that uses continuous-wave (CW) lasers to ionize selected isotopes of krypton with high isotopic selectivity. The experiments show that the ionization rate is at least a factor of 100 lower than calculated with our model that has been described in a previous report. This discrepancy may be due to a much smaller excitation cross section that expected based on previous work and/or the aberrations in the ultraviolet beam used for the first step in the excitation. Additional problems with damage to mirrors, alignment instabilities, and manufacturers halting production of key products make this approach not worth further development at this time

  5. CO self-shielding as the origin of oxygen isotope anomalies in the early solar nebula.

    PubMed

    Lyons, J R; Young, E D

    2005-05-19

    The abundances of oxygen isotopes in the most refractory mineral phases (calcium-aluminium-rich inclusions, CAIs) in meteorites have hitherto defied explanation. Most processes fractionate isotopes by nuclear mass; that is, 18O is twice as fractionated as 17O, relative to 16O. In CAIs 17O and 18O are nearly equally fractionated, implying a fundamentally different mechanism. The CAI data were originally interpreted as evidence for supernova input of pure 16O into the solar nebula, but the lack of a similar isotope trend in other elements argues against this explanation. A symmetry-dependent fractionation mechanism may have occurred in the inner solar nebula, but experimental evidence is lacking. Isotope-selective photodissociation of CO in the innermost solar nebula might explain the CAI data, but the high temperatures in this region would have rapidly erased the signature. Here we report time-dependent calculations of CO photodissociation in the cooler surface region of a turbulent nebula. If the surface were irradiated by a far-ultraviolet flux approximately 10(3) times that of the local interstellar medium (for example, owing to an O or B star within approximately 1 pc of the protosun), then substantial fractionation of the oxygen isotopes was possible on a timescale of approximately 10(5) years. We predict that similarly irradiated protoplanetary disks will have H2O enriched in 17O and 18O by several tens of per cent relative to CO. PMID:15902251

  6. Oxygen Isotopic Anomaly in Terrestrial Atmospheric Carbonates and its Implications to Understand the Role of Water on Mars

    NASA Astrophysics Data System (ADS)

    Thiemens, M. H.; Shaheen, R.

    2010-12-01

    Mineral aerosols produced from wind-blown soils are an important component of the earth system and comprise about 1000-3000 Tg.yr-1 compared to 400 Tg.yr-1 of secondary aerosols (e.g. carbonaceous substances, organics, sulfate and nitrates). Aerosols have important consequences for health, visibility and the hydrological cycle as they provide reactive surfaces for heterogeneous chemical transformation that may influence gas phase chemistry in the atmosphere. Tropospheric ozone produced in a cascade of chemical reactions involving NOx and VOC’s, can interact with aerosol surfaces to produce new compounds. Oxygen triple isotopic compositions of atmospheric carbonates have been used for the first time to track heterogeneous chemistry at the aerosol surfaces and to resolve a chemical mechanism that only occurs on particle surfaces. Fine and coarse aerosol samples were collected on filter papers in La Jolla, CA for one week. Aerosol samples were digested with phosphoric acid and released CO2 was purified chromatographically and analyzed for O isotopes after fluorination. Data indicated oxygen isotopic anomaly (Δ17O = δ17O - 0.524 δ18O) ranging from 0.9 to 3.9 per mill. Laboratory experiments revealed that adsorbed water on particle surfaces facilitates the interaction of the gaseous CO2 and O3 with formation of anomalous hydrogen peroxide and carbonates. This newly identified chemical reaction scenario provides a new explanation for production of the isotopically anomalous carbonates found in the SNC Martian meteorites and terrestrial atmospheric carbonates and it also amplifies understanding of water related processes on the surface of Mars. The formation of peroxide via this heterogeneous reaction on aerosols surface suggests a new oxidative process of utility in understanding ozone and oxygen chemistry both at Mars and Earth.

  7. Design documentation: Krypton encapsulation preconceptual design

    SciTech Connect

    Knecht, D.A.

    1994-10-01

    US EPA regulations limit the release of Krypton-85 to the environment from commercial facilities after January 1, 1983. In order to comply with these regulations, Krypton-85, which would be released during reprocessing of commercial nuclear fuel, must be collected and stored. Technology currently exists for separation of krypton from other inert gases, and for its storage as a compressed gas in steel cylinders. The requirements, which would be imposed for 100-year storage of Krypton-85, have led to development of processes for encapsulation of krypton within a stable solid matrix. The objective of this effort was to provide preconceptual engineering designs, technical evaluations, and life cycle costing data for comparison of two alternate candidate processes for encapsulation of Krypton-85. This report has been prepared by The Ralph M. Parsons Company for the US Department of Energy.

  8. Simulation of the diurnal variations of the oxygen isotope anomaly (Δ17O) of reactive atmospheric species

    NASA Astrophysics Data System (ADS)

    Morin, S.; Sander, R.; Savarino, J.

    2011-04-01

    The isotope anomaly (Δ17O) of secondary atmospheric species such as nitrate (NO3-) or hydrogen peroxide (H2O2) has potential to provide useful constrains on their formation pathways. Indeed, the Δ17O of their precursors (NOx, HOx etc.) differs and depends on their interactions with ozone, which is the main source of non-zero Δ17O in the atmosphere. Interpreting variations of Δ17O in secondary species requires an in-depth understanding of the Δ17O of their precursors taking into account non-linear chemical regimes operating under various environmental settings. This article reviews and illustrates a series of basic concepts relevant to the propagation of the Δ17O of ozone to other reactive or secondary atmospheric species within a photochemical box model. We present results from numerical simulations carried out using the atmospheric chemistry box model CAABA/MECCA to explicitly compute the diurnal variations of the isotope anomaly of short-lived species such as NOx and HOx. Using a simplified but realistic tropospheric gas-phase chemistry mechanism, Δ17O was propagated from ozone to other species (NO, NO2, OH, HO2, RO2, NO3, N2O5, HONO, HNO3, HNO4, H2O2) according to the mass-balance equations, through the implementation of various sets of hypotheses pertaining to the transfer of Δ17O during chemical reactions. The model results confirm that diurnal variations in Δ17O of NOx predicted by the photochemical steady-state relationship during the day match those from the explicit treatment, but not at night. Indeed, the Δ17O of NOx is "frozen" at night as soon as the photolytical lifetime of NOx drops below ca. 10 min. We introduce and quantify the diurnally-integrated isotopic signature (DIIS) of sources of atmospheric nitrate and H2O2, which is of particular relevance to larger-scale simulations of Δ17O where high computational costs cannot be afforded.

  9. Tales of volcanoes and El-Niño southern oscillations with the oxygen isotope anomaly of sulfate aerosol

    PubMed Central

    Shaheen, Robina; Abauanza, Mariana; Jackson, Teresa L.; McCabe, Justin; Savarino, Joel; Thiemens, Mark H.

    2013-01-01

    The ability of sulfate aerosols to reflect solar radiation and simultaneously act as cloud condensation nuclei renders them central players in the global climate system. The oxidation of S(IV) compounds and their transport as stable S(VI) in the Earth’s system are intricately linked to planetary scale processes, and precise characterization of the overall process requires a detailed understanding of the linkage between climate dynamics and the chemistry leading to the product sulfate. This paper reports a high-resolution, 22-y (1980–2002) record of the oxygen-triple isotopic composition of sulfate (SO4) aerosols retrieved from a snow pit at the South Pole. Observed variation in the O-isotopic anomaly of SO4 aerosol is linked to the ozone variation in the tropical upper troposphere/lower stratosphere via the Ozone El-Niño Southern Oscillations (ENSO) Index (OEI). Higher ∆17O values (3.3‰, 4.5‰, and 4.2‰) were observed during the three largest ENSO events of the past 2 decades. Volcanic events inject significant quantities of SO4 aerosol into the stratosphere, which are known to affect ENSO strength by modulating stratospheric ozone levels (OEI = 6 and ∆17O = 3.3‰, OEI = 11 and ∆17O = 4.5‰) and normal oxidative pathways. Our high-resolution data indicated that ∆17O of sulfate aerosols can record extreme phases of naturally occurring climate cycles, such as ENSOs, which couple variations in the ozone levels in the atmosphere and the hydrosphere via temperature driven changes in relative humidity levels. A longer term, higher resolution oxygen-triple isotope analysis of sulfate aerosols from ice cores, encompassing more ENSO periods, is required to reconstruct paleo-ENSO events and paleotropical ozone variations. PMID:23447567

  10. Tales of volcanoes and El-Nino southern oscillations with the oxygen isotope anomaly of sulfate aerosol.

    PubMed

    Shaheen, Robina; Abauanza, Mariana; Jackson, Teresa L; McCabe, Justin; Savarino, Joel; Thiemens, Mark H

    2013-10-29

    The ability of sulfate aerosols to reflect solar radiation and simultaneously act as cloud condensation nuclei renders them central players in the global climate system. The oxidation of S(IV) compounds and their transport as stable S(VI) in the Earth's system are intricately linked to planetary scale processes, and precise characterization of the overall process requires a detailed understanding of the linkage between climate dynamics and the chemistry leading to the product sulfate. This paper reports a high-resolution, 22-y (1980-2002) record of the oxygen-triple isotopic composition of sulfate (SO4) aerosols retrieved from a snow pit at the South Pole. Observed variation in the O-isotopic anomaly of SO4 aerosol is linked to the ozone variation in the tropical upper troposphere/lower stratosphere via the Ozone El-Niño Southern Oscillations (ENSO) Index (OEI). Higher (17)O values (3.3‰, 4.5‰, and 4.2‰) were observed during the three largest ENSO events of the past 2 decades. Volcanic events inject significant quantities of SO4 aerosol into the stratosphere, which are known to affect ENSO strength by modulating stratospheric ozone levels (OEI = 6 and (17)O = 3.3‰, OEI = 11 and (17)O = 4.5‰) and normal oxidative pathways. Our high-resolution data indicated that (17)O of sulfate aerosols can record extreme phases of naturally occurring climate cycles, such as ENSOs, which couple variations in the ozone levels in the atmosphere and the hydrosphere via temperature driven changes in relative humidity levels. A longer term, higher resolution oxygen-triple isotope analysis of sulfate aerosols from ice cores, encompassing more ENSO periods, is required to reconstruct paleo-ENSO events and paleotropical ozone variations. PMID:23447567

  11. Isotope systematics of Li, Sr, Nd, and volatiles in Indian Ocean MORBs of the Rodrigues Triple Junction: Constraints on the origin of the DUPAL anomaly

    NASA Astrophysics Data System (ADS)

    Nishio, Yoshiro; Nakai, Shun'ichi; Ishii, Teruaki; Sano, Yuji

    2007-02-01

    The DUPAL anomaly, a radiogenic isotope anomaly discovered in the Indian Ocean mantle, has been interpreted as due to a large-scale mantle heterogeneity. To provide new constraints on the DUPAL origin, we analyzed isotope ratios of Li, Sr, and Nd in fresh N-MORB glasses recovered from the Rodrigues Triple Junction in the Indian Ocean, and from the North Atlantic. The Li isotopic compositions of the Indian Ocean DUPAL N-MORBs were comparable to those of the North Atlantic non-DUPAL N-MORBs. The source of the DUPAL signature in Indian Ocean MORBs and the E-MORB-type enriched mantle source have quite different Li isotopic compositions. The 143Nd/ 144Nd values of both sources are significantly lower than those of the North Atlantic N-MORBs. The δ 7Li values of most oceanic island basalts with similar low 143Nd/ 144Nd signatures are also higher than those of the North Atlantic N-MORBs, except for several Koolau lavas. The Li isotope results support the recent proposal that significant amounts of recycled lower continental crust might produce the radiogenic isotope signatures of the Indian Ocean DUPAL source.

  12. Silver isotopic anomalies in iron meteorites - Cosmic-ray production and other possible sources

    NASA Technical Reports Server (NTRS)

    Reedy, R. C.

    1980-01-01

    Sources of excess Ag-107 observed in iron meteorites are investigated with emphasis on reactions of cosmic-ray particles with palladium. Cross sections for the production of the silver isotopes from palladium by energetic cosmic-ray particles are estimated to calculate spallogenic production rates relative to that of Mn-53 from iron. The upper limits for the production rates of Ag-107 and Ag-109 by energetic galactic cosmic-ray particles are 690 and 270 atoms/min/kg(Pd), respectively, and the maximum rate for making excess Ag-107 by spallation reactions is 400 atoms/min/kg(Pd). The excess Ag-107 cannot be produced by a long exposure to cosmic-ray particles, and because it is harder to make the amount of Pd-107 observed in the iron meteorites by an early intense proton irradiation than it is to make the Al-26 observed in other meteorites, it is concluded that the excess Ag-107 is due to the decay of nucleosynthetic Pd-107 in the iron meteorites.

  13. Evolution, Abundance and Biocalcification of Calcareous Nannoplankton During the Aptian (Early Cretaceous): Causes and Consequences for C Isotopic Anomalies, Climate Changes and the Carbon Cycle.

    NASA Astrophysics Data System (ADS)

    Erba, E.

    2005-12-01

    The mid Cretaceous is marked by extreme greenhouse conditions, coeval with emplacement of large igneous provinces, C isotopic anomalies, major changes in structure and composition of the oceans, and accelerated rates in the evolutionary history of calcareous plankton. The Aptian is a crucial interval to decipher links between biotic evolution and environmental pressure: it is appealing for understanding nannofloral biocalcification and feedbacks in the carbonate system and in the global carbon cycle. Ontong Java, Manihiki and Kerguelen Plateaus formed in the Aptian affecting the ocean-atmosphere system with excess CO2, changes in Ca2+ and Mg2+ concentrations, and varying nutrient cycling. Two large C isotopic anomalies are associated with episodes of prolonged high primary productivity, changes in alkality, global warming and cooling, anoxia, speciations and extinctions in planktonic communities. Nannofossil diversity, abundance and biocalcification are quantified in continuous, complete, pelagic sections to derive biosphere-geosphere interactions at short and long time scales. The early Aptian C isotopic anomaly interrupts a speciation episode in calcareous nannoplankton paralleled by a drastic reduction in nannofossil paleofluxes culminating in the nannoconid crisis preceding the Oceanic Anoxic Event 1a and the negative C isotopic spike linked to clathrate melting presumably triggered by the thermal maximum at the onset of the mid Cretaceous greenhouse climate. No extinctions are recorded. In the early late Aptian resumption of nannoconid production and appearance of several taxa are coeval with a return to normal C isotopic values. The occurrence of calpionellids and diversified planktonic foraminifers indicate successful biocalcification and restoration of the thermocline. In the late Aptian a drop in nannofossil abundance and accelerated extinction rates are associated with another C isotopic excursion under cool conditions possibly due to a prolonged volcanic

  14. Nitrogen isotope ratios of nitrate and N* anomalies in the subtropical South Pacific

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Chisato; Makabe, Akiko; Shiozaki, Takuhei; Toyoda, Sakae; Yoshida, Osamu; Furuya, Ken; Yoshida, Naohiro

    2015-05-01

    Nitrogen isotopic ratios of nitrate (δ15N-NO3-) were analyzed above 1000 m water depth along 17°S in the subtropical South Pacific during the revisit WOCE P21 cruise in 2009. The δ15N-NO3- and N* values were as high as 17‰ and as low as -18 μmol N L-1, respectively, at depths around 250 m east of 115°W, but were as low as 5‰ and as high as +1 μmol N L-1, respectively, in subsurface waters west of 170°W. The relationships among NO3- concentrations, N* values, δ15N-NO3- values, and oxygen and nitrite concentrations suggest that a few samples east of 90°W were from suboxic and nitrite-accumulated conditions and were possibly affected by in situ water column denitrification. Most of the high-δ15N-NO3- and negative-N* waters were probably generated by mixing between Subantarctic Mode Water from the Southern Ocean and Oxygen Deficit Zone Water from the eastern tropical South Pacific, with remineralization of organic matter occurring during transportation. Moreover, the relationship between δ15N-NO3- and N* values, as well as Trichodesmium abundances and size-specific nitrogen fixation rates at the surface, suggest that the low-δ15N-NO3- and positive-N* subsurface waters between 160°E and 170°W were generated by the input of remineralized particles created by in situ nitrogen fixation, mainly by Trichodesmium spp. Therefore, the δ15N values of sediments in this region are expected to reveal past changes in nitrogen fixation or denitrification rates in the subtropical South Pacific. The copyright line for this article was changed on 5 JUN 2015 after original online publication.

  15. Global Neoproterozoic (Sturtian) post-glacial sulfide-sulfur isotope anomaly recognised in Namibia

    NASA Astrophysics Data System (ADS)

    Gorjan, Paul; Walter, Malcolm R.; Swart, Roger

    2003-02-01

    The Neoproterozoic Earth experienced at least two, probably global, glaciations. Each glaciation was superceded by deposition of a layer of carbonate ('cap-carbonate') that has a distinctive lithology and depletion in 13C ( δ13C carbonate ˜ -5‰). The ˜700 Ma Sturtian glaciation is followed by deposition of a cap-carbonate and post-glacial succession which contain bacterially produced sulfides extremely enriched in 34S (average δ34S sulfide ˜ +30‰) with maximum values up to +60‰. This level of 34S enrichment in sulfides is unique to the Sturtian post-glacial succession and recognised in Australia, Canada, and China. In the Neoproterozoic of the Nama Basin, Namibia, the Gobabis Member is the basal unit of the Court Formation, which overlies the glacial Blaubeker Formation. δ13C carbonate analyses from the Gobabis Member range from -5.2 to -2.2‰ (average = -3.7‰; n = 10). δ34S sulfide ranges from +16.1 to +61.1‰ (average = +37.6‰; n = 8). These results are consistent with a Sturtian age for the Blaubeker Formation and overlying Gobabis Member, which have previously been interpreted as Sturtian. The sulfur isotopic results are comparable with δ34S sulfide in Sturtian post-glacial units of Australia, Canada and China. This adds to the evidence for correlation of the Blaubeker Formation with Sturtian glaciations on other continents. The cause of such elevated δ34S sulfide is enigmatic. Geochemical evidence suggests the sulfide was not formed from low sulfate waters nor in euxinic conditions, which discounts any known modern analogue. 34S enrichment in sulfides is therefore postulated to be caused by enrichment of 34S in contemporaneous seawater ( δ34S sulfate up to +60‰?). The rise in seawater δ34S sulfate is considered to be the result of intense bacterial sulfate reduction in an anoxic ocean during the Sturtian glaciation.

  16. First krypton-81 dating of glacial ice at Taylor Glacier, Antarctica

    NASA Astrophysics Data System (ADS)

    Severinghaus, J. P.

    2015-12-01

    A long-held dream of glaciologists has been the direct radiometric dating of ancient glacial ice. Carbon-14 is unfortunately complicated by in-situ cosmogenic production of this isotope from cosmic ray spallation on oxygen nuclei in the ice. Krypton-81 is an ideal tracer in several ways: it has no anthropogenic sources, is made in the atmosphere by cosmic ray spallation on stable krypton nuclei, and it has a half-life of 229 kyr, which is a useful age range for ancient glacial ice samples. However, the abundance of krypton-81 is dauntingly low. Recent analytical advances by a team of physicists at Argonne National Labs has now made it possible to measure practical quantities of ice (50 kg) by Atom Trap Trace Analysis (ATTA), a technique using lasers to cool krypton-81 atoms to absolute zero and trap them, enabling accurate counting of single atoms. The precision attained by this technique approaches 0.5%, implying an age accuracy of about 1000 yr for samples from the last interglacial period. Here we show that krypton-81 dating has been successfully applied for the first time, to an outcrop of ancient ice dating from the last interglacial period (125 kyr BP) at Taylor Glacier, Antarctica, which is independently dated using methane and d18O of atmospheric oxygen for stratigraphic matching to well-dated Chinese speleothem records.

  17. Carbon isotope curve and iridium anomaly in the Albian-Cenomanian paleoceanic deposits of the Eastern Kamchatka

    NASA Astrophysics Data System (ADS)

    Savelyev, D. P.; Savelyeva, O. L.; Palechek, T. N.; Pokrovsky, B. G.

    2012-04-01

    determined contents of carbon and oxygen stable isotopes in limestones and have compared the received results to isotope curves of other regions. In studied section the curve of d13C is characterized by a clearly expressed positive shift at the level of the lower carbonaceous bed. Below it and in the overlapping stratum of siliceous limestone (1 cm thickness) d13C has the values of 1.9-2.1 pro mille and above it d13C increases up to 2.5-3 pro mille. The precise d13C maximum after a sharp shift is correlatable with the form of a d13C curve of the Middle Cenomanian Tethyan sections. Accordingly, it is possible to assert, that the lower carbonaceous bed was formed during the mid-Cenomanian anoxic event (MCE). Gradual increase of d13C in the upper part of our section is similar to change of d13C in Upper Cenomanian fragments of Tethyan sections, i.e. the lower carbonaceous bed corresponds to anoxic event at the Cenomanian/Turonian boundary (OAE2). Neutron activation analysis indicates increased up to 9 ppb concentration of Ir at the bottom of the lower carbonaceous bed (inorganic part of the sample was analyzed comprising 46% of the bulk rock). This anomaly correlates in the studied section with a positive shift of d13C. Taking into account radiolarian age data this allows to correlate the anomaly with the MCE. A source of iridium and other elements of the platinum group could be basalts and hyaloclastites from the eruptions during the sedimentation period. Anoxic conditions promoted deposit enrichment in ore elements. This work was supported by the RFBR (No. 10-05-00065).

  18. Krypton based adsorption type cryogenic refrigerator

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor); Schember, Helene (Inventor)

    1987-01-01

    Krypton and monolithic porous carbon such as Saran carbon are used respectively as the sorbate and sorbent of an absorption type refrigerator to improve refrigeration efficiency and operational longevity.

  19. Krypton based adsorption type cryogenic refrigerator

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor); Schember, Helene R. (Inventor)

    1989-01-01

    Krypton and a monolithic porous carbon such as Saran carbon are used respectively as the sorbate and sorbent of an adsorption type refrigerator to improve refrigeration efficiency and operational longevity.

  20. Krypton tagging velocimetry of an underexpanded jet.

    PubMed

    Parziale, N J; Smith, M S; Marineau, E C

    2015-06-01

    In this work, we present the excitation/emission strategy, experimental setup, and results of an implementation of krypton tagging velocimetry (KTV). KTV is performed as follows: (i) seed a base flow with krypton; (ii) photosynthesize metastable krypton atoms with a frequency-doubled dye laser to form the tagged tracer; (iii) record the translation of the tagged metastable krypton by imaging the laser-induced fluorescence (LIF) that is produced with an additional dye laser. The principle strength of KTV, relative to other tagging velocimetry techniques, is the use of a chemically inert tracer. KTV results are presented for an underexpanded jet of three mixtures of varying Kr/N2 concentration. It is demonstrated that KTV can be used in gas mixtures of relatively low krypton mole fraction (0.5% Kr/99.5% N2), and the KTV data from that experiment are found to be in good agreement with an empirical fit found in the literature. We find that KTV is useful to perform instantaneous velocity measurements with metastable krypton as a chemically inert, dilute, long-lifetime tracer in gas-phase flows. PMID:26192670

  1. Preferential site occupancy observed in coexpanded argon-krypton clusters

    SciTech Connect

    Lundwall, M.; Bergersen, H.; Lindblad, A.; Oehrwall, G.; Svensson, S.; Bjoerneholm, O.; Tchaplyguine, M.

    2006-10-15

    Free heterogeneous argon-krypton clusters have been produced by coexpansion and investigated by means of x-ray photoelectron spectroscopy. By examining cluster surface and bulk binding energy shifts, relative intensities, and peak widths, we show that in the mixed argon-krypton clusters the krypton atoms favor the bulk and argon atoms are pushed to the surface. Furthermore, we show that krypton atoms in the surface layer occupy high-coordination sites and that heterogeneous argon-krypton clusters produced by coexpansion show the same surface structure as argon host clusters doped with krypton. These observations are supported by site-dependent calculations of chemical shifts.

  2. Widespread tungsten isotope anomalies and W mobility in crustal and mantle rocks of the Eoarchean Saglek Block, northern Labrador, Canada: Implications for early Earth processes and W recycling

    NASA Astrophysics Data System (ADS)

    Liu, Jingao; Touboul, Mathieu; Ishikawa, Akira; Walker, Richard J.; Graham Pearson, D.

    2016-08-01

    Well-resolved 182W isotope anomalies, relative to the present mantle, in Hadean-Archean terrestrial rocks have been interpreted to reflect the effects of variable late accretion and early mantle differentiation processes. To further explore these early Earth processes, we have carried out W concentration and isotopic measurements of Eoarchean ultramafic rocks, including lithospheric mantle rocks, meta-komatiites, a layered ultramafic body and associated crustal gneisses and amphibolites from the Uivak gneiss terrane of the Saglek Block, northern Labrador, Canada. These analyses are augmented by in situ W concentration measurements of individual phases in order to examine the major hosts of W in these rocks. Although the W budget in some rocks can be largely explained by a combination of their major phases, W in other rocks is hosted mainly in secondary grain-boundary assemblages, as well as in cryptic, unidentified W-bearing 'nugget' minerals. Whole rock W concentrations in the ultramafic rocks show unexpected enrichments relative, to elements with similar incompatibilities. By contrast, W concentrations are low in the Uivak gneisses. These data, along with the in situ W concentration data, suggest metamorphic transport/re-distribution of W from the regional felsic rocks, the Uivak gneiss precursors, to the spatially associated ultramafic rocks. All but one sample from the lithologically varied Eoarchean Saglek suite is characterized by generally uniform ∼ + 11 ppm enrichments in 182W relative to Earth's modern mantle. Modeling shows that the W isotopic enrichments in the ultramafic rocks were primarily inherited from the surrounding 182W-rich felsic precursor rocks, and that the W isotopic composition of the original ultramafic rocks cannot be determined. The observed W isotopic composition of mafic to ultramafic rocks in intimate contact with ancient crust should be viewed with caution in order to plate constraints on the early Hf-W isotopic evolution of the

  3. Determination of oxygen self-diffusion in akermanite, anorthite, diopside, and spinel: Implications for oxygen isotopic anomalies and the thermal histories of Ca-Al-rich inclusions

    SciTech Connect

    Ryerson, F.J. ); McKeegan, K.D. )

    1994-09-01

    Oxygen self-diffusion coefficients have been measured for three natural diopsidic clinopyroxenes, a natural anorthite, a synthetic magnesium aluminate spinel, and a synthetic akermanite for oxygen fugacities ranging from the NNO to IW buffers. The oxygen diffusion data are used to evaluate the effects of three different types of thermal histories upon the oxygen isotopic compositions of minerals found in Type B Ca-Al-rich inclusions (CAIBs) in carbonaceous chondrites: (1) gas-solid exchange during isothermal heating, (2) gas-solid exchange as a function of cooling rate subsequent to instantaneous heating, and (3) isotopic exchange with a gaseous reservoir during partial melting and recrystallization. With the assumptions that the mineral compositions within a CAIB were uniformly enriched in [sup 16]O prior to any thermal processing, that effective diffusion dimensions may be estimated from observed grain sizes, and that diffusion in diopside is similar to that in fassaitic clinopyroxene, none of the above scenarios can reproduce the relative oxygen isotopic anomalies observed in CAIBs without improbably long or unrealistically intense thermal histories relative to current theoretical models of nebular evolution. The failure of these simple models, coupled with recent observations of disturbed magnesium isotopic abundances and correlated petrographic features in anorthite and melilite indicative of alteration and recrystallization, suggests that the oxygen isotopic compositions of these phases may have also been modified by alteration and recrystallization possibly interspersed with multiple melting events. Because the modal abundance of spinel remains relatively constant for plausible melting scenarios, and its relatively sluggish diffusion kinetics prevent substantial equilibration, Mg-Al spinel is the most reliable indicator of the oxygen isotopic composition of precursor material which formed Type B CAIs.

  4. Correlated Si isotope anomalies and large C-13 enrichments in a family of exotic SiC grains

    NASA Technical Reports Server (NTRS)

    Stone, J.; Hutcheon, I. D.; Epstein, S.; Wasserburg, G. J.

    1991-01-01

    A hypothesis is presented to the effect that the distinctive morphological characteristics and comparatively simple Si isotope systematics identify the platy SiC crystals as a genetically related family, formed around a single isotopically heterogeneous presolar star on an association of related stars. The enrichments in C-13 and the Si isotope systematics of the platy SiC are broadly consistent with theoretical models of nucleosynthesis in low-mass, carbon stars on the ASG. The Si isotope array most plausibly reflects mixing between (Si-28)-rich material, inherited from a previous generation of stars, and material enriched in Si-29 and Si-30, produced in intershell regions by neutron capture during He-burning. The absence of a correlation between the Si and C isotopic compositions of the SiC suggests either episodic condensation of SiC, extending over several thermal pulses, in the atmosphere of a single star, or the derivation of the SiC from several stars characterized by different rates of C-13 production.

  5. Simulation of the diurnal variations of the isotope anomaly (?17O) of reactive trace gases (NOx, HOx) and implications for the ?17O of nitrate.

    NASA Astrophysics Data System (ADS)

    Morin, Samuel; Sander, Rolf; Savarino, Joël.

    2010-05-01

    The isotope anomaly of secondary atmospheric species such as nitrate (NO3-) has potential to provide useful constrains on their formation pathways. Indeed, the ?17O of their precursors (NOx, HOx etc.) differs and depends on their interactions with ozone, which is the main source of non-zero ?17O in the atmosphere. Interpreting variations of ?17O in nitrate requires an in-depth understanding of the ?17O of its precursors taking into account non-linear chemical regimes operating under various environmental settings. In addition, the role of isotope exchange reactions must be carefully accounted for. To investigate the relevance of various assessments of the isotopic signature of nitrate production pathways that have recently been proposed in the literature, an atmospheric chemistry box model (MECCA, Sander et al., 2005, ACP)) was used to explicitly compute the diurnal variations of the isotope anomaly of NOx, HOx under several conditions prevailing in the marine boundary layer. ?17O was propagated from ozone to other species (NO, NO2, OH, HO2, RO2, NO3, N2O5, HONO, HNO3, HNO4, H2O2) according to the classical mass-balance equation applied at each time step of the model (30 seconds typically). The model confirms that diurnal variations in ?17O of NOx are well predicted by the photochemical steady-state relationship introduced by Michalski et al. (2003, GRL) during the day, but that at night a different approach must be employed (e.g. « fossilization » of the ?17O of NOx as soon as the photochemical lifetime of NOx drops below ca. 5 minutes). The model also allows to evaluate the impact on ?17O of NOx and nitrate of the frequently made simplifying assumption that ?17O(HOx)=0 permil, with and without mass-independent fractionation during the H+O2-HO2 reaction. Recommendations for the modeling of ?17O of nitrate will be given, based on the extensive model work carried out. In addition, the link between diurnal variations of the ?17O of nitrate precursors and seasonal

  6. Determination of Oxygen Self-Diffusion in Akermanite, Anorthite, Diopside, and Spinel: Implications for Oxygen Isotopic Anomalies and the Thermal Histories of Ca-Al-rich Inclusions

    NASA Astrophysics Data System (ADS)

    Ryerson, F. J.; McKeegan, K. D.

    1993-07-01

    anomalies observed in CAIBs and/or yield improbably long or unrealistically intense thermal histories relative to both current theoretical models of nebular evolution and inferences from other isotopic systems. The failure of these simple models, coupled with recent observations of "disturbed" Mg isotopic abundances and petrographic features in anorthite and melilite indicative of alteration and recrystallization [5,6], suggests that the oxygen isotopic compositions of these phases may have also been modified by alteration and recrystallization during multiple melting events. Because the modal abundance of spinel remains relatively constant for plausible melting scenarios and its relatively sluggish diffusion kinetics prevent substantial equilibration, Mg-Al spinel is a reliable indicator of the oxygen isotopic composition of precursor material that formed CAIBs. References: [1] Connolly C. and Muehlenbachs K. (1988) GCA, 52, 1585-1592. [2] Elphick S. C. et al. (1988) Contrib. Mineral. Petrol., 100, 490-495. [3] Reddy K. P. and Cooper A. R. (1981) J. Am. Ceram. Soc., 64, 368-371. [4] Yunmoto H. et al. (1989) GCA, 53, 2387-2394. [5] Podosek F. A. et al. (1991) GCA, 55, 1083-1110. [6] MacPherson G. J. and Davis A. M. (1993) GCA, 57, 231-243.

  7. Factors Affecting the Efficiency of Krypton Hall Thrusters

    NASA Technical Reports Server (NTRS)

    Hofer, Richard R.; Peterson, Peter Y.; Jacobson, David T.; Manzella, David M.

    2004-01-01

    The krypton-fueled Hall thruster offers the possibility of high-specific impulse and long lifetime. NASA's series of Hall thrusters have demonstrated krypton efficiencies only 5 - 15% less than xenon. Larger thrusters have smaller differences in efficiency. Plasma measurements have demonstrated that efficiency is reduced due to a decrease in mass utilization. Current efforts are considering the implications of these results, and how design changes can be made to increase the efficiency of krypton Hall thrusters.

  8. Isotopic anomalies of Ne, Xe, and C in meteorites. I - Separation of carriers by density and chemical resistance

    NASA Technical Reports Server (NTRS)

    Ming, Tang; Lewis, Roy S.; Anders, Edward; Grady, M. M.; Wright, I. P.

    1988-01-01

    The carriers of presolar noble gases were studied by isotopically analyzing 19 separates from the Murray and Murchison C2 chondrites for Ne, Xe, C, and N. It is found that the carriers of Ne-E(H) and Xe-S are resistant to HCl, HF, boiling HClO4, and CrO3-H2SO4, and thus must be either diamond or some resistant carbide or oxide. The carrier of Ne-E(L) may be some form of amorphous carbon with delta C13 of about +340 percent. A new carbon component, C theta, found as 0.2-2-micron inclusions in Murchison spinel, is amorphous and contains little or no noble gas. A new heavy nitrogen component is found which has an abundance of about 1 ppm in the bulk meteorite, combusts at 450-500 C, and may be associated wtih isotopically normal carbon or with C-alpha.

  9. Isotopic anomalies of Ne, Xe, and C in meteorites. I - Separation of carriers by density and chemical resistance

    NASA Astrophysics Data System (ADS)

    Ming, T.; Lewis, R. S.; Anders, E.; Grady, M. M.; Wright, I. P.; Pillinger, C. T.

    1988-05-01

    The carriers of presolar noble gases were studied by isotopically analyzing 19 separates from the Murray and Murchison C2 chondrites for Ne, Xe, C, and N. It is found that the carriers of Ne-E(H) and Xe-S are resistant to HCl, HF, boiling HClO4, and CrO3-H2SO4, and thus must be either diamond or some resistant carbide or oxide. The carrier of Ne-E(L) may be some form of amorphous carbon with delta C13 of about +340 percent. A new carbon component, C theta, found as 0.2-2-micron inclusions in Murchison spinel, is amorphous and contains little or no noble gas. A new heavy nitrogen component is found which has an abundance of about 1 ppm in the bulk meteorite, combusts at 450-500 C, and may be associated wtih isotopically normal carbon or with C-alpha.

  10. A purity monitor for the KEDR liquid krypton calorimeter

    NASA Astrophysics Data System (ADS)

    Evtushenko, P. N.; Kotov, K. Yu.; Maslennikov, A. L.; Peleganchuk, S. V.; Snopkov, R. G.; Rogozin, A. I.; Tikhonov, Yu. A.

    2016-06-01

    We present a purity monitor for the KEDR liquid krypton calorimeter. A new method is suggested based on the usage of a short pulse of a gas discharge as a source of ultraviolet radiation for the photoproduction of electrons in a drift cell of the monitor. This paper describes the design of the monitor, the results of experiments with gaseous and liquid krypton, as well as the experience of using the developed device in the process of krypton purification for the KEDR liquid krypton calorimeter.

  11. Stable-isotopic anomalies and the accretionary assemblage of the Earth and Mars: A subordinate role for carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Warren, Paul H.

    2011-11-01

    Plots such as ɛ 54Cr vs. ɛ 50Ti and ɛ 54Cr vs. Δ 17O reveal a fundamental dichotomy among planetary materials. The "carbonaceous" chondrites, by virtue of high ɛ 50Ti and high ɛ 62Ni, as well as, especially for any given Δ 17O, high ɛ 54Cr, are separated by a wide margin from all other materials. The significance of the bimodality is further manifested by several types of meteorites with petrological-geochemical characteristics that suggest membership in the opposite category from the true pedigree as revealed by the stable isotopes. Ureilites, for example, despite having diversely low Δ 17O and about the same average carbon content as the most C-rich carbonaceous chondrite, have clear stable-isotopic signatures of noncarbonaceous pedigree. The striking bimodality on the ɛ 54Cr vs. ɛ 50Ti and ɛ 54Cr vs. Δ 17O diagrams suggests that the highest taxonomic division in meteorite/planetary classification should be between carbonaceous and noncarbonaceous materials. The bimodality may be an extreme manifestation of the effects of episodic accretion of early solids in the protoplanetary nebula. However, an alternative, admittedly speculative, explanation is that the bimodality corresponds to a division between materials that originally accreted in the outer solar system (carbonaceous) and materials that accreted in the inner solar system (noncarbonaceous). In any event, both the Earth and Mars plot squarely within the noncarbonaceous composition-space. Applying the lever rule to putative mixing lines on the ɛ 50Ti vs. ɛ 54Cr and Δ 17O vs. ɛ 54Cr diagrams, the carbonaceous/(carbonaceous + noncarbonaceous) mixing ratio C/( C + NC) is most likely close to (very roughly) 24% for Earth and 9% for Mars. Estimated upper limits for C/( C + NC) are 32% for Earth and 18% for Mars. However, the uncertainties are such that isotopic data do not require or even significantly suggest that Earth has higher C/( C + NC) than Mars. Among known chondrite groups, EH yields a

  12. Anomalous Oxygen and Krypton Abundances in Interstellar Gas

    NASA Technical Reports Server (NTRS)

    Meyer, David M.

    2004-01-01

    The primary objective of this program was to obtain FUSE observations of the interstellar H2 absorption toward a sample of stars observed with the HST STIS spectrograph as part of the ISM SNAP Survey. This Survey was designed to produce a database of high quality, high resolution W spectra from which interstellar gas-phase elemental abundances could be derived for large portions of the Galaxy. In particular, oxygen and krypton were chosen as excellent tracers for measuring the homogeneity of the interstellar gas due to their weak depletion into dust grains. The gas-phase 0 and Kr abundances relative to total hydrogen column density had previously been shown with HST GHRS measurements to be essentially constant in the local Milky Way. One of the main motivations of the ISM SNAP Survey was to determine if this constancy held at greater distances and in denser sightlines (where depletion into dust could be a possibility). The initial ISM SNAP STIS observations indicated a number of sightlines with unusual 0 and Kr abundances relative to the measured H I column densities. Since the appropriate benchmark for accurate abundance comparisons is the total hydrogen column density (H I plus H2), FUSE observations of interstellar H2 were carried out in these sightlines in order to determine if they represent cases of true abundance anomalies.

  13. Search for extinct natural radioactivity of Pb205 via thallium-isotope anomalies in chondrites and lunar soil.

    NASA Technical Reports Server (NTRS)

    Huey, J. M.; Kohman, T. P.

    1972-01-01

    Thallium and Pb204 contents were determined by stable-isotope-dilution analysis in 16 chondrites, one achondrite, and Apollo 11 and 12 lunar fines. Meteoritic thallium contents vary over a large range, 0.02 to 100 ppb, corresponding to the fact that thallium is a highly fractionated volatile element. Lunar thallium contents are less than 5 ppb. The Tl205/Tl203 ratio was determined in most of the samples, with precision ranging from 0.03% to several percent depending mainly on the amount of thallium present. No variations from the terrestrial ratio were observed. The chondritic isochron slope for Pb205 (13.8-m.y. half-life) is less than or equal to 0.00009 (99% confidence level), corresponding to an interval of at least 60 m.y. and possibly exceeding 120 m.y. between the termination of s-process nucleosynthesis and the lead-thallium fractionations.

  14. Determination of the hyperfine structure constants of the 87Rb and 85Rb 4 D5 /2 state and the isotope hyperfine anomaly

    NASA Astrophysics Data System (ADS)

    Wang, Jie; Liu, Huifeng; Yang, Guang; Yang, Baodong; Wang, Junmin

    2014-11-01

    The hyperfine structure (hfs) splittings of the 4 D5 /2 state for two isotopes of 87Rb and 85Rb atoms are measured based on double-resonance optical pumping spectra in a 5 S1 /2-5 P3 /2-4 D5 /2 ladder-type atomic system. The frequency calibration is performed by employing a wideband fiber-pigtailed phase-type electro-optic modulator together with a Fabry-Pérot cavity to cancel the error arising from nonlinear frequency scanning. The hfs magnetic dipole constant A of the 4 D5 /2 state is determined to be -16.801 ± 0.005 MHz for 87Rb and -4.978 ± 0.004 MHz for 85Rb . The hfs electric quadrupole constant B of the 4 D5 /2 state is determined to be 3.645 ± 0.030 MHz for 87Rb and 6.560 ± 0.052 MHz for 85Rb . The values of A and B for the 87Rb4 D5 /2 state are twice as accurate as previous work with thermal atoms using a femtosecond laser comb and the values of A and B for the 85Rb4 D5 /2 state are 3 times and 25 times more accurate than previous work in laser-cooled atoms using Fabry-Pérot interferometer, respectively. According to this high precision of the hfs constants and the previously measured nuclear g factors of the two isotopes, the value of the d -electron hyperfine anomaly 87Δ85(4 D5 /2 ) is derived to be -0.0041 ± 0.0009.

  15. HETEROGENEOUS ISOTOPIC ANOMALIES OF SM AND GD IN THE NORTON COUNTY METEORITE: EVIDENCE FOR IRRADIATION FROM THE ACTIVE EARLY SUN

    SciTech Connect

    Hidaka, Hiroshi; Kondo, Tomoyo; Yoneda, Shigekazu

    2012-02-20

    Large and heterogeneous isotopic variations of {sup 150}Sm/{sup 149}Sm and {sup 158}Gd/{sup 157}Gd due to neutron capture reactions caused by cosmic-ray irradiation were found in chemical and mineral separates from the Norton County meteorite. The light-colored separates, consisting mainly of enstatite (Mg{sub 2}Si{sub 2}O{sub 6}), have a very large neutron fluence of 1.98 Multiplication-Sign 10{sup 17} n cm{sup -2}, which is 10 times higher than that of the whole rock. Furthermore, four chemical separates showed a large variation in neutron fluences, ranging from 1.82 Multiplication-Sign 10{sup 16} to 1.87 Multiplication-Sign 10{sup 17} n cm{sup -2}. The variable amounts of neutron fluences from a small single fragment of the Norton County meteorite cannot be simply explained by single-stage cosmic-ray irradiation in space. Rare earth element (REE) analyses revealed that the fractions with high neutron fluences have similar chemical properties to those in the early condensates in the solar system, showing depletions of Eu and Yb in their REE abundance patterns. The data provide evidence for an activity of the early Sun (T Tauri), suggesting the migration of early and intense irradiation materials into the Norton County meteorite's parent body.

  16. Geochemical Fingerprinting of Trans-Atlantic African Dust Based on Radiogenic Sr-Nd-Hf Isotopes and Rare Earth Element Anomalies

    NASA Astrophysics Data System (ADS)

    Pourmand, A.; Prospero, J. M.; Sharifi, A.

    2014-12-01

    Mineral dust is an important component of Earth's climate system and biogeochemical cycles on a global scale. In order to understand the relationship between climate processes in the source areas and the properties of aerosols at distant receptor sites, we must be able to identify the source provenance of dust. Here we present a multiproxy study that characterizes the temporal variability in the geochemical composition of long-range African dust (LRAD) collected between 2003 and 2011 in the trade winds on the Caribbean island of Barbados. We find systematic differences between Sr-Nd-Hf isotopic composition and rare earth element anomalies of individual dust events and evidence of seasonal shifts in dust source activity and transport. These results indicate that coherent geochemical source signatures of LRAD can be preserved even after transport across thousands of kilometers. We investigated the possibility of identifying the potential source areas through comparisons with literature data. However, these data are almost entirely based on measurements of soil and sediment samples; this could lead to biases because of soil-aerosol particle size and composition differences. Nonetheless, our data suggest that many samples are linked to sources in Mali and sub-Saharan regions. Radiogenic Nd-Hf composition of aerosols can potentially be a useful proxy to study the proximity of mineral dust sources to depositional sites. In order to establish firmer links between LRAD and dust source areas, however, we require much more data on the geochemical composition of aerosols from potential source areas in North Africa.

  17. Geochemical Fingerprinting of Trans-Atlantic African Dust Based on Radiogenic Sr-Nd-Hf Isotopes and Rare Earth Element Anomalies

    NASA Astrophysics Data System (ADS)

    Pourmand, Ali; Prospero, Joseph; Sharifi, Arash

    2015-04-01

    Mineral dust is an important component of Earth's climate system and biogeochemical cycles on a global scale. In order to understand the relationship between climate processes in the source areas and the properties of aerosols at distant receptor sites, we must be able to identify the source provenance of dust. Here we present a multiproxy study that characterizes the temporal variability in the geochemical composition of long-range African dust (LRAD) collected between 2003 and 2011 in the trade winds on the Caribbean island of Barbados. We find systematic differences between Sr-Nd-Hf isotopic composition and rare earth element anomalies of individual dust events and evidence of seasonal shifts in dust source activity and transport. These results indicate that coherent geochemical source signatures of LRAD can be preserved even after transport across thousands of kilometers. We investigated the possibility of identifying the potential source areas through comparisons with literature data. However, these data are almost entirely based on measurements of soil and sediment samples; this could lead to biases because of soil-aerosol particle size and composition differences. Nonetheless, our data suggest that many samples are linked to sources in Mali and sub-Saharan regions. Radiogenic Nd-Hf composition of aerosols can potentially be a useful proxy to study the proximity of mineral dust sources to depositional sites. In order to establish firmer links between LRAD and dust source areas, however, we require much more data on the geochemical composition of aerosols from potential source areas in North Africa.

  18. A Distant Planet: Finding Superman's Krypton

    NASA Astrophysics Data System (ADS)

    Ricca, B.

    2016-01-01

    In 2012, Neil deGrasse Tyson made headlines when he appeared in a Superman comic book and pinpointed a real planet (located in Corvus) that matched the description of Superman's homeworld, the fictional planet of Krypton. This story tracked all over the world. Why? I will look at the figure of Superman, whose backstory—orphan from an exploding planet—is somehow known by everyone from the age of eight on. I will look at how specific astronomical phenomena (in the sky and in the news) may have inspired Superman's young teenaged creators in the 1930s to create this iconic modern myth—a myth, like many, grounded in astronomy. My goal is to show that comics—which we normally think of as juvenile, throwaway entertainment— actually tried to base themselves (and certainly were inspired by) actual astronomical events in the thirties and forties, made more accessible to the public by new scientific explanations, including a real supernova that may have inspired the destruction of Krypton.

  19. Solid state storage of radioactive krypton in a silica matrix

    SciTech Connect

    Tingey, G.L.; Lytle, J.M.; Gray, W.J.; Wheeler, K.R.

    1980-12-01

    The feasibility of loading a low density SiO/sub 2/ glass with krypton for storage of radioactive /sup 85/Kr has been demonstrated by studies using non-radioactive krypton. A 96% SiO/sub 2/ glass with 28% porosity was heated at an elevated pressure of Kr gas to a temperature of 850 to 900/sup 0/C and held at that temperature to sinter the glass-krypton composite to a density of about 2 g/cm/sup 3/. A krypton content of 30 cm/sup 3/ of Kr(STP)/cm/sup 3/ of glass has been demonstrated when loading pressures of 140 MPa are used. Krypton release rates from the glass are lower than reported for any other waste form considered currently. At 420/sup 0/C a diffusion parameter, D/r/sub 0//sup 2/, of 8.66 x 10/sup -13/ min/sup -1/ was determined which leads to a total release of 0.7% of the krypton in 10 years. Release rates increase moderately with increasing temperature up to 600/sup 0/C and increase rapidly above 600/sup 0/C. The lower loading pressures (about 40 MPa) may appear to yield a more favorable product from the point of view of krypton release than the high pressures. Advantages and disadvantages of the technique are given in the conclusions section.

  20. Stable Isotope Anomalies and Low Chloride Concentrations in Pore Water of CH4-Rich Sediments at the Tanegashima Mud Volcano, Japan

    NASA Astrophysics Data System (ADS)

    Nakayama, N.; Tsunogai, U.; Ashi, J.; Gamo, T.

    2004-12-01

    Pore water from sediments collected at a Tanegashima mud volcano was analyzed for δ 13C (PDB) of dissolved CH4 together with other chemical components, Cl- and SO42-, and the δ 18O and δ D (SMOW). The Tanegashima mud volcanoes are located at the water depths from 1400 m to 1800 m, off Tanegashima island between Ryukyu trench and Ryukyu arc of Japan. It is situated at the end of south-western convergent plate boundary on Nankai-trough, which forms a part of Philippine Sea plate subducting under Eurasian plate. This cruise was conducted as a part of the JNOC (Japan National Oil Corporation) geochemical survey by R/V Hakurei-maru II. The concentrations of CH4 were generally higher than 100 micro-mol/kg. Its highest concentration (715 micro-mol/kg) was found in the crest core of a mud volcano. The δ 13C values ranged from -32 to -50 ‰ . C2H6 was detected only in the pore waters collected from the vicinity of the crest of the mud volcano. The highest δ 13C (around -22 ‰ ) and low C1/C2 concentration ratios (less than 100) were measured at the crest site, supporting the thermogenical production of methane. Other geochemical anomalies were also observed in the crest pore water. The concentrations of Cl- in the pore water at this site were extremely depleted to a minimum of 350 mmol/kg. The Cl- anomaly has not been previously reported for pore water from mud volcanoes around Japan. An endmember of isotopic composition of the fluid is estimated to be +12 ‰ for δ 18O and -40 ‰ for δ D. From these results we conclude that the most likely process to reduce pore water salinity is primarily the mixing of clay mineral dehydration water with seawater. The thermogenic methane found in the crest pore waters of the Tanegashima mud volcano may be brought from the depths of sediments due to the migration of fluid evolved by mineral the dehydration process.

  1. Low-energy positron interactions with krypton

    SciTech Connect

    Makochekanwa, C.; Machacek, J. R.; Jones, A. C. L.; Caradonna, P.; Slaughter, D. S.; McEachran, R. P.; Sullivan, J. P.; Buckman, S. J.; Bellm, S.; Lohmann, B.; Fursa, D. V.; Bray, I.; Mueller, D.W.; Stauffer, A. D.; Hoshino, M.

    2011-03-15

    Cross sections for positron scattering from krypton have been measured with an energy resolution of {approx}60 meV over the energy range 0.5-60 eV. Absolute values of the grand total ({sigma}{sub GT}), positronium formation ({sigma}{sub Ps}), and grand total minus positronium formation ({sigma}{sub GT}-{sigma}{sub Ps},) cross sections are presented. Theoretical estimations of {sigma}{sub GT} and {sigma}{sub GT}-{sigma}{sub Ps} are also performed for this target using the convergent close-coupling method and the relativistic optical potential approach. We also provide experimental and theoretical results for elastic differential cross sections, for selected energies both below and above the Ps threshold. Where available, the present results are compared to both experimental and theoretical values from the literature.

  2. Photoassociative Spectroscopy of Ultracold Argon and Krypton

    NASA Astrophysics Data System (ADS)

    Omar, M. K.; Williams, W. D.; Sukenik, C. I.

    2016-05-01

    We report on photoassociative spectroscopy experiments performed separately on ultracold 40 Ar and ultracold 84 Kr with the spectroscopy laser tuned around the trapping transition for each species (ns[ 3 / 2 ] 2 --> np[ 5 / 2 ] 3 where n = 4 for argon and n = 5 for krypton). Previous studies in argon observed several discrete features in the spectrum that have now been positively identified as arising from otherwise undetectable frequency sidebands on the spectroscopy laser and not from molecular structure. Spectra have been taken over a range of laser intensities and show a broad (several GHz) signature of single photon photo-association, but with no individual vibrational levels resolved. We will discuss our results and compare our spectra to those obtained in ultracold, noble gas photoassociative spectroscopy experiments conducted by other groups in recent years. Supported in part by the National Science Foundation, Award, No. PHY-0855290.

  3. Stress enhanced diffusion of krypton ions in polycrystalline titanium

    SciTech Connect

    Nsengiyumva, S.; Raji, A. T.; Rivière, J. P.; Britton, D. T.; Härting, M.

    2014-07-14

    An experimental investigation on the mutual influence of pre-existing residual stress and point defect following ion implantation is presented. The study has been carried out using polycrystalline titanium samples energetically implanted with krypton ions at different fluences. Ion beam analysis was used to determine the concentration profile of the injected krypton ions, while synchrotron X-ray diffraction has been used for stress determination. Ion beam analysis and synchrotron X-ray diffraction stress profile measurements of the implanted titanium samples show a clear evidence of stress-enhanced diffusion of krypton ions in titanium. It is further observed that for the titanium samples implanted at low fluence, ion implantation modifies the pre-existing residual stress through the introduction of point and open volume defects. The stress fields resulting from the ion implantation act to drift the krypton inclusions towards the surface of titanium.

  4. CAMPing by the sea: Evidence for synchrony of volcanism and the end-Triassic extinction and carbon isotope anomaly from a marine Triassic-Jurassic boundary section

    NASA Astrophysics Data System (ADS)

    Pálfy, J.; Zajzon, N.

    2012-04-01

    The end-Triassic extinction (ETE) is one of the five largest Phanerozoic mass extinctions, associated with and likely triggered by rapid and severe environmental change. Volcanism in the Central Atlantic Magmatic Province (CAMP) has been proposed as the main trigger, but direct evidence for this linkage is scarce. To help constrain scenarios for the Triassic-Jurassic boundary (TJB) events, we obtained a temporally highly resolved, multidisciplinary dataset from the Kendlbachgraben section in the Northern Calcareous Alps in Austria. The section belongs to the same paleogeographic unit (Eiberg Basin) and share similar stratigraphies with the newly selected base Jurassic GSSP at Kuhjoch. The topmost beds of the Rhaetian Kössen Formation yielded an REE pattern that differs from all other levels in an enrichment of heavy REEs, hinting at some minor contribution from mantle-derived magmatic material to the sedimentary basin. Micromineralogy of the same bed revealed pseudomorphs of altered, euhedral pyroxene and amphibole crystals. Their well-faceted morphology excludes any terrestrial weathering and transport, but is consistent with their origin from air-fallen distal mafic volcanic ash. Peculiar spherical or rounded grains, altered to illite/aluminoceladonite were also observed, likely representing altered volcanic glass. The dominant clay mineral of this bed is low- to medium-charged smectite, accompanied by vermiculite, both typical alteration products of mafic rocks. These features from a bed deposited very near to the TJB are interpreted as direct evidence of CAMP volcanism, immediately preceding the main extinction event and the initial negative carbon isotope anomaly. Clay mineralogy of the Rhaetian-Hettangian Kendlbach Formation (overlying the Kössen Formation) reveals a kaolinite-dominated interval at the base of the formation, followed by an illite-dominated interval. Thus a hot and humid period may have characterized the TJB, in agreement with a previously

  5. Holonomy anomalies

    SciTech Connect

    Bagger, J.; Nemeschansky, D.; Yankielowicz, S.

    1985-05-01

    A new type of anomaly is discussed that afflicts certain non-linear sigma models with fermions. This anomaly is similar to the ordinary gauge and gravitational anomalies since it reflects a topological obstruction to the reparametrization invariance of the quantum effective action. Nonlinear sigma models are constructed based on homogeneous spaces G/H. Anomalies arising when the fermions are chiral are shown to be cancelled sometimes by Chern-Simons terms. Nonlinear sigma models are considered based on general Riemannian manifolds. 9 refs. (LEW)

  6. Krypton and xenon in lunar fines

    NASA Technical Reports Server (NTRS)

    Basford, J. R.; Dragon, J. C.; Pepin, R. O.; Coscio, M. R., Jr.; Murthy, V. R.

    1973-01-01

    Data from grain-size separates, stepwise-heated fractions, and bulk analyses of 20 samples of fines and breccias from five lunar sites are used to define three-isotope and ordinate intercept correlations in an attempt to resolve the lunar heavy rare gas system in a statistically valid approach. Tables of concentrations and isotope compositions are given.

  7. Kinetic modelling of krypton fluoride laser systems

    SciTech Connect

    Jancaitis, K.S.

    1983-11-01

    A kinetic model has been developed for the KrF* rare gas halide laser system, specifically for electron-beam pumped mixtures of krypton, fluorine, and either helium or argon. The excitation produced in the laser gas by the e-beam was calculated numerically using an algorithm checked by comparing the predicted ionization yields in the pure rare gases with their experimental values. The excitation of the laser media by multi-kilovolt x-rays was also modeled and shown to be similar to that produced by high energy electrons. A system of equations describing the transfer of the initial gas excitation into the laser upper level was assembled using reaction rate constants from both experiment and theory. A one-dimensional treatment of the interaction of the laser radiation with the gas was formulated which considered spontaneous and stimulated emission and absorption. The predictions of this model were in good agreement with the fluorescence signals and gain and absorption measured experimentally.

  8. Bangui Anomaly

    NASA Technical Reports Server (NTRS)

    Taylor, Patrick T.

    2004-01-01

    Bangui anomaly is the name given to one of the Earth s largest crustal magnetic anomalies and the largest over the African continent. It covers two-thirds of the Central African Republic and therefore the name derives from the capitol city-Bangui that is also near the center of this feature. From surface magnetic survey data Godivier and Le Donche (1962) were the first to describe this anomaly. Subsequently high-altitude world magnetic surveying by the U.S. Naval Oceanographic Office (Project Magnet) recorded a greater than 1000 nT dipolar, peak-to-trough anomaly with the major portion being negative (figure 1). Satellite observations (Cosmos 49) were first reported in 1964, these revealed a 40nT anomaly at 350 km altitude. Subsequently the higher altitude (417-499km) POGO (Polar Orbiting Geomagnetic Observatory) satellite data recorded peak-to-trough anomalies of 20 nT these data were added to Cosmos 49 measurements by Regan et al. (1975) for a regional satellite altitude map. In October 1979, with the launch of Magsat, a satellite designed to measure crustal magnetic anomalies, a more uniform satellite altitude magnetic map was obtained. These data, computed at 375 km altitude recorded a -22 nT anomaly (figure 2). This elliptically shaped anomaly is approximately 760 by 1000 km and is centered at 6%, 18%. The Bangui anomaly is composed of three segments; there are two positive anomalies lobes north and south of a large central negative field. This displays the classic pattern of a magnetic anomalous body being magnetized by induction in a zero inclination field. This is not surprising since the magnetic equator passes near the center of this body.

  9. Influence of radiation damage on krypton diffusion in silicon carbide

    NASA Astrophysics Data System (ADS)

    Friedland, E.; Hlatshwayo, T. T.; van der Berg, N. G.; Mabena, M. C.

    2015-07-01

    Diffusion of krypton in poly and single crystalline silicon carbide is investigated and compared with the previously obtained results for xenon, which pointed to a different diffusion mechanism than observed for chemically active elements. For this purpose 360 keV krypton ions were implanted in commercial 6H-SiC and CVD-SiC wafers at room temperature, 350 °C and 600 °C. Width broadening of the implantation profiles and krypton retention during isochronal and isothermal annealing up to temperatures of 1400 °C was determined by RBS-analysis, whilst in the case of 6H-SiC damage profiles were simultaneously obtained by α-particle channeling. Little diffusion and no krypton loss was detected in the initially amorphized and eventually recrystallized surface layer of cold implanted 6H-SiC during annealing up to 1200 °C. Above that temperature thermal etching of the implanted surface became increasingly important. No diffusion or krypton loss is detected in the hot implanted 6H-SiC samples during annealing up to 1400 °C. Radiation damage dependent grain boundary diffusion is observed at 1300 °C in CVD-SiC. The results seem to indicate, that the chemically inert noble gas atoms do not form defect-impurity complexes, which strongly influence the diffusion behavior of other diffusors in silicon carbide.

  10. The krypton and xenon markets up to the year 2000

    NASA Astrophysics Data System (ADS)

    Hammarlund, Nils

    1992-05-01

    Krypton and xenon are rare gases which are found in air in concentrations of about 1.14 and 0.087 ppm, respectively. They are produced in specially equipped, very large air separation units by adding a special raw gas extraction unit. Then this raw gas is purified and the krypton and xenon are separated by cryogenic methods. These rare gases are used in the lamp industry, for medical applications and in laser and research applications. The market for krypton and xenon is growing. The production capacity for these gases is limited and this results in a cyclic behavior of availability and market price. In the next few years, 10-20 million liters of krypton and one to two million liters of xenon will become available on the market due to new investments in the USA, South Africa and the AGA AB joint venture in the USSR. The total world production capacity of krypton and xenon will increase to 60-80 million liters. To influence the availability of these gases it is important to have close partnership between user and producer, which will realize bright and unorthodox ideas for the supply and use of these rare gases.

  11. 10 CFR 30.19 - Self-luminous products containing tritium, krypton-85, or promethium-147.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Self-luminous products containing tritium, krypton-85, or..., krypton-85, or promethium-147. (a) Except for persons who manufacture, process, produce, or initially transfer for sale or distribution self-luminous products containing tritium, krypton-85, or...

  12. 10 CFR 30.19 - Self-luminous products containing tritium, krypton-85, or promethium-147.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Self-luminous products containing tritium, krypton-85, or..., krypton-85, or promethium-147. (a) Except for persons who manufacture, process, produce, or initially transfer for sale or distribution self-luminous products containing tritium, krypton-85, or...

  13. 10 CFR 30.19 - Self-luminous products containing tritium, krypton-85, or promethium-147.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Self-luminous products containing tritium, krypton-85, or..., krypton-85, or promethium-147. (a) Except for persons who manufacture, process, produce, or initially transfer for sale or distribution self-luminous products containing tritium, krypton-85, or...

  14. 10 CFR 30.19 - Self-luminous products containing tritium, krypton-85, or promethium-147.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Self-luminous products containing tritium, krypton-85, or..., krypton-85, or promethium-147. (a) Except for persons who manufacture, process, produce, or initially transfer for sale or distribution self-luminous products containing tritium, krypton-85, or...

  15. 10 CFR 30.19 - Self-luminous products containing tritium, krypton-85, or promethium-147.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Self-luminous products containing tritium, krypton-85, or..., krypton-85, or promethium-147. (a) Except for persons who manufacture, process, produce, or initially transfer for sale or distribution self-luminous products containing tritium, krypton-85, or...

  16. Neutron capture time scale of the s-process, estimated from s-process krypton in a meteorite

    NASA Technical Reports Server (NTRS)

    Matsuda, J.-I.; Lewis, R. S.; Anders, E.

    1980-01-01

    A krypton fraction enriched in s-process isotopes was extracted from a mineral fraction of the Murchison C2 chondrite. The (Kr-86)/(Kr-84) ratio is enhanced by 6 standard deviations, showing that significant amounts of Kr-86 were made in the s-process, despite the short, 10.8 yr beta-decay half-life of its precursor, Kr-85. Judging from this sample, the mean neutron capture time in the s-process was on the order of 5-100 yr for nuclei with cross sections of 125 mb.

  17. Metastable Krypton Beam Source via Two-Photon Pumping Technique

    SciTech Connect

    Wong, W.W.; Young, L.

    2003-01-01

    Metastable beams of rare gas atoms have wide applications in chemical analysis of samples, as well as in aiding understanding of fundamental processes and physical attributes. Most current sources of metastable rare gas atomic beams, however, are limited in their flux density, which greatly reduces their utility in applications such as low level trace analysis and precision measurements. Previous work has demonstrated feasibility of metastable krypton production via two-photon pumping, and this paper extends that possibility into beam form. Further optimization on this scheme, moreover, promises 100-fold increase of metastable krypton flux density over that of an rf-driven discharge.

  18. Atom Trap, Krypton-81, and Saharan Water

    SciTech Connect

    Lu, Zheng-Tian

    2005-08-24

    Since radiocarbon dating was first demonstrated in 1949, the field of trace analyses of long-lived cosmogenic isotopes has seen steady growth in both analytical methods and applicable isotopes. The impact of such analyses has reached a wide range of scientific and technological areas. A new method, named Atom Trap Trace Analysis (ATTA), was developed by our group and used to analyze {sup 81}Kr (t{sub 1/2} = 2.3 x 10{sup 5} years, isotopic abundance {approx} 1 x 10{sup -12}) in environmental samples. In this method, individual {sup 81}Kr atoms are selectively captured and detected with a laser-based atom trap. {sup 81}Kr is produced by cosmic rays in the upper atmosphere. It is the ideal tracer for dating ice and groundwater in the age range of 10{sup 4}-10{sup 6} years. As the first real-world application of ATTA, we have determined the mean residence time of the old groundwater in the Nubian Aquifer located underneath the Sahara Desert. Moreover, this method of capturing and probing atoms of rare isotopes is also applied to experiments that study exotic nuclear structure and test fundamental symmetries.

  19. Anomalous krypton in the Allende meteorite

    NASA Technical Reports Server (NTRS)

    Frick, U.

    1977-01-01

    The reported investigation provides important new data for the heavy noble gases, especially Kr, in the Allende meteorite. The data are used to criticize the original model of Lewis et al. (1975) based on the noble gas data of these researchers. The conclusions reached in the investigation support alternative models which have been mainly based on Xe data by Lewis et al. (1975, 1977). Because of the relatively high noble gas abundances in the separates studied, disturbance from nuclear effects occurring in situ such as spallation and neutron capture is insignificant, offering an opportunity to study primordial Ar, Kr, and Xe. The isotopic and abundance data obtained from the samples largely confirm the noble gas results of Lewis et al. (1975, 1977) where isotopic correlations agree with the correlations of the considered samples. It is found that both Kr and Xe data are consistent with a two component mixture of 'ordinary' as well as 'anomalous' planetary gases.

  20. DOWN'S ANOMALY.

    ERIC Educational Resources Information Center

    PENROSE, L.S.; SMITH, G.F.

    BOTH CLINICAL AND PATHOLOGICAL ASPECTS AND MATHEMATICAL ELABORATIONS OF DOWN'S ANOMALY, KNOWN ALSO AS MONGOLISM, ARE PRESENTED IN THIS REFERENCE MANUAL FOR PROFESSIONAL PERSONNEL. INFORMATION PROVIDED CONCERNS (1) HISTORICAL STUDIES, (2) PHYSICAL SIGNS, (3) BONES AND MUSCLES, (4) MENTAL DEVELOPMENT, (5) DERMATOGLYPHS, (6) HEMATOLOGY, (7)…

  1. Empirical evaluation of the radiative cooling coefficient for krypton gas in the FTU plasma

    SciTech Connect

    Fournier, K.B.; Pacella, D.; Gregory, B.C.; May, M.J.; Mazzitelli, G.; Gabellieri, L.; Leigheb, M.; Finkenthal, M.; Stutman, D.; Soukanovskii, V.; Goldstein, W.H.

    1997-11-18

    For future fusion reactors, a careful balance must be achieved between the cooling of the outer plasma via impurity radiation and the deleterious effects of inevitable core penetration by impurity ions. We have injected krypton gas into the Frascati Tokamak Upgrade (FTU) plasma. The measured visible bremsstrahlung and bolometric signals from krypton have been inverted and the resulting radial impurity density profile and power loss profile for krypton gas are extracted. Using the measured electron density and temperature profiles, the radiative cooling coefficient for krypton is derived. The level of intrinsic impurities (Mo, Cr, Mn and Fe) in the plasma during the krypton puffing is monitored with a VUV SPRED spectrometer. Models for krypton emissivity from the literature are compared to our measured results. 7 figs.

  2. Auger decay of 3p-ionized krypton

    SciTech Connect

    Jonauskas, V.; Kucas, S.; Karazija, R.

    2011-11-15

    A theoretical study of Auger cascades during the decay of 3p{sub 1/2} and 3p{sub 3/2} vacancies in krypton has been performed by level-by-level calculations using a wide configuration interaction basis. Auger spectra for all steps of the cascades are presented and are compared with the existing experimental data. Good agreement of our results with the branching ratios of ions measured by a coincidence technique is obtained.

  3. Dust Particle Growth in a Sputtering Discharge with Krypton

    SciTech Connect

    Tawidian, H.; Mikikian, M.; Lecas, T.; Boufendi, L.

    2011-11-29

    Dust particles are grown in the PKE chamber by sputtering materials. The sputtering efficiency and the gas phase reactions can be affected by the gas type and particularly by the ion mass. Due to the presence of growing dust particles, the huge loss of electrons can trigger many instabilities in the plasma. These instabilities, the growth kinetics and the structure of the dust cloud, are compared by using two different gases: argon and krypton.

  4. Electron impact excitation of autoionising states of krypton

    NASA Technical Reports Server (NTRS)

    Srivastava, S. K.; Trajmar, S.

    1978-01-01

    Energy-loss spectra of krypton in the region between 21 and 29 eV have been obtained at electron impact energies of 30, 60 and 100 eV. For each energy, the angular distribution of intensities has been measured at 5, 10 and 15 deg scattering angles. Assignments of spectral features found in this region are suggested and a comparison is made with previous measurements.

  5. Characterization of a Diverging Cusped Field Thruster Operating on Krypton

    NASA Astrophysics Data System (ADS)

    MacDonald-Tenenbaum, Natalia; Tango, Landon; Hargus, William, Jr.; Nakles, Michael

    2014-10-01

    The Diverging Cusped Field Thruster (DCFT) is a low-power plasma with a cusped magnetic field profile. The magnetic fields have strong gradients that cause energetic electrons to mirror back and forth within the discharge chamber, enhancing propellant ionization. Radial portions of the magnetic field are seen only at magnet interfaces, thereby mitigating the ion impingement and heat flux to the channel walls that reduces thruster lifetime. The DCFT has been studied extensively while operating on xenon. This work represents the initial efforts at characterizing the DCFT operating on krypton. Krypton has gained interest in recent years as an alternate propellant for plasma propulsion, mainly because its lower cost has the potential to provide great savings for satellite missions. The results presented include a mapping of changes in the DCFT's discharge current with varying applied anode voltages and propellant mass flow rates, and frequency analysis of the discharge current oscillations. Additionally, time-averaged and time-synchronized laser induced fluorescence velocimetry are used to examine the ionization and acceleration regions of the discharge channel in an effort to better understand the dynamics of the thruster operation on krypton.

  6. Statistical clumped isotope signatures

    PubMed Central

    Röckmann, T.; Popa, M. E.; Krol, M. C.; Hofmann, M. E. G.

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk (≈average) isotopic composition of the involved atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies (anti-clumping) when the indistinguishable atoms originate from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule. The size of the anti-clumping signal is closely related to the difference of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly, relative to an expected (e.g. thermodynamical) clumped isotope composition, may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules. PMID:27535168

  7. Statistical clumped isotope signatures.

    PubMed

    Röckmann, T; Popa, M E; Krol, M C; Hofmann, M E G

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk (≈average) isotopic composition of the involved atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies (anti-clumping) when the indistinguishable atoms originate from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule. The size of the anti-clumping signal is closely related to the difference of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly, relative to an expected (e.g. thermodynamical) clumped isotope composition, may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules. PMID:27535168

  8. Accurate ab initio potential for the krypton dimer and transport properties of the low-density krypton gas.

    PubMed

    Waldrop, Jonathan M; Song, Bo; Patkowski, Konrad; Wang, Xiaopo

    2015-05-28

    A new highly accurate potential energy curve for the krypton dimer was constructed using coupled-cluster calculations up to the singles, doubles, triples, and perturbative quadruples level, including corrections for core-core and core-valence correlation and for relativistic effects. The ab initio data points were fitted to an analytic potential which was used to compute the most important transport properties of the krypton gas. The viscosity, thermal conductivity, self-diffusion coefficient, and thermal diffusion factor were calculated by the kinetic theory at low density and temperatures from 116 to 5000 K. The comparisons with literature experimental data as well as with values from other pair potentials indicate that our new potential is superior to all previous ones. The transport property values computed in this work are recommended as standard values over the complete temperature range. PMID:26026447

  9. Abundance Anomaly of the 13C Isotopic Species of c-C3H2 in the Low-mass Star Formation Region L1527

    NASA Astrophysics Data System (ADS)

    Yoshida, Kento; Sakai, Nami; Tokudome, Tomoya; López-Sepulcre, Ana; Watanabe, Yoshimasa; Takano, Shuro; Lefloch, Bertrand; Ceccarelli, Cecilia; Bachiller, Rafael; Caux, Emmanuel; Vastel, Charlotte; Yamamoto, Satoshi

    2015-07-01

    The rotational spectral lines of c-C3H2 and two kinds of the 13C isotopic species, c-{}13{{CCCH}}2 ({C}2v symmetry) and c-{{CC}}13{{CH}}2 (Cs symmetry), have been observed in the 1–3 mm band toward the low-mass star-forming region L1527. We have detected 7, 3, and 6 lines of c-C3H2, c-{}13{{CCCH}}2, and c-{{CC}}13{{CH}}2, respectively, with the Nobeyama 45 m telescope and 34, 6, and 13 lines, respectively, with the IRAM 30 m telescope, where seven, two, and two transitions, respectively, are observed with both telescopes. With these data, we have evaluated the column densities of the normal and 13C isotopic species. The [c-C3H2]/[c-{}13{{CCCH}}2] ratio is determined to be 310 ± 80, while the [c-C3H2]/[c-{{CC}}13{{CH}}2] ratio is determined to be 61 ± 11. The [c-C3H2]/[c-{}13{{CCCH}}2] and [c-C3H2]/[c-{{CC}}13{{CH}}2] ratios expected from the elemental 12C/13C ratio are 60–70 and 30–35, respectively, where the latter takes into account the statistical factor of 2 for the two equivalent carbon atoms in c-C3H2. Hence, this observation further confirms the dilution of the 13C species in carbon-chain molecules and their related molecules, which are thought to originate from the dilution of 13C+ in the gas-phase C+ due to the isotope exchange reaction: {}13{{{C}}}++{CO}\\to {}13{CO}+{{{C}}}+. Moreover, the abundances of the two 13C isotopic species are different from each other. The ratio of c-{}13{{CCCH}}2 species relative to c-{{CC}}13{{CH}}2 is determined to be 0.20 ± 0.05. If 13C were randomly substituted for the three carbon atoms, the [c-{}13{{CCCH}}2]/[c-{{CC}}13{{CH}}2] ratio would be 0.5. Hence, the observed ratio indicates that c-{{CC}}13{{CH}}2 exists more favorably. Possible origins of the different abundances are discussed. Based on observations carried out with the IRAM 30 m Telescope and the NRO 45 m Telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). NRO is a branch of the National Astronomical Observatory of Japan

  10. Internal plasma potential measurements of a Hall thruster using xenon and krypton propellant

    SciTech Connect

    Linnell, Jesse A.; Gallimore, Alec D.

    2006-09-15

    For krypton to become a realistic option for Hall thruster operation, it is necessary to understand the performance gap between xenon and krypton and what can be done to reduce it. A floating emissive probe is used with the Plasmadynamics and Electric Propulsion Laboratory's High-speed Axial Reciprocating Probe system to map the internal plasma potential structure of the NASA-173Mv1 Hall thruster [R. R. Hofer, R. S. Jankovsky, and A. D. Gallimore, J. Propulsion Power 22, 721 (2006); and ibid.22, 732 (2006)] using xenon and krypton propellant. Measurements are taken for both propellants at discharge voltages of 500 and 600 V. Electron temperatures and electric fields are also reported. The acceleration zone and equipotential lines are found to be strongly linked to the magnetic-field lines. The electrostatic plasma lens of the NASA-173Mv1 Hall thruster strongly focuses the xenon ions toward the center of the discharge channel, whereas the krypton ions are defocused. Krypton is also found to have a longer acceleration zone than the xenon cases. These results explain the large beam divergence observed with krypton operation. Krypton and xenon have similar maximum electron temperatures and similar lengths of the high electron temperature zone, although the high electron temperature zone is located farther downstream in the krypton case.

  11. 10 CFR 32.22 - Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements for license...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Self-luminous products containing tritium, krypton-85 or... containing tritium, krypton-85 or promethium-147: Requirements for license to manufacture, process, produce... self-luminous products containing tritium, krypton-85, or promethium-147, or to initially transfer...

  12. 10 CFR 32.22 - Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements for license...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Self-luminous products containing tritium, krypton-85 or... containing tritium, krypton-85 or promethium-147: Requirements for license to manufacture, process, produce... self-luminous products containing tritium, krypton-85, or promethium-147, or to initially transfer...

  13. 10 CFR 32.22 - Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements for license...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Self-luminous products containing tritium, krypton-85 or... containing tritium, krypton-85 or promethium-147: Requirements for license to manufacture, process, produce... self-luminous products containing tritium, krypton-85, or promethium-147, or to initially transfer...

  14. 10 CFR 32.22 - Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements for license...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Self-luminous products containing tritium, krypton-85 or... containing tritium, krypton-85 or promethium-147: Requirements for license to manufacture, process, produce... self-luminous products containing tritium, krypton-85, or promethium-147, or to initially transfer...

  15. 10 CFR 32.22 - Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements for license...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Self-luminous products containing tritium, krypton-85 or... containing tritium, krypton-85 or promethium-147: Requirements for license to manufacture, process, produce... self-luminous products containing tritium, krypton-85, or promethium-147, or to initially transfer...

  16. Krypton gas cylinders as a source of radiation.

    PubMed

    Fischer, Helmut W; Bielefeld, Tom; Hettwig, Bernd

    2010-07-01

    A standard 40 foot shipping container with a cargo of pressurized krypton gas in 159 steel cylinders, which had triggered a radiation alarm, was investigated to address radiation safety and illicit nuclear trafficking concerns. The investigation included contamination and dose rate measurements as well as in situ high resolution gamma spectroscopy. The dose rate measurements gave a maximum value of 0.07 microSv h(-1) above background (0.08 to 0.11 microSv h(-1)) on the cylinder surface and no detectable increase above background at distances of 1 m and higher. Contamination monitor readings showed a similar relative increase (plus 8 cpm) above background (about 12 cpm) to the dose rate readings. Quantitative gamma spectroscopy revealed a contamination of the gas with 85Kr at a level of 3.5 x 10(5) Bq kg(-1). This value was found to be consistent with analytical and numerical estimates based on current data for atmospheric 85Kr, which is captured from ambient air together with stable krypton during the production process. This incident demonstrates an apparent lack of radiation-related knowledge by those who handle krypton gas, as well as by border control personnel and emergency responders. We therefore propose to improve labeling and documentation standards for such shipments. This effort may be facilitated by introducing the new category of "technically enhanced artificial radioactive material," or "TEARM" (similar to the existing "naturally occurring radioactive material" or "NORM" and "technically enhanced naturally occurring radioactive material" or "TENORM" categories). PMID:20539125

  17. Investigation of the thermal and photochemical reactions of ozone with styrene in argon and krypton matrices

    NASA Astrophysics Data System (ADS)

    Coleman, Bridgett E.; Ault, Bruce S.

    2012-09-01

    The matrix isolation technique, combined with infrared spectroscopy and twin jet codeposition, has been used to characterize intermediates formed during the ozonolysis of styrene. Absorptions assigned to early intermediates grew in after warming the matrix from 19 K to 68 K in the twin jet krypton matrix experiments. A number of these absorptions have been assigned to the primary ozonide, formaldehyde-O-oxide Criegee intermediate, and secondary ozonide of styrene, transient species not previously observed for this system. In contrast, the room temperature reaction of ozone with styrene led to the observation of "late," stable products of this ozonolysis reaction. These product absorptions were observed after merged jet deposition, followed by cryogenic trapping in solid argon. Irradiation with λ ⩾ 220 nm of merged and twin jet argon matrices involving ozone led to O atom production and subsequent reaction with styrene. Identification of intermediates formed during the ozonolysis of styrene was further supported by 18O isotopic labeling experiments as well as theoretical density functional calculations at the B3LYP/6-311G++(d,2p) level.

  18. Gauge anomalies, gravitational anomalies, and superstrings

    SciTech Connect

    Bardeen, W.A.

    1985-08-01

    The structure of gauge and gravitational anomalies will be reviewed. The impact of these anomalies on the construction, consistency, and application of the new superstring theories will be discussed. 25 refs.

  19. ANOMALY STRUCTURE OF SUPERGRAVITY AND ANOMALY CANCELLATION

    SciTech Connect

    Butter, Daniel; Gaillard, Mary K.

    2009-06-10

    We display the full anomaly structure of supergravity, including new D-term contributions to the conformal anomaly. This expression has the super-Weyl and chiral U(1){sub K} transformation properties that are required for implementation of the Green-Schwarz mechanism for anomaly cancellation. We outline the procedure for full anomaly cancellation. Our results have implications for effective supergravity theories from the weakly coupled heterotic string theory.

  20. Supershort avalanche electron beam in SF6 and krypton

    NASA Astrophysics Data System (ADS)

    Zhang, Cheng; Tarasenko, Victor F.; Gu, Jianwei; Baksht, Evgeni Kh.; Beloplotov, Dmitry V.; Burachenko, Alexander G.; Yan, Ping; Lomaev, Mikhail I.; Shao, Tao

    2016-03-01

    Runaway electrons play an important role in the avalanche formation in nanosecond- and subnanosecond- pulse discharges. In this paper, characteristics of a supershort avalanche electron beam (SAEB) generated at the subnanosecond and nanosecond breakdown in sulfur hexafluoride (SF6 ) in an inhomogeneous electric field were studied. One pulser operated at negative polarity with voltage pulse amplitude of ˜130 kV and rise time of 0.3 ns. The other pulser operated at negative polarity with voltage pulse amplitude of 70 kV and rise time of ˜1.6 ns . SAEB parameters in SF6 are compared with those obtained in krypton (Kr), nitrogen (N2 ), air, and mixtures of SF6 with krypton or nitrogen. Experimental results showed that SAEB currents appeared during the rise-time of the voltage pulse for both pulsers. Moreover, amplitudes of the SAEB current in SF6 and Kr approximately ranged from several to tens of milliamps at atmospheric pressure, which were smaller than those in N2 and air (ranging from hundreds of milliamps to several amperes). Furthermore, the concentration of SF6 additive could significantly reduce the SAEB current in N2-SF6 mixture, but it slightly affected the SAEB current in Kr -SF6 mixture because of the atomic/molecular ionization cross section of the gas had a much greater impact on the SAEB current rather than the electronegativity.

  1. Krypton-85 hydrofracture engineering feasibility and safety evaluation

    SciTech Connect

    Peretz, F.J.; Muller, M.E.; Pan, P.Y.

    1981-07-01

    Engineering studies have been made to determine the hazards associated with the disposal of /sup 85/Kr using the hydrofracture process. To assess the hazards, an effort has been made to identify the equipment required to entrain and dissolve the noble gas into the grout stream at hydrofracture pressure (up to 350 bar). Off-the-shelf or slightly modified equipment has been identified for safe and effective compression and gas-grout mixing. Each monthly injection disposes of 1.6 x 10/sup 6/ Ci of /sup 85/Kr. By connecting only one gas cylinder to the injection system at a time, the maximum amount of krypton likely to be released as a result of equipment failure is limited to 128,000 Ci. An evaluation by Los Alamos Technical Associates shows that releasing this amount of gas in less than one hour under worst-case meteorological conditions through a 30-m stack would result in a whole-body dose of 170 millirem at a distance of 1 km from the facility. A krypton collection and recovery system can further reduce this dose to 17 millirem; increasing the distance to the site boundary to 3 km can also reduce the dose by a factor of ten. Lung and skin dose estimates are 1.6 and 120 times the whole-body dose, respectively. These are all worst-case values; releases under more typical conditions would result in a significantly lower dose. No insurmountable safety or engineering problems have been identified.

  2. Quantum beats in attosecond time-resolved autoionization of krypton

    NASA Astrophysics Data System (ADS)

    Cheng, Yan; Chini, Michael; Tong, Xiao-Min; Chew, Andrew; Biedermann, Julius; Wu, Yi; Cunningham, Eric; Chang, Zenghu

    2015-05-01

    The recent development of attosecond transient absorption spectroscopy (ATAS) has allowed probing of electron dynamics in atoms with few-femtosecond to sub-cycle time scales. Recently, the contribution of quantum beating to the two-color multi-photon excitation process has been proposed and demonstrated in the attosecond transient absorption experiment in the bound state of atoms. Here we performed an attosecond transient absorption experiment with krypton atoms, the attosecond pulse launched electronic wave packets composed of multiple bound excited states and spin-orbit coupling induced autoionization states of krypton atoms. Quantum beats were observed in the autoionizing states near the ionization threshold. Recurrences were observed in the 4s24p5(2 P° 1/2) 6d, 4s24p5(2 P°1/2) 7d, 4s24p5(2 P° 1/2) 8d states with periods of 5-10 fs. The relative phase among these autoionizing states can be retrieved from such measurement, thus allowed the reconstruction of the valence state wave packets. This material is based upon work supported by Army Research Office, Air Force Office of Scientific Research, the National Science Foundation, and the DARPA PULSE program by a grant from AMRDEC.

  3. The elliptic anomaly

    NASA Technical Reports Server (NTRS)

    Janin, G.; Bond, V. R.

    1980-01-01

    An independent variable different from the time for elliptic orbit integration is used. Such a time transformation provides an analytical step-size regulation along the orbit. An intermediate anomaly (an anomaly intermediate between the eccentric and the true anomaly) is suggested for optimum performances. A particular case of an intermediate anomaly (the elliptic anomaly) is defined, and its relation with the other anomalies is developed.

  4. Reconstruction of the West Pacific ENSO precipitation anomaly using the compound-specific hydrogen isotopic record of marine lake sediments of Palau

    NASA Astrophysics Data System (ADS)

    Smittenberg, R. H.; Sachs, J. P.; Dawson, M. N.

    2004-12-01

    There is still much uncertainty whether the El Niño Southern Oscillation (ENSO) will become stronger or more frequent in a warming global climate. A principal reason for this uncertainty stems from a glaring lack of paleoclimate data in the equatorial Pacific, which hampers model validation. To partly resolve this data deficiency, sediments of three marine anoxic lakes were cored in Palau, an island group that lies in the heart of the West Pacific Warm Pool. The lakes contain seawater that seeps through fissures in the surrounding karst, and they are permanently stratified due to fresh water input provided by the year-round wet climate (map 1970-2000 = 3.7m). During ENSO events, however, the islands suffer from drought. The surface water hydrogen isotopic compositions in the lakes are sensitive to the relative proportions of D-depleted rainwater and D-enriched seawater, and are therefore sensitive to ENSO events. The lake surface water H/D values are recorded by algal and bacterial biomarkers that are preserved well in the highly organic and anoxic sediments, which accumulate relatively fast (mean 1 mm/yr). Ongoing down core measurement will eventually result in a precipitation proxy record of the islands. To obtain endmember D/H values, a comprehensive set of water samples from sea, lakes and rain water was obtained, as well as suspended particulate matter. Higher plant biomarker D/H values derived from the jungle vegetation surrounding the lakes may render supporting climatic proxy data, being influenced by evapotranspiration. Some lakes are inhabited by millions of jellyfish (Mastigias) that live in symbiosis with zooxanthellae. The jellyfish of one of the investigated lakes disappeared completely after the last large ENSO event in 1998 (returning in 2000-01), and a correlation is suggested. To reconstruct the history of jellyfish occurrence, jellyfish and sedimentary lipids were extracted and compared. In addition to a possible ENSO proxy record, this

  5. Measurement of the Radiative Cooling Coefficient of Krypton Gas in the Frascati Tokamak Upgrade

    NASA Astrophysics Data System (ADS)

    Fournier, K. B.; Goldstein, W. H.; Pacella, D.; Mazzitelli, G.; Gabellieri, L.; Leigheb, M.; de Angelis, R.; May, M. J.; Regan, S. P.; Stutman, D.; Soukhanovskii, V.; Finkenthal, M.; Moos, H. W.

    1997-11-01

    For future fusion reactors, a careful balance must be achieved between the cooling of the outer plasma via impurity radiation and the deleterious effects of inevitable core penetration by impurity ions. We extract the krypton impurity radial profile and the radiative cooling rate for krypton gas in the Frascati Tokamak Upgrade (FTU). The measured bolometric, soft x-ray and visible bremmstrhalung signals are Abel inverted and then incorporated in an analytic model. Using the known (calculated) ionization state distribution, the radial power loss profile for krypton is derived. Anamolous transport is assumed to have a negligible affect on the total krypton radiation profile; this assumption is confirmed using the derived krypton radiation rate in a plasma transport modeling code. The level of intrinsic impurities (Mo, Cr, Mn and Fe) in the plasma during the krypton puffing is monitored with a VUV SPRED spectrometer. Models for krypton emissivity from the literature are compared to our measured results. These initial results are part of a multiwavelength impurity spectroscopy campaign that will measure transport profiles and basic atomic data in the FTU. Work carried out under the auspices of the U.S. DoE, Contract No. W-7405-ENG-48.

  6. The NA62 liquid Krypton calorimeter's new readout system

    NASA Astrophysics Data System (ADS)

    Ceccucci, A.; Fantechi, R.; Farthouat, P.; Lamanna, G.; Rouet, J.; Ryjov, V.; Venditti, S.

    2014-01-01

    The NA62 experiment [1] at CERN SPS (Super Proton Synchrotron) accelerator aims at studying Kaon decays with high precision. The high resolution Liquid Krypton (LKr) calorimeter, built for the NA48 [2] experiment, is a crucial part of the experiment photon-veto system; to cope with the new requirements, the back-end electronics of the LKr had to be completely renewed. Due to the huge number of the calorimeter readout channels ( ~ 14 K) and the maintenance requirement over 10 years of the experiment lifetime, the decision to sub-contract the development and production to industry was taken in 2011. This paper presents the primary test results of the Calorimeter REAdout Module (CREAM) [3] prototype delivered by the manufacturer in March 2013. All essential features, analog performance, data processing and readout, are covered.

  7. The NA62 Liquid Krypton calorimeter readout architecture

    NASA Astrophysics Data System (ADS)

    Ceccucci, A.; Fantechi, R.; Farthouat, P.; Ryjov, V.; De Simone, N.; Venditti, S.

    2016-01-01

    The NA62 experiment [1] at the CERN SPS (Super Proton Synchrotron) accelerator studies the ultra-rare decays of charged kaons. The high-resolution Liquid Krypton (LKr) electromagnetic calorimeter of the former NA48 experiment [2] is a key component of the experiment photon-veto system. The new LKr readout system comprises 14,000 14-bit ADC acquisition channels, 432× 1 Gbit Ethernet data request and readout links routed by 28× 10 Gbit network switches to the experiment computer farm, and timing, trigger and control (TTC) distribution system. This paper presents the architecture of the LKr readout and TTC systems, the overall performance and the first successfully collected experiment physics data.

  8. Investigation of many-body forces in krypton and xenon

    SciTech Connect

    Salacuse, J.J.; Egelstaff, P.A.

    1988-10-15

    The simplicity of the state dependence at relatively high temperatures ofthe many-body potential contribution to the pressure and energy has been pointed out previously (J. Ram and P. A. Egelstaff, J. Phys. Chem. Liq. 14, 29 (1984); A. Teitsima and P. A. Egelstaff, Phys. Rev. A 21, 367 (1980)). In this paper, we investigate how far these many-body potential terms may be represented by simple models in the case of krypton on the 423-, 273-, 190-, and 150-K isotherms, and xenon on the 170-, 210-, and 270-K isotherms. At the higher temperatures the best agreement is found for the mean-field type of theory, and some consequences are pointed out. On the lower isotherms a state point is found where the many-body energy vanishes, and large departures from mean-field behavior are observed. This is attributed to the influence of short-ranged many-body forces.

  9. Sheath oscillation characteristics and effect on near-wall conduction in a krypton Hall thruster

    SciTech Connect

    Zhang, Fengkui Kong, Lingyi; Li, Chenliang; Yang, Haiwei; Li, Wei

    2014-11-15

    Despite its affordability, the krypton Hall-effect thruster in applications always had problems in regard to performance. The reason for this degradation is studied from the perspective of the near-wall conductivity of electrons. Using the particle-in-cell method, the sheath oscillation characteristics and its effect on near-wall conduction are compared in the krypton and xenon Hall-effect thrusters both with wall material composed of BNSiO{sub 2}. Comparing these two thrusters, the sheath in the krypton-plasma thruster will oscillate at low electron temperatures. The near-wall conduction current is only produced by collisions between electrons and wall, thereby causing a deficiency in the channel current. The sheath displays spatial oscillations only at high electron temperature; electrons are then reflected to produce the non-oscillation conduction current needed for the krypton-plasma thruster. However, it is accompanied with intensified oscillations.

  10. Sheath oscillation characteristics and effect on near-wall conduction in a krypton Hall thruster

    NASA Astrophysics Data System (ADS)

    Zhang, Fengkui; Kong, Lingyi; Li, Chenliang; Yang, Haiwei; Li, Wei

    2014-11-01

    Despite its affordability, the krypton Hall-effect thruster in applications always had problems in regard to performance. The reason for this degradation is studied from the perspective of the near-wall conductivity of electrons. Using the particle-in-cell method, the sheath oscillation characteristics and its effect on near-wall conduction are compared in the krypton and xenon Hall-effect thrusters both with wall material composed of BNSiO 2 . Comparing these two thrusters, the sheath in the krypton-plasma thruster will oscillate at low electron temperatures. The near-wall conduction current is only produced by collisions between electrons and wall, thereby causing a deficiency in the channel current. The sheath displays spatial oscillations only at high electron temperature; electrons are then reflected to produce the non-oscillation conduction current needed for the krypton-plasma thruster. However, it is accompanied with intensified oscillations.

  11. DEVELOPMENT OF A HYDROGEN MORDENITE SORBENT FOR THE CAPTURE OF KRYPTON FROM USED NUCLEAR FUEL REPROCESSING OFF-GAS STREAMS

    SciTech Connect

    Mitchell Greenhalgh; Troy G. Garn; Jack D. Law

    2014-04-01

    A novel new sorbent for the separation of krypton from off-gas streams resulting from the reprocessing of used nuclear fuel has been developed and evaluated. A hydrogen mordenite powder was successfully incorporated into a macroporous polymer binder and formed into spherical beads. The engineered form sorbent retained the characteristic surface area and microporosity indicative of mordenite powder. The sorbent was evaluated for krypton adsorption capacities utilizing thermal swing operations achieving capacities of 100 mmol of krypton per kilogram of sorbent at a temperature of 191 K. A krypton adsorption isotherm was also obtained at 191 K with varying krypton feed gas concentrations. Adsorption/desorption cycling effects were also evaluated with results indicating that the sorbent experienced no decrease in krypton capacity throughout testing.

  12. Photolytic separation of isotopes in cryogenic solution

    DOEpatents

    Freund, Samuel M.; Maier, II, William B.; Holland, Redus F.; Beattie, Willard H.

    1985-01-01

    Separation of carbon isotopes by photolysis of CS.sub.2 in cryogenic solutions of nitrogen, krypton and argon with 206 nm light from an iodine resonance lamp is reported. The spectral distribution of the ultraviolet absorption depends on solvent. Thus, in liquid nitrogen the photolytic decomposition rate of .sup.13 CS.sub.2 is greater than that of .sup.12 CS.sub.2 (because the absorption of 206 nm radiation is greater for .sup.13 CS.sub.2), whereas in liquid krypton and liquid argon the reverse is true. The shift in ultraviolet spectrum is a general phenomenon readily characterized as a function of solvent polarizability, and exhibits behavior similar to that for vibrational transitions occurring in the infrared.

  13. Photolytic separation of isotopes in cryogenic solution

    DOEpatents

    Freund, S.M.; Maier, W.B. II; Holland, R.F.; Battie, W.H.

    Separation of carbon isotopes by photolysis of CS/sub 2/ in cryogenic solutions of nitrogen, krypton and argon with 206 nm light from an iodine resonance lamp is reported. The spectral distributionn of the ultraviolet absorption depends on solvent. Thus, in liquid nitrogen the photolytic decomposition rate of /sup 13/CS/sub 2/ is greater than that of /sup 12/CS/sub 2/ (because the absorption of 206 nm radiation is greater for /sup 13/CS/sub 2/), whereas in liquid krypton and liquid argon the reverse is true. The shift in ultraviolet spectrum is a general phenomenon readily characterized as a function of solvent polarizability, and exhibits behavior similar to that for vibrational transitions occurring in the infrared.

  14. Pathway to Cryogen Free Production of Hyperpolarized Krypton-83 and Xenon-129

    PubMed Central

    Six, Joseph S.; Hughes-Riley, Theodore; Stupic, Karl F.; Pavlovskaya, Galina E.; Meersmann, Thomas

    2012-01-01

    Hyperpolarized (hp) 129Xe and hp 83Kr for magnetic resonance imaging (MRI) are typically obtained through spin-exchange optical pumping (SEOP) in gas mixtures with dilute concentrations of the respective noble gas. The usage of dilute noble gases mixtures requires cryogenic gas separation after SEOP, a step that makes clinical and preclinical applications of hp 129Xe MRI cumbersome. For hp 83Kr MRI, cryogenic concentration is not practical due to depolarization that is caused by quadrupolar relaxation in the condensed phase. In this work, the concept of stopped flow SEOP with concentrated noble gas mixtures at low pressures was explored using a laser with 23.3 W of output power and 0.25 nm linewidth. For 129Xe SEOP without cryogenic separation, the highest obtained MR signal intensity from the hp xenon-nitrogen gas mixture was equivalent to that arising from 15.5±1.9% spin polarized 129Xe in pure xenon gas. The production rate of the hp gas mixture, measured at 298 K, was 1.8 cm3/min. For hp 83Kr, the equivalent of 4.4±0.5% spin polarization in pure krypton at a production rate of 2 cm3/min was produced. The general dependency of spin polarization upon gas pressure obtained in stopped flow SEOP is reported for various noble gas concentrations. Aspects of SEOP specific to the two noble gas isotopes are discussed and compared with current theoretical opinions. A non-linear pressure broadening of the Rb D1 transition was observed and taken into account for the qualitative description of the SEOP process. PMID:23209620

  15. Lymphatic Anomalies Registry

    ClinicalTrials.gov

    2016-07-26

    Lymphatic Malformation; Generalized Lymphatic Anomaly (GLA); Central Conducting Lymphatic Anomaly; CLOVES Syndrome; Gorham-Stout Disease ("Disappearing Bone Disease"); Blue Rubber Bleb Nevus Syndrome; Kaposiform Lymphangiomatosis; Kaposiform Hemangioendothelioma/Tufted Angioma; Klippel-Trenaunay Syndrome; Lymphangiomatosis

  16. An experimental study of the isotopic enrichment in Ar, Kr, and Xe when trapped in water ice

    NASA Technical Reports Server (NTRS)

    Notesco, G.; Laufer, D.; Bar-Nun, A.; Owen, T.

    1999-01-01

    The isotopic enrichment of argon, krypton, and xenon, when trapped in water ice, was studied experimentally. The isotopes were found to be enriched according to their (m1/m2)1/2 ratio. These enrichment factors could be useful for comparison among the uncertain cosmic or solar isotopic ratios, the hopeful in situ cometary ratio, and those in Earth's atmosphere, in the context of cometary delivery of volatiles to Earth.

  17. First Detection of Krypton and Xenon in a White Dwarf

    NASA Technical Reports Server (NTRS)

    Werner, Klaus; Rauch, Thomas; Ringat, Ellen; Kruk, Jeffrey W.

    2012-01-01

    We report on the first detection of the noble gases krypton (Z = 36) and xenon (54) in a white dwarf. About 20 KrVI-VII and Xe VI-VII lines were discovered in the ultraviolet spectrum of the hot DO-type white dwarf RE 0503-289. The observations, performed with the Far Ultraviolet Spectroscopic Explorer, also reveal highly ionized photospheric lines from other trans-iron group elements, namely Ga (31), Ge (32), As (33), Se (34), Mo (42), Sn (50), Te (52), and I (53), from which gallium and molybdenum are new discoveries in white dwarfs, too. For Kr and Xe, we performed an NLTE analysis and derived mass fractions of log Kr = -4.3 plus or minus 0.5 and log Xe = -4.2 plus or minus 0.6, corresponding to an enrichment by factors of 450 and 3800, respectively, relative to the Sun. The origin of the large overabundances is unclear. We discuss the roles of neutron-capture nucleosynthesis in the-precursor star and radiation-driven diffusion. It is possible that diffusion is insignificant and thaI the observed metal abundances constrain the evolutionary history of the star. Its hydrogen deficiency may be the consequence of a late helium-shell nash or a binary white dwarf merger.

  18. FIRST DETECTION OF KRYPTON AND XENON IN A WHITE DWARF

    SciTech Connect

    Werner, Klaus; Rauch, Thomas; Ringat, Ellen; Kruk, Jeffrey W.

    2012-07-01

    We report on the first detection of the noble gases krypton (Z = 36) and xenon (54) in a white dwarf. About 20 Kr VI- VII and Xe VI- VII lines were discovered in the ultraviolet spectrum of the hot DO-type white dwarf RE 0503-289. The observations, performed with the Far Ultraviolet Spectroscopic Explorer, also reveal highly ionized photospheric lines from other trans-iron group elements, namely Ga (31), Ge (32), As (33), Se (34), Mo (42), Sn (50), Te (52), and I (53), from which gallium and molybdenum are new discoveries in white dwarfs, too. For Kr and Xe, we performed an NLTE analysis and derived mass fractions of log Kr = -4.3 {+-} 0.5 and log Xe = -4.2 {+-} 0.6, corresponding to an enrichment by factors of 450 and 3800, respectively, relative to the Sun. The origin of the large overabundances is unclear. We discuss the roles of neutron-capture nucleosynthesis in the precursor star and radiation-driven diffusion. It is possible that diffusion is insignificant and that the observed metal abundances constrain the evolutionary history of the star. Its hydrogen deficiency may be the consequence of a late helium-shell flash or a binary white dwarf merger.

  19. High-energy krypton fluoride lasers for inertial fusion.

    PubMed

    Obenschain, Stephen; Lehmberg, Robert; Kehne, David; Hegeler, Frank; Wolford, Matthew; Sethian, John; Weaver, James; Karasik, Max

    2015-11-01

    Laser fusion researchers have realized since the 1970s that the deep UV light from excimer lasers would be an advantage as a driver for robust high-performance capsule implosions for inertial confinement fusion (ICF). Most of this research has centered on the krypton-fluoride (KrF) laser. In this article we review the advantages of the KrF laser for direct-drive ICF, the history of high-energy KrF laser development, and the present state of the art and describe a development path to the performance needed for laser fusion and its energy application. We include descriptions of the architecture and performance of the multi-kilojoule Nike KrF laser-target facility and the 700 J Electra high-repetition-rate KrF laser that were developed at the U.S. Naval Research Laboratory. Nike and Electra are the most advanced KrF lasers for inertial fusion research and energy applications. PMID:26560597

  20. Thermal beam of metastable krypton atoms produced by optical excitation

    SciTech Connect

    Ding, Y.; Hu, S.-M.; Bailey, K.; Davis, A. M.; Dunford, R. W.; Lu, Z.-T.; O'Connor, T. P.; Young, L.

    2007-02-15

    A room-temperature beam of krypton atoms in the metastable 5s[3/2]{sub 2} level is demonstrated via an optical excitation method. A Kr-discharge lamp is used to produce vacuum ultraviolet photons at 124 nm for the first-step excitation from the ground level 4p{sup 6} {sup 1}S{sub 0} to the 5s[3/2]{sub 1} level. An 819 nm Ti:sapphire laser is used for the second-step excitation from 5s[3/2]{sub 1} to 5s[3/2]{sub 2} followed by a spontaneous decay to the 5s[3/2]{sub 2} metastable level. A metastable atomic beam with an angular flux density of 3x10{sup 14} s{sup -1} sr{sup -1} is achieved at the total gas flow rate of 0.01 cm{sup 3}/s at STP (or 3x10{sup 17} at./s). The dependences of the flux on the gas flow rate, laser power, and lamp parameters are investigated.

  1. Shock Compression of Cryogenic Noble Gas Mixtures: Xenon - Krypton

    NASA Astrophysics Data System (ADS)

    Root, Seth; Magyar, Rudolph; Lemke, Raymond; Mattsson, Thomas

    2013-06-01

    In past work, we have examined the multi-Mbar response of cryogenically cooled liquid xenon and liquid krypton measuring their Hugoniots to 8 Mbar. These results were utilized in the development of new EOS models for Xe and Kr to use in high energy density physics applications. The previous work demonstrated the usefulness of integrating high accuracy shock compression experiments with DFT to generate the basis for equation of state (EOS) models. In many physics applications, such as Z-pinch experiments, gas mixtures are used instead. However, we do not have reliable experimental data on these mixtures to provide informed decisions about the EOS models or mixture rules. To improve our understanding of mixtures at extreme conditions, we performed dynamic compression experiments using Sandia's Z - facility on a 70/30 molar ratio Kr/Xe cryogenically cooled liquid mixture. We measured the Hugoniot state and reshock state of the liquid mixture to several Mbar. The experimental data validated the DFT simulations for identical molar ratio mixtures. The combined experimental and DFT results are used to assess the EOS models and test the mixture rules. 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 Securities Administration under Contract No. DE-AC04-94AL85000.

  2. Modified effective range analysis of electron scattering from krypton

    NASA Astrophysics Data System (ADS)

    Fedus, Kamil

    2014-10-01

    The elastic cross sections for electron scattering on krypton from zero energy up to 10 eV have been analyzed by the modified effective range method. A simple model based on the analytical solution of the Schrödinger equation with the polarization potential using explicitly determined scattering phase shifts for the three lowest partial waves describes the elastic differential, integral and momentum transfer cross sections up to the energy threshold of the first inelastic process well. In detail, the contribution of the long-range polarization potential to the scattering phase shift is exactly expressed, while the contribution of the short-range effects is modelled by simple quadratic expressions (the effective range expansions). The effective range parameters are determined empirically by comparison with the latest experimental differential cross sections. Presently, the calculated integral and momentum transfer cross sections are validated against numerous electron scattering experiments and the most recent quantum-mechanical theories. To complete the picture, the two-term Boltzmann analysis is employed to determine the electron transport coefficients; the agreement with the electron swarm experimental data is found to be very good.

  3. Large area electron beam pumped krypton fluoride laser amplifier

    SciTech Connect

    Sethian, J.D.; Obenschain, S.P.; Gerber, K.A.; Pawley, C.J.; Serlin, V.; Sullivan, C.A.; Webster, W.; Deniz, A.V.; Lehecka, T.; McGeoch, M.W.; Altes, R.A.; Corcoran, P.A.; Smith, I.D.; Barr, O.C.

    1997-06-01

    Nike is a recently completed multi-kilojoule krypton fluoride (KrF) laser that has been built to study the physics of direct drive inertial confinement fusion. This paper describes in detail both the pulsed power and optical performance of the largest amplifier in the Nike laser, the 60 cm amplifier. This is a double pass, double sided, electron beam-pumped system that amplifies the laser beam from an input of 50 J to an output of up to 5 kJ. It has an optical aperture of 60 cm {times} 60 cm and a gain length of 200 cm. The two electron beams are 60 cm high {times} 200 cm wide, have a voltage of 640 kV, a current of 540 kA, and a flat top power pulse duration of 250 ns. A 2 kG magnetic field is used to guide the beams and prevent self-pinching. Each electron beam is produced by its own Marx/pulse forming line system. The amplifier has been fully integrated into the Nike system and is used on a daily basis for laser-target experiments. {copyright} {ital 1997 American Institute of Physics.}

  4. Inertial Fusion Target Physics Advantages with the Krypton Fluoride Laser

    NASA Astrophysics Data System (ADS)

    Obenschain, Stephen

    2010-11-01

    The krypton fluoride (KrF) laser's short wavelength, broad bandwidth and capability to provide extremely uniform target illumination are advantages towards obtaining high gain direct drive implosions. The short wavelength helps suppress deleterious laser-plasma instabilities, and allows one to employ higher ablation pressures. In addition, the KrF architecture allows one to zoom down the focal diameter to follow the size of the imploding pellet, thereby improving the coupling efficiency. The NRL researchers have been conducting theoretical and experimental studies to quantify the beneficial effects of utilizing KrF light. Experiments using the Nike facility have confirmed that KrF light significantly increases the threshold for laser-plasma instability. This presentation will discuss the observed target physics with KrF light and its effects towards facilitating the high gains needed for power production with inertial fusion. Simulations indicate that shock ignited designs can achieve gains above 200 with KrF energies as low a 1 megajoule. For fusion energy a laser driver must be capable of high repetition rates (5-10 Hz) along with adequate efficiency and durability. The Electra KrF 30-cm aperture electron-beam-pumped amplifier has demonstrated long duration continuous operation at high-repetition rates. This and other advances show that the KrF laser should be able to meet the requirements.

  5. Krypton charge exchange cross sections for Hall effect thruster models

    SciTech Connect

    Hause, Michael L.; Prince, Benjamin D.; Bemish, Raymond J.

    2013-04-28

    Following discharge from a Hall effect thruster, charge exchange occurs between ions and un-ionized propellant atoms. The low-energy cations produced can disturb operation of onboard instrumentation or the thruster itself. Charge-exchange cross sections for both singly and doubly charged propellant atoms are required to model these interactions. While xenon is the most common propellant currently used in Hall effect thrusters, other propellants are being considered, in particular, krypton. We present here guided-ion beam measurements and comparisons to semiclassical calculations for Kr{sup +} + Kr and Kr{sup 2+} + Kr cross sections. The measurements of symmetric Kr{sup +} + Kr charge exchange are in good agreement with both the calculations including spin-orbit effects and previous measurements. For the symmetric Kr{sup 2+} + Kr reaction, we present cross section measurements for center-of-mass energies between 1 eV and 300 eV, which spans energies not previously examined experimentally. These cross section measurements compare well with a simple one-electron transfer model. Finally, cross sections for the asymmetric Kr{sup 2+} + Kr {yields} Kr{sup +} + Kr{sup +} reaction show an onset near 12 eV, reaching cross sections near constant value of 1.6 A{sup 2} with an exception near 70-80 eV.

  6. Radioactive Iodine and Krypton Control for Nuclear Fuel Reprocessing Facilities

    SciTech Connect

    N. R. Soelberg; J. D. Law; T. G. Garn; M. Greenhalgh; R. T. Jubin; P. Thallapally; D. M. Strachan

    2013-08-01

    The removal of volatile radionuclides generated during used nuclear fuel reprocessing in the US is almost certain to be necessary for the licensing of a reprocessing facility in the US. Various control technologies have been developed, tested, or used over the past 50 years for control of volatile radionuclide emissions from used fuel reprocessing plants. The US DOE has sponsored, since 2009, an Off-gas Sigma Team to perform research and development focused on the most pressing volatile radionuclide control and immobilization problems. In this paper, we focus on the control requirements and methodologies for 85Kr and 129I. Numerous candidate technologies have been studied and developed at laboratory and pilot-plant scales in an effort to meet the need for high iodine control efficiency and to advance alternatives to cryogenic separations for krypton control. Several of these show promising results. Iodine decontamination factors as high as 105, iodine loading capacities, and other adsorption parameters including adsorption rates have been demonstrated under some conditions for both silver zeolite (AgZ) and Ag-functionalized aerogel. Sorbents, including an engineered form of AgZ and selected metal organic framework materials (MOFs), have been successfully demonstrated to capture Kr and Xe without the need for separations at cryogenic temperatures.

  7. Analysis of spacecraft anomalies

    NASA Technical Reports Server (NTRS)

    Bloomquist, C. E.; Graham, W. C.

    1976-01-01

    The anomalies from 316 spacecraft covering the entire U.S. space program were analyzed to determine if there were any experimental or technological programs which could be implemented to remove the anomalies from future space activity. Thirty specific categories of anomalies were found to cover nearly 85 percent of all observed anomalies. Thirteen experiments were defined to deal with 17 of these categories; nine additional experiments were identified to deal with other classes of observed and anticipated anomalies. Preliminary analyses indicate that all 22 experimental programs are both technically feasible and economically viable.

  8. The atmosphere of Mars near the surface - Isotope ratios and upper limits on noble gases

    NASA Technical Reports Server (NTRS)

    Biemann, K.; Lafleur, A. L.; Owen, T.; Rushneck, D. R.; Howarth, D. W.

    1976-01-01

    Several analyses of the Martian atmosphere have been carried out with the mass spectrometer in the molecular-analysis experiment. The ratios of abundant isotopes of carbon and oxygen are within 10 per cent of terrestrial values, whereas nitrogen-15 is considerably enriched on Mars. Argon-38 has been detected, and new limits on abundances of krypton and xenon have been set. The limit on krypton is sufficiently low to suggest that the inventories of volatile substances on Mars and on earth may be distinctly different.

  9. Krypton separation from ambient air for application in collinear fast beam laser spectroscopy.

    PubMed

    Mohamed, Tarek; Strohaber, James; Nava, Ricardo; Kolomenskii, Alexandre; Thonnard, Norbert; Schuessler, Hans A

    2012-07-01

    A portable apparatus for the separation of krypton from environmental air samples was tested. The apparatus is based on the cryogenic trapping of gases at liquid nitrogen temperature followed by controlled releases at higher temperatures. The setup consists of a liquid nitrogen trap for the removal of H(2)O and CO(2), followed by charcoal-filled coils that sequentially collect and release krypton and other gases providing four stages of gas chromatography to achieve separation and purification of krypton from mainly N(2), O(2), and Ar. Residual reactive gases remaining after the final stage of chromatography are removed with a hot Ti sponge getter. A thermal conductivity detector is used to monitor the characteristic elution times of the various components of condensed gases in the traps during step-wise warming of the traps from liquid nitrogen temperatures to 0 °C, and then to 100 °C. This allows optimizing the switching times of the valves between the stages of gas chromatography so that mainly krypton is selected and loaded to the next stage while exhausting the other gases using a He carrier. A krypton separation efficiency of ~80 % was determined using a quadrupole mass spectrometer. PMID:22549732

  10. 32.8-nm X-ray laser produced in a krypton cluster jet

    SciTech Connect

    Ivanova, E P; Vinokhodov, A Yu

    2013-12-31

    We have interpreted the well-known experimental quantum yield data for a 32.8-nm X-ray laser operating at the 3d{sup 9}4d (J = 0) – 3d{sup 9}4p (J = 1) transition of Kr{sup 8+} with the use of gaseous krypton or a krypton cluster jet. Proceeding from our model we propose a novel scheme for the 32.8-nm laser produced in a krypton cluster jet. The quantum yield is shown to saturate for a plasma length of ∼300 μm, a krypton ion density n{sub Kr} ∼ (4 – 9) × 10{sup 19} cm{sup -3}, and an electron temperature Te ∼ 5000 eV. In this case, the energy conversion coefficient amounts to ∼5 × 10{sup -3} of the pump pulse energy. We propose the experimental setup for producing a highefficiency subpicosecond X-ray laser in a krypton cluster jet. (lasers)

  11. Discovery of Cadmium, Indium, and Tin Isotopes

    NASA Astrophysics Data System (ADS)

    Amos, Stephanie; Thoennessen, Michael

    2009-10-01

    As of today, no comprehensive study has been made covering the initial observations and identifications of isotopes. A project has been undertaken at MSU to document the discovery of all the known isotopes. The criteria defining discovery of a given isotope is the publication of clear mass and element assignment in a refereed journal. Prior to the current work the documentation of the discovery of eleven elements had been completed^1. These elements are cerium^2, arsenic, gold, tungsten, krypton, silver, vanadium, einsteinium, iron, barium, and cobalt. We will present the new documentation for the cadmium, indium, and tin isotopes. Thirty-seven cadmium isotopes, thirty-eight indium isotopes, and thirty-eight tin isotopes have been discovered so far. The description for each discovered isotope includes the year of discovery, the article published on the discovery, the article's author, the method of production, the method of identification, and any previous information concerning the isotope discovery. A summary and overview of all ˜500 isotopes documented so far as a function of discovery year, method and place will also be presented. ^1http://www.nscl.msu.edu/˜thoennes/2009/discovery.htm ^2J.Q. Ginepro, J. Snyder, and M. Thoennessen, At. Data Nucl. Data. Tables, in press (2009), doi:10.1016/j.adt.2009.06.002

  12. Equation of state of dense neon and krypton plasmas in the partial ionization regime

    SciTech Connect

    Chen, Q. F. Zheng, J.; Gu, Y. J.; Li, Z. G.

    2015-12-15

    The compression behaviors of dense neon and krypton plasmas over a wide pressure-temperature range are investigated by self-consistent fluid variational theory. The ionization degree and equation of state of dense neon and krypton are calculated in the density-temperature range of 0.01–10 g/cm{sup 3} and 4–50 kK. A region of thermodynamic instability is found which is related to the plasma phase transition. The calculated shock adiabat and principal Hugoniot of liquid krypton are in good agreement with available experimental data. The predicted results of shock-compressed liquid neon are presented, which provide a guide for dynamical experiments or numerical first-principle calculations aimed at studying the compression properties of liquid neon in the partial ionization regime.

  13. Krypton Adsorption on Zeolite-Templated Carbon and Anomalous Surface Thermodynamics.

    PubMed

    Murialdo, Maxwell; Stadie, Nicholas P; Ahn, Channing C; Fultz, Brent

    2015-07-28

    Krypton adsorption was measured at eight temperatures between 253 and 433 K on a zeolite-templated carbon and two commercial carbons. The data were fitted using a generalized Langmuir isotherm model and thermodynamic properties were extracted. Differing from that on commercial carbons, krypton adsorption on the zeolite-templated carbon is accompanied by an increasing isosteric enthalpy of adsorption, rising by up to 1.4 kJ mol(-1) as a function of coverage. This increase is a result of enhanced adsorbate-adsorbate interactions promoted by the ordered, nanostructured surface of the adsorbent. An assessment of the strength and nature of these adsorbate-adsorbate interactions is made by comparing the measured isosteric enthalpies of adsorption (and other thermodynamic quantities) to fundamental metrics of intermolecular interactions of krypton and other common gases. PMID:26136159

  14. Elastic electron scattering in krypton in the energy range from 5 to 10 eV

    SciTech Connect

    Linert, Ireneusz; Mielewska, Brygida; Zubek, Mariusz; King, George C.

    2010-01-15

    Differential cross sections for elastic electron scattering in krypton have been measured at the energies of 5,7.5, and 10 eV over the scattering angle range from 30 deg. to 180 deg. The measurements for backward scattering employed the magnetic angle-changing technique. These differential cross sections have been integrated to yield the elastic integral and momentum transfer cross sections at the above energies. These new results are compared with the most recent measurements and calculations of the respective cross sections in krypton. The dependence of the differential cross sections on atomic polarizability of the heavier rare gas atoms argon, krypton, and xenon has also been investigated over the electron energy range 5-30 eV and for forward, backward, and intermediate scattering angles.

  15. Molecular dynamics study of diffusion of krypton in water at different temperatures

    NASA Astrophysics Data System (ADS)

    Bhandari, Dipendra; Adhikari, N. P.

    2016-04-01

    Molecular dynamics study of diffusion of two krypton atoms in 300 SPC/E water molecules at temperatures 293, 303, 313, 323 and 333 K has been carried out. Self-diffusion coefficient of krypton and water along with their mutual diffusion coefficients are estimated. Self-diffusion coefficient for krypton is calculated by using Mean Square Displacement (MSD) method and Velocity Autocorrelation (VACF) method, while that for water is calculated by using MSD method only. The mutual diffusion coefficient is estimated by using the Darken’s relation. The diffusion coefficients are found to follow the Arrhenius behavior. The structural properties of the system have been estimated by the study of solute-solute, solvent-solvent, and solute-solvent Radial Distribution Function (RDF).

  16. Self-Associating Behavior of Acetone in Liquid Krypton.

    PubMed

    De Beuckeleer, Liene I; Herrebout, Wouter A

    2016-02-18

    Acetone molecules are inclined to self-associate through dipole-dipole interactions because of their large dipole moment. Infrared spectroscopy of compounds dissolved in liquid noble gases supported by high level ab initio calculations allows investigating the self-associating behavior and determining the thermodynamical properties. In this study, infrared spectra of various concentrations of acetone dissolved in liquid krypton are recorded at constant temperature. Overlapping monomer and dimer spectra are separated by analyzing the obtained data sets with numerical methods based on least-squares fitting. Although acetone is known to self-associate, only a few spectral features have been presented in literature before. In this study, the application of new numerical approaches succeeds in resolving overlapping spectra and allows observing isolated acetone dimer absorption bands for the complete mid infrared spectrum. By use of data sets of spectra recorded at temperatures between 134 and 142 K, the experimental standard dimerization enthalpy was determined to be -10.8 kJ mol(-1). MP2/aug-cc-pVDZ calculations predicted a stacked and planar dimer geometry of which the stacked geometry is more stable. Combining MP2 energies and single point corrections involving CCSD(T) calculations and complete basis set extrapolations based on the MP2/aug-cc-pVDZ equilibrium geometry lead to complexation energy of -28.4 kJ mol(-1) for the stacked geometry and -15.1 kJ mol(-1) for the planar geometry. The corresponding values for the complexation enthalpies in solution, obtained by combining these values with corrections for thermal and solvent influences are -13.7 and -5.8 kJ mol(-1). PMID:26805773

  17. Wavelengths and lifetimes of transitions in highly-ionized krypton

    SciTech Connect

    Barry, H.G.; Dunford, R.W.; Gemmel, D.S.

    1995-08-01

    We began a program to test relativistic Hartree-Fock calculations in 3-, 4-, and 5- electron systems by making precision wavelength and lifetime measurements. This is an extension of previous work at ATLAS in which we obtained precision lifetime and wavelength measurements in one- and two-electron systems. We are starting by making accurate wavelength and lifetime measurements of the spectra of multielectron krypton in the far ultraviolet region, at wavelengths of 50 to 400 {Angstrom}. Although there was considerable theoretical progress in this area recently, little accurate data exists for ions above Z=18, except for the wavelengths of the lithium-like transitions. Our spectra are taken using a beam-foil chamber coupled to a 2.2-m McPherson grazing incidence monochromator. This system was upgraded recently to provide efficient light collection and to take advantage of the time structure of ATLAS. The exit slits of the monochromator were replaced by a position-sensitive channel plate with high spatial and time resolution. The channel plate is mounted on a movable chariot on the Rowland circle of the monochromator. The chariot can be translated along the circle, and it can be rotated about a tangent point of the circle. This latter movement allows us to optimize resolution and efficiency depending on the needs of the experiment. Backgrounds due to electrons, neutrons, gamma rays, and dark count from the detector are greatly reduced using a time window (1-2 ns) triggered from the ATLAS beam pulse structure (82 ns pulse separation).

  18. [Kimmerle's anomaly and stroke].

    PubMed

    Barsukov, S F; Antonov, G I

    1992-10-01

    The anomaly of cranio-vertebral area can frequently be the reason of acute cerebrovascular disorders in vertebro-basilar field. The frequent C1 pathology in the Kimmerle's anomaly. The anatomic studies has shown that 30% of people had this type of anomaly. This pathology can lead to severe vascular diseases of cerebrum because of the squeezing effect upon vertebral arteries in the zone of osteal ponticulus of the rear arch of atlas. PMID:1481402

  19. Purely-long-range krypton molecules in singly and doubly excited binding potentials

    SciTech Connect

    Smith, Z. S.; Harmon, A.; Banister, J.; Norman, R.; Hoogeboom-Pot, K.; Walhout, M.

    2010-01-15

    Diatomic potentials for krypton are computed and also probed experimentally. For a probe-laser wavelength near 811 nm, several strong dipole-dipole interactions produce purely-long-range potential wells in the singly excited manifold of (s+p) potentials and in the doubly excited manifold of (p+p) and (s+d) potentials. Evidence of resonant photoassociation into bound states of these potential wells is observed in the emission of ions and ultraviolet photons from a magneto-optically trapped krypton cloud.

  20. Emission in argon and krypton at 147 nm excited by runaway-electron-induced diffusion discharge

    SciTech Connect

    Gerasimov, Gennadii N; Krylov, B E; Lomaev, Mikhail I; Rybka, D V; Tarasenko, Viktor F

    2010-05-26

    Plasma emission of a pulsed diffuse discharge produced at increased pressures due to the preionisation of the gap by runaway electrons is studied in argon, krypton, and xenon. Nanosecond voltage pulses with the amplitude {approx}220 kV were applied to the discharge gap. It is shown that the presence of xenon ({approx}0.01%) in argon and krypton leads to the emergence of high-power narrowband radiation at awavelength of 147 nm. It is assumed that this radiation belongs to the bands of heteronuclear molecules Xe*Ar and Xe*Kr.

  1. X-ray Emission Wavelengths of Argon, Krypton, Xenon, and Curium

    NASA Astrophysics Data System (ADS)

    Kleykamp, H.

    1992-03-01

    The wavelengths of the L series of argon, krypton and xenon, the K series of argon, and the M series of curium were measured by means of wavelength dispersive X-ray microanalysis. The specimens for the investigations were TiC layers which had been HF sputtered under reduced argon pressure by the PVD method, krypton and xenon implanted zeolites, and a curium doped borosilicate glass. The obtained relative intensities of the X-ray emission lines were normalized to the maximum intensity of the line of the respective series

  2. Taussig-Bing Anomaly

    PubMed Central

    Konstantinov, Igor E.

    2009-01-01

    Taussig-Bing anomaly is a rare congenital heart malformation that was first described in 1949 by Helen B. Taussig (1898–1986) and Richard J. Bing (1909–). Although substantial improvement has since been achieved in surgical results of the repair of the anomaly, management of the Taussig-Bing anomaly remains challenging. A history of the original description of the anomaly, the life stories of the individuals who first described it, and the current outcomes of its surgical management are reviewed herein. PMID:20069085

  3. Breaking through the Glass Ceiling: The Correlation Between the Self-Diffusivity in and Krypton Permeation through Deeply Supercooled Liquid Nanoscale Methanol Films

    SciTech Connect

    Smith, R. Scott; Matthiesen, Jesper; Kay, Bruce D.

    2010-03-28

    Molecular beam techniques, temperature-programmed desorption (TPD), and reflection absorption infrared spectroscopy (RAIRS) are used to explore the relationship between krypton permeation through and the self-diffusivity of supercooled liquid methanol at temperatures near (100-115 K) the glass transition temperature, Tg (103 K). Layered films, consisting of CH3OH and CD3OH, are deposited ontop of a monolayer of Kr on a graphene covered Pt(111) substrate at 25 K. Concurrent Kr TPD and RAIRS spectra are acquired during the heating of the composite film to temperatures above Tg. The CO vibrational stretch is sensitive to the local molecular environment and is used to determine the supercooled liquid diffusivity from the intermixing of the isotopic layers. We find that the Kr permeation and the diffusivity of the supercooled liquid are directly and quantitatively correlated. These results validate the rare gas permeation technique as a tool for probing the diffusivity of supercooled liquids.

  4. Breaking through the glass ceiling: The correlation between the self-diffusivity in and krypton permeation through deeply supercooled liquid nanoscale methanol films

    NASA Astrophysics Data System (ADS)

    Smith, R. Scott; Matthiesen, Jesper; Kay, Bruce D.

    2010-03-01

    Molecular beam techniques, temperature-programmed desorption (TPD), and reflection absorption infrared spectroscopy (RAIRS) are used to explore the relationship between krypton permeation through and the self-diffusivity of supercooled liquid methanol at temperatures (100-115 K) near the glass transition temperature, Tg (103 K). Layered films, consisting of CH3OH and CD3OH, are deposited on top of a monolayer of Kr on a graphene covered Pt(111) substrate at 25 K. Concurrent Kr TPD and RAIRS spectra are acquired during the heating of the composite film to temperatures above Tg. The CO vibrational stretch is sensitive to the local molecular environment and is used to determine the supercooled liquid diffusivity from the intermixing of the isotopic layers. We find that the Kr permeation and the diffusivity of the supercooled liquid are directly and quantitatively correlated. These results validate the rare-gas permeation technique as a tool for probing the diffusivity of supercooled liquids.

  5. Deactivation of krypton atoms in the metastable 5s({sup 3}P{sub 2}) state in collisions with krypton and argon atoms

    SciTech Connect

    Zayarnyi, D A; L'dov, A Yu; Kholin, I V

    2009-09-30

    The collision deactivation of the metastable 5s[3/2]{sub 2}{sup o}({sup 3}P{sub 2}) state of krypton atoms is studied by the absorption probe method in electron-beam-excited high-pressure Ar-Kr mixtures with a low krypton content. The rate constants of plasma-chemical reactions Kr* + Kr + Ar {yields} Kr{sub 2}* + Ar [(4.1{+-}0.4)x10{sup -33} cm{sup 6} s{sup -1}] and Kr* + 2Ar {yields} ArKr* + Ar (less than 10{sup -35} cm{sup 6} s{sup -1}) are measured for the first time and the rate constant of the reaction Kr* + Ar {yields} products + Ar [(3.8{+-}0.4)x10{sup -15} cm{sup 3} s{sup -1}] is refined. (active media)

  6. Beta-decay study of neutron rich isotopes of Bromine and Krypton

    SciTech Connect

    Miernik, Krzysztof A; Gross, Carl J; Grzywacz, Robert Kazimierz; Madurga, M; Mendez, II, Anthony J; Miller, D.; Padgett, S; Paulauskas, Stanley V; Rykaczewski, Krzysztof Piotr; Stracener, Daniel W; Wolinska-Cichocka, Marzena; Zganjar, E. F.; Batchelder, J. C.; Brewer, N.T.; Cartegni, L.; Fijalkowska, Aleksandra G; Hamilton, J. H.; Hwang, J. K.; Ilyushkin, S.; Jost, Carola U; Karny, M.; Korgul, A.; Krolas, W.; Liu, S.H.; Ramayya, A. V.; Surman, Rebecca; Winger, J. A.; Wolinska-Cichocka, M

    2013-01-01

    Short lived neutron rich nuclei including 93 Br, 93 Kr and 94 Kr were produced in proton induced fission of 238 U at the HRIBF in Oak Ridge. Their beta decay was studied by means of a high resolution on line mass separator and beta gamma spectroscopy methods. The half life of 93Br T1/2 = 152(8) ms and delayed branching ratio of Pn = 53-8+11 may be compared to the previously reported values of T1/2 = 102(10) ms and Pn = 68(7)%. At the same time the half life of 94Kr T1/2 = 227(14) ms and B delayed branching ratio of Pn = 1.9+0.6 0.2 % of 93Kr are in very good agreement with literature values. The decay properties of 93Br include four new gamma transitions following beta delayed neutron emission.

  7. Competing Orders and Anomalies.

    PubMed

    Moon, Eun-Gook

    2016-01-01

    A conservation law is one of the most fundamental properties in nature, but a certain class of conservation "laws" could be spoiled by intrinsic quantum mechanical effects, so-called quantum anomalies. Profound properties of the anomalies have deepened our understanding in quantum many body systems. Here, we investigate quantum anomaly effects in quantum phase transitions between competing orders and striking consequences of their presence. We explicitly calculate topological nature of anomalies of non-linear sigma models (NLSMs) with the Wess-Zumino-Witten (WZW) terms. The non-perturbative nature is directly related with the 't Hooft anomaly matching condition: anomalies are conserved in renormalization group flow. By applying the matching condition, we show massless excitations are enforced by the anomalies in a whole phase diagram in sharp contrast to the case of the Landau-Ginzburg-Wilson theory which only has massive excitations in symmetric phases. Furthermore, we find non-perturbative criteria to characterize quantum phase transitions between competing orders. For example, in 4D, we show the two competing order parameter theories, CP(1) and the NLSM with WZW, describe different universality class. Physical realizations and experimental implication of the anomalies are also discussed. PMID:27499184

  8. Competing Orders and Anomalies

    PubMed Central

    Moon, Eun-Gook

    2016-01-01

    A conservation law is one of the most fundamental properties in nature, but a certain class of conservation “laws” could be spoiled by intrinsic quantum mechanical effects, so-called quantum anomalies. Profound properties of the anomalies have deepened our understanding in quantum many body systems. Here, we investigate quantum anomaly effects in quantum phase transitions between competing orders and striking consequences of their presence. We explicitly calculate topological nature of anomalies of non-linear sigma models (NLSMs) with the Wess-Zumino-Witten (WZW) terms. The non-perturbative nature is directly related with the ’t Hooft anomaly matching condition: anomalies are conserved in renormalization group flow. By applying the matching condition, we show massless excitations are enforced by the anomalies in a whole phase diagram in sharp contrast to the case of the Landau-Ginzburg-Wilson theory which only has massive excitations in symmetric phases. Furthermore, we find non-perturbative criteria to characterize quantum phase transitions between competing orders. For example, in 4D, we show the two competing order parameter theories, CP(1) and the NLSM with WZW, describe different universality class. Physical realizations and experimental implication of the anomalies are also discussed. PMID:27499184

  9. Competing Orders and Anomalies

    NASA Astrophysics Data System (ADS)

    Moon, Eun-Gook

    2016-08-01

    A conservation law is one of the most fundamental properties in nature, but a certain class of conservation “laws” could be spoiled by intrinsic quantum mechanical effects, so-called quantum anomalies. Profound properties of the anomalies have deepened our understanding in quantum many body systems. Here, we investigate quantum anomaly effects in quantum phase transitions between competing orders and striking consequences of their presence. We explicitly calculate topological nature of anomalies of non-linear sigma models (NLSMs) with the Wess-Zumino-Witten (WZW) terms. The non-perturbative nature is directly related with the ’t Hooft anomaly matching condition: anomalies are conserved in renormalization group flow. By applying the matching condition, we show massless excitations are enforced by the anomalies in a whole phase diagram in sharp contrast to the case of the Landau-Ginzburg-Wilson theory which only has massive excitations in symmetric phases. Furthermore, we find non-perturbative criteria to characterize quantum phase transitions between competing orders. For example, in 4D, we show the two competing order parameter theories, CP(1) and the NLSM with WZW, describe different universality class. Physical realizations and experimental implication of the anomalies are also discussed.

  10. Quenching of the resonance 5s({sup 3}P{sub 1}) state of krypton atoms in collisions with krypton and helium atoms

    SciTech Connect

    Zayarnyi, D A; L'dov, A Yu; Kholin, I V

    2014-11-30

    The processes of collision quenching of the resonance 5s[3/2]{sub 1}{sup o}({sup 3}P{sub 1}) state of the krypton atom are studied by the absorption probe method in electron-beam-excited high-pressure He – Kr mixtures with a low content of krypton. The rate constants of plasmochemical reactions Kr* + Kr + He → Kr*{sub 2} + He [(4.21 ± 0.42) × 10{sup -33} cm{sup 6} s{sup -1}], Kr* + 2He → HeKr* + He [(4.5 ± 1.2) × 10{sup -36} cm{sup 6} s{sup -1}] and Kr* + He → products + He [(2.21 ± 0.22) × 10{sup -15} cm{sup 3} s{sup -1}] are measured for the first time. The rate constants of similar reactions are refined for krypton in the metastable 5s[3/2]{sub 2}{sup o} ({sup 3}P{sub 2}) state. (laser applications and other topics in quantum electronics)

  11. Isotopic microanalysis of returned comet nucleus samples

    NASA Technical Reports Server (NTRS)

    Zinner, Ernst

    1989-01-01

    If isotopic measurements of interplanetary dust particles (IDPs) and primitive meteorites can serve as a guide to the isotopic analysis of returned comet nucleus material, an essential requirement will be the capability for microanalysis. The reason is that in both types of extraterrestrial samples large isotopic heterogeneities on a small spatial scale have become apparent once it was possible to measure isotopes in small samples. In the discovery of large isotopic anomalies the ion microprobe has played a significant role because of its high spatial resolution for isotopic ratio measurements. The largest isotopic anomalies in C, N, O, Mg, Si, Ca and Ti found to date were measured by ion microprobe mass spectrometry. The most striking examples are D/H measurements in IDPs and isotopic measurements of C, N and Si in SiC from the CM chondrites Murray and Murchison.

  12. Effective and accurate approach for modeling of commensurate-incommensurate transition in krypton monolayer on graphite.

    PubMed

    Ustinov, E A

    2014-10-01

    Commensurate-incommensurate (C-IC) transition of krypton molecular layer on graphite received much attention in recent decades in theoretical and experimental researches. However, there still exists a possibility of generalization of the phenomenon from thermodynamic viewpoint on the basis of accurate molecular simulation. Recently, a new technique was developed for analysis of two-dimensional (2D) phase transitions in systems involving a crystalline phase, which is based on accounting for the effect of temperature and the chemical potential on the lattice constant of the 2D layer using the Gibbs-Duhem equation [E. A. Ustinov, J. Chem. Phys. 140, 074706 (2014)]. The technique has allowed for determination of phase diagrams of 2D argon layers on the uniform surface and in slit pores. This paper extends the developed methodology on systems accounting for the periodic modulation of the substrate potential. The main advantage of the developed approach is that it provides highly accurate evaluation of the chemical potential of crystalline layers, which allows reliable determination of temperature and other parameters of various 2D phase transitions. Applicability of the methodology is demonstrated on the krypton-graphite system. Analysis of phase diagram of the krypton molecular layer, thermodynamic functions of coexisting phases, and a method of prediction of adsorption isotherms is considered accounting for a compression of the graphite due to the krypton-carbon interaction. The temperature and heat of C-IC transition has been reliably determined for the gas-solid and solid-solid system. PMID:25296827

  13. The refractive index of krypton for lambda in the closed interval 168-288 nm

    NASA Technical Reports Server (NTRS)

    Smith, P. L.; Parkinson, W. H.; Huber, M. C. E.

    1975-01-01

    The index of refraction of krypton has been measured at 27 wavelengths between and including 168 and 288 nm. The probable error of each measurement is plus or minus 0.1%. Our results are compared with other measurements. Our data are about 3.8% smaller than those of Abjean et al.

  14. Use of krypton laser stimulation in the treatment of dry eye syndrome

    NASA Astrophysics Data System (ADS)

    Kecik, Tadeusz; Switka-Wieclawska, Iwona; Ciszewska, Joanna; Portacha, Lidia

    1991-08-01

    We''d like to present the use of krypton laser stimulation in the treatment of dry eye syndrom. 10 patients with dry eye syndrom were treated with irradiation of the lacrimal gland. Schirmer test and break up time were performed before and after therapy. After 10 days of treatment we observed higher value of secreted tear amount.

  15. Müllerian anomalies.

    PubMed

    Gell, Jennifer S

    2003-11-01

    The reproductive organs in both males and females consist of gonads, internal ductal structures, and external genitalia. Normal sexual differentiation is dependent on the genetic sex determined by the presence or absence of the Y chromosome at fertilization. Testes develop under the influence of the Y chromosome and ovaries develop when no Y chromosome is present. In the absence of testes and their normal hormonal products, sexual differentiation proceeds along the female pathway, resulting in a normal female phenotype. Anatomic gynecologic anomalies occur when there is failure of normal embryologic ductal development. These anomalies include congenital absence of the vagina as well as defects in lateral and vertical fusion of the Müllerian ducts. Treatment of müllerian anomalies begins with the correct identification of the anomaly and an understanding of the embryologic origin. This includes evaluation for other associated anomalies such as renal or skeletal abnormalities. After correct identification, treatment options include nonsurgical as well as surgical intervention. This chapter serves to review the embryology and development of the reproductive system and to describe common genital tract anomalies. Details of surgical or nonsurgical correction of these anomalies are presented. PMID:14724770

  16. Behavioral economics without anomalies.

    PubMed Central

    Rachlin, H

    1995-01-01

    Behavioral economics is often conceived as the study of anomalies superimposed on a rational system. As research has progressed, anomalies have multiplied until little is left of rationality. Another conception of behavioral economics is based on the axiom that value is always maximized. It incorporates so-called anomalies either as conflicts between temporal patterns of behavior and the individual acts comprising those patterns or as outcomes of nonexponential time discounting. This second conception of behavioral economics is both empirically based and internally consistent. PMID:8551195

  17. Krypton and xenon fractionation in North American tektites

    NASA Astrophysics Data System (ADS)

    Palma, R. L.; Rao, M. N.; Rowe, M. W.; Koeberl, C.

    1997-01-01

    Elemental and isotopic compositions of the noble gases have been determined in six North American tektites (4 bediasites and 2 georgiaites) and one Ivory Coast tektite. Radiogenically produced 4He may explain the large 4He/36Ar ratios measured relative to air, despite significant diffusive losses. The neon isotopic composition is enriched in 20Ne consistent with a single stage mass fractionation process. The enormous 20Ne/36Ar enrichments observed in all tektite samples, similar to those reported from other tektites and impact glasses, are attributed to atmospheric diffusion into the samples following solidification. The North American tektites show a systematic increase in 84Kr/36Ar and 132Xe/36Ar relative to air, with enrichments greater than those determined for any other tektite group or terrestrial samples other than shales. These enrichments are inconsistent with existing models of dissolving Kr and Xe in tektite glass without elemental fractionation at atmospheric pressures equivalent to ~40 km altitude. The Kr and Xe isotopic compositions are indistinguishable from atmospheric within experimental uncertainty.

  18. Anomalies and entanglement entropy

    NASA Astrophysics Data System (ADS)

    Nishioka, Tatsuma; Yarom, Amos

    2016-03-01

    We initiate a systematic study of entanglement and Rényi entropies in the presence of gauge and gravitational anomalies in even-dimensional quantum field theories. We argue that the mixed and gravitational anomalies are sensitive to boosts and obtain a closed form expression for their behavior under such transformations. Explicit constructions exhibiting the dependence of entanglement entropy on boosts is provided for theories on spacetimes with non-trivial magnetic fluxes and (or) non-vanishing Pontryagin classes.

  19. Dual diaphragmatic anomalies.

    PubMed

    Padmanabhan, Arjun; Thomas, Abin Varghese

    2016-01-01

    Although diaphragmatic anomalies such as an eventration and hiatus hernia are commonly encountered in incidental chest X-ray imaging, the presence of concomitant multiple anomalies is extremely rare. This is all the more true in adults. Herein, we present the case of a 75-year-old female, while undergoing a routine chest X-ray imaging, was found to have eventration of right hemidiaphragm along with a hiatus hernia as well. PMID:27625457

  20. Dual diaphragmatic anomalies

    PubMed Central

    Padmanabhan, Arjun; Thomas, Abin Varghese

    2016-01-01

    Although diaphragmatic anomalies such as an eventration and hiatus hernia are commonly encountered in incidental chest X-ray imaging, the presence of concomitant multiple anomalies is extremely rare. This is all the more true in adults. Herein, we present the case of a 75-year-old female, while undergoing a routine chest X-ray imaging, was found to have eventration of right hemidiaphragm along with a hiatus hernia as well.

  1. On isostatic geoid anomalies

    NASA Technical Reports Server (NTRS)

    Haxby, W. F.; Turcotte, D. L.

    1978-01-01

    In regions of slowly varying lateral density changes, the gravity and geoid anomalies may be expressed as power series expansions in topography. Geoid anomalies in isostatically compensated regions can be directly related to the local dipole moment of the density-depth distribution. This relationship is used to obtain theoretical geoid anomalies for different models of isostatic compensation. The classical Pratt and Airy models give geoid height-elevation relationships differing in functional form but predicting geoid anomalies of comparable magnitude. The thermal cooling model explaining ocean floor subsidence away from mid-ocean ridges predicts a linear age-geoid height relationship of 0.16 m/m.y. Geos 3 altimetry profiles were examined to test these theoretical relationships. A profile over the mid-Atlantic ridge is closely matched by the geoid curve derived from the thermal cooling model. The observed geoid anomaly over the Atlantic margin of North America can be explained by Airy compensation. The relation between geoid anomaly and bathymetry across the Bermuda Swell is consistent with Pratt compensation with a 100-km depth of compensation.

  2. State-of-the-art ab initio potential energy curve for the krypton atom pair and thermophysical properties of dilute krypton gas.

    PubMed

    Jäger, Benjamin; Hellmann, Robert; Bich, Eckard; Vogel, Eckhard

    2016-03-21

    A new reference krypton-krypton interatomic potential energy curve was developed by means of quantum-chemical ab initio calculations for 36 interatomic separations. Highly accurate values for the interaction energies at the complete basis set limit were obtained using the coupled-cluster method with single, double, and perturbative triple excitations as well as t-aug-cc-pV5Z and t-aug-cc-pV6Z basis sets including mid-bond functions, with the 6Z basis set being newly constructed for this study. Higher orders of coupled-cluster terms were considered in a successive scheme up to full quadruple excitations. Core-core and core-valence correlation effects were included. Furthermore, relativistic effects were studied not only at a scalar relativistic level using second-order direct perturbation theory, but also utilizing full four-component and Gaunt-effect computations. An analytical pair potential function was fitted to the interaction energies, which is characterized by a depth of 200.88 K with an estimated standard uncertainty of 0.51 K. Thermophysical properties of low-density krypton were calculated for temperatures up to 5000 K. Second and third virial coefficients were obtained from statistical thermodynamics. Viscosity and thermal conductivity as well as the self-diffusion coefficient were computed using the kinetic theory of gases. The theoretical results are compared with experimental data and with results for other pair potential functions from the literature, especially with those calculated from the recently developed ab initio potential of Waldrop et al. [J. Chem. Phys. 142, 204307 (2015)]. Highly accurate experimental viscosity data indicate that both the present ab initio pair potential and the one of Waldrop et al. can be regarded as reference potentials, even though the quantum-chemical methods and basis sets differ. However, the uncertainties of the present potential and of the derived properties are estimated to be considerably lower. PMID:27004873

  3. State-of-the-art ab initio potential energy curve for the krypton atom pair and thermophysical properties of dilute krypton gas

    NASA Astrophysics Data System (ADS)

    Jäger, Benjamin; Hellmann, Robert; Bich, Eckard; Vogel, Eckhard

    2016-03-01

    A new reference krypton-krypton interatomic potential energy curve was developed by means of quantum-chemical ab initio calculations for 36 interatomic separations. Highly accurate values for the interaction energies at the complete basis set limit were obtained using the coupled-cluster method with single, double, and perturbative triple excitations as well as t-aug-cc-pV5Z and t-aug-cc-pV6Z basis sets including mid-bond functions, with the 6Z basis set being newly constructed for this study. Higher orders of coupled-cluster terms were considered in a successive scheme up to full quadruple excitations. Core-core and core-valence correlation effects were included. Furthermore, relativistic effects were studied not only at a scalar relativistic level using second-order direct perturbation theory, but also utilizing full four-component and Gaunt-effect computations. An analytical pair potential function was fitted to the interaction energies, which is characterized by a depth of 200.88 K with an estimated standard uncertainty of 0.51 K. Thermophysical properties of low-density krypton were calculated for temperatures up to 5000 K. Second and third virial coefficients were obtained from statistical thermodynamics. Viscosity and thermal conductivity as well as the self-diffusion coefficient were computed using the kinetic theory of gases. The theoretical results are compared with experimental data and with results for other pair potential functions from the literature, especially with those calculated from the recently developed ab initio potential of Waldrop et al. [J. Chem. Phys. 142, 204307 (2015)]. Highly accurate experimental viscosity data indicate that both the present ab initio pair potential and the one of Waldrop et al. can be regarded as reference potentials, even though the quantum-chemical methods and basis sets differ. However, the uncertainties of the present potential and of the derived properties are estimated to be considerably lower.

  4. A multi-isotopic and trace element investigation of the Cretaceous-Tertiary boundary layer at Stevns Klint, Denmark - inferences for the origin and nature of siderophile and lithophile element geochemical anomalies

    NASA Astrophysics Data System (ADS)

    Frei, Robert; Frei, Karin M.

    2002-10-01

    Os, Sr, Nd and Pb isotope data were collected from a profile across the Cretaceous-Tertiary (K-T) boundary layer at Stevns Klint, Denmark. ɛNd [ T=65 Ma] values from within the boundary layer (Fish Clay) are lower by ˜1 ɛ unit than those of the underlying Maastrichtian limestone and the overlying Danian chalk sequences. Systematic profile-upward changes of Pb, Sr and Os isotopic compositions and concentrations in the boundary layer cannot be accounted for by in situ growth of daughter products since the sedimentation of the Fish Clay. While Os, Nd and Pb isotopes indicate the admixing of less radiogenic components to the Fish Clay, Sr isotopes show elevated radiogenic values in the boundary layer, relative to the carbonate sequences beneath and above it. The sudden change in lithophile (e.g., Sr, Pb and Nd) isotope compositions at the base of the Fish Clay and profile-upward trends of 87Sr/ 86Sr and 206Pb/ 204Pb ratios towards those of the overlying Danian chalk are interpreted to reflect recovery from enhanced, acid rain-induced continental (local?) weathering input to the seawater. However, a continental crustal source is invalid for the siderophile element Os. In the light of evidence from chromium isotopes for a cosmic origin of the platinum group elements (PGEs) and certain moderately siderophile elements (Cr, Ni, Co, V) in K-T boundary sediments, including Stevns Klint [Shukolyukov and Lugmair, Science 282 (1998) 927-929], and supported by the finding of projectile debris [Bauluz et al., Earth Planet. Sci. Lett. 182 (2000) 127-136] and the occurrence of abundant Ni-rich spinel at many K-T sites [Robin et al., Nature 363 (1993) 615-617; Kyte, Nature 396 (1998) 237-239], we favor to explain the sudden drop of 187Os/ 188Os ratios from 0.210 to 0.160 at the K-T boundary to derive from global fall-out of extraterrestrial matter. The present 186Os/ 188Os ratio of 0.119836±0.000004 measured in the basal layer of the Fish Clay is within the uncertainty a

  5. Astrometric solar system anomalies

    SciTech Connect

    Nieto, Michael Martin; Anderson, John D

    2009-01-01

    There are at least four unexplained anomalies connected with astrometric data. perhaps the most disturbing is the fact that when a spacecraft on a flyby trajectory approaches the Earth within 2000 km or less, it often experiences a change in total orbital energy per unit mass. next, a secular change in the astronomical unit AU is definitely a concern. It is increasing by about 15 cm yr{sup -1}. The other two anomalies are perhaps less disturbing because of known sources of nongravitational acceleration. The first is an apparent slowing of the two Pioneer spacecraft as they exit the solar system in opposite directions. Some astronomers and physicists are convinced this effect is of concern, but many others are convinced it is produced by a nearly identical thermal emission from both spacecraft, in a direction away from the Sun, thereby producing acceleration toward the Sun. The fourth anomaly is a measured increase in the eccentricity of the Moon's orbit. Here again, an increase is expected from tidal friction in both the Earth and Moon. However, there is a reported unexplained increase that is significant at the three-sigma level. It is produent to suspect that all four anomalies have mundane explanations, or that one or more anomalies are a result of systematic error. Yet they might eventually be explained by new physics. For example, a slightly modified theory of gravitation is not ruled out, perhaps analogous to Einstein's 1916 explanation for the excess precession of Mercury's perihelion.

  6. Photochemistry of the ozone-water complex in cryogenic neon, argon, and krypton matrixes.

    PubMed

    Tsuge, Masashi; Tsuji, Kazuhide; Kawai, Akio; Shibuya, Kazuhiko

    2013-12-12

    The photochemistry of ozone-water complexes and the wavelength dependence of the reactions were studied by matrix isolation FTIR spectrometry in neon, argon, and krypton matrixes. Hydrogen peroxide was formed upon the irradiation of UV light below 355 nm. Quantitative analyses of the reactant and product were performed to evaluate the matrix cage effect of the photoreaction. In argon and krypton matrixes, a bimolecular O((1)D) + H2O → H2O2 reaction was found to occur to form hydrogen peroxide, where the O((1)D) atom generated by the photolysis of ozone diffused in the cryogenic solids to encounter water. In a neon matrix, hydrogen peroxide was generated through intracage photoreaction of the ozone-water complex, indicating that a neon matrix medium is most appropriate to study the photochemistry of the ozone-water complex. PMID:24252115

  7. Demonstrate the removal efficiency and capacity of MOF materials for krypton recovery

    SciTech Connect

    Thallapally, Praveen K.; Liu, Jian; Strachan, Denis M.

    2013-08-23

    Metal organic framework materials (MOFs) were developed and tested in support of the U.S. Department of Energy Office of Nuclear Energy, Fuel Cycle Technology Separations and Waste Forms Campaign. Specifically, materials are being developed for the removal of xenon (Xe) and krypton (Kr) from gaseous products of nuclear fuel reprocessing unit operations. Two metal organic framework structures were investigated in greater detail to demonstrate the removal efficiency and capacity of MOF materials for krypton recovery. Our two bed breakthrough measurements on NiDOBDC and FMOFCu indicate these materials can capture and separate parts per million levels of Xe and Kr from air. The removal efficiency and adsorption capacity for Kr on these two MOFs were further increased upon removal of Xe upfront.

  8. Transpupillary CW YAG laser coagulation. A comparison with argon green and krypton red lasers.

    PubMed

    Peyman, G A; Conway, M D; House, B

    1983-08-01

    The authors have developed a CW YAG laser for transpupillary coagulation. The effects of CW YAG coagulation on the retina, retinal vessels, and fovea were compared with those produced by the krypton red and argon green lasers. To produce threshold coagulative lesions in monkeys and rabbits, we needed five to ten times more energy with the CW YAG than with the krypton red or argon green lasers. Nerve fiber damage was observed only when coagulating retinal vessels with the argon green laser. At the parameters used, none of the lasers damaged the sensory retina of the fovea. The CW YAG may be used as a new mode of laser coagulation in the treatment of retinal diseases. PMID:6688868

  9. Unusual mercury isotopic compositions in aqueous environment

    NASA Astrophysics Data System (ADS)

    Chen, J.; Hintelmann, H.; Zheng, W.; Feng, X.; Cai, H.; Wang, Z.; Yuan, S.

    2014-12-01

    Preliminary studies have demonstrated both mass-dependent fractionation (MDF) and mass-independent fractionation (MIF) of Hg isotopes in natural samples. Laboratory experiments showed that photochemical reduction of inorganic mercury (iHg) and methylmercury (MMHg) and liquid-vapour evaporation could produce MIF of odd Hg isotopes. This was thought to cause the MIF actually observed in aquatic organisms. Although isotopic measurements of Hg in aqueous environment would give direct evidence, little data was reported for surface water samples. Recent work reported, unexpectedly, positive MIF of odd Hg isotopes in both precipitation and ambient air, in contrast with the prediction of laboratory experiments and measurements of Hg accumulated in lichens . Intriguingly, MIF of even-mass Hg isotope (200Hg) was also recently determined in the atmosphere. In contrast with the now mainstream observation of odd Hg isotope anomaly that has several theoretical explanations, the hitherto mysterious even Hg isotope anomalies were neither reported in laboratory experiments, nor predicted by isotope fractionation mechanisms, highlighting the importance of further study on Hg isotopes in variable systems. Our measurements of lichens and lake water samples from different countries show for the first time significant Δ200Hg in surface terrestrial reservoirs, realizing a direct connection of even Hg isotope anomaly in the terrestrial reservoirs to the atmospheric deposition, and fulfilling the gap of Δ200Hg between the atmosphere and the terrestrial receptors. The specific odd Hg isotope compositions determined in lake waters also support the atmosphere contribution, and may be directly linked to the high Δ199Hg values largely determined and manifested on the top of aqueous food web. Our data show that the watershed Hg input is another contributing source, rather than the in-lake processes, to explain the lacustrine Hg isotope anomalies. Interestingly, lake sediments are isotopically

  10. Measurement of the K?2/K?1 ratio in heliumlike krypton

    SciTech Connect

    Beiersdorfer, P; Gu, M F; Brown, G V; Chen, H; Kelley, R; Kilbourne, C A; Porter, F S; Smith, A J; Thorn, D B

    2008-08-25

    We report the measurement of the K{beta}{sub 2}/K{beta}{sub 1} ratio of He-like krypton using the SuperEBIT electron beam ion trap at the Lawrence Livermore National Laboratory. The energy of these lines are about 15 keV, which is twice as high as the energy of such lines measured before. A comparison with theoretical predictions shows poor agreement, concerning the trend uncovered earlier where the measured result is considerably larger than predicted.