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1

METEORITIC KRYPTON AND BARIUM VERSUS THE GENERAL ISOTOPIC ANOMALIES IN METEORITIC XENON  

Microsoft Academic Search

General isotopic anomalies in meteoritic xenon are described in detail. ; Where superior isotopic analyses exist, the xenon anomalies appear to be the same ; for all meteorites. In other cases there is fair evidence that the xenon ; examined is a mixture of meteoritic and contaminating atmospheric xenon. Two ; superior krypton analyses for carbonaceous chondrites show no anomalies

D. Krummenacher; C. M. Merrihue; R. O. Pepin; J. H. Reynolds

1962-01-01

2

Discovery of the Krypton Isotopes  

E-print Network

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

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

2009-04-15

3

Discovery of the krypton isotopes  

SciTech Connect

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.

Heim, M.; Fritsch, A.; Schuh, A.; Shore, A. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Thoennessen, M. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)], E-mail: thoennessen@nscl.msu.edu

2010-07-15

4

Discovery of the Krypton Isotopes  

E-print Network

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

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

2009-01-01

5

Shape coexistence in light Krypton isotopes , A. Grgen  

E-print Network

Shape coexistence in light Krypton isotopes E. Clément , A. Görgen , E. Bouchez , A. Chatillon , W, UK Abstract. Shape coexistence in the light krypton isotopes was studied in a series of experiments is the A 70 region around selenium (Z=34) and krypton (Z=36) isotopes near the N = Z line, in which oblate

Paris-Sud XI, Université de

6

Shape Coexistence In Light Krypton Isotopes  

SciTech Connect

Shape coexistence in the light krypton isotopes was studied in a series of experiments at GANIL using various experimental techniques. A new low-lying 0+ state, a so-called shape isomer, was found in delayed conversion-electron spectroscopy after fragmentation reactions. The systematics of such low-lying 0+ states suggests that the ground states of the isotopes 78Kr and 76Kr have prolate deformation, while states with prolate and oblate shape are practically degenerate and strongly mixed in 74Kr, and that the oblate configuration becomes the ground state in 72Kr. This scenario was tested in experiments performing low-energy Coulomb excitation of radioactive 76Kr and 74Kr beams from the SPIRAL facility. Both transitional and diagonal electromagnetic matrix elements were extracted from the observed {gamma}-ray yields. The results find the prolate shape for the ground-state bands in 76Kr and 74Kr and an oblate deformation for the excited 2{sub 2}{sup +} state in 74Kr, confirming the proposed scenario of shape coexistence.

Clement, E.; Goergen, A.; Bouchez, E.; Chatillon, A.; Korten, W.; Le Coz, Y.; Theisen, Ch.; Huerstel, A.; Lucas, R.; Wilson, J.N. [DAPNIA/SPhN, CEA Saclay, F-91191 Gif-sur-Yvette (France); Andreoiu, C.; Butler, P.; Herzberg, R.-D.; Iwanicki, J.; Jenkins, D.; Jones, G. [Dept. of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Becker, F.; Gerl, J. [Gesellschaft fuer Schwerionenforschwg, D-64291 Darmstadt (Germany); Blank, B.; Hannachi, F. [CEN Bordeaux-Gradignan, IN2P3-CNRS, F-33175 Gradignan Cedex (France)] [and others

2005-04-05

7

Physicochemical isotope anomalies  

SciTech Connect

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.

Esat, T.M. (Australian National Univ., Canberra)

1988-06-01

8

Krypton isotope analysis using near-resonant stimulated Raman spectroscopy  

SciTech Connect

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.

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

1994-12-01

9

Shape Transitions and Jacobian Instability in Excited Krypton Isotopes  

NASA Astrophysics Data System (ADS)

Shape transitions as a function of angular momentum in even-even krypton isotopes with A = 72-84 have been investigated using the cranked Nilsson-Strutinsky method. The Jacobi shape transition from noncollective oblate to super or hyperdeformed collective prolate or triaxial shape taking place in rotating nuclei as in the case of gravitating rotating stars is studied in krypton isotopes. The cranked Nilsson-Strutinsky method with a method of tuning the angular velocity to get the fixed spins is used in the calculations. Our results show that all the krypton isotopes considered in this study are the good candidates for detecting the Jacobi shape transition. Shape evolutions as a function of spin and temperature with thermal fluctuations are studied using the Landau theory of phase transitions. The constants appearing in the Landau expression for the free energy are determined by using the free energy surfaces at ? = 0 calculated by the Strutinsky method. We show that in the presence of thermal fluctuations, the averaged shapes obtained for the considered isotopes differ from the most probable shapes. The sharp Jacobi transitions are modified due to the effect of thermal fluctuations.

Selvam, V.; Devadhason, D. R. Jayahar; Beula, J. M.

2014-12-01

10

Shape coexistence in light Krypton isotopes A. Gorgen,1 E. Clement,1 E. Bouchez,1 A. Chatillon,1  

E-print Network

Shape coexistence in light Krypton isotopes A. G¨orgen,1 E. Cl´ement,1 E. Bouchez,1 A. Chatillon,1 Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen ?, Denmark The light Krypton isotopes were studied schemes of the light even-even Krypton isotopes illustrating the systematics of low-lying 0+ states

Paris-Sud XI, Université de

11

s-process studies - Xenon and krypton isotopic abundances  

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

12

Shape coexistence and evolution in neutron-deficient krypton isotopes  

E-print Network

Total Routhian Surface (TRS) calculations have been performed to investigate shape coexistence and evolution in neutron-deficient krypton isotopes ${}^{72,74,76}$Kr. The ground-state shape is found to change from oblate in ${}^{72}$Kr to prolate in ${}^{74,76}$Kr, in agreement with experimental data. Quadrupole deformations of the ground states and coexisting $0^{+}_{2}$ states as well as excitation energies of the latter are also well reproduced. While the general agreement between calculated moments of inertia and those deduced from observed spectra confirms the prolate nature of the low-lying yrast states of all three isotopes (except the ground state of ${}^{72}$Kr), the deviation at low spins suggests significant shape mixing. The role of triaxiality in describing shape coexistence and evolution in these nuclei is finally discussed.

Z. J. Bai; X. M. Fu; C. F. Jiao; F. R. Xu

2015-03-31

13

Shape coexistence and evolution in neutron-deficient krypton isotopes  

E-print Network

Total Routhian Surface (TRS) calculations have been performed to investigate shape coexistence and evolution in neutron-deficient krypton isotopes ${}^{72,74,76}$Kr. The ground-state shape is found to change from oblate in ${}^{72}$Kr to prolate in ${}^{74,76}$Kr, in agreement with experimental data. Quadrupole deformations of the ground states and coexisting $0^{+}_{2}$ states as well as excitation energies of the latter are also well reproduced. While the general agreement between calculated moments of inertia and those deduced from observed spectra confirms the prolate nature of the low-lying yrast states of all three isotopes (except the ground state of ${}^{72}$Kr), the deviation at low spins suggests significant shape mixing. The role of triaxiality in describing shape coexistence and evolution in these nuclei is finally discussed.

Bai, Z J; Jiao, C F; Xu, F R

2015-01-01

14

Xenon and krypton isotopes in extraterrestrial regolith soils and in the solar wind  

Microsoft Academic Search

Isotopic distributions of pure solar-wind xenon and krypton are derived from an extensive data base of xenon and krypton compositions evolved from lunar and meteoritic regolith samples by acid-etching or combustion-pyrolysis experiments in several different laboratories. Regolith Xe and Kr are nonuniform mixtures of primary solar-wind components with others arising in situ from cosmic-ray spallation, neutron-capture in iodine and bromine,

R. O. Pepin; R. H. Becker; P. E. Rider

1995-01-01

15

Isotope shift and hyperfine structure studies of the krypton ion and the thallium atom  

E-print Network

ISOTOPE SHIFT AND HYPERFINE STRUCTURE STUDIES OF THE KRYPTON ION AND THE THALLIUM ATOM A Thesis by YINGFENG LI Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE August 1991 Major Subject: Physics ISOTPE SHIFT AND HYPERFINE STRUCTURE STUDIES OF THE KRYPTON ION AND THE THALLIUM ATOM A Thesis by YINGFENG LI Approved as to style and content by: Hans A. Schuessler (Chair of Committee...

Li, Yingfeng

1991-01-01

16

Cross-section measurements of krypton 78 to 86 isotopes in the spallation of palladium and silver.  

E-print Network

981 Cross-section measurements of krypton 78 to 86 isotopes in the spallation of palladium « cosmogénique » du krypton dans les météorites de fer est due aux réactions nuclé- aires induites par le, cibles dont la contribution au krypton cosmogénique dans les météorites de fer est dominante. Abstract

Paris-Sud XI, Université de

17

Chromium isotopic anomalies in the Allende meteorite  

NASA Technical Reports Server (NTRS)

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.

Papanastassiou, D. A.

1986-01-01

18

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

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

19

Mass Spectrometric Measurement of Martian Krypton and Xenon Isotopic Abundance  

NASA Technical Reports Server (NTRS)

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.

Mahaffy, P.; Mauersberger, K.

1993-01-01

20

Isotopic analyses of krypton and xenon in fourteen stone meteorites  

Microsoft Academic Search

The concentrations and isotopic compositions of Kr and Xe in twelve chondrites and two achondrites have been determined. In addition to the trapped component, Kr and Xe produced by spallation and (n, v.\\/) reactions as well as fission and radiogenic Xe have been found. Because of the chemical uniformity of the ordinary chondrites the concentrations of spallation-produced Kr and Xe

O. Eugster; P. Eberhardt; J. Geiss

1969-01-01

21

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

NASA Technical Reports Server (NTRS)

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.

Soli, George A.; Nichols, Donald K.

1989-01-01

22

The Measurement of the Partition Coefficient of Krypton between Brain Cortex and Blood by a Double Isotope Method  

Microsoft Academic Search

The brain cortex-blood partition coefficient for krypton has been estimated in dogs using a double isotope method. Allowance has been made for the blood content of the brain tissue. The average value of 091 6% for a blood haematocrit of 50% was obtained. This value compares favourably with the figure of 092 obtained by other workers using an autoradiographic technique

H. I. Glass; A. M. Harper

1962-01-01

23

Nucleosynthetic strontium isotope anomalies in carbonaceous chondrites  

NASA Astrophysics Data System (ADS)

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 ?84Sr 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 ?84Sr patterns across leaching samples for individual chondrites differed from one another. The highest ?84Sr 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 ?84Sr 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 ?84Sr-?54Cr 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 ?84Sr and ?54Cr values, whereas carbonaceous chondrites and noncarbonaceous meteorites had intermediate and the lowest ?84Sr and ?54Cr values, respectively. The positive trend was interpreted as resulting from global thermal processing in which sublimation of high ?84Sr and ?54Cr carriers generated the excess ?84Sr and ?54Cr signatures in CAIs, while noncarbonaceous planetesimals accreted from materials that underwent significant thermal processing and thus had relatively low ?84Sr and ?54Cr 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 combinations (e.g., ?54Cr-?50Ti, ?54Cr-?17O). A plausible scenario for creation of the intrinsic variations involves local thermal processing (e.g., flash heating for chondrule formation) caused by additional selective destruction of presolar grains differently than that caused by global thermal processing. The existence of such a global positive trend and local variations for two meteorite groups suggests a complicated dynamic history for the dust grains with respect to thermal processing, material transportation, and mixing in the protoplanetary disk prior to planetesimal formation.

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

2015-04-01

24

Titanium isotopic anomalies in chondrules from carbonaceous chondrites  

NASA Astrophysics Data System (ADS)

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.

Niemeyer, S.

1988-02-01

25

Barium and neodymium isotopic anomalies in the Allende meteorite  

Microsoft Academic Search

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

M. T. McCulloch; G. J. Wasserburg

1978-01-01

26

Isotopic Anomalies in CP Stars: Helium, Mercury, Platinum, and Calcium  

E-print Network

We review the classical observational results for isotopic abundance variations for several elements in CP stars. We concentrate on the "newest" anomaly, in calcium. The cosmically very rare isotope, Ca-48 can rival and even dominate the more common, alpha nuclide, Ca-40. Relevant examples are found in the hot, non-magnetic HgMn stars, and the field horizontal-branch star, Feige 86. The calcium anomaly is also present in cool, magnetic stars, including the notorious HD 101065, Przybylski's star.

C. R. Cowley; S. Hubrig; F. Castelli

2007-11-15

27

Models for Interpreting Tungsten Isotope Anomalies in the Earth's Crust  

NASA Astrophysics Data System (ADS)

There have been several reports of positive tungsten isotope anomalies of about +15 ppm in rocks from Nuvvuagittuq (4.3 Ga), Isua (3.8 Ga) and Kostomuksha (2.8 Ga) that challenge models of differentiation and mantle mixing. Here, we employ constraints from experimental partitioning of W between metal and silicate, and from partial melting models, to evaluate the production and preservation of these W isotope anomalies in the Earth's earliest crust. We will also provide a revised interpretation of the Kostomuksha W isotope anomalies based on flow differentiation and metamorphism of komatiites. Two sets of models are produced. Model Set 1: Because D(metal-silicate) for W diminishes with increasing depth, the deep mantle has a higher W abundance, and a lower Hf/W ratio and consequently evolves a negative anomaly in W while the upper mantle evolves a complementary positive anomaly. Subsequent solid-state convection (4.55-2.8 Ga) mixes away the complementary W isotope anomalies to yield the modern mantle null value. This set of models predicts that the complementary negative anomalies in W should eventually be discovered in ancient magmatic rocks of deep mantle origin such as komatiites. Model Set 2: Tungsten is significantly more incompatible (like U, Th and Ba) than Hf, the latter being similar in compatibility to Sm. Our results show that extraction of low-degree partial melts (<2%) leaving a Hadean depleted mantle that can have Sm/Nd~20% higher than chondrites also creates a f(Hf/W)~2-3, sufficient to generate the anomalies observed in Archean rocks. These models increase Hf/W and Sm/Nd ratios in a correlated fashion explaining the tendency of positive W isotope anomalies to occur in rocks with positive Nd isotope anomalies. Recycling of the complementary Hadean crust would result in negative anomalies in later plume lavas, while partitioning of W into an enriched "hidden reservoir" would not. Nd isotope anomalies indicate a melting event around 35-75 Ma after solar system formation, the upper end of which is consistent with our models of Hf/W fractionation, that also yield a depleted mantle composition consistent with DMM. Production of the anomalies is accompanied by the need to preserve the anomalies. We argue that the most effective means of preserving the W isotope anomalies is by crustal storage, and we hypothesize that W is efficiently recycled back to juvenile crust during subduction zone processing. Eventually, the addition of juvenile W from the mantle will dilute the positive W isotope anomalies stored in the early crust. The amount of juvenile W required to be added is about a factor of 4 or more, and it is likely that this occurred during the late Archean crustal growth phase (2.5 Ga), so that positive W isotope anomalies are not likely to occur in much younger rocks. A secular decline in crustal W isotope anomalies is predicted.

Humayun, M.; Brandon, A. D.; Righter, K.

2012-12-01

28

Barium and neodymium isotopic anomalies in the Allende meteorite  

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

29

Skyrme-HFB Calculations in Coordinate Space for the Krypton Isotopes Up to the Two-Neutron Dripline  

E-print Network

For axially symmetric even-even nuclei, we solve the Hartree-Fock-Bogoliubov (HFB) equations on a 2-D grid in cylindrical coordinates. The Skyrme SLy4 interaction is used for the mean field and a zero-range interaction for the pairing field. After decoupling the HFB lattice equations, we obtain quasiparticle states with equivalent single-particle energies up to 100 MeV or more. We present results for the Krypton isotope chain up to the two-neutron dripline, including two-neutron separation energies, pairing gaps, and quadrupole deformations for the ground states and isomeric minima.

V. E. Oberacker; A. Blazkiewicz; A. S. Umar

2007-01-11

30

Independent Yields of Krypton and Xenon Isotopes in Thermal-Neutron Fission of 235U. Observation of an Odd-Even Effect in the Element Yield Distribution  

Microsoft Academic Search

The fractional and independent fission yields of krypton isotopes (masses 87 to 94) and xenon isotopes (masses 137-143) produced in thermal-neutron fission of 235U were measured using a mass separator operating in an on-line mode with a fission source exposed to time-controlled neutron fluxes. The noble-gas isotopes were collected simultaneously at given times and each mass was measured separately. The

B. Ehrenberg; S. Amiel

1972-01-01

31

Neutron-rich chromium isotope anomalies in supernova nanoparticles  

E-print Network

Neutron-rich isotopes with masses near that of iron are produced in type Ia and II supernovae. Traces of such nucleosynthesis are found in primitive meteorites in the form of variations in the isotopic abundance of 54Cr, the most neutron-rich stable isotope of chromium. The hosts of these isotopic anomalies must be presolar grains that condensed in the outflows of supernovae, 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 54Cr 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 54Cr-anomalies as nanoparticles, most likely spinels that show large enrichments in 54Cr relative to solar composition (54Cr/52Cr ratio >3.6xsolar). Such large enrichments in 54Cr can only be produced in supernovae. The mineralogy of the gr...

Dauphas, Nicolas; Chen, James; Roskosz, Mathieu; Papanastassiou, Dimitri; Stodolna, Julien; Guan, Yunbin; Ma, Chi; Eiler, John

2010-01-01

32

Isotopic anomalies in high Z elements: Uranium  

SciTech Connect

Uranium in terrestrial volcanic ejecta from mantle-related sources has been analyzed mass spectrometrically. The objective was to seek supporting evidence for or refutation isotopic variations reported by Fried et al. (1985) for some such samples. The possibility that terrestrial U is not of constant isotopic composition is extraordinary. If true, mechanisms for creating the variation must be sought and the lack of homogenization within the earth addressed. Samples of 100 grams or more were processed in order to minimize reagent and environmental (laboratory) blank interference and to permit isolation of large amounts (several to tens of ..mu..g) of U for the mass spectrometer (MS) measurements, which utilizes aliquots of /approximately/1 ..mu..g. Aliquants from four volcanic samples gave data which indicate enrichments of /sub 235/U ranging from 0.2% to 5.9% in the 235/238 ratio relative normal uranium ratios. These relative enrichments are consistent with, and in some cases, higher than the 0.18% enrichment reported by Fried et al. (1985) for two volcanic lava samples. However, we were not able to reproduce their results on the Kilauea lava for which they report 0.18% /sup 235/U enrichment. The relative error in our MS ratios is 0.05% -- 0.07%. 1 tab.

Jovanovic, S.; Reed, G.W. Jr.; Essling, A.M.; Rauh, E.G.; Graczyk, D.G.

1989-03-01

33

More on Ru Endemic Isotope Anomalies in Meteorites  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

34

NEUTRON-RICH CHROMIUM ISOTOPE ANOMALIES IN SUPERNOVA NANOPARTICLES  

SciTech Connect

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.

Dauphas, N. [Origins Laboratory, Department of the Geophysical Sciences and Enrico Fermi Institute, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637 (United States); Remusat, L.; Papanastassiou, D. A.; Guan, Y.; Ma, C.; Eiler, J. M. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Chen, J. H. [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Roskosz, M.; Stodolna, J., E-mail: dauphas@uchicago.ed [Unite Materiaux et Transformations, Universite de Lille 1, CNRS UMR 8207, 59655 Villeneuve d'Ascq (France)

2010-09-10

35

Oxygen isotopic anomalies in Allende inclusion HAL  

NASA Astrophysics Data System (ADS)

An oxygen isotopic study which demonstrates the Allende inclusion HAL is a FUN object is discussed; the hibonite core, black inner rim and fine-grained outer rim have beem sampled. The oxygen in HAL is found to be heterogeneous, the rim samples having oxygen compositions similar to that of melilites and alteration products in other Allende inclusions including the FUN inclusion EK1-4-1, while the oxygen in the hibonite core shows the most extreme deviation from the AD line so far observed. The oxygen in HAL hibonite, in ED1-4-1 spinel and in spinels of usual Allende inclusions form an approximate linear array with a slope close to 1/2. With regard to the fractionation process, it is noted that the fractionation per amu for various elements does not correlate inversely with mass and that fractionation is elementally selective, probably according to volatility.

Lee, T.; Mayeda, T. K.; Clayton, R. N.

1980-07-01

36

NEUTRON-POOR NICKEL ISOTOPE ANOMALIES IN METEORITES  

SciTech Connect

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 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 that the Ni isotopic variability of the solar system cannot be explained by mixing with a component of bulk stellar ejecta from either SN II, Wolf-Rayet or, an asymptotic giant branch source and is unlikely to result from bulk mixing of material from an SN Ia. However, variable admixture of material from the Si/S zone of an SN II can create all the characteristics of Ni isotope variations in solar system materials. Moreover, these characteristics can also be provided by an SN II with a range of masses from 15 to 40 M{sub Sun }, showing that input from SN II is a robust source for Ni isotope variations in the solar system. Correlations of Ni isotope anomalies with O, Cr, and Ti isotope ratios and Pb/Yb in bulk meteorites suggest that the heterogeneous distribution of isotopic anomalies in the early solar system likely resulted from nebular sorting of chemically or physically different materials bearing different amounts of isotopes synthesized proximally to the collapse of the protosolar nebula.

Steele, Robert C. J.; Coath, Christopher D.; Regelous, Marcel; Elliott, Tim [Bristol Isotope Group, School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol BS8 1RJ (United Kingdom); Russell, Sara, E-mail: r.steele@uclmail.net [Meteoritics and Cosmic mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD (United Kingdom)

2012-10-10

37

Beyond relativistic mean-field studies of low-lying states in neutron-deficient krypton isotopes  

E-print Network

Neutron-deficient krypton isotopes are of particular interest due to the coexistence of oblate and prolate shapes in low-lying states and the transition of ground-state from one dominate shape to another as a function of neutron number. A detailed interpretation of these phenomena in neutron-deficient Kr isotopes requires the use of a method going beyond a mean-field approach that permits to determine spectra and transition probabilities. The aim of this work is to provide a systematic calculation of low-lying state in the even-even 68-86Kr isotopes and to understand the shape coexistence phenomenon and the onset of large collectivity around N=40 from beyond relativistic mean-field studies. The starting point of our method is a set of relativistic mean-field+BCS wave functions generated with a constraint on triaxial deformations (beta, gamma). The excitation energies and electric multipole transition strengths of low-lying states are calculated by solving a five-dimensional collective Hamiltonian (5DCH) with ...

Fu, Y; Xiang, J; Li, Z P; Yao, J M; Meng, J

2013-01-01

38

MULTIPLE ORIGINS OF NITROGEN ISOTOPIC ANOMALIES IN METEORITES AND COMETS  

SciTech Connect

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.

Aleon, Jerome, E-mail: Jerome.Aleon@csnsm.in2p3.f [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, CSNSM-CNRS-IN2 P3, Bat 104, Orsay Campus 91405 (France)

2010-10-20

39

NUCLEAR-CHARGE DISTRIBUTION IN FISSION: CUMULATIVE YIELDS OF SHORT-LIVED KRYPTON AND XENON ISOTOPES FROM THERMAL-NEUTRON FISSION OF ²³⁵U  

Microsoft Academic Search

Experiments are described in which use was nnade of the very large ; emanating powers of barium stearate and uranyl stearate for determination of ; cumulative yields for a number of krypton and xenon isotopes formed in the ; thermal-neutron fission of U²³⁵. The results, expressed as the fraction of ; the total chain yield, are: Kr⁸⁹ 0.960 plus or

A Wahl

1958-01-01

40

Beyond relativistic mean-field studies of low-lying states in neutron-deficient krypton isotopes  

E-print Network

Neutron-deficient krypton isotopes are of particular interest due to the coexistence of oblate and prolate shapes in low-lying states and the transition of ground-state from one dominate shape to another as a function of neutron number. A detailed interpretation of these phenomena in neutron-deficient Kr isotopes requires the use of a method going beyond a mean-field approach that permits to determine spectra and transition probabilities. The aim of this work is to provide a systematic calculation of low-lying state in the even-even 68-86Kr isotopes and to understand the shape coexistence phenomenon and the onset of large collectivity around N=40 from beyond relativistic mean-field studies. The starting point of our method is a set of relativistic mean-field+BCS wave functions generated with a constraint on triaxial deformations (beta, gamma). The excitation energies and electric multipole transition strengths of low-lying states are calculated by solving a five-dimensional collective Hamiltonian (5DCH) with parameters determined by the mean-field wave functions. To examine the role of triaxiality, a configuration mixing of both particle number (PN) and angular momentum (AM) projected axially deformed states is also carried out within the exact generator coordinate method (GCM) based on the same energy density functional. The energy surfaces, the excitation energies of 0^+_2, 2^+_1, 2^+_2 states, as well as the E0 and E2 transition strengths are compared with the results of similar 5DCH calculations but with parameters determined by the non-relativistic mean-field wave functions, as well as with the available data...

Y. Fu; H. Mei; J. Xiang; Z. P. Li; J. M. Yao; J. Meng

2013-04-15

41

Description of even-even Krypton isotopes by the Interacting Boson Approximation  

Microsoft Academic Search

Energy spectra andB(E2) values of the even-even Kr isotopes7482Kr have been analyzed in terms of the IBA-2 model of Otsuka, Arima and Iachello [6, 7]. We can reproduce the variation of collectivity along the isotope chain by means of a consistent set of 5 parameters, essentially only one of them has been varied with neutron number. The low lying 02+

U. Kaup; A. Gelberg

1979-01-01

42

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

NASA Technical Reports Server (NTRS)

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.

Marti, K.

1980-01-01

43

Structure of Krypton isotopes calculated with symmetry conserving configuration mixing methods  

E-print Network

Shape transitions and shape coexistence in the $^{70-98}$Kr region are studied in a unified view with state-of-the-art beyond self-consistent mean field methods based on the Gogny D1S interaction. Beyond mean field effects are taken into account through the exact angular momentum and particle number restoration and the possibility of axial and non-axial shape mixing. The results of the low-lying properties of these isotopes are in good agreement with the experimental data when the triaxial degree of freedom is included. Shape transitions from axial-oblate ($^{70-72}$Kr) to triaxial-prolate ($^{74-78}$Kr) and from spherical-triaxial ($^{86-92}$Kr) to axial-oblate ($^{94-98}$Kr) ground states are obtained. Additionally, low-lying $0^{+}$ excited states and quasi-gamma bands are found showing the richness of the collective structure in this region.

Toms R. Rodrguez

2014-08-25

44

Structure of Krypton isotopes calculated with symmetry conserving configuration mixing methods  

E-print Network

Shape transitions and shape coexistence in the $^{70-98}$Kr region are studied in a unified view with state-of-the-art beyond self-consistent mean field methods based on the Gogny D1S interaction. Beyond mean field effects are taken into account through the exact angular momentum and particle number restoration and the possibility of axial and non-axial shape mixing. The results of the low-lying properties of these isotopes are in good agreement with the experimental data when the triaxial degree of freedom is included. Shape transitions from axial-oblate ($^{70-72}$Kr) to triaxial-prolate ($^{74-78}$Kr) and from spherical-triaxial ($^{86-92}$Kr) to axial-oblate ($^{94-98}$Kr) ground states are obtained. Additionally, low-lying $0^{+}$ excited states and quasi-gamma bands are found showing the richness of the collective structure in this region.

Rodrguez, Toms R

2014-01-01

45

The atmosphere of Mars - Detection of krypton and xenon  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

46

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

NASA Astrophysics Data System (ADS)

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 (?17O - ?18O (?17O ? {(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 isotopic fractionation, that is, a slope = 1.0 linear array in an oxygen three isotope plot ?17O - ?18O. Therefore, the prediction of the self-shielding hypothesis that the solar oxygen isotopic composition must be different from planetary objects is not supported by the CAI oxygen isotopic data, and we think that the general homogeneity of isotopic composition in the early solar nebula is still a valid assumption. References [1] Clayton R.N. et al, Science, 182, 485-88, 1973. [2] Yurimoto H. et al. Applied Surface Science, 793, 203-204, 2003. [3] Clayton R., Nature 415, 317, 2002. [4] Burnett D.S. et al., Space Science Review, 105, 509-543, 2003. [5] McKeegan K. et al. 2009. Abstract #2494. 40th LPSC, 2009. [5] Wieler R. Meteoritics & Planetary Science, 44, A218, 2009. [|#22#|

Ozima, M.; Yamada, A.

2009-12-01

47

Xenon and Krypton in the Bruderheim Meteorite  

Microsoft Academic Search

In a series of heating experiments, xenon, radiogenic XeR, and krypton con- tents, and the xenon and krypton isotopic composition of the Bruderheim meteorite were studied for the separated minerals feldspar, pyroxene, olivine, and trollire and for numerous chondrule fractions. Important differences among the individual minerals and between min- erals and chondrules were observed, and the following conclusions were reached:

Craig Merrihue

1966-01-01

48

The Qinglongshan oxygen and hydrogen isotope anomaly near Donghai in Jiangsu Province, China  

Microsoft Academic Search

The Qinglongshan isotope anomaly has unusually low values of both ?18O and ?D. Grnets from coesite-bearing eclogite are as low as ?11 (VSMOW) and rutiles are ?15. Phengites have ?D of ?120 (VSMOW). The low values were acquired in an ancient geothermal system prior to subduction during Triassic continental collision. New data shows that depleted isotope values in different rock

Douglas Rumble; T.-F Yui

1998-01-01

49

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

NASA Technical Reports Server (NTRS)

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.

Clayton, D. D.

1978-01-01

50

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)

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 ? in eucrites to +4 ? in CO and CV chondrites). Isotopic anomalies in ?48Ca correlate with ?50Ti: ? 48Ca=(1.090.11)? 50Ti+(0.030.14). 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.

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

2014-12-01

51

Nitrogen Isotopic Anomalies in a Hydrous Interplanetary Dust Particle  

NASA Technical Reports Server (NTRS)

Interplanetary dust particles (IDPs) collected in the stratosphere are the fine-grained end member (5 - 50 microns in size) of the meteoritic material available for investigation in the laboratory. IDPs are derived from either cometary or asteroidal sources. Some IDPs contain cosmically primitive materials with isotopic signatures reflecting presolar origins. Recent detailed studies using the NanoSIMS have shown there is a wide variation of isotopic signatures within individual IDPs; grains with a presolar signature have been observed surrounded by material with a solar isotopic composition. The majority of IDPs studied have been anhydrous. We report here results from integrated NanoSIMS/FIB/TEM/Synchrotron IR studies of a hydrous IDP, focused on understanding the correlations between the isotopic, mineralogical and chemical compositions of IDPs.

Smith, J. B.; Dai, Z. R.; Weber, P. K.; Graham, G. A.; Hutcheon, I. D.; Bajt, S.; Ishii, H.; Bradley, J. P.

2005-01-01

52

Endemic Ru Isotopic Anomalies in Iron Meteorites and in Allende  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

53

Oxygen isotope anomalies of the Sun and the original environment of the Solar system  

E-print Network

We present results from a model of oxygen isotopic anomaly production through selective photodissociation of CO within the collapsing proto-Solar cloud. Our model produces a proto-Sun with a wide range of Delta_17O values depending on the intensity of the ultraviolet radiation field. Dramatically different results from two recent Solar wind oxygen isotope measurements indicate that a variety of compositions remain possible for the solar oxygen isotope composition. However, constrained by other measurements from comets and meteorites, our models imply the birth of the Sun in a stellar cluster with an enhanced radiation field and are therefore consistent with a supernova source for 60Fe in meteorites.

Jeong-Eun Lee; Edwin A. Bergin; James R. Lyons

2008-03-15

54

Sulfur and Hydrogen Isotope Anomalies in Meteorite Sulfonic Acids  

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

55

Sulfur and Hydrogen Isotope Anomalies in Meteorite Sulfonic Acids  

NASA Astrophysics Data System (ADS)

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.

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

1997-08-01

56

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

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) chemistry in the interstellar medium or perhaps the outer regions of the solar nebula. In other extraterrestrial samples, D isotopic anomalies, but not those of {sup 15}N, may be explained in part by exposure to ionizing electron radiation.

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

2010-01-01

57

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

NASA Astrophysics Data System (ADS)

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 ?183W (?iW 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 ?182W and ?183W, providing a direct empirical means to correct the ?182W of any CAI for nucleosynthetic isotope anomalies using their measured ?183W. After correction for nucleosynthetic W isotope variations, the CAI data define an initial 182Hf/180Hf of (1.0180.043)10-4 and an initial ?182W of -3.490.07. The Hf-W formation intervals of the angrites D'Orbigny and Sahara 99555 relative to this CAI initial is 4.80.6 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.

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

2014-10-01

58

Anomalies.  

ERIC Educational Resources Information Center

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,

Online-Offline, 1999

1999-01-01

59

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

PubMed Central

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 (8230?N), where there is downward transport of stratospheric air to the polar troposphere, and were analyzed for ?17O and ?18O 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, ?MDF(H2O) = 0.529 0.003 [2? standard error (SE)], was determined from 27 CLP samples collected in 2003?2005. An oxygen isotopic anomaly of ?17O = 76 16 ppm (2? 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 ?17O 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 ?17O 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 (2? SE) relative to Vienna Standard Mean Ocean Water. PMID:24009339

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

2013-01-01

60

Oxygen Isotope Anomalies in Orgueil Corundum: Confirmation of Presolar Origin  

NASA Astrophysics Data System (ADS)

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 mean value of delta^17O = -45.1 +- 2.1 per mil and delta^18O = -41.2 +- 2.2 per mil, very similar to the composition of Allende CAI spinel [8]. The Orgueil spinel and hibonite are slightly less ^16O-rich with delta^18O values between -18 per mil and -42 per mil. One Orgueil spinel and four corundums have normal O-isotope compositions with delta^17O ~ delta^18O ~ 0. The only other refractory oxide grains with similar composition are a group of Cr-rich Murchison spinel [9]. Two Orgueil corundums are enriched in the heavier O-isotopes and have compositions falling along the terrestrial fractionation line (delta^17O ~ 42 per mil, delta^18O ~ 75 per mil). This is the heaviest oxygen isotopic composition reported in meteoritic materials. If this composition is derived from isotopically normal oxygen by mass-dependent fractionation, the magnitude of fractionation is similar to that measured in the Allende FUN inclusion HAL [10]. References: [1] Huss G. R. et al. (1992) LPS XXIII, 563. [2] Zinner E. K. et al. (1991) Nature, 349, 51. [3] Nittler L. R. et al. (1993) LPS XXIV, 1087. [4] Lambert D. L. (1988) In Evolution of Peculiar Red Giant Stars, 101. [5] Forestini M. et al. (1991) Astron. Astrophys., 252, 597. [6] Wasserburg G. J. et al. (1993) LPS XXIV, 1487. [7] Virag S. A. et al. (1991) GCA, 55, 2045. [8] Clayton R. N. et al. (1977) EPSL, 34, 209. [9] Grossman L. et al. (1988) LPS XIX, 435-436. [10] Lee T. et al. (1980) GRL, 7, 498- 496. Division Contribution 5273(815); NASA NAGW-3297. Fig. 1, which appears here in the hard copy, shows oxygen isotopic composition of refractory oxide grains from Orgueil and Allende. The insert is an expanded view of the region inside the open box, near delta^17O ~ delta^18O ~ 0. The solid lines in the insert represent the terrestrial fractionation line (slope = 1/2) and the ^16O-mixing line (slope = 1). Ratios are shown as the per mil deviation from SMOW; errors are +-2 sigma(sub)mean.

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

1993-07-01

61

Anomaly in the nuclear charge radii of Zr isotopes  

NASA Astrophysics Data System (ADS)

The recent laser spectroscopic measurements of nuclear root-mean-square charge radii on a chain of Zr isotopes exhibit a rich structure. A prominent kink is observed at 90Zr and a sharp change is noticed between 98Zr and 100Zr , in the neutron rich region. In the present work, the ground state properties of these nuclei are calculated in the relativistic mean field (RMF) framework. The calculations are in good accord with the experiment. The RMF densities are folded with the extended Jeukenne, Lejeune, and Mahaux energy and density dependent nucleon-nucleon interaction to yield the semimicroscopic optical potential which in turn is used to calculate the elastic scattering cross sections for 50 MeV proton scattering from a chain of Zr isotopes. The differential cross sections obtained from the calculations agree remarkably well with the experiment. The calculation reveals a correlation between the mean-square charge radii and the corresponding reaction cross sections for A?88 . There is a monotonic increase in ?R from A=84 to 106 with the hint of a slight jump from A=98 to A=100 .

Hemalatha, M.; Bhagwat, A.; Shrivastava, A.; Kailas, S.; Gambhir, Y. K.

2004-10-01

62

Zr isotope anomalies in chondrites and the presence of 92Nb in the early solar system  

NASA Astrophysics Data System (ADS)

The presence of Zr isotope anomalies in the early solar system is demonstrated with the identification of 92Zr excesses and 96Zr deficits in several chondrites and the CAI Allende inclusions. The isotopic composition of Zr in carbonaceous, enstatite, and ordinary chondrites, along with four SNC meteorites, was analyzed by plasma source mass spectrometry. Most chondrite samples show negative96Zr anomalies, which indicate the presence of a pre-solar nucleosynthetic component. Six of them also display a distinct negative92Zr anomaly, reaching down to -2.70.8 ? units for Forest Vale (H4). The CAI inclusions from Allende, which are among the oldest known igneous objects of the solar system and have the highest Zr/Nb ratios, also show negative ?92Zr of -2.40.5. Although a substantial fraction of the Zr isotope variability may be due to pre-solar nucleosynthetic processes, part of the 92Zr excess must result from the decay of the now extinct 92Nb.

Sanloup, Chrystle; Blichert-Toft, Janne; Tlouk, Philippe; Gillet, Philippe; Albarde, Francis

2000-12-01

63

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

NASA Technical Reports Server (NTRS)

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 defined by Delta-33 = (delta)S-33 -0.50(delta)S-34 and Delta-36 = (delta)s-36 - 1.97 (delta)S-34. From these relationships Delta-33 = 1.24 % and Delta-36 = 0.89 % are observed. These anomalies, particularly the Delta-33, lie well outside the range of analytical uncertainty. They are the largest observed in any meteoritic component and the first found in an organosulfur compound. As discussed by Thiemens and Jackson, due to it's position on the periodic chart, sulfur undergoes chemically induced mass independent isotopic fractionations as does oxygen. Experiments by Mauersberger et. al. show that in such processes, the magnitude of fractionation for the different isotopically substituted species varies with mass and angular momentum; thus, anomalies are expected for both S-33 and S-36, but not necessarily of the same magnitude. Laboratory experiments have also confirmed that chemically produced, mass independent fractionations are mediated by molecular symmetry factors. A chemical source of fractionation requires that the sulfur isotopic anomaly was established in the gas phase, probably in reactions involving symmetric CS2. The discovery of an anomalous sulfur isotopic composition in a specific molecule containing excess deuterium is an important advance in the understanding of the cosmochemistry of sulfur. This evidence suggests that methanesulfonic acid was synthesized by interstellar processes. Further measurements and details of possible synthesis and fractionation mechanisms will be presented.

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

1996-01-01

64

Helium, neon, argon, krypton and xenon in gas emanations from Yellowstone and Lassen volcanic National Parks  

Microsoft Academic Search

The abundance of helium, neon, argon, krypton and xenon were measured in gas emanations from thermal springs in Yellowstone National Park, Wyoming and Lassen National Park, California. The determinations were made using an isotope dilution procedure. The isotopic composition of argon and the relative abundances of argon, neon, krypton and xenon indicate that these gases originated from the atmosphere through

E. Mazor; G. J. Wasserburg

1965-01-01

65

From helium-6 to krypton-81  

NASA Astrophysics Data System (ADS)

A new method of ultrasensitive trace-isotope analysis has been developed based upon the technique of laser manipulation of neutral atoms. It has been used to count individual 85Kr and 81Kr atoms present in a natural krypton sample with isotopic abundances in the range of 10-11 and 10-13, respectively. The atom counts are free of contamination from other isotopes, elements, or molecules. The method is applicable to other trace-isotopes that can be efficiently captured with a magneto-optical trap, and has a broad range of potential applications.

Lu, Zheng-Tian

2001-11-01

66

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

PubMed Central

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 (0.43.9). 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

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

2010-01-01

67

Model Calculations of Continuous-Wave Laser Ionization of Krypton  

SciTech Connect

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.

Bret D. Cannon

1999-07-27

68

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

NASA Astrophysics Data System (ADS)

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.

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

1987-12-01

69

The effect of rising atmospheric oxygen on carbon and sulfur isotope anomalies in the Neoproterozoic Johnnie Formation, Death Valley, USA  

Microsoft Academic Search

Carbonates within the Rainstorm Member in the terminal Neoproterozoic Johnnie Formation of Death Valley, California record a remarkable negative carbon isotope anomaly to a nadir of near ?11 that accompanies a dramatic rise in trace sulfate abundance and fall of carbonate associated sulfate ?34S values. The carbonates, including the laterally extensive Johnnie Oolite, were deposited during marine flooding

Alan J. Kaufman; Frank A. Corsetti; Michael A. Varni

2007-01-01

70

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

Microsoft Academic Search

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 (?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.,

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

1998-01-01

71

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

PubMed

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

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

2015-04-10

72

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

NASA Astrophysics Data System (ADS)

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 Earths 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.

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

2015-04-01

73

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

PubMed

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

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

2013-01-01

74

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

PubMed

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

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

2014-04-15

75

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

NASA Astrophysics Data System (ADS)

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 (?17O = 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 sulfate aerosol to the stratosphere. The new results demonstrate that combined O-triple isotopes and S-quadruple isotopes may help to recognize paleo ENSO events and their impact on the oxidation history of sulfate aerosols. 1. R. Shaheen, M. A., T. Jackson, J. McCabe, J. Savarino, M. H. Thiemens. (2013) A Window to the Paleoclimate- Tales of Volcanoes and El-Nino Southern Oscillations with the Oxygen Isotope Anomaly of Sulfate Aerosols, Proceedings of the National Academy of Sciences of the United States of America. 2. Farquhar, J., Savarino, J., Airieau, S., and Thiemens, M. H. (2001) Observation of wavelength-sensitive mass-independent sulfur isotope effects during SO2 photolysis: Implications for the early atmosphere, Journal of Geophysical Research-Planets 106, 32829-32839.

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

2013-12-01

76

Krypton and xenon in the atmosphere of Venus  

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

77

Calcium Isotopic Anomalies in the Allende CAIs and the Angrite Angra dos Reis  

NASA Astrophysics Data System (ADS)

Both negative 48Ca and 50Ti anomalies of the Angrite Angra dos Reis was identified in this study, and the result supported previous study of correlated negative 54Cr and 50Ti anomalies in achondrites.

Chen, H. W.; Chen, J. C.; Lee, T.; Shen, J. J.

2010-03-01

78

"Carbon Isotope Anomaly in the major Plant C1 Pool and its Biogeochemical Implications"  

E-print Network

;-notation definition Relative Isotope Abundance: Isotopic compositions are usually expressed in term (carbohydrates including cellulose, hemicellulose, pectin) that are combined with lignin with lesser amounts

79

The Dupal isotopic anomaly in the southern Paleo-Asian Ocean: Nd-Pb isotope evidence from ophiolites in Northwest China  

NASA Astrophysics Data System (ADS)

It has been suggested that the Dupal isotopic anomaly in the mantle can be traced in the Paleozoic ophiolites from the Neo- and Paleo-Tethyan Ocean (275-350 Ma). The Karamaili ophiolite (KO) and Dalabute ophiolite (DO) in the eastern and western corners, respectively, of the Junggar basin in NW China represent remnants of the relatively older (> 350 Ma) Paleo-Asian Ocean (PAO) crust. Thus, these ophiolites can provide additional constraints on the long-term composition and evolution of the Paleozoic suboceanic mantle. We present new major-trace element and Sr, Nd and high-precision Pb isotope data for the basalts, gabbros and a plagioclase separate from the KO and DO. Our results indicate that the PAO crust indeed has a Dupal-like isotopic signature. In detail, all samples have relatively low ?Nd(t) and high 208Pb/204Pb(t) for given 206Pb/204Pb(t) ratios (i.e., positive ?8/4 values), similar to the Dupal isotopic characteristics of Indian Ocean mid-ocean ridge basalts (MORB). The trace element signature of DO mafic rocks is similar to that of normal- and enriched-MORB whereas that of the KO is transitional between MORB and arc basalt. Therefore, the DO mantle domain reflects the PAO asthenosphere and the KO domain additionally shows the influence of the subduction process. Geochemical modeling using Th/Nd as well as Nd and Pb isotopic ratios indicates that up to 2% subduction component had been added to a depleted Indian MORB-type mantle to produce the bulk of KO rocks. The subduction component in the KO rocks consisted of variable proportions of ? 1% partial melt of unradiogenic sediment similar to modern Izu-Bonin trench sediment and hydrous fluid dehydrated from the subducted altered oceanic crust. The Devonian asthenospheric mantle beneath the southern PAO is isotopically heterogeneous, but lends support to the idea that the Dupal isotopic anomaly existed prior to the opening of the Indian Ocean. Finally, plate tectonic reconstruction indicates that the anomaly was present in the Neo- and Paleo-Tethyan oceans in the southern hemisphere and in the southern part of PAO in the northern hemisphere during the late Paleozoic.

Liu, Xijun; Xu, Jifeng; Castillo, Paterno R.; Xiao, Wenjiao; Shi, Yu; Feng, Zuohai; Guo, Lin

2014-02-01

80

Krypton Ion Thruster Performance  

NASA Technical Reports Server (NTRS)

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.

Patterson, Michael J.; Williams, George J.

1992-01-01

81

Krypton ion thruster performance  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

82

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

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

83

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

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

84

Optical isotope shift and hyperfine structure measurements in preparation of the ultra-sensitive detection of krypton atoms using stepwise laser excitation and field ionization  

E-print Network

quadrupole moment Q, of nuclei with different nuclear spin I. Observed linewidth compared to individual broadening effects encountered in the present CFBS experiments . . XIII Compilation of isotope sluft data for the investigated stable Kr isotopes..., including underground tests, nuclear power plants and nuclear fuel reprocessing. Mainly a fission product, 5 Kr is also created when converting (breeding) ' U or U into Pu. Some of the production mechanisms are: 255 U 149B ssmK + 2 21. 149B 55Kr+ 2 +n...

Lassen, Jens

1996-01-01

85

Decay of 48-50Ar isotopes  

NASA Astrophysics Data System (ADS)

Information on ?-decay properties of neutron-rich 48-50Ar was obtained at the ISOLDE mass-separator facility at CERN using isobaric selectivity. This was achieved by a combination of a plasma-ion source with a cooled transfer line and subsequent mass-separation. Normally, argon beams cannot be mass-separated from intense multi-charged symmetric fission krypton and xenon. Several techniques were used successfully in order to overcome this problem. Implication of the obtained information for a better understanding of the origin of the 48Ca/46Ca isotopic anomaly discovered in inclusions from the Allende meteorite is discussed.

Weissman, L.; Bergmann, U.; Cederkall, J.; Fraile, L.; Franchoo, S.; Fynbo, H. O. U.; Fritioff, T.; Koster, U.; Arnd, O.; Dillman, I.; Hallmann, O.; Kratz, K.-L.; Pfeiffer, B.; Wohr, A.; Gaudefroy, L.; Sorlin, O.; ISOLDE Collaboration

2012-02-01

86

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

SciTech Connect

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.

Burkhardt, Christoph; Wieler, Rainer [Institute of Geochemistry and Petrology, Clausiusstrasse 25, ETH Zurich, CH-8092 Zurich (Switzerland); Kleine, Thorsten [Institut fuer Planetologie, Westfaelische Wilhelms-Universitaet Muenster, Wilhelm-Klemm-Strasse 10, D-48149 Muenster (Germany); Dauphas, Nicolas, E-mail: burkhardt@erdw.ethz.ch [Origins Laboratory, Department of the Geophysical Sciences and Enrico Fermi Institute, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637 (United States)

2012-07-01

87

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

USGS Publications Warehouse

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.

Tatsumoto, M.; Nakamura, Y.

1991-01-01

88

Nuclear structure of the Z = 35 isotopes bromine-75,77 and the N = 41 isotones selenium-75 and krypton-77  

NASA Astrophysics Data System (ADS)

High-spin states in the Z = 35 isotopes, 77Br and 75Br, and the N = 41 isotones 77Kr and 75Se were studied for the purpose of investigating three-quasiparticle bands. Three fusion-evaporation thin- target experiments were performed. Two were with beams supplied by the FSU Tandem/LINAC accelerator facility: 65Cu(18O,/alpha 2n)77Br at 65 MeV and 48Ti(30Si,2pn;p2n)75Se;75Br at 90 MeV. These experiments used the FSU/PITT Ge detector array for the collection of ?-? coincidence data. Beam for the third experiment, 58Ni(29Si,2/alpha 2p)77Kr at 128 MeV, was provided by the 88-inch cyclotron at Lawrence Berkeley National Laboratory, with data acquisition by the G sc AMMASPHERE and M sc ICROBALL detector arrays. Construction of level schemes, assignments of decays, excitation energies, spins and parities were achieved through examination of coincidence data, relative intensity measurements and angular correlation analysis. Level inversion was exhibited by the yrast positive- parity structures of the bromine isotopes, with unfavored sequences investigated as a measure of tri-axiality. Extra g9/over 2 bands were found in the positive- parities of the bromine isotopes, and have been interpreted using Particle-Rotor Coupling calculations. Unusual band structures were found in the negative parity sequences of the N = 41 isotones. These bands appear highly deformed and in 77Kr become yrast at high spin. An Orphan band, which is a M1 dominated decay sequence, with little or no intra-band E2 decays, is studied in 77Br. A 3qp structure based on deformation-driving, low-K unique-parity and intruder orbitals is suggested for these negative-parity bands in 77Br, 75Se, and 77Kr. Analysis of the M sc ICROBALL charged-particle data required the development of particle-gating codes, which were used in the reduction of the 77Kr data. Continuing this line of analysis, algorithms for kinematic-correction of Doppler-shifted ?-decays were developed by the author, which were used in the reduction of G sc AMMASPHERE data of the 76,78Kr and 80Sr isotopes. Techniques for neutron channel selection were also developed. Additions to the level schemes of various secondary products of the 48Ti(30Si,xpynz/alpha) reaction are also included.

Solomon, Geoffrey Zebrack

1998-10-01

89

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

NASA Astrophysics Data System (ADS)

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. Finally, this work demonstrates that hp krypton-83 MRI of intact, excised lungs is feasible. No attempts have been made to observe pathology specific contrast, but this work represents the first steps in developing hp krypton into a useful biomedical tool. Although the signal must be improved for biomedical applications, additional enhancements of up to 180 times greater than the currently obtained signal are possible through improved SEOP, and another order of magnitude increase can be obtained through isotopic enrichment.

Cleveland, Zackary I.

90

Atom Trap, Krypton-81, and Egypt  

NASA Astrophysics Data System (ADS)

We have improved our atom-counting system with the goal of realizing ^81Kr-dating of ancient groundwater and polar ice. We use Atom Trap Trace Analysis (ATTA) to count individual ^85Kr (t_1/2 = 10.8 yr) and ^81Kr (t_1/2 = 2 times 10^5 yr) atoms present in a natural krypton gas sample with isotopic abundances in the range of 10-11 and 10-13, respectively. The counting efficiency demonstrated with our first-generation machine was 2 10-7. By implementing a RF-driven discharge source of metastable krypton atoms and by adding a gas recirculation system, we can increase the counting efficiency by at least three orders of magnitude. These improvements will allow us to perform Kr81-dating of ancient groundwater samples, which requires a counting efficiency of 10-4. The calibration of the system is in progress. Collaborating with an international team of geologists, we plan to extract water samples in Nubian Aquifer of Egypt and determine the age of groundwater in that area with our ATTA system. Details of the latest results will be discussed at this poster. This work is supported by the U.S. Department of Energy under contract W-31-109-ENG-38.

Du, Xu; Bailey, Kevin; Lu, Zheng-Tian; Mueller, Peter; O'Connor, Thomas; Young, Linda

2002-05-01

91

LARGE NITROGEN ISOTOPIC ANOMALIES IN ANTARCTIC MICROMETEORITES. P. Haenecour1,2  

E-print Network

solar values for the bulk AMM, and the N and C isotopic compositions were normalized to synthetic Si3N4 is more consistent with those typically ob- served in presolar Si3N4 and some SiC grains [8]. However

92

Isotope Anomalies in the Fe-group Elements in Meteorites and Connection to Nucleosynthesis in AGB Stars  

E-print Network

We study the effects of neutron captures in AGB stars on \\oq Fe-group\\cqb elements, with an emphasis on Cr, Fe, and Ni. These elements show anomalies in $^{54}$Cr, $^{58}$Fe, and $^{64}$Ni in solar-system materials, which are commonly attributed to SNe. However, as large fractions of the interstellar medium (ISM) were reprocessed in AGB stars, these elements were reprocessed, too. We calculate the effects of such reprocessing on Cr, Fe, and Ni through 1.5\\msb and 3\\msb AGB models, adopting solar and 1/3 solar metallicities. All cases produce excesses of $^{54}$Cr, $^{58}$Fe, and $^{64}$Ni, while the other isotopes are little altered; hence, the observations may be explained by AGB processing. The results are robust and not dependent on the detailed initial isotopic composition. Consequences for other \\oq Fe group\\cqb elements are then explored. They include $^{50}$Ti excesses, and some production of $^{46,47,49}$Ti. In many circumstellar condensates, Ti quantitatively reflects these effects of AGB neutron cap...

Wasserburg, Gerald J; Busso, Maurizio

2015-01-01

93

JOURNAL DE PHYSIQUE CoZZoque C8, suppZ6ment au n08, Tome 41, aotit 1980, pageC8-886 ARE AMORPHOUS ALLOYS SUITABLE AS A STORAGE MATRIX FOR F I S S I O N PRODUCT KRYPTON ?  

E-print Network

ALLOYS SUITABLE AS A STORAGE MATRIX FOR F I S S I O N PRODUCT KRYPTON ? H.J. Schmidt, E. enrich*, T without One ton of spent LWR-fuel contains about 1 m3 fis- pressure, accumulating only a small krypton. krypton. The radioactive xenon - isotops are de- The implantation process and the properties of cri- cayed

Paris-Sud XI, Université de

94

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

PubMed

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-Nio 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

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

2013-10-29

95

Tales of volcanoes and El-Nio southern oscillations with the oxygen isotope anomaly of sulfate aerosol  

PubMed Central

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 Earths 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 (19802002) 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-Nio 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

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

2013-01-01

96

Extreme Carbon Isotope Anomalies of the Proterozoic Eon: Fact or Fiction?  

NASA Astrophysics Data System (ADS)

Post-Paleozoic carbon isotope variations constructed from time-series analyses of calcareous microfossils generally pale in comparison with the extreme variations recorded in Paleozoic and Proterozoic aged successions. The latter are primarily preserved in fine-grained inorganic carbonates, which due to their great antiquity and potential for diagenetic alteration have been viewed by some as imperfect recorders of seawater chemistry. In part, this bias stems from the study of Modern carbonate platforms, where significant carbon isotope variations result from vital effects, bioturbation, and sea grass aeration of sediments. In addition, the open framework of biotic reefs allows for the infiltration of diagenetic fluids through lithified platforms. None of these biological issues, however, applies to Proterozoic carbonate accumulations, which are generally fine-grained and pervasively cemented. While geochemical tests of diagenetic alteration have been used for Proterozoic samples (e.g., ?18O, ??13C, and Mn/Sr), they have been variably applied and appear as moving targets from basin to basin, if reported at all. Greatest confidence in the validity of carbon isotope trends come from stratigraphic measurements that reveal smooth ?13C variations, and the comparative analysis of multiple, broadly equivalent basins. For both the Neoproterozoic and the Paleoproterozoic these show profound changes in carbon isotope distribution with time, especially related to widespread paleoclimatic and biotic events. High resolution stratigraphic and geochemical studies of carbonate and co-existing organic matter in post-glacial Neoproterozoic cap carbonates from Namibia and Brazil, and of Ediacaran aged successions in the western USA, South China, and elsewhere provide new insight into extremes of the ancient carbon cycle. On the one hand, the standard model of proportional fluxes is consistent with detailed observations of the cap carbonates. However, there is also strong evidence for carbon limitation to photoautotrophs in the immediate glacial aftermath, and of an unusually strong surface-to-deep ?13C gradient. On the other hand, the standard model is difficult to reconcile with the > -10 carbon isotope excursions in the Ediacaran Period. These require an additional source of 13C depleted alkalinity, which based on the invariance of the organic carbon isotope record support the idea that Proterozoic seawater was buffered by a proportionally larger DOC pool until very near the end of the eon.

Kaufman, A. J.

2008-12-01

97

In-Beam Gamma-Ray Spectroscopy of KRYPTON-80 and SELENIUM-70 and Coulomb Excitation Studies of Light Mass Neodymium Isotopes.  

NASA Astrophysics Data System (ADS)

The levels of ('80)Kr have been investigated using in-beam (gamma)-spectroscopy techniques via the ('70)Zn(('12)C,2n)('80)Kr reaction with 38.4 MeV ('12)C ions. The energies, relative intensities and angular distributions of the (gamma)-rays were measured. The proposed level scheme shows four bands; three of even-parity and one of odd-parity. Two-quasi -particle-plus-rotor calculations for ('80)Kr suggest that the even-parity band built on the (8('+)) state at 3701.6 keV has primarily a proton (g(,9/2))('2) configuration and the odd-parity band built on the 5('-) state at 2861.0 keV has an essentially pure two-quasi-proton (f(,5/2),g(,9/2))5(' -) configuration. The observed back-bending in the Yrast band is attributed to the crossing of the ground band and the excited positive-parity band. The level structure of ('70)Se was studied via ('58)Ni(('14)N,pn)('70)Se reaction at a beam energy of 38 MeV. Measurements were made of (gamma)-ray angular distributions and (gamma)-(gamma) coincidence spectra, (gamma)-ray angular distributions and (gamma)-(gamma) directional correlations. Level energies, decay modes, spins and parities, (gamma)-ray radiative admixtures and (gamma)-ray branching ratios were deduced. The levels in the Yrast band through 8('+), a second 0('+), state at 2011.2 keV, and a 3('-) state at 2519.2 keV are some of the new results obtained from the present investigation. The moment-of-inertia plot show a break around 6('+) for the Yrast levels, which is attributed to band crossing. IBA calculations were performed, and the results show good agreement with the experimental values. Coulomb excitation studies of even-even Nd isotopes have been done by using ((alpha),(alpha)') experiments. Semi -classical codes were used to determine the E2 and/ or E4 moments (in case of ('150)Nd).

Ahmed, Abuzeid Younis

98

The astrophysical interpretation of isotope anomalies in graphite and SiC grains of chondrites  

NASA Technical Reports Server (NTRS)

The C, N, and Mg isotopic compositions in graphite and SiC grains of carbonaceous chondrites can be explained by nuclear processes in massive O,B stars of second generation passed a stage of WR star with intensive stellar wind, where grain condensation had taken place. The interstellar graphite and SiC grains with anomalous isotopic compositions of C, N, Ne, and Si and other elements of nucleosynthetic origin, found in non-equilibrated chondrites, are most suitable for determination of astro-physical objects, where nucleosynthesis had taken place. Two objects were examined: (1) massive O,B stars of second generation passed a stage of WR star with intensive stellar wind (O,B-WR model) and (2) low-mass stars (1 less than or equal to M/solar mass less than or equal to 3) during thermally pulsing asymptotic giant branch phase (TP-AGB model).

Lavrukhina, A. K.

1993-01-01

99

Stratigraphic investigations of carbon isotope anomalies and Neoproterozoic ice ages in Death Valley, California  

Microsoft Academic Search

An unusual richness of biogeochemical events is recorded in Neoproterozoic- Cambrian strata of the Death Valley re- gion, California, United States. Eight neg- ative carbon isotope (d13C) excursions are found in carbonate units between 1.08 Ga and the Precambrian\\/Cambrian boundary; four of these excursions occur in carbonates that contain textural features similar to those found globally in postglacial ''cap carbonates''

Frank A. Corsetti; Alan J. Kaufman

2003-01-01

100

Finding of probable Tunguska Cosmic Body material:. isotopic anomalies of carbon and hydrogen in peat  

NASA Astrophysics Data System (ADS)

Method of a search for traces of Tunguska Cosmic Body (TCB) material using layer-by-layer analysis of the isotopic composition of light elements in peat has been offered. Four peat columns sampled at the explosion epicentre indicated significant carbon and hydrogen isotopic effects in its near catastrophic layers. The shifts, opposite in direction, for carbon (? 13C reaches +4.3) and hydrogen (?D reaches -22) cannot be attributed to any known terrestrial reasons (fall-out of terrestrial dust and fire soot; emission from the Earth of oil-gas streams; climate changes, humification of peat, and so on). Moreover, the isotopic effects are clearly associated with the area and with the time of the 1908 event. They are absent in the uppermost and the lowest peat layers and also in the control peat columns sampled at the remote places. Since calculated ?13C value for an admixture of carbon (+51-64) is very high, these effects may not be explained by contamination of peat with material similar to ordinary chondrites or achondrites, too. Such heavy carbon occurs in the most primitive CI and CM types of carbonaceous chondrites. However, C/Ir ratio in a cosmic admixture is 10,000 times as many as in CI chondrites that points to cometary nature of the TCB. The isotopic effects are in agreement with the increase of the Ir content observed in peat, but, at the same time, small content of Ir points to the low content of dust in the Tunguska comet that sharply differs it from Halleys comet.

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

1999-06-01

101

Experimental Investigation of Continuous-Wave Laser Ionization of Krypton  

SciTech Connect

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

Cannon, Bret D.; Shannon, Robert F.

2001-10-30

102

Atom Trap, Krypton-81, and Egypt  

NASA Astrophysics Data System (ADS)

We are developing the Atom Trap Trace Analysis (ATTA) method for the analysis of two long-lived rare krypton isotopes, ^81Kr (t_1/2=2.3 10^5 years, I.A. 10-13) and ^85Kr (t_1/2=10.8 years, I.A. 10-11). ^81Kr analyses can be used to determine the ages of old ice and groundwater in a range (5 10^4 - 2 10^6 years) beyond the reach of radio-carbon dating; Analyses of ^85Kr , a fission product of uranium and plutonium, can serve as a means to help verify compliance with the Nuclear Non-Proliferation Treaty. In ATTA, individual atoms of the desired isotope are selectively captured into a laser trap and detected by observing the fluorescence of trapped atoms. The first application of ATTA is dating the ancient groundwater of the Nubian Aquifer underneath the Western Desert of Egypt. This is one of the largest aquifers in the world. The residence time of its water are of great interest in fundamental geology as well as for utilitarian reasons. This work marks the beginning of a useful tool in Earth sciences. * This work is supported by the U.S. Department of Energy, Division of Nuclear Physics, under contract W-31-109-ENG-38.

Lu, Zheng-Tian

2003-10-01

103

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

NASA Astrophysics Data System (ADS)

We studied Albian-Cenomanian paleoceanic carbonate-siliceous deposits of the Kamchatsky Mys Peninsula (Eastern Kamchatka, Russia). They are deposited in association with pillow-basalts and hyaloclastites. The thickness of the studied section is about 10 m. The deposits are represented mainly by rhythmical intercalation of red-brown radiolarian jaspers, pink nannoplankton limestones as well as siliceous limestones. In the middle and upper parts of the section there are two beds enriched by organic carbon. The largest organic matter contents in this beds amount to 68%. The calculated values of the hydrogen and oxygen indexes indicate that the carbonaceous beds consist of marine organic matter. The accumulation of the carbonaceous beds reflects oxygen depletion in intermediate oceanic waters (ocean anoxic events, OAE). The structure of the studied section emphasizes its similarity to the contemporary deposits recovered by ODP and DSDP sites on Hess and Shatsky Rises. Two orders of rhythmicity were observed in the section. The rhythmicity of the first order (average thickness of a rhythm is 5-7 cm) is an alternation of reddish brown radiolarian jaspers and pink nannofossil limestones. The rhythmicity of the second order is characterized by an increase in thickness of the jasper or limy layer in every 4th-5th rhythm of the first order and marked by an elevation of the silica content in calcareous layers. The rhythmicity formation can be attributed to fluctuation of astronomical parameters (Milankovitch cycles) with periods of 21 and 100 kyr. The character of atmospheric circulation and ocean currents served as transmission link. The section was sampled layerwise and more than 100 samples were taken. The radiolarians were extracted from the samples of jaspers and siliceous limestones lying between carbonaceous beds. The educed radiolarian complexes allowed us to define the age of the deposits as Cenomanian. For more detailed dating of members of the section we have 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).

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

2012-04-01

104

The triple point of krypton  

NASA Astrophysics Data System (ADS)

Phase transitions of pure substances provide the key reference temperatures, otherwise known as "defining fixed points", of the International Temperature Scale. At temperatures below the triple point of mercury (234.3156 K), the substances involved are gases at room temperature and include the triple points of hydrogen (13.8033 K), neon (24.5561 K), oxygen (54.3584 K) and argon (83.8058 K). The Consultative Committee for Thermometry also provides a list of "secondary reference points" whose quality approaches (or is equivalent to) that of the defining fixed points of the ITS Here, we report direct measurements of the triple point of krypton on the ITS-90, review the historical measurements that CCT WG2 relied upon for its 1996 assessment, and demonstrate that the triple point of krypton is a "first quality" secondary reference point. Based on our measurements, the temperature of the triple point of krypton is 115.7755 K 0.3 mK (k=1).

Hill, K. D.

2013-09-01

105

The effect of rising atmospheric oxygen on carbon and sulfur isotope anomalies recorded in the Neoproterozoic Johnnie Formation, Death Valley, USA  

NASA Astrophysics Data System (ADS)

Carbonates within the Rainstorm Member in the terminal Neoproterozoic Johnnie Formation of Death Valley, California record a remarkable negative ? 13C anomaly to a nadir of near -11 , accompanied by a dramatic rise in trace sulfate abundance (>500 ppm) and drop in carbonate associated sulfate ? 34S values from 26.6 to 15.8 . The carbonates, including the laterally extensive Johnnie Oolite, were deposited during marine flooding atop a sequence boundary best observed in cratonward sections. A similarly dramatic carbon isotope anomaly is recorded in broadly equivalent successions that post-date known Marinoan glacial deposits and pre-date the Precambrian-Cambrian boundary in Oman, India, China, Australia, and Namibia. The cause of the carbon and sulfur isotopic excursions was likely associated with a rise in atmospheric O2, which resulted in 1) the oxidation of exposed continental shelf sediments rich in fossil organic matter and sulfides, providing a source of 12C, 32S, and sulfate; and 2) the ventilation of the oceans. Large metazoan fossils (Ediacaran animals) first appear directly above this anomaly, suggesting that a critical threshold with respect to atmospheric O2 had been crossed at this time. A negative ? 13C excursion of similar magnitude occurs in overlying strata at the Precambrian-Cambrian boundary, which may reflect similar processes.

Kaufman, A. J.; Corsetti, F. A.

2004-12-01

106

Atmospheric Krypton and Xenon Measurements from Mars Science Laboratory  

NASA Astrophysics Data System (ADS)

The heavy noble gases krypton and xenon are important tracers of planetary processes from accretion to differentiation and to atmospheric escape. Their abundance and stable isotopic ratios are also indicative of sources as well. The Sample Analysis at Mars (SAM) investigation on the Curiosity rover has measured the Martian atmosphere and reported on the volume mixing ratio of its major constituents (Mahaffy et al., 2013). Here we report the abundance and isotopic ratios of Kr and Xe in the atmosphere of Mars as obtained by semi-static operation of the SAM quadrupole mass spectrometer. Viking provided the first in situ detection of these gases (Owen et al, 1977), suggesting upper limits of 300 ppb for Kr and 80 ppb for Xe, based upon calibration gases with terrestrial isotopic abundances. The abundances of individual isotopes as well as their ratios to one another have been derived from martian meteorite samples by many investigators (e.g., Becker & Pepin, 1984; Bogard & Garrison, 1998). The SAM heavy noble gas data complement the argon isotopic data reported in Mahaffy et al., 2013. Becker, R. H., & Pepin, R. O. (1984). The case for a Martian origin of the shergottites: Nitrogen and noble gases in EETA 79001. Earth and Planetary Science Letters, 69(2), 225-242. Bogard, D. D., & Garrison, D. H. (1998). Relative abundances of argon, krypton, and xenon in the Martian atmosphere as measured in Martian meteorites. Geochimica et cosmochimica acta, 62(10), 1829-1835. Mahaffy, et al., (2013) Abundance and isotopic composition of gases in the martian atmosphere from the Curiosity rover. Science 341, 263-266 Owen, T. et al.,(1977). The composition of the atmosphere at the surface of Mars. Journal of Geophysical research, 82(28), 4635-4639.

Conrad, P. G.; Malespin, C. A.; Franz, H.; Manning, H. L.; Trainer, M. G.; Wong, M. H.; Brunner, A.; Atreya, S. K.; Pepin, R. O.; Jones, J. H.; Owen, T. C.; Mahaffy, P. R.

2013-12-01

107

Ultrasensitive isotope trace analyses with a magneto-optical trap  

PubMed

Laser manipulation of neutral atoms has been used to count individual krypton-85 and krypton-81 atoms present in a natural krypton gas sample with isotopic abundances in the range of 10(-11) and 10(-13), respectively. This method of isotope trace analysis 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(-7). System improvements could increase the efficiency by many orders of magnitude. PMID:10550048

Chen; Li; Bailey; O'Connor; Young; Lu

1999-11-01

108

Krypton-85 in the atmosphere  

E-print Network

Measurement results are presented on 85Kr content in the atmosphere over the European part of Russia in 1971-1995 based on the analysis of the commercial krypton, which is separated from air by industrial plants. Our results are by 15 per cent lower then 85Kr activites observed over West Europe. According our prediction by 2030 85Kr content in the atmosphere over Europe will amount to 1,5-3 Bq in m3 air. Average 85Kr release to the atmosphere from regeneration of spent nuclear fuel (SNF) is estimated, some 180 TBq per a ton SNF. It is advisable to recommence monitoring of 85Kr content within Russia.

Korsakov, A T

2013-01-01

109

Krypton-85 in the atmosphere  

E-print Network

Measurement results are presented on 85Kr content in the atmosphere over the European part of Russia in 1971-1995 based on the analysis of the commercial krypton, which is separated from air by industrial plants. Our results are by 15 per cent lower then 85Kr activites observed over West Europe. According our prediction by 2030 85Kr content in the atmosphere over Europe will amount to 1,5-3 Bq in m3 air. Average 85Kr release to the atmosphere from regeneration of spent nuclear fuel (SNF) is estimated, some 180 TBq per a ton SNF. It is advisable to recommence monitoring of 85Kr content within Russia.

A. T. Korsakov; E. G. Tertyshnik

2013-07-09

110

Seismically triggered anomalies in the isotope signatures of mantle-derived gases detected at degassing sites along two neighboring faults in NW Bohemia, central Europe  

NASA Astrophysics Data System (ADS)

The Vogtland and NW Bohemia region is known for its earthquake swarms; the most intensive swarm since 1985/86 occurred in October 2008. To find further indications for the interaction of ascending mantle-derived fluids and the occurrence of earthquake swarms, detailed fortnightly studies of gas compositions (CO2, N2, Ar, He, H2, and CH4) and isotope ratios (?13C, ?15N, and 3He/4He) were carried out between October 2008 and April 2011 at four locations close to the Nov Kostel focal zone and at the Wettinquelle spring (Bad Brambach). From the start of the 2008 earthquake swarm seismically induced isotope-geochemical anomalies were recorded at locations along the Po?atky-Plesn fault zone (PPZ) and were, for the first time, also found at degassing locations on the Marinsk Lzn? fault zone (MLF). Variations were observed in both the temporal and spatial distributions of the anomalies as well in anomaly strengths, probably due to the positions of these fault zones relative to the focal zone, and to differences in fluid migration pathways. Prior to both the 2000 and 2008 swarms, 3He/4He ratios > 6 Ra were recorded at the Bublk mofette. These anomalous pre-seismic 3He/4He ratios suggest that both the 2000 and 2008 swarms may have been associated with the supply of fresh magma from a less degassed reservoir in the lithospheric mantle. The temporal ?13CCO2 pattern from detailed studies at Bublk between 2005 and 2011 indicates progressive magma degassing, as well as seismically induced variations in the ?13C, providing additional support to the interpretation derived from the 3He/4He ratios.

Bruer, Karin; Kmpf, Horst; Strauch, Gerhard

2014-07-01

111

Krypton based adsorption type cryogenic refrigerator  

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

112

Krypton based adsorption type cryogenic refrigerator  

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

113

Isotopic Characterization of Lavas from the Great Meteor, Hyeres and Plato Seamounts: Influence of the Azores Mantle Anomaly  

Microsoft Academic Search

Dredging operations were performed south of the Azores Archipelago, during LEG 2 of cruise EMEPC\\/Aores\\/G3\\/2007, and lava samples (basalts s.l.) were recovered on the Great Meteor, Hyeres and Plato seamounts (Loureno et al., 2008). The resulting new isotopic data (Sr, Nd, Pb) is reported and compared with the existing isotopic signature of the Azores Region. The studied lavas exhibit porphyritc

L. P. Ribeiro; P. Madureira; N. Loureno; F. Pimentel; M. P. Abreu

2008-01-01

114

Preferential site occupancy observed in coexpanded argon-krypton clusters  

SciTech Connect

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.

Lundwall, M.; Bergersen, H.; Lindblad, A.; Oehrwall, G.; Svensson, S.; Bjoerneholm, O. [Department of Physics, Uppsala University, Box 530, SE-751 21 Uppsala (Sweden); Tchaplyguine, M. [MAX-lab, Lund University, P.O. Box 118, SE-221 00 Lund (Sweden)

2006-10-15

115

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

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

116

Isotope anomalies of carbon, hydrogen and nitrogen in peat from the area of the tunguska cosmic body explosion (1908).  

PubMed

Abstract Peat profiles from the area of the Tunguska explosion epicentre indicate significant carbon and hydrogen isotopic effects which are clearly associated with the zone of the 1908 "catastrophe", and which cannot be attributed to any known terrestrial processes. We explain them with the presence of extraterrestrial matter similar to carbonaceous chondrites or, more probably, to cometary matter. Initial data on nitrogen content and its isotope composition are consistent with the assumption of acid rainfall following the passage and explosion of the Tunguska cosmic body, as is known to have occurred during the Cretaceous-Tertiary boundary. PMID:21892866

Kolesnikov, E M; Bttger, T; Hiller, A; Junge, F W; Kolesnikova, N V

1996-12-01

117

SST Anomalies + Wind Anomalies  

NSDL National Science Digital Library

Sea surface temperature (SST) anomalies and sea surface wind anomalies show the development of the 2002-2003 El Nino based on data from NASAs Aqua and QuikSCAT spacecraft. The wind data has been processed using the Variational Analysis Method (VAM).

Greg Shirah

2003-02-03

118

Isotope Anomalies of Carbon, Hydrogen and Nitrogen in Peat from the Area of the Tunguska Cosmic Body Explosion (1908)  

Microsoft Academic Search

Peat profiles from the area of the Tunguska explosion epicentre indicate significant carbon and hydrogen isotopic effects which are clearly associated with the zone of the 1908 catastrophe, and which cannot be attributed to any known terrestrial processes. We explain them with the presence of extraterrestrial matter similar to carbonaceous chondrites or, more probably, to cometary matter. Initial data on

E. M. Kolesnikov; T. Bttger; A. Hiller; F. W. Junge; N. V. Kolesnikova

1996-01-01

119

Isotopic Characterization of Lavas from the Great Meteor, Hyeres and Plato Seamounts: Influence of the Azores Mantle Anomaly  

NASA Astrophysics Data System (ADS)

Dredging operations were performed south of the Azores Archipelago, during LEG 2 of cruise EMEPC/Aores/G3/2007, and lava samples (basalts s.l.) were recovered on the Great Meteor, Hyeres and Plato seamounts (Loureno et al., 2008). The resulting new isotopic data (Sr, Nd, Pb) is reported and compared with the existing isotopic signature of the Azores Region. The studied lavas exhibit porphyritc and vesicular textures and a phenocryst assemblage of olivine, clinopyroxene, plagioclase and oxides in variable proportions, which are immersed in a microcrystalline matrix dominated by plagioclase and oxides. The samples with MgO > 6% are alkaline basalts and basanites, presenting enrichment in LREE, with average (La/Sm)n ratios of 2.4 and (La/Yb)n ratios ranging between 8.1 and 15.1 (Madureira et al., 2008) . Also spiderdiagrams evidences Nb and Ta enrichment over LILE, typical of OIB with HIMU affinity (Weaver, 1991). The Sr and Nd isotopic ratios fall within the Azores isotopic signature, in particular that of the central island group. Such ratios follow a compositional trend extending from enriched MAR basalts towards lavas with a stronger HIMU component. The lead isotopes plot below the NHRL, with 7/4 ranging between -1.45 and -5.72 and 8/4 between -1.0 and -8.63. It is also noteworthy, that the 206Pb/204Pb isotopic ratio increases with latitude (19.44-19.87 in Great Meteor basalts to 20.11-20.17 in Plato samples). The increase in 206Pb/204Pb isotopic ratio with latitude is interpreted as the result of an increase of the influence of the Azores mantle domain (White et al. 1976) in agreement with Gente et al., (2003) proposal of a long-lived interaction (85 Ma) between the MAR and the Azores enriched mantle source, with the migration of the later towards NNE. Loureno et al. 2008 GRA, vol. 10 Gente et al., G3, vol. 10. Madureira et al., 2008 GRA, vol. 10. Weaver, B.L. 1991 EPSL 104, 381-397. White et al. 1976 Nature, 263.

Ribeiro, L. P.; Madureira, P.; Loureno, N.; Pimentel, F.; Abreu, M. P.; E @ Team

2008-12-01

120

Natural versus anthropogenic sources in the surface- and groundwater dissolved load of the Dommel river (Meuse basin): Constraints by boron and strontium isotopes and gadolinium anomaly  

NASA Astrophysics Data System (ADS)

SummaryThe river Dommel, a tributary of the Meuse River, drains an area of intensive agriculture (livestock farming, maize and grassland over 50% of the basin), and a dense population of about 600,000 people representing 20% of the total area. The combined human activities in the Dommel catchment lead to a large amount of dissolved elements and compounds released in surface- and groundwaters. The aim of this study was to discriminate the natural (including infiltration of Meuse water) versus anthropogenic sources of the dissolved load, and to identify the various pollution sources such as agriculture, industrial activity, and wastewater treatment plants, using geochemical tools including major- and trace elements, Sr and B isotopes, and rare earth elements (REE). For that purpose, a same-day geochemical "Snapshot" picture of the entire basin was combined with monthly monitoring in strategic points. The major- and trace elements analyses allowed discriminating the main pollution sources affecting the basin, i.e. point versus diffuse sources. Strontium isotopes helped to identify each tributary and to calculate mixing proportions. Combining these calculations with the Sr-isotopic data obtained from the "Snapshot" sampling campaign during a low-flow period, shows that Meuse water infiltration represents 25% of the total Dommel discharge. Boron isotopes used for assessing the amount of water affected by anthropogenic input cannot discriminate between the two main anthropogenic inputs, i.e. urban wastewater and the zinc-smelter effluent, as they have similar ?11B values. Finally, the REE, and especially the use of Gd anomalies (Gd ?), demonstrated the generalized impact of urban wastewater on the streams of the Dommel Basin. The coupled use of different geochemical tracers (Sr and B isotopes together with Gd ?) in addition to the standard major-element analyses, led to discriminating the various anthropogenic components influencing the Dommel Basin water quality. With these tools it also became possible to assess the complex water circulation and exchanges between water compartments, including the major role of Meuse water through the Bocholt-Herenthals canal.

Petelet-Giraud, Emmanuelle; Klaver, Gerard; Negrel, Philippe

2009-05-01

121

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

NASA Astrophysics Data System (ADS)

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.

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

1988-05-01

122

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

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

123

Detection of krypton in xenon for dark matter applications  

E-print Network

We extend our technique for observing very small concentrations of impurities in xenon gas to the problem of krypton detection. We use a conventional mass spectrometer to identify the krypton content of the xenon, but we improve the sensitivity of the device by about five orders of magnitude with a liquid nitrogen cold trap. We find that the absolute krypton concentration of the xenon can be inferred from the mass spectrometry measurements, and we identify krypton signals at concentrations as low as 0.5x10^{-12} mol/mol (Kr/Xe). This technique simplifies the monitoring of krypton backgrounds for WIMP dark matter searches in liquid xenon.

Dobi, Attila; Hall, Carter; Langford, Thomas; Slutsky, Simon; Yen, Yung-Ruey

2011-01-01

124

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)

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-Prot 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-Prot 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 87?85(4 D5 /2 ) is derived to be -0.0041 0.0009.

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

2014-11-01

125

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

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

126

Krypton Fluoride Laser Driven Inertial Fusion Energy  

E-print Network

1 Krypton Fluoride Laser Driven Inertial Fusion Energy Presented to NAS Committee on the Prospects breeding Reaction chamber Electricity or Hydrogen Generatortarget target factory Laser Array Final optics Fluoride (KrF) Laser? · Gas Laser--Excimer (Excited Dimer) · Fundamental wavelength is 248 nm · Energy

127

Heterogeneous Isotopic Anomalies of Sm and Gd in the Norton County Meteorite: Evidence for Irradiation from the Active Early Sun  

NASA Astrophysics Data System (ADS)

Large and heterogeneous isotopic variations of 150Sm/149Sm and 158Gd/157Gd 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 (Mg2Si2O6), have a very large neutron fluence of 1.98 1017 n cm-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 1016 to 1.87 1017 n cm-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.

Hidaka, Hiroshi; Kondo, Tomoyo; Yoneda, Shigekazu

2012-02-01

128

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

SciTech Connect

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.

Hidaka, Hiroshi; Kondo, Tomoyo [Department of Earth and Planetary Systems Science, Hiroshima University, Higashi-Hiroshima 739-8526 (Japan); Yoneda, Shigekazu, E-mail: hidaka@hiroshima-u.ac.jp [Department of Science and Engineering, National Museum of Nature and Science, Tokyo 169-0073 (Japan)

2012-02-20

129

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

Code of Federal Regulations, 2014 CFR

...Self-luminous products containing tritium, krypton-85, or promethium-147. 30.19...Self-luminous products containing tritium, krypton-85, or promethium-147. (a...self-luminous products containing tritium, krypton-85, or promethium-147,...

2014-01-01

130

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

Code of Federal Regulations, 2011 CFR

...Self-luminous products containing tritium, krypton-85, or promethium-147. 30.19...Self-luminous products containing tritium, krypton-85, or promethium-147. (a...self-luminous products containing tritium, krypton-85, or promethium-147,...

2011-01-01

131

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

Code of Federal Regulations, 2013 CFR

...Self-luminous products containing tritium, krypton-85, or promethium-147. 30.19...Self-luminous products containing tritium, krypton-85, or promethium-147. (a...self-luminous products containing tritium, krypton-85, or promethium-147,...

2013-01-01

132

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

Code of Federal Regulations, 2010 CFR

...Self-luminous products containing tritium, krypton-85, or promethium-147. 30.19...Self-luminous products containing tritium, krypton-85, or promethium-147. (a...self-luminous products containing tritium, krypton-85, or promethium-147,...

2010-01-01

133

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

Code of Federal Regulations, 2012 CFR

...Self-luminous products containing tritium, krypton-85, or promethium-147. 30.19...Self-luminous products containing tritium, krypton-85, or promethium-147. (a...self-luminous products containing tritium, krypton-85, or promethium-147,...

2012-01-01

134

Factors Affecting the Efficiency of Krypton Hall Thrusters  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

135

Krypton adsorption on (0001) graphite pre-plated with cyclohexane  

E-print Network

91 Krypton adsorption on (0001) graphite pre-plated with cyclohexane A. Razafitianamaharavo (1), N juin 1989, accepté sous forme définitive le 20 septembre 1989) Résumé. 2014 La physisorption de krypton étudiée par volumétrie entre 71 et 83 K. L'adsorption de krypton, fortement inhibée par la présence du

Paris-Sud XI, Université de

136

Factors Affecting the Efficiency of Krypton Hall Thrusters  

Microsoft Academic Search

The use of krypton as a propellant for Hall thrusters is attractive for NASA missions that require both high-specific impulse and high-propellant throughput. Due to its low molecular weight, the theoretical specific impulse for krypton is 20due to the lower sputtering yield and reduced fraction of multiply-charged ions. While investigators at other laboratories have observed reductions in krypton thruster efficiency

Richard Hofer; Peter Peterson; David Manzella; David Jacobson

2004-01-01

137

Analysis of HARP TPC krypton data  

E-print Network

This memo describes the procedure which was adopted to equalize the response of the 3972 pads of the HARP TPC, using radioactive 83mKr gas. The results obtained from the study of reconstructed krypton clusters in the calibration data taken in 2002 are reported. Two complementary methods were employed in the data analysis. Compatible results were obtained for channel-to-channel equalization constants. An estimate of the overall systematic uncertainty was derived.

Dydak, F

2004-01-01

138

The argon and krypton interatomic potentials revisited  

Microsoft Academic Search

Accurate interatomic potentials are constructed which represent subtle but significant improvements for the argon and krypton interactions. The potentials are of the HFD-B form with definite advantages over the HFD-C form. These new potentials incorporate recent determinations of the C6 dispersion coefficient and accurately predict the best available spectroscopy, scattering and bulk data, some of which data were published after

Ronald A. Aziz; M. J. Slaman

1986-01-01

139

Anomalous Oxygen and Krypton Abundances in Interstellar Gas  

NASA Technical Reports Server (NTRS)

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.

Meyer, David M.

2004-01-01

140

The LUX experiment - Design and performance of the krypton removal system  

NASA Astrophysics Data System (ADS)

LUX is an experiment built to detect weakly interacting massive particles as a candidate for cold dark matter using liquid xenon as a target material. Since xenon is a noble gas, a getter is used to remove most impurities. However, noble gas impurities remain, including radioactive krypton and argon isotopes which could dominate the dark matter signal. To remove these contaminants, a chromatographic separation system based on adsorption on activated charcoal was built using helium as a carrier gas. This talk will review the design and performance of the chromatographic system as it processed the LUX xenon stockpile in the fall of 2012.

Lee, Chang

2013-04-01

141

Energy Levels and Observed Spectral Lines of Krypton, Kr I through Kr XXXVI  

E-print Network

Energy Levels and Observed Spectral Lines of Krypton, Kr I through Kr XXXVI E. B. Salomana of the krypton atom, in all stages of ionization for which experimental data are available, have been compiled data; energy levels; Kr; krypton; krypton ions; observed spectral lines; spectra. CONTENTS 1

Magee, Joseph W.

142

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)

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 Kssen 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 Kssen 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 suggested super-greenhouse episode, which was likely connected to degassing during CAMP volcanism. On the other hand, our study of pyrite, and the stratigraphic distribution of abundance of Ce and other redox sensitive elements provide little support for widespread anoxia, which was also cited previously as a possible cause for the marine TJB extinction.

Plfy, J.; Zajzon, N.

2012-04-01

143

Shell Structure and Shape Changes in Neutron Rich Krypton Isotopes  

SciTech Connect

B(E2;2{sub 1}{sup +}{yields}0{sub 1}{sup +}) values have been measured for the unstable nuclei {sup 88}Kr (N = 52) and {sup 92}Kr (N = 56) using projectile Coulomb excitation at ISOLDE, CERN. With this experiment the local maximum in E(2{sub 1}{sup +}) in {sup 92}Kr and the role of the N = 56 subshell closure can be studied.

Muecher, D.; Jolie, J.; Blazhev, A.; Eberth, J.; Fransen, C.; Scherillo, A.; Warr, N.; Weisshaar, D. [Institut fuer Kernphysik, Universitaet zu Koeln, D-50937 Koeln (Germany); Iwanicki, J.; Czosnyka, T.; Kownacki, J.; Napiorkowski, P.; Zielinska, M. [Heavy Ion Laboratory, Warsaw University, 02-093 Warsaw (Poland); Stefanescu, I.; Walle, J. van de; Huyse, M.; Duppen, P. van [KU Leuven, Instituut voor Kern-en Stralingsfysica, B-3001 Leuven (Belgium); Becker, F.; Gerl, J.; Mandal, S. [Gesellschaft fuer Schwerionenforschung, 64291 Darmstadt (Germany)] (and others)

2009-01-28

144

Learning about Poland Anomaly  

MedlinePLUS

... genetic terms used on this page Learning About Poland Anomaly What is Poland anomaly? What are the ... Anomaly Additional Resources for Poland Anomaly What is Poland anomaly? Named after Sir Alfred Poland, Poland anomaly ( ...

145

Bangui Anomaly  

NASA Technical Reports Server (NTRS)

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.

Taylor, Patrick T.

2004-01-01

146

Stress enhanced diffusion of krypton ions in polycrystalline titanium  

SciTech Connect

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.

Nsengiyumva, S., E-mail: s.nsengiyumva@ru.ac.za [Department of Physics and Electronics, Rhodes University, Grahamstown 6140 (South Africa); Raji, A. T. [School of Interdisciplinary Research and Graduate Studies, University of South Africa, Mucklenuek Campus, P O Box 392, UNISA 0003, Pretoria (South Africa); Rivire, J. P. [Laboratoire de Mtallurgie Physique, UMR 6630 CNRS- Universit de Poitiers, Bd M. et P. Curie, BP30179, 86962 Chasseneuil Futuroscope, Cedex (France); Britton, D. T.; Hrting, M. [NanoSciences Innovation Center, Department of Physics, University of Cape Town, Rondebosch 7701 (South Africa)

2014-07-14

147

Low-energy positron interactions with krypton  

NASA Astrophysics Data System (ADS)

Cross sections for positron scattering from krypton have been measured with an energy resolution of 60 meV over the energy range 0.5-60 eV. Absolute values of the grand total (?GT), positronium formation (?Ps), and grand total minus positronium formation (?GT-?Ps,) cross sections are presented. Theoretical estimations of ?GT and ?GT-?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.

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.

2011-03-01

148

Low-energy positron interactions with krypton  

SciTech Connect

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.

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. [ARC Centre for Antimatter-Matter Studies, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); ARC Centre for Antimatter-Matter Studies, The University of Adelaide, Adelaide, South Australia (Australia); ARC Centre for Antimatter-Matter Studies, Curtin University of Technology, GPO Box U1987, Perth, Western Australia 6845 (Australia); Physics Department, University of North Texas, Denton, Texas 76201 (United States); Department of Physics and Astronomy, York University, Toronto (Canada); Department of Physics, Sophia University, Chiyoda-ku, Tokyo (Japan)

2011-03-15

149

Hyperfine structure and hyperfine anomaly in Pb  

E-print Network

The hyperfine structure in the 6p2-configuration in lead has been analysed and the results is compared with calculations. The hyperfine anomaly and improved values of the nuclear magnetic moment for four lead isotopes is obtained, using the results from the analysis. The results open up for new measurements of the hyperfine structure in unstable lead isotopes, in order to extract information of the hyperfine anomaly and distribution of magnetisation in the nucleus.

J. R. Persson

2014-07-11

150

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

Code of Federal Regulations, 2014 CFR

...Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements...Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements...self-luminous products containing tritium, krypton-85, or promethium-147, or to...

2014-01-01

151

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

Code of Federal Regulations, 2011 CFR

...Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements...Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements...self-luminous products containing tritium, krypton-85, or promethium-147, or to...

2011-01-01

152

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

Code of Federal Regulations, 2013 CFR

...Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements...Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements...self-luminous products containing tritium, krypton-85, or promethium-147, or to...

2013-01-01

153

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

Code of Federal Regulations, 2010 CFR

...Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements...Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements...self-luminous products containing tritium, krypton-85, or promethium-147, or to...

2010-01-01

154

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

Code of Federal Regulations, 2012 CFR

...Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements...Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements...self-luminous products containing tritium, krypton-85, or promethium-147, or to...

2012-01-01

155

TheD-100 Performance and Plume Characterization on Krypton  

Microsoft Academic Search

The performance of a D-100 thruster with anode layer, designed to operate on xenon at a nominal operating power of 4.5 kW, was investigated during operation on krypton. This evaluation was preliminary to a more thorough investigation of D-100 operation on alternative propellants, such as mixtures of krypton and xenon. Several operating regimes were evaluated ranging in power from 0.9

Colleen M. Marrese; James M. Haas; Matthew T. Domonkost; Alec D. Gallimore

156

Numerical investigation of the Krypton Large IMpulse Thruster  

NASA Astrophysics Data System (ADS)

Although xenon has long remained the propellant of choice for Hall effect and ion thrusters, its very high price has motivated the investigation of other noble gases as cost-effective options. The development of a 500 W-class Hall thruster at the Institute of Plasma Physics and Laser Microfusion (IPPLM) aims at demonstrating the possibility of operating with krypton at efficiencies close to that obtained with xenon. However, krypton's lower ionization cross-sections need to be compensated by a significant increase of the mass flow rate in comparison with xenon. The subsequent increase of the thermal load has a large impact on the thermal design of the thruster. In order to assess the operating parameters and the thermal fluxes expected during krypton operation, an extensive parametric study of Krypton Large Impulse Thruster's performance was conducted with the one-dimensional time-dependent hydrodynamic HETMAn solver developed at IPPLM. Comparative computations for xenon and krypton confirm that high efficiencies with krypton are possible, with a predicted maximum efficiency only a few per cent below that of xenon, although at mass flow rates 50% higher.

Kurzyna, Jacek

2014-05-01

157

Krypton and xenon in lunar fines  

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

158

An atom trap trace analysis (ATTA) system for measuring ultra-low contamination by krypton in xenon dark matter detectors  

NASA Astrophysics Data System (ADS)

The XENON dark matter experiment aims to detect hypothetical weakly interacting massive particles (WIMPs) scattering off nuclei within its liquid xenon (LXe) target. The trace 85Kr in the xenon target undergoes beta-decay with a 687 keV end point and 10.8 year halflife, which contributes background events and limits the sensitivity of the experiment. In order to achieve the desired sensitivity, the contamination by krypton is reduced to the part per trillion (ppt) level by cryogenic distillation. The conventional methods are not well suited for measuring the krypton contamination at such a low level. In this work, we have developed an atom trap trace analysis (ATTA) device to detect the ultra-low krypton concentration in the xenon target. This project was proposed to the National Science Foundation (NSF) as a Major Research Instrumentation (MRI) development [Aprile and Zelevinsky, 2009] and is funded by NSF and Columbia University. The ATTA method, originally developed at Argonne National Laboratory, uses standard laser cooling and trapping techniques, and counts single trapped atoms. Since the isotopic abundance of 85Kr in nature is 1.5 x 10-11, the 85Kr/Xe level is expected to be 10-23, which is beyond the capability of our method. Thus we detect the most abundant (57%) isotope 84Kr, and infer the 85Kr contamination from their known abundances. To avoid contamination by krypton, the setup is tested and optimized with 40 Ar which has a similar cooling wavelength to 84Kr. Two main challenges in this experiment are to obtain a trapping efficiency high enough to detect krypton impurities at the ppt level, and to achieve the resolution to discriminate single atoms. The device is specially designed and adjusted to meet these challenges. After achieving these criteria with argon gas, we precisely characterize the efficiency of the system using Kr-Xe mixtures with known ratios, and find that 90 minutes are required to trap one 84Kr atom at the 1-ppt Kr/Xe contamination. This thesis describes the design, construction, and experimental results of the ATTA project at Columbia University.

Yoon, Tae Hyun

159

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

NASA Technical Reports Server (NTRS)

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.

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

1980-01-01

160

Positron scattering measurements from Krypton and Xenon  

NASA Astrophysics Data System (ADS)

As a part of a comprehensive program of low energy positron scattering, measurements have been made for a variety of scattering processes from the heavier rare gases, krypton and xenon. In the case of positron scattering, there have been large disagreements between different experiments, and experimental and theoretical determinations of scattering cross sections for these targets. A wide range of low energy positron scattering measurements is now possible, thanks to the development of the Surko trap and beam system, which provides a high energy resolution source of positrons [1-3]. The resulting positron beam is magnetised, and techniques developed for measuring cross sections in the magnetic fields mean that a wide range of scattering processes are now able to be investigated with high accuracy. This presentation will present measurements of total scattering, positronium formation and elastic differential scattering for both of these targets. The strongly forward peaked nature of the differential cross sections will be highlighted, especially as it relates to previous disagreements between different experimental measurements of the grand total cross section. In the case of positronium formation, the difference between present measurements and previous studies will also be discussed. [1] T. Murphy and C. M. Surko, Phys. Rev. A 46, 5696 (1992) [2] S. J. Gilbert et al., Appl. Phys. Lett. 70, 1944 (1997) [3] J. P. Sullivan et al. Phys. Rev. A 66, 042708 (2002)

Sullivan, James; Machacek, Joshua; Makochekanwa, Casten; Jones, Adric; Caradonna, Peter; Slaughter, Daniel; Buckman, Stephen; Mueller, Dennis

2012-06-01

161

Kinetic modelling of krypton fluoride laser systems  

SciTech Connect

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.

Jancaitis, K.S.

1983-11-01

162

2 0-3D TRANSITION. MULTILAYER ADSORPTION OF ARGON AND KRYPTON  

E-print Network

2 0-3D TRANSITION. MULTILAYER ADSORPTION OF ARGON AND KRYPTON ON LAMELLAR HALIDES Y. LARHER and F'isothermes d'adsorption d'argon et de krypton sur la facede clivage de divers halog6nures lamellaires ont CtC d. Abstract. - Sets of adsorption isotherms of argon and krypton on the cleavage face of a number of lamellar

Paris-Sud XI, Université de

163

An atom trap trace analysis (ATTA) system for measuring ultra-low contamination by krypton in  

E-print Network

An atom trap trace analysis (ATTA) system for measuring ultra-low contamination by krypton in xenon ultra-low contamination by krypton in xenon dark matter detectors Tae Hyun Yoon The XENON dark matter of the experiment. In order to achieve the desired sensitivity, the contamination by krypton is reduced to the part

Zelevinsky, Tanya

164

Amorphization of -Thorium Phosphate Diphosphate (-TPD) irradiated with high energy krypton ions  

E-print Network

Amorphization of -Thorium Phosphate Diphosphate (-TPD) irradiated with high energy krypton ions C the irradiation of -TPD with 840-MeV krypton ions. In storage conditions, the energy of both -particles and recoil nuclei is much lower (see above). However, the high energy of krypton ions was chosen with the double aim

Paris-Sud XI, Université de

165

An atom trap trace analysis system for measuring krypton contamination in xenon dark matter detectors  

E-print Network

An atom trap trace analysis system for measuring krypton contamination in xenon dark matter OF SCIENTIFIC INSTRUMENTS 84, 093105 (2013) An atom trap trace analysis system for measuring krypton krypton (Kr) contamination at the part per million (ppm) level. The Kr contamination con- tributes

Zelevinsky, Tanya

166

Efficiency Analysis of a Hall Thruster Operating with Krypton and Xenon  

Microsoft Academic Search

Krypton has recently become the focus of attention in the Hall thruster community because of its relatively large specific impulse as compared to xenon and its potential to operate with comparable efficiencies. However, before krypton can be considered a viable propellant choice for missions, the performance gap between xenon and krypton must be reduced. A series of diagnostic measurements are

Jesse A. Linnell; Alec D. Gallimore

2006-01-01

167

Energy of the Quasi-free Electron in Argon and Krypton C. M. Evans1,  

E-print Network

Energy of the Quasi-free Electron in Argon and Krypton C. M. Evans1, and G. L. Findley2, 1 high-n molecular Rydberg states in argon and krypton perturbers are presented as a function in argon and krypton is developed. This model, which contains only one adjustable parameter, uses a local

Findley, Gary L.

168

Moon Anomalies  

NSDL National Science Digital Library

In this activity, learners will investigate and try to explain various lunar anomalies. They will present hypotheses (both written and oral) and then debate the merits of each hypothesis, with no right or wrong answers. This activity is in Unit 2 of the teachers guide, Exploring the Moon, which is designed for use especially, but not exclusively, with the Lunar Sample Disk program.

169

Energy of the Quasi-free Electron in Supercritical Krypton near the Critical Point Luxi Li and C. M. Evans  

E-print Network

Energy of the Quasi-free Electron in Supercritical Krypton near the Critical Point Luxi Li and C. M and C2H5I Rydberg states doped into krypton are presented as a function of krypton number density along the critical isotherm. These data exhibit a decrease in the krypton induced shift of the dopant ionization

Evans, Cherice M.

170

The NA62 Liquid Krypton Electromagnetic Calorimeter Level 0 Trigger  

E-print Network

The NA62 experiment at CERN SPS aims to measure the Branching Ratio of the very rare kaon decay K+ -> pi+ nu nubar collecting O(100) events with a 10% background to make a stringent test of the Standard Model. One of the main backgrounds to the proposed measurement is represented by the K+ -> pi+ pi0 decay. To suppress this background an efficient photo veto system is foreseen. In the 1-10 mrad angular region the NA48 high performance liquid krypton electromagnetic calorimeter is used. The design, implementation and current status of the Liquid Krypton Electromagnetic Calorimeter Level 0 Trigger are presented.

Bonaiuto, V; Paoluzzi, G; Salamon, A; Salina, G; Santovetti, E; Sargeni, F; Scarf, F M

2012-01-01

171

The NA62 Liquid Krypton Electromagnetic Calorimeter Level 0 Trigger  

E-print Network

The NA62 experiment at CERN SPS aims to measure the Branching Ratio of the very rare kaon decay K+ -> pi+ nu nubar collecting O(100) events with a 10% background to make a stringent test of the Standard Model. One of the main backgrounds to the proposed measurement is represented by the K+ -> pi+ pi0 decay. To suppress this background an efficient photo veto system is foreseen. In the 1-10 mrad angular region the NA48 high performance liquid krypton electromagnetic calorimeter is used. The design, implementation and current status of the Liquid Krypton Electromagnetic Calorimeter Level 0 Trigger are presented.

V. Bonaiuto; A. Fucci; G. Paoluzzi; A. Salamon; G. Salina; E. Santovetti; F. Sargeni; F. M. Scarfi'

2012-01-16

172

The NA62 Liquid Krypton Electromagnetic Calorimeter Level 0 Trigger  

E-print Network

The NA62 experiment at CERN SPS aims to measure the Branching Ratio of the very rare kaon decay K+ -> pi+ nu nubar collecting O(100) events with a 10% background to make a stringent test of the Standard Model. One of the main backgrounds to the proposed measurement is represented by the K+ -> pi+ pi0 decay. To suppress this background an efficient photo veto system is foreseen. In the 1-10 mrad angular region the NA48 high performance liquid krypton electromagnetic calorimeter is used. The design, implementation and current status of the Liquid Krypton Electromagnetic Calorimeter Level 0 Trigger are presented.

Vincenzo Bonaiuto; Adolfo Fucci; Giovanni Paoluzzi; Andrea Salamon; Gaetano Salina; Emanuele Santovetti; Fausto Sargeni; Francesco M. Scarfi'

2012-01-18

173

HKrF in solid krypton  

NASA Astrophysics Data System (ADS)

A new krypton-containing compound, HKrF, has been prepared in a low-temperature Kr matrix via VUV photolysis of the HF precursor and posterior thermal mobilization of H and F atoms. All three fundamental vibrations have been observed in the FTIR spectra at 1950 cm-1 (H-Kr stretch), 650 cm-1 (bending), and 415 cm-1 (Kr-F stretch). Two distinct sites of HKrF have been identified. The energy difference between the H-Kr stretching vibrations for the two sites is remarkably large (26 cm-1), indicating a strong influence of the environment. In annealing after the photolysis of the precursor, HKrF is formed in two different stages: at 13-16 K from closely trapped H+F pairs and at T>24 K due to more extensive mobility of H and F atoms in the matrix. HKrF in a less stable site decreases at temperatures above 32 K, the other site being stable up to the sublimation temperature of the matrix. The photodecomposition cross section for HKrF has been measured between 193 and 350 nm and compared with the cross sections of the previously reported HArF and HKrCl molecules. The condensed-phase VSCF (vibrational self-consistent field) calculations suggest that the more stable form is a single-substitutional site and the less stable form is a double-substitutional site of HKrF in solid Kr. The gas to matrix shifts for these sites are predicted to be +(9-26) cm-1 for the H-Kr stretching and the bending vibrations and -(7-10) cm-1 for the Kr-F stretching vibrations.

Pettersson, Mika; Khriachtchev, Leonid; Lignell, Antti; Rsnen, Markku; Bihary, Z.; Gerber, R. B.

2002-02-01

174

Quenching of the resonance 5s(3P1) state of krypton atoms in collisions with krypton and helium atoms  

NASA Astrophysics Data System (ADS)

The processes of collision quenching of the resonance 5s[3/2]1o(3P1) 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*2 + He [(4.21 0.42) 10-33 cm6 s-1], Kr* + 2He ? HeKr* + He [(4.5 1.2) 10-36 cm6 s-1] and Kr* + He ? products + He [(2.21 0.22) 10-15 cm3 s-1] are measured for the first time. The rate constants of similar reactions are refined for krypton in the metastable 5s[3/2]2o (3P2) state.

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

2014-11-01

175

Atom Trap, Krypton-81, and Global Groundwater  

NASA Astrophysics Data System (ADS)

The long-lived noble-gas isotope ^81Kr is the ideal tracer for old water and ice in the age range of 10^5 -- 10^6 years, a range beyond the reach of ^14C. ^81Kr-dating, a concept pursued in the past four decades by numerous laboratories employing a variety of techniques, is now available for the first time to the earth science community at large. This is made possible by the development of an atom counter based on the Atom Trap Trace Analysis (ATTA) method, in which individual atoms of the desired isotope are selectively captured and detected with a laser-based atom trap. ATTA possesses superior selectivity, and is thus far used to analyze the environmental radioactive isotopes ^81Kr, ^85Kr, and ^39Ar. These three isotopes have extremely low isotopic abundances in the range of 10-16 to 10-11, and cover a wide range of ages and applications. In collaboration with earth scientists, we are dating groundwater and mapping its flow in some major aquifers around the world.

Lu, Zheng-Tian

2012-03-01

176

Atom Trap, Krypton-81, and Saharan Water  

SciTech Connect

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.

Lu, Zheng-Tian (ANL) [ANL

2005-08-24

177

Atom Trap, Krypton-81, and Saharan Water  

NASA Astrophysics Data System (ADS)

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 ^81Kr (t1/2 = 2.3x10^5 years, isotopic abundance 1x10-12) in environmental samples. In this method, individual ^81Kr atoms are selectively captured and detected with a laser-based atom trap. ^81Kr is produced by cosmic rays in the upper atmosphere. It is the ideal tracer for dating ice and groundwater in the age range of 10^4--10^6 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. This work was supported by the U.S. DOE, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.

Lu, Zheng-Tian

2007-04-01

178

Binding energies of neon and krypton cluster ions  

NASA Astrophysics Data System (ADS)

We have measured the kinetic energy released in the metastable fragmentation of mass selected neon and krypton cluster ions, produced by electron impact ionization of a neutral cluster beam. Finite heat bath theory is applied to determine the transition state temperatures and binding energies of the metastable cluster ions.

Parajuli, R.; Matt, S.; Echt, O.; Stamatovic, A.; Scheier, P.; Mrk, T. D.

2002-01-01

179

Ultraviolet Absorption of Solid Argon, Krypton, and Xenon  

Microsoft Academic Search

The absorption spectra of thin films of argon, krypton, and xenon have been measured between 20 and 50K in the region from 1600 to 900 (8 to 14 eV). The spectra show: (a) strong doublets corresponding to the atomic resonance doublets, (b) lines apparently of nonatomic nature, and (c) absorption continua. The experimental results are discussed in terms of

Giancarlo Baldini

1962-01-01

180

Photocoagulation of disciform macular lesions with krypton laser  

Microsoft Academic Search

Ten vascular disciform mucular lesions were treated by krypton laser photocoagulation. In 8 the lesion resolved after therapy, and in 7 the retina remained flat for 6 months. On those patients treated successfully 6 had a visual acuity of 6\\/12 or better. The morphology of the laser lesion differed from that of the argon lesion in that there is no

A C Bird; R H Grey

1979-01-01

181

Performances of the NA48 Liquid Krypton calorimeter  

E-print Network

The NA48 experiments aims at a precise measurement of direct CP violation in the neutral Kaon system. This puts stringent requirements on the electromagnetic calorimeter used to detect photons of average energy 25 GeV. The choice of NA48 is a quasi homogeneous Liquid Krypton calorimeter with fast readout. The operation of this device and the performances achieved are described.

Guillaume Unal

2000-12-05

182

Anomalous krypton in the Allende meteorite  

NASA Technical Reports Server (NTRS)

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.

Frick, U.

1977-01-01

183

Structural characterization of krypton physisorption on (0001) graphite pre-plated with cyclohexane  

E-print Network

1961 Structural characterization of krypton physisorption on (0001) graphite pre) Résumé. 2014 Le film mixte formé lors de la physisorption de krypton sur une surface de graphite (0001 difficultés d'atteinte de l'équilibre d'adsorption liées à la densité du Papyex. L'adsorption de krypton à 77

Boyer, Edmond

184

High density self-broadening of the first xenon and krypton resonance line (*)  

E-print Network

9 High density self-broadening of the first xenon and krypton resonance line (*) P. Laporte and H,96 nm du xénon et 123,58 nm du krypton est étudié dans le domaine de densité 1-100 amagat (2,7 x 1019 xenon line and 123.58 nm krypton line is studied in the density range 1-100 amagat (2.7 x 1019 2014 2

Paris-Sud XI, Université de

185

A Principled Anomalies as  

E-print Network

Events Anomaly Definition Main Theorem Application Conclusion Standard Methods Mahalanobis distance Mahalanobis Distance Mahalanobis distance generalizes the t-test normalizes distances according Anomalies as Rare Events Anomaly Definition Main Theorem Application Conclusion Mahalanobis Distance

Wang, Xiaorui "Ray"

186

Structure of liquid krypton under atmospheric pressure: An EXAFS and reverse Monte Carlo study  

SciTech Connect

The local atomic structure of liquid krypton under atmospheric pressure has been studied with the technique of x-ray absorption fine structure (XAFS). For measuring the XAFS of liquid krypton at low temperature, a special sample holding method is applied. The x-ray absorption spectra of gaseous and solid krypton are also measured for the comparison and data analysis. Based on the reverse Monte Carlo simulation and the constructed configurations, the radial distribution function as well as the coordination number and bond-angle distribution of liquid krypton is given.

Wang Qiang; Li Chenxi; Niu Xiaojuan; Shen Rong; Lu Kunquan; Wei Shiqiang; Wu Zhonghua; Liu Tao; Xie Yaning; Hu Tiandou [Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029 (China); Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039 (China)

2005-09-01

187

Monitoring of krypton-85 activity in the atmosphere around Prague  

Microsoft Academic Search

The results of measurements of Krypton-85 (85Kr) concentrations in the ground-level air of Prague between 1983 and 1992 are presented and time-related changes analysed. The long-term trend in activity level of 85Kr has been steadily increasing with a growth rate of 0.04 Bq.m-3 (STP) per year. Some peaks of 85Kr activity were observed due to the influence of undispersed radioactive

Ludmila Wilhelmov; Milan Tomek; Karel tukheil

1995-01-01

188

Auger decay of 3p-ionized krypton  

SciTech Connect

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.

Jonauskas, V.; Kucas, S.; Karazija, R. [Institute of Theoretical Physics and Astronomy, Vilnius University, A. Gostauto 12, Vilnius LT-01108 (Lithuania)

2011-11-15

189

Decay of Excited Species in a Pulsed Discharge in Krypton  

Microsoft Academic Search

The emission in the afterglow of a pulsed discharge in krypton has been investigated. Measurements of the decay times of the resonance radiation at lambda1236 and a diffuse molecular radiation at lambda1250 and longer wavelengths have been made as functions of pressure at 295 and 196K. The measurements have been interpreted on the assumption of a simple two-time-constant

R. Turner

1967-01-01

190

Electron beam pumped krypton fluoride lasers for fusion energy  

Microsoft Academic Search

High-energy electron beam pumped krypton fluoride (KrF) gas lasers are an attractive choice for inertial fusion energy (IFE). Their short wavelength and demonstrated high beam uniformity optimizes the laser-target physics, and their pulsed power technology scales to a large system. This paper presents the principals of this type of laser and the progress toward developing technologies that can meet the

JOHN D. SETHIAN; MATTHEW C. MYERS; ROBERT H. LEHMBERG; PAUL C. KEPPLE; S. P. Obenschain; FRANK HEGELER; M. Friedman; MATTHEW F. WOLFORD; RUSSELL V. SMILGYS; STEPHEN B. SWANEKAMP; DOUGLAS WEIDENHEIMER; DAVID GIORGI; DALE R. WELCH; DAVID V. ROSE; STUART SEARLES

2004-01-01

191

Electron impact excitation of autoionising states of krypton  

NASA Technical Reports Server (NTRS)

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.

Srivastava, S. K.; Trajmar, S.

1978-01-01

192

Dust Particle Growth in a Sputtering Discharge with Krypton  

SciTech Connect

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.

Tawidian, H.; Mikikian, M.; Lecas, T.; Boufendi, L. [GREM, UMR6606 CNRS/Universite d'Orleans, 14 rue d'Issoudun BP6744, 45067 Orleans Cedex 2 (France)

2011-11-29

193

Krypton droplet plasma disassembly in an intense laser field  

NASA Astrophysics Data System (ADS)

We have investigated the disassembly time of cryogenically cooled krypton droplets irradiated by two 100-ps, 1064-nm laser pulses separated by a variable time delay. Workers at Sandia have shown high efficiency EUV generation from the interaction of 10-ns laser pulses with xenon droplets [1]. However, it has been found that EUV generation from micron-sized Kr droplets is most efficient for laser pulses which are 300 ps in duration [2]. Our pulsed source produces krypton droplets whose size is varied by precisely controlling the temperature of a valve backed with krypton at high pressure. The first laser pulse heats the droplets, forming a plasma, and the second pulse serves as a heater probe for measuring the characteristic disassembly time of the Kr droplets. Using EUV and X-ray signals generated by the second pulse as diagnostics, the disassembly time is shown to be as long as several nanoseconds, depending on average droplet radius. We will also present results from our simulations of the laser-droplet interaction. This work is supported by the National Science Foundation. [1] G. D. Kubiak et al., EUV, X-Ray and Neutron Optics and Sources, C. A. MacDonald et al., eds., Proc. SPIE 3767, 136-142 (1999). [2] E. Parra et al., Phys. Rev. E 62, R5931-R5934 (2000).

McNaught, S. J.; Fan, J.; Parra, E.; Milchberg, H. M.

2001-04-01

194

The Homogeneity of Interstellar Krypton in the Galactic Disk  

E-print Network

We present an analysis of high resolution HST Space Telescope Imaging Spectrograph (STIS) observations of Kr I 1236 Angstrom absorption in seven sight lines that probe a variety of interstellar environments. In combination with krypton and hydrogen column densities derived from current and archival STIS and Far-Ultraviolet Spectroscopic Explorer data, the number of sight lines with reliable Kr/H ISM abundance ratios has been increased by 50% to 26--including paths that sample a range of nearly 5 orders of magnitude in f(H_2), over 2 orders of magnitude in , and extending up to 4.8 kpc in length. For sight lines contained entirely within the local spiral arm (the Orion Spur), the spread of Kr/H ratios about the mean of log_10[N(Kr)/N(H)]_ISM = -9.02+/-0.02 is remarkably tight (0.06 dex), less than the typical datapoint uncertainty. Intriguingly, the only two sight lines that extend through neighboring structures, in particular gas associated with the Carina/Sagittarius Arm, exhibit relatively large, near-solar krypton abundances (log_10[N(Kr)/N(H)]_combined = -8.75+0.09_-0.11). Although these deviations are only measured at the 2 sigma level, they suggest the possibility that krypton abundances beyond the Orion Spur may differ from the local value.

Stefan I. B. Cartledge; David M. Meyer; J. T. Lauroesch

2003-07-09

195

Volume 171, number $6 CHEMICAL PHYSICS LETTERS I7 August 1990 Photodissociation of F2 in crystalline krypton  

E-print Network

in crystalline krypton: effect of molecule-lattice prealignment H. Kunttu and V.A. Apkarian Institutefor Surface 1990;in final form I June 1990 Photodissociation studies of F2 isolated in crystalline krypton

Apkarian, V. Ara

196

Krypton assay in xenon at the ppq level using a gas chromatographic system combined with a mass spectrometer  

E-print Network

We have developed a new method to measure krypton traces in xenon at so far unprecedented low concentrations. This is a mandatory task for many near-future low-background particle physics detectors. Our system is based on a cryogenic gas chromatographic krypton/xenon separation and a subsequent mass spectroscopic krypton quantification. We prove this system to reach a detection limit of 8 ppq (parts per quadrillion) and present results of distilled xenon with krypton concentrations below 1 ppt.

Lindemann, Sebastian

2014-01-01

197

Chiral anomalies and differential geometry  

SciTech Connect

Some properties of chiral anomalies are described from a geometric point of view. Topics include chiral anomalies and differential forms, transformation properties of the anomalies, identification and use of the anomalies, and normalization of the anomalies. 22 references. (WHK)

Zumino, B.

1983-10-01

198

ISOTOPIC COMPOSITION OF PRIMORDIAL XENON  

Microsoft Academic Search

A large excess of Xe¹²⁹ and secondary anomalous abundances for ; many of the other isotopes of xenon were previously reported for the meteorite, ; Richardton. Similar secondary anomalies in xenon are reported for the meteorite ; Murray. For every isotope other than Xe¹²⁹, the ratio of the Murray ; percent abundance to the Richardton percent abundance was the same

J. Reynolds

1960-01-01

199

Ultra hard x rays from krypton clusters heated by intense laser fields R. C. Issac,a)  

E-print Network

Ultra hard x rays from krypton clusters heated by intense laser fields R. C. Issac,a) G. Vieux, B of ultrashort laser pulses with krypton clusters at intensity up to 1.3 1018 Wcm 2 has been investigated. Intense K and K emission from krypton at 12.66 and 14.1 keV, respectively, has been observed using

Strathclyde, University of

200

X-ray diffraction of krypton and xenon mixtures adsorbed on graphite T. Ceva, M. Goldmann (*) and C. Marti  

E-print Network

1527 X- ray diffraction of krypton and xenon mixtures adsorbed on graphite T. Ceva, M. Goldmann 1986) Résumé. 2014 En étudiant, par diffraction des rayons X, les mélanges xenon-krypton absorbés sur. Abstract 2014 Mixtures of xenon and krypton adsorbed on graphite at 45 K are studied by X ray diffraction

Boyer, Edmond

201

Dielectric measurements of adsorbed krypton on lamellar halides J. P. Laheurte, J. C. Noiray, M. Obadia and J. P. Romagnan  

E-print Network

559 Dielectric measurements of adsorbed krypton on lamellar halides J. P. Laheurte, J. C. Noiray, M isothermes d'adsorption et les isothermes diélectriques pour le krypton adsorbé sur des halo- génures. 2014 We present simultaneous measurements of adsorption isotherms and dielectric isotherms for krypton

Paris-Sud XI, Université de

202

Mesure de constantes de structure hyperfine de niveaux 6p du xnon et 5p du krypton  

E-print Network

863 Mesure de constantes de structure hyperfine de niveaux 6p du xénon et 5p du krypton H. Abu' n' p d'atomes de gaz rares : neon, krypton et xenon. Toutes ces experiences ont pour point commun l xenon et du krypton sont relies a ces demiers par des transitions dans le domaine du proche infrarouge

Paris-Sud XI, Université de

203

Energy of the quasi-free electron in argon, krypton and xenon Xianbo Shi a,b  

E-print Network

Energy of the quasi-free electron in argon, krypton and xenon Xianbo Shi a,b , Luxi Li a,b , C. M ionization measurements of various high-n molecular Rydberg states doped into argon, krypton and xenon, krypton and xenon from the dilute gas up to the density of the triple point liquid, on both critical

Findley, Gary L.

204

658 IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 60, NO. 2, APRIL 2013 Design and Simulation of Liquid Krypton  

E-print Network

of Liquid Krypton as Gamma Ray Detector Syed M. Hassan, Ahmed Hassanein, David S. Koltick, Nader Satvat MeV within liquid krypton to understand geometry effects and energy containment. Two Monte Carlo Terms--Gamma ray detector, Geant4, liquid krypton, liquid noble gas, MCNP5, Monte Carlo simulation. I

Harilal, S. S.

205

A comparative histopathological study of argon and krypton laser irradiations of the human retina  

Microsoft Academic Search

A series of comparative exposures to both argon and krypton lasers have been made at 3 locations in a human retina--the fovea, the macula, and intraretinal vessels. In the fovea argon irradiations resulted in damage to both the inner and outer retinal layers as a result of absorption within the pigment epithelium and the macular pigment, while krypton exposures damaged

J Marshall; A C Bird

1979-01-01

206

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

SciTech Connect

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.

Linnell, Jesse A.; Gallimore, Alec D. [Plasmadynamics and Electric Propulsion Laboratory, Department of Aerospace Engineering, University of Michigan, 1919 Green Road B107, Ann Arbor, Michigan 48109 (United States)

2006-09-15

207

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

NASA Astrophysics Data System (ADS)

We have interpreted the well-known experimental quantum yield data for a 32.8-nm X-ray laser operating at the 3d94d (J = 0) - 3d94p (J = 1) transition of Kr8+ 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 ?m, a krypton ion density nKr ~ (4 - 9) 1019 cm-3, and an electron temperature Te ~ 5000 eV. In this case, the energy conversion coefficient amounts to ~5 10-3 of the pump pulse energy. We propose the experimental setup for producing a highefficiency subpicosecond X-ray laser in a krypton cluster jet.

Ivanova, E. P.; Vinokhodov, A. Yu

2013-12-01

208

Photolytic separation of isotopes in cryogenic solution  

DOEpatents

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.

Freund, Samuel M. (Santa Fe, NM); Maier, II, William B. (Los Alamos, NM); Holland, Redus F. (Los Alamos, NM); Beattie, Willard H. (Los Alamos, NM)

1985-01-01

209

A new capability in isotope geochemistry  

NASA Astrophysics Data System (ADS)

International Workshop on Tracer Applications of Noble Gas Radionuclides; Argonne, Illinois, 21-22 June 2012 The noble gas radionuclides krypton-81 (81Kr; 229,000-year half-life), krypton-85 (85Kr; 10.8-year half-life), and argon-39 (39Ar; 269-year half-life) have ideal properties for tracing fluid transport in Earth systems. Their principal applications include determination of groundwater residence times (81Kr, 85Kr, and 39Ar) and seawater ventilation ages (39Ar). In practice, however, few studies have employed noble gas radionuclides because of the large sample sizes required and the complex analytical systems required for measuring their extremely low isotopic abundances (10-16 to 10-11). Most published studies have used low-level radioactive decay counting for 39Ar and 85Kr, but the low activity of 81Kr has necessitated the development of various atom-counting methods over the past 4 decades.

Sturchio, Neil C.; Lu, Zheng-Tian; Schlosser, Peter

2012-10-01

210

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

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

211

Low energy positron scattering from krypton and xenon  

NASA Astrophysics Data System (ADS)

Absolute grand total, positronium formation, and grand total minus positronium formation cross sections for positron scattering from krypton and xenon have been measured with an energy resolution of ~60 meV over the energy range 0.5-60 eV. Experimental results for elastic differential cross sections measured using the same apparatus, for selected energies both below and above the Ps threshold, are also presented. Theoretical estimations of these cross sections are also performed using the convergent close coupling method (CCC) and the relativistic optical potential (ROP) approach.

Makochekanwa, C.; Machacek, J. R.; Jones, A. C. L.; Caradonna, P.; Slaughter, D. S.; McEachran, R. P.; Sullivan, J. P.; Buckman, S. J.; Fursa, D.; Bray, I.; Stauffer, A. D.

2012-11-01

212

Nuclear resonant scattering of synchrotron radiation by gaseous krypton  

NASA Astrophysics Data System (ADS)

We have observed scattering of synchrotron radiation by the 9.4-keV nuclear resonance of gaseous 83Kr. In a gas, there is no recoilless absorption (no Mssbauer effect). A cell of krypton gas (natural abundance, 12% 83Kr) was placed after a Si(111) monochromator. Incoherent resonant nuclear scattering, 0.3 cts/s, was separated from nonresonant electronic scattering, 7107 cts/s, using the time resolution of an avalanche diode detector. The resonance energy was found to be 9403.5+/-1.8 eV. The time dependence of the scattered radiation agrees with a previous measurement of the excited-state lifetime.

Baron, A. Q. R.; Chumakov, A. I.; Ruby, S. L.; Arthur, J.; Brown, G. S.; Smirnov, G. V.; van Brck, U.

1995-06-01

213

Krypton-81m ventilation scanning: acute respiratory disease  

SciTech Connect

From experience with 700 patients undergoing ventilation and perfusion lung scanning with krypton-81m/technetium-99m technique, 34 patients suffering from nonembolic acute respiratory disease were selected for review. In 16 patients with pneumonia, all had defects of ventilation corresponding to, or larger than, the radiologic consolidation. In 13 patients there was some preservation of perfusion in the consolidated region. In two of the three patients with matched defects, the pneumonia was of long standing. In seven patients with collapse or atelectasis and in 11 patients with acute reversible bronchial obstruction and normal volume lungs, a similar pattern or ventillation and perfusion was observed.

Lavender, J.P. (Royal Postgraduate Medical School, London, England); Irving, H.; Armstrong, J.D. II

1981-02-01

214

The adsorption of argon, krypton and xenon on activated charcoal  

SciTech Connect

Charcoal adsorption beds are commonly used to remove radioactive noble gases from contaminated gas streams. The design of such beds requires the adsorption coefficient for the noble gas. Here an extension of the Dubinin-Radushkevich theory of adsorption is developed to correlate the effects of temperature, pressure, concentration, and carrier gas on the adsorption coefficients of krypton, xenon, and argon on activated carbon. This model is validated with previously published adsorption measurements. It accurately predicts the equilibrium adsorption coefficient at any temperature and pressure if the potential energies of adsorption, the micropore volume, and the van der Waals constants of the gases are known. 18 refs., 4 figs.

Underhill, D.W. [Univ. of South Carolina, Columbia, SC (United States)

1996-08-01

215

Ejection ages from krypton-81krypton83 dating and pre-atmospheric sizes of martian meteorites  

Microsoft Academic Search

Cosmic-ray exposure (CRE) ages and Mars ejection times were calculated from the radionuclide 81Kr and stable Kr isotopes for seven martian meteorites. The following 81Kr-Kr CRE ages were obtained: Los Angeles = 3.35 +\\/- 0.70 Ma; Queen Alexandra Range 94201 = 2.22 +\\/- 0.35 Ma; Shergotty = 3.05 +\\/- 0.50 Ma; Zagami = 2.98 +\\/- 0.30 Ma; Nakhla = 10.8

O. Eugster; H. Busemann; S. Lorenzetti; D. Terribilini

2002-01-01

216

SST Anomalies + Wind Anomalies (with dates)  

NSDL National Science Digital Library

Sea surface temperature (SST) anomalies and sea surface wind anomalies show the development of the 2002-2003 El Nino based on data from NASAs Aqua and QuikSCAT spacecraft. The wind data has been processed using the Variational Analysis Method (VAM).

Greg Shirah

2003-02-03

217

Krypton-85 hydrofracture engineering feasibility and safety evaluation  

SciTech Connect

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.

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

1981-07-01

218

Lymphatic Anomalies Registry  

ClinicalTrials.gov

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

2015-03-21

219

Anomalies of nuclear criticality  

SciTech Connect

During the development of nuclear energy, a number of apparent anomalies have become evident in nuclear criticality. Some of these have appeared in the open literature and some have not. Yet, a naive extrapolation or application of existing data, without knowledge of the anomalies, could lead to potentially serious consequences. This report discusses several of these anomalies.

Clayton, E.D.

1979-06-01

220

Analysis of spacecraft anomalies  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

221

Lifshitz scale anomalies  

NASA Astrophysics Data System (ADS)

We analyse scale anomalies in Lifshitz field theories, formulated as the relative cohomology of the scaling operator with respect to foliation preserving diffeomorphisms. We construct a detailed framework that enables us to calculate the anomalies for any number of spatial dimensions, and for any value of the dynamical exponent. We derive selection rules, and establish the anomaly structure in diverse universal sectors. We present the complete cohomologies for various examples in one, two and three space dimensions for several values of the dynamical exponent. Our calculations indicate that all the Lifshitz scale anomalies are trivial descents, called B-type in the terminology of conformal anomalies. However, not all the trivial descents are cohomologically non-trivial. We compare the conformal anomalies to Lifshitz scale anomalies with a dynamical exponent equal to one.

Arav, Igal; Chapman, Shira; Oz, Yaron

2015-02-01

222

VOLUME 83, NUMBER 5 P H Y S I C A L R E V I E W L E T T E R S 2 AUGUST 1999 Hyperfine Anomaly Measurements in Francium Isotopes  

E-print Network

Measurements in Francium Isotopes and the Radial Distribution of Neutrons J. S. Grossman, L. A. Orozco, M. R structure. Francium is an excellent element for understanding the atom-nucleus hyperfine interactions francium isotopes. Previous measurements of the 7P1 2 [17] were not of suf- ficient precision to observe

Orozco, Luis A.

223

The wash-out of intraarterially injected Krypton 85 from the intestine of the cat  

Microsoft Academic Search

Zusammenfassung Der zeitliche Verlauf der Elimination von intraarteriell injiziertem Krypton aus den Geweben des Katzendarmes wurde untersucht. Die gefundene Eliminationskurve konnte in vier Teilkurven aufgelst und die anatomische Lokalisierung und funktionelle Bedeutung dieser Komponenten kurz diskutiert werden.

O. Lundgren; M. Kampp

1966-01-01

224

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

225

Calibration of the STAR Forward Time Projection Chamber with Krypton-83m  

E-print Network

The principles of the calibration of a time projection chamber with radioactive Krypton-83 are explained. The calculation of gain correction factors and the methods of obtaining a precise energy calibration are illustrated. The properties and advantages of \

V. Eckardt; T. Eggert; H. Fessler; H. Hmmler; G. Lo Curto; M. Oldenburg; N. Schmitz; A. Schttauf; J. Seyboth; P. Seyboth; M. Vidal

2001-01-31

226

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

SciTech Connect

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.

Zhang, Fengkui, E-mail: fengkuizhang@163.com; Kong, Lingyi; Li, Chenliang; Yang, Haiwei; Li, Wei [College of Aerospace and Civil Engineering, Harbin Engineering University, Harbin 150001 (China)

2014-11-15

227

The blood flow of the cerebral cortex determined by radioactive krypton 85  

Microsoft Academic Search

Zusammenfassung Der radioaktive indifferente Luftbestandteil Krypton85 (in Ringer-Flssigkeit) wird in die Arteria carotis communis injiziert und die Radioaktivitt ber der freigelegten Gehirnoberflche verfolgt. Die Methode ergibt reproduzierbare quantitativecorticale Perfusionswerte und eignet sich auch fr andere Gewebe.

N. A. Lassen; D. H. Ingvar

1961-01-01

228

The NA48 Liquid Krypton Calorimeter Description and Performances  

E-print Network

The NA48 experiment at CERN aims at making a precision study of direct CP violation in the neutral kaons, by measuring $Re(\\epsilon'/\\epsilon)$ with an accuracy better than 0.02%. To achieve this goal, the experiment requires a neutral detector with fast response, high efficiency in a high-rate environment (\\sim MHz), long-term stability, sub-nanosecond time resolution, millimetric space precision, and an excellent energy resolution (1%) in the $5 \\to 100$ GeV range. To achieve these performances, a quasi-homogeneous Liquid Krypton calorimeter has been chosen, designed with a projective tower geometry, high transversal segmentation, and fast digital readout. The calorimeter was operative during the '97 data taking period, its performances were thoroughly studied, and found to be in agreement with design requirements. A detector description and performances analysis are here presented.

Jose Ocariz

1999-01-11

229

Investigation of many-body forces in krypton and xenon  

SciTech Connect

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.

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

1988-10-15

230

Performance of an electromagnetic liquid krypton calorimeter based on a ribbon electrode tower structure  

Microsoft Academic Search

The NA48 collaboration is preparing a new experiment at CERN aiming to study CP violation in the K0-K0 system with an accuracy of 2 10?4 in the parameter Re(??\\/?). Decays in two ?0's will be recorded by a quasi-homogeneous liquid krypton calorimeter. A liquid krypton calorimeter has been chosen to combine good energy, position and time resolution with precise

G. D. Barr; C. Bruschini; C. Bocquet; P. Buchholz; D. Cundy; N. Doble; W. Funk; L. Gatignon; A. Gonidec; B. Hallgren; G. Kesseler; A. Lacourt; G. Laverrire; G. Linser; M. Martini; A. Norton; D. Schinzel; W. Seidl; M. S. Sozzi; H. Taureg; O. Vossnack; H. Wahl; P. Wertelaers; J. Weterings; M. Ziolkowski; A. Kalinin; V. Kekelidze; Yu. Kozhevnikov; L. Bertolotto; V. Carassiti; J. Duclos; A. Gianoli; P. L. Frabetti; M. Savri; O. Zeitnitz; M. Calvetti; P. Lubrano; M. Pepe; P. Calafiura; C. Cerri; F. Costantini; R. Fantechi; B. Gorini; I. Mannelli; V. Marzulli; D. Bdrde; P. Debu; A. Givernaud; L. Gosset; J. Heitzmann; E. Mazzucato; B. Peyaud; R. Turlay; C. Biino; A. Ceccucci; P. Maas; S. Palestini

1996-01-01

231

Noble gas abundance and isotope ratios in the atmosphere of Jupiter from the Galileo Probe Mass Spectrometer  

Microsoft Academic Search

The Galileo Probe Mass Spectrometer provided the first data on the noble gas mixing and isotope ratios in the Jovian atmosphere. These measurements and the comparison with solar values constrain models of Jupiter's formation. Significant refinements to the initially reported abundances of argon, krypton, and xenon have been enabled through post-encounter laboratory calibrations using a refurbished engineering unit mass spectrometer

P. R. Mahaffy; H. B. Niemann; A. Alpert; S. K. Atreya; J. Demick; T. M. Donahue; D. N. Harpold; T. C. Owen

2000-01-01

232

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

SciTech Connect

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.

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

2014-04-01

233

Pathway to cryogen free production of hyperpolarized Krypton-83 and Xenon-129.  

PubMed

Hyperpolarized (hp) (129)Xe and hp (83)Kr 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 (129)Xe MRI cumbersome. For hp (83)Kr 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 (129)Xe SEOP without cryogenic separation, the highest obtained MR signal intensity from the hp xenon-nitrogen gas mixture was equivalent to that arising from 15.51.9% spin polarized (129)Xe in pure xenon gas. The production rate of the hp gas mixture, measured at 298 K, was 1.8 cm(3)/min. For hp (83)Kr, the equivalent of 4.40.5% spin polarization in pure krypton at a production rate of 2 cm(3)/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 D(1) transition was observed and taken into account for the qualitative description of the SEOP process. PMID:23209620

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

2012-01-01

234

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

PubMed Central

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 15.51.9% 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 4.40.5% 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

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

2012-01-01

235

TUDE EXPRIMENTALE DES AILES DE LA RAIE 2 537 DU MERCURE PERTURBE PAR LE KRYPTON ET LE XNON  

E-print Network

831 ?TUDE EXP?RIMENTALE DES AILES DE LA RAIE 2 537 ? DU MERCURE PERTURB?E PAR LE KRYPTON ET LE mercure-krypton et vapeur de mercure-xénon sur un domaine spectral allant de 120 à 7 500 GHz de part et d'intérêt. Abstract. 2014 For atomic densities of krypton and xenon less than 1020 at/cm3 we have measured

Paris-Sud XI, Université de

236

Proprits du film de krypton adsorb sur la face (0001) du graphite pralablement recouverte d'hexafluorure de soufre  

E-print Network

1797 Propriétés du film de krypton adsorbé sur la face (0001) du graphite préalablement recouverte 28 mai 1986, accepte le 24 juin 1986) Résumé. - La physisorption de krypton sur la face (0001) du 70 et 80 K. La présence de SF6 contrarie fortement l'adsorption du krypton qui ne s'adsorbe de façon

Paris-Sud XI, Université de

237

Taussig-Bing Anomaly  

PubMed Central

Taussig-Bing anomaly is a rare congenital heart malformation that was first described in 1949 by Helen B. Taussig (18981986) 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

Konstantinov, Igor E.

2009-01-01

238

On an additional realization of supersymmetry in orthopositronium lifetime anomalies  

E-print Network

Expansion of Standard Model for the quantitative description of the orthopositronium lifetime anomalies (from QED to supersymmetric QED) allows to formulate experimental tests of supervision of additional realization of the supersymmetry in final state of the positron beta-decay of the nuclei such as Na-22, Ga-68. The expermentum crucis program is based on supervision of the orthopositronium "isotope anomaly", on the quantitative description of the "lifetime anomaly", and will allow to resolve the alternative as results of the last Michigan work (2003).

B. M. Levin; V. I. Sokolov

2007-03-16

239

PHYSICAL REVIE% 8 VOLUME 37, NUMBER 2 15 JANUARY 1988-I Dynamics of xenon, krypton, and methane monolayers in registry with graphite  

E-print Network

PHYSICAL REVIE% 8 VOLUME 37, NUMBER 2 15 JANUARY 1988-I Dynamics of xenon, krypton, and methane of monolayers of xenon, krypton, and methane adsorbed on graphite. Only the ~3Xv 3 sohd phase is considered

Glyde, Henry R.

240

First Detection of Krypton and Xenon in a White Dwarf  

NASA Astrophysics Data System (ADS)

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.

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

2012-07-01

241

Krypton charge exchange cross sections for Hall effect thruster models  

NASA Astrophysics Data System (ADS)

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+ + Kr and Kr2+ + Kr cross sections. The measurements of symmetric Kr+ + Kr charge exchange are in good agreement with both the calculations including spin-orbit effects and previous measurements. For the symmetric Kr2+ + 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 Kr2+ + Kr ? Kr+ + Kr+ reaction show an onset near 12 eV, reaching cross sections near constant value of 1.6 2 with an exception near 70-80 eV.

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

2013-04-01

242

Modified effective range analysis of electron scattering from krypton  

NASA Astrophysics Data System (ADS)

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 Schrdinger 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.

Fedus, Kamil

2014-10-01

243

Krypton charge exchange cross sections for Hall effect thruster models  

SciTech Connect

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.

Hause, Michael L. [Institute for Scientific Research, Boston College, Chestnut Hill, Massachusetts 02159 (United States); Prince, Benjamin D.; Bemish, Raymond J. [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, New Mexico 87117 (United States)

2013-04-28

244

FIRST DETECTION OF KRYPTON AND XENON IN A WHITE DWARF  

SciTech Connect

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.

Werner, Klaus; Rauch, Thomas; Ringat, Ellen [Institute for Astronomy and Astrophysics, Kepler Center for Astro and Particle Physics, Eberhard Karls University Tuebingen, Sand 1, 72076 Tuebingen (Germany); Kruk, Jeffrey W. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2012-07-01

245

First Detection of Krypton and Xenon in a White Dwarf  

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

246

Radioactive Iodine and Krypton Control for Nuclear Fuel Reprocessing Facilities  

SciTech Connect

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.

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

2013-08-01

247

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

PubMed

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 0C, and then to 100C. 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

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

2012-07-01

248

Krypton Separation from Ambient Air for Application in Collinear Fast Beam Laser Spectroscopy  

NASA Astrophysics Data System (ADS)

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 H2O and CO2, 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 N2, O2, 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.

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

2012-07-01

249

Variability of atmospheric krypton-85 activity concentrations observed close to the ITCZ in the southern hemisphere.  

PubMed

Krypton-85 activity concentrations in surface air have been measured at Darwin, which is located in northern Australia and is influenced by seasonal monsoonal activity. Measurements between August 2007 and May 2010 covered three wet seasons. The mean activity concentration of krypton-85 measured during this period was 1.310.02Bqm(-3). A linear model fitted to the average monthly data, using month and monsoon as predictors, shows that krypton-85 activity concentration measured during the sampling period has declined by 0.01Bqm(-3) per year. Although there is no statistically significant difference in mean activity concentration of krypton-85 between wet and dry season, the model implies that activity concentration is higher by about 0.015Bqm(-3) during months influenced by the monsoon when a north westerly flow prevails. Backward dispersion runs using the Lagrangian particle dispersion model Hysplit4 highlight possible source regions during an active monsoon located deep in the northern hemisphere, and include reprocessing facilities in Japan and India. However, the contribution of these facilities to krypton-85 activity concentrations in Darwin would be less than 0.003Bqm(-3). PMID:24184817

Bollhfer, A; Schlosser, C; Ross, J O; Sartorius, H; Schmid, S

2014-01-01

250

Quartz-crystal microbalance studies of the slippage of solid and liquid krypton monolayers on metal(111) and C60 surfaces  

E-print Network

Quartz-crystal microbalance studies of the slippage of solid and liquid krypton monolayers on metal of the nanotribology of solid and liquid krypton monolayers adsorbed on Cu 111 , Ag 111 , Ni 111 , and C60 substrates at 77.4 K. We document the liquid- solid phase transition and compare the slip times of the krypton

Krim, Jacqueline

251

JOWRNAL DE PHYSIQUE Colloque C4, supplkment au no 10, Tome 38, octobre 1977, page C4-99 KRYPTON OVERLAYERS ON GRAPHITE :LOW ENERGY ELECTRON  

E-print Network

JOWRNAL DE PHYSIQUE Colloque C4, supplkment au no 10, Tome 38, octobre 1977, page C4-99 KRYPTON Btudier I'adsorption de krypton sur la face (0001) du graphite. Les pressions et temperatures de the adsorption of krypton on the (0001) plane of graphite. The pressures and temperatures for two dimensional

Boyer, Edmond

252

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

SciTech Connect

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.

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

2010-03-28

253

Hydrodynamics with Triangle Anomalies  

E-print Network

We consider the hydrodynamic regime of theories with quantum anomalies for global currents. We show that a hitherto discarded term in the conserve current is not only allowed by symmetries, but is in fact required by triangle anomalies and the second law of thermodynamics. This term leads to a number of new effects, one of which is chiral separation in a rotating fluid at nonzero chemical potential. The new kinetic coefficients can be expressed, in a unique fashion, through the anomalies coefficients and the equation of state. We briefly discuss the relevance of this new hydrodynamic term for physical situations, including heavy ion collisions.

Dam T. Son; Piotr Surowka

2009-07-13

254

Hydrodynamics with Triangle Anomalies  

SciTech Connect

We consider the hydrodynamic regime of theories with quantum anomalies for global currents. We show that a hitherto discarded term in the conserved current is not only allowed by symmetries, but is in fact required by triangle anomalies and the second law of thermodynamics. This term leads to a number of new effects, one of which is chiral separation in a rotating fluid at nonzero chemical potential. The new kinetic coefficients can be expressed, in a unique fashion, through the anomaly coefficients and the equation of state. We briefly discuss the relevance of this new hydrodynamic term for physical situations, including heavy-ion collisions.

Son, Dam T. [Institute for Nuclear Theory, University of Washington, Seattle, Washington 98195-1550 (United States); Surowka, Piotr [Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States); Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland)

2009-11-06

255

Gravitational Anomaly and Transport  

E-print Network

Quantum anomalies give rise to new transport phenomena. In particular a magnetic field can induce an anomalous current via the chiral magnetic effect and a vortex in the relativistic fluid can also induce a current via the chiral vortical effect. The related transport coefficients can be calculated via Kubo formulas. We evaluate the Kubo formula for the anomalous vortical conductivity at weak coupling and show that it receives contributions proportional to the gravitational anomaly coefficient. The gravitational anomaly gives rise to an anomalous vortical effect even for an uncharged fluid.

Landsteiner, Karl; Pena-Benitez, Francisco

2011-01-01

256

Gravitational Anomaly and Transport  

E-print Network

Quantum anomalies give rise to new transport phenomena. In particular a magnetic field can induce an anomalous current via the chiral magnetic effect and a vortex in the relativistic fluid can also induce a current via the chiral vortical effect. The related transport coefficients can be calculated via Kubo formulas. We evaluate the Kubo formula for the anomalous vortical conductivity at weak coupling and show that it receives contributions proportional to the gravitational anomaly coefficient. The gravitational anomaly gives rise to an anomalous vortical effect even for an uncharged fluid.

Karl Landsteiner; Eugenio Megias; Francisco Pena-Benitez

2011-07-06

257

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

SciTech Connect

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.

Linert, Ireneusz; Mielewska, Brygida; Zubek, Mariusz [Department of Physics of Electronic Phenomena, Gdansk University of Technology, 80-233 Gdansk (Poland); King, George C. [School of Physics and Astronomy, Manchester University, Manchester M13 9 PL (United Kingdom)

2010-01-15

258

Opening of single-walled carbon nanotubes: evidence given by krypton and xenon adsorption  

NASA Astrophysics Data System (ADS)

Adsorption isotherms of krypton between 77 and 93 K and xenon between 110 and 120 K on mechanically-opened single-walled carbon nanotubes (SWNTs) have been measured. The comparison of the results with those obtained under the same conditions on closed nanotubes is discussed. Evidence of adsorption inside the tubes is given through the appearance of an additional adsorbed amount at very low relative pressure on the isotherms. Different orderings are predicted for xenon and krypton, based on their respective adsorbed amounts inside the nanotubes, and on geometrical considerations. Finally, the fraction of opened nanotubes accessible to xenon and krypton was estimated, as well as the impurity content originating from the cutting process.

Babaa, M. R.; Stepanek, I.; Masenelli-Varlot, K.; Dupont-Pavlovsky, N.; McRae, E.; Bernier, P.

2003-05-01

259

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)

Os, Sr, Nd and Pb isotope data were collected from a profile across the Cretaceous-Tertiary (K-T) boundary layer at Stevns Klint, Denmark. ?Nd [ T=65 Ma] values from within the boundary layer (Fish Clay) are lower by 1 ? 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 0.1198360.000004 measured in the basal layer of the Fish Clay is within the uncertainty a chondritic value. We therefore exclude the possibility of a major contribution of PGEs to the sediment from iron meteorites. Chondrite-normalized (Ru/Ir) N ratios of 0.950.14 and (Os/Ir) N ratios of 0.930.14 in the Fish Clay cannot distinguish between abundance ratios of different types of chondrites, and strongly sub-chondritic (Pt/Ir) N ratios of 0.620.09 (2?) suggest differential PGE remobilization through the sedimentary column (and consequently the alteration of inter-element ratios). PGEs and the moderately siderophile elements Cr, Ni, V, and Co form an elemental association with systematically upward-decreasing concentrations in the Fish Clay. Low Co/Ni ratios of 0.12 in the Fish Clay relative to values of 0.35 in the over- and underlying carbonate sequences support mixing of meteorite-derived (Co/Ni 0.05) and terrestrial upper mantle/crustal (Co/Ni >0.3) sources. While lithophile element isotope data indicate an increased continental crustal input to the Fish Clay at the K-T transition, the uncertainty with respect to possible post-depositional alteration of abundance patterns of siderophile and moderately siderophile elements - though not affecting the chondritic isotopic composition of Os - does not allow confirmation of indications from chromium isotopes for a carbonaceous (CV-type) meteorite as the preferred K-T impactor type by Shukolyukov and Lugmair [Science 282 (1998) 927-929].

Frei, Robert; Frei, Karin M.

2002-10-01

260

Coronary Artery Anomalies  

MedlinePLUS

... terms: CAA, anomalous coronary artery (ACA), sudden cardiac arrest, sudden cardiac death A coronary artery anomaly (CAA) ... exercise Sudden cardiac death (also called sudden cardiac arrest) is the most dangerous symptom of a CAA. ...

261

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

SciTech Connect

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.

Miernik, Krzysztof A [ORNL; Gross, Carl J [ORNL; Grzywacz, Robert Kazimierz [ORNL; Madurga, M [University of Tennessee, Knoxville (UTK); Mendez, II, Anthony J [ORNL; Miller, D. [University of Tennessee, Knoxville (UTK); Padgett, S [University of Tennessee, Knoxville (UTK); Paulauskas, Stanley V [ORNL; Rykaczewski, Krzysztof Piotr [ORNL; Stracener, Daniel W [ORNL; Wolinska-Cichocka, Marzena [ORNL; Zganjar, E. F. [Louisiana State University; Batchelder, J. C. [Oak Ridge Associated Universities (ORAU); Brewer, N.T. [Vanderbilt University; Cartegni, L. [University of Tennessee, Knoxville (UTK); Fijalkowska, Aleksandra G [ORNL; Hamilton, J. H. [Vanderbilt University; Hwang, J. K. [Vanderbilt University; Ilyushkin, S. [Mississippi State University (MSU); Jost, Carola U [ORNL; Karny, M. [University of Warsaw; Korgul, A. [University of Warsaw; Krolas, W. [Oak Ridge Associated Universities (ORAU); Liu, S.H. [UNIRIB/ORAU and Vanderbilt University, Nashville, Tennessee; Mazzocchi, C. [University of Warsaw; Ramayya, A. V. [Vanderbilt University; Surman, Rebecca [Union College; Winger, J. A. [Mississippi State University (MSU); Wolinska-Cichocka, M [Oak Ridge Associated Universities (ORAU)

2013-01-01

262

Search for isotope effects in the diffusion of methane in krypton at various densities  

Microsoft Academic Search

Experimental measurements of the diffusion coefficient of CH4 in Kr at T=220K in the density range 0

P. Codastefano; M. A. Ricci; D. Rocca

1977-01-01

263

Congenital vascular anomalies  

Microsoft Academic Search

Opinion statementCongenital vascular anomalies are rare. The cardiovascular specialist should nevertheless be aware of the more common types\\u000a of vascular anomalies and understand the implications for patient treatment and the likelihood of associated morbidity. The\\u000a presentation of congenital arteriovenous malformations can range from asymptomatic or cosmetic lesions, to those causing ischemia,\\u000a ulceration, hemorrhage, or high-output congestive heart failure. Treatment of

Edwin C. Gravereaux; Louis L. Nguyen; Leslie D. Cunningham

2004-01-01

264

The Pioneer Anomaly  

E-print Network

Analysis of the radio-metric data from Pioneer 10 and 11 spacecrafts has indicated the presence of an unmodeled acceleration starting at 20 AU, which has become known as the Pioneer anomaly. The nature of this acceleration is uncertain. In this paper we give a description of the effect and review some relevant mechanisms proposed to explain the observed anomaly. We also discuss on some future projects to investigate this phenomenon.

de Diego, Jose A

2008-01-01

265

The Pioneer Anomaly  

E-print Network

Analysis of the radio-metric data from Pioneer 10 and 11 spacecrafts has indicated the presence of an unmodeled acceleration starting at 20 AU, which has become known as the Pioneer anomaly. The nature of this acceleration is uncertain. In this paper we give a description of the effect and review some relevant mechanisms proposed to explain the observed anomaly. We also discuss on some future projects to investigate this phenomenon.

Jose A. de Diego; Dario Nunez

2008-07-07

266

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

SciTech Connect

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.

Smith, Z. S.; Harmon, A.; Banister, J.; Norman, R.; Hoogeboom-Pot, K.; Walhout, M. [Department of Physics and Astronomy, Calvin College, Grand Rapids, Michigan 49546 (United States)

2010-01-15

267

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

SciTech Connect

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.

Gerasimov, Gennadii N; Krylov, B E [Research Center 'Vavilov State Optical Institute', St.Petersburg (Russian Federation); Lomaev, Mikhail I; Rybka, D V; Tarasenko, Viktor F [Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, Tomsk (Russian Federation)

2010-05-26

268

A beam of metastable krypton atoms extracted from a microwave-driven discharge.  

SciTech Connect

A microwave-driven discharge is used to produce a thermal beam of metastable krypton atoms at the 5s[3/2]{sub 2} level with an angular flux density of 7 x 10{sup 14} s{sup -1} sr{sup -1}, while consuming 1 x 10{sup 17} krypton atoms/s. This source of atomic beam uses commercially available microwave parts, and has achieved comparable beam flux and excitation efficiency with a previously described source that employs a rf-driven discharge [C. Y. Chen et al., Rev. Sci. Instrum. 72, 271 (2001)].

Ding, Y.; Bailey, K.; Davis, A. M.; Hu, S.-M.; Lu, Z.-T.; O'Connor, T. P.; Physics; Univ. of Chicago; Unvi. of Science and Technology of China

2006-01-01

269

Ca isotope variations in Allende  

NASA Technical Reports Server (NTRS)

Ca-isotope measurements of Allende Ca-Al-rich inclusions (CAIs), together with those on an apatite-enriched fraction from Orgueil, indicate the existence of widespread excesses on the neutron-rich isotope Ca-48. Isotopic anomalies are noted in 7 out of 11 CAIs analyzed. This abundance of isotopic excesses places Ca alongside Ti and O, although no clear correlation has yet been found between Ca-48 and Ti-50, which are thought to be coproduced by neutron-rich nucleosynthetic processes within stars. It is suggested that the higher volatility of Ca, by comparison with Ti compounds, led to a variable dilution with isotopically normal Ca in vaporization and recondensation processes in stellar envelopes, the interstellar medium, and/or the solar nebula.

Jungck, M. H. A.; Shimamura, T.; Lugmair, G. W.

1984-01-01

270

The isotope hydrology of Quaternary climate change.  

PubMed

Understanding the links between climate change and human migration and culture is an important theme in Quaternary archaeology. While oxygen and hydrogen stable isotopes in high-latitude ice cores provide the ultimate detailed record of palaeoclimate extending back to the Middle Pleistocene, groundwater can act as a climate archive for areas at lower latitudes, permitting a degree of calibration for proxy records such as lake sediments, bones, and organic matter. Not only can oxygen and hydrogen stable isotopes be measured on waters, but the temperature of recharge can be calculated from the amount of the atmospheric noble gases neon, argon, krypton, and xenon in solution, while residence time can be estimated from the decay of the radioisotopes carbon-14, chlorine-36, and krypton-81 over timescales comparable to the ice core record. The Pleistocene-Holocene transition is well characterised in aquifers worldwide, and it is apparent that isotope-temperature relationships of the present day are not necessarily transferable to past climatic regimes, with important implications for the interpretation of proxy isotope data. Groundwaters dating back to one million years, i.e., to beyond the Middle Pleistocene, are only found in major aquifer basins and information is relatively sparse and of low resolution. Speleothem fluid inclusions offer a way of considerably increasing this resolution, but both speleothem formation and large-scale groundwater recharge requires humid conditions, which may be relatively infrequent for areas currently experiencing arid climates. Both types of record therefore require caution in their interpretation when considering a particular archaeological context. PMID:21051074

Darling, W G

2011-04-01

271

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

SciTech Connect

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)

Zayarnyi, D A; L'dov, A Yu; Kholin, I V [P N Lebedev Physical Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2009-09-30

272

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

SciTech Connect

We have used the absorption probe method to study the processes of collisional quenching of the metastable 5s [3/2]{sup o}{sub 2}({sup 3}P{sub 2}) state of the krypton atom in electron-beam-excited high-pressure He Kr mixtures with a low content of krypton. The rate constants of plasma-chemical reactions Kr* + Kr + He ? Kr*{sub 2}+He [(2.88 0.29) 10{sup -33} cm{sup 6} s{sup -1}], Kr* + 2He ? HeKr* + He [(4.6 1.3) 10{sup -36} cm{sup 6} s{sup -1}] and Kr* + He ? products + He [(1.51 0.15) 10{sup -15} cm{sup 3} s{sup -1}] are measured for the first time. The rate constants of similar reactions in the Ar Kr mixture are refined. (active media)

Zayarnyi, D A; L'dov, A Yu; Kholin, I V [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2013-08-31

273

Impact and applications : atom trap, krypton-81, and Saharan water.  

SciTech Connect

Much can be learned from the analysis of the ubiquitous long-lived radioactive isotopes. In the late 1940s, Willard Libby and coworkers first detected the cosmogenic {sup 14}C(t{sub 1/2} = 5.7 x 10{sup 3} yr, isotopic abundance {sup 14}C/C = 1 x 10{sup -12}) in nature and demonstrated that such analysis could be used for archaeological dating. Since then, two by now well-established methods, Low-Level Counting (LLC) and Accelerator Mass Spectrometry (AMS), have been used to analyze {sup 14}C and many other radioisotopes and to extract valuable information encoded in the production, transport, and decay processes of these isotopes.

Lu, Z.-T.; Physics

2008-01-01

274

Astrometric solar system anomalies  

SciTech Connect

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.

Nieto, Michael Martin [Los Alamos National Laboratory; Anderson, John D [PROPULSION LABORATORY

2009-01-01

275

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

NASA Astrophysics Data System (ADS)

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.

Ustinov, E. A.

2014-10-01

276

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

PubMed

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

Ustinov, E A

2014-10-01

277

Identification of Krypton Kr XVIII to Kr XXIX Spectra Excited in TFR Tokamak Plasmas  

Microsoft Academic Search

The emission spectrum of krypton (injected into TFR tokamak plasmas) has been recorded photographically in the 15-300 spectral range by means of a 2 m grazing incidence spectrograph. Preliminary identification work, based on isoelectronic regularities from known spectra of other ions and ionization equilibrium calculations, has allowed 48 lines (belonging to the O I, F I, Na I, Mg

J. F. Wyart

1985-01-01

278

Auger decay in krypton induced by attosecond pulse trains and twin pulses  

E-print Network

Using attoscience, we study the electron correlations responsible for Auger decay in krypton atoms. The Auger decay is induced by a pulse train or a twin pulse composed of subpulses of attosecond duration. During the Auger decay an optical dressing laser may be present. Interference effects between the ejected Auger electron wave packets are predicted.

Buth, Christian

2009-01-01

279

Adsorption measurements of argon, neon, krypton, nitrogen, and methane on activated carbon up to 650 MPa  

Microsoft Academic Search

The physisorption of argon, krypton, neon, nitrogen, and methane on GAC activated carbon has been measured in the above critical region by a dielectric method. The measurements were done at room temperature and at pressures up to 650 MPa corresponding to reduced densities of up to 3.25. With the exception of nitrogen, all the measured excess adsorption isotherms show a

P. Malbrunot; D. Vidal; J. Vermesse; R. Chahine; T. K. Bose

1992-01-01

280

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

NASA Technical Reports Server (NTRS)

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.

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

1975-01-01

281

An Essential Hybrid Reasoning System: Knowledge and Symbol Level Accounts of KRYPTON  

Microsoft Academic Search

Hybrid inference systems are an important way to address the fact that intelligent systems have muiltifaceted rep- resentational and reasoning competence. KRYPTON is an experimental prototype that competently handles both terminological and assertional knowledge; these two kinds of information are tightly linked by having sentences in an assertional component be formed using structured com plex predicates denned in a complementary

Ronald J. Brachman; Victoria P. Gilbert; Hector J. Levesque

1985-01-01

282

Treatment of retinal detachment with congenital optic pit by krypton laser photocoagulation  

Microsoft Academic Search

Five patients with a congenital pit of the optic nerve and serous detachment of the macular retina were treated with krypton laser photocoagulation to the juxtapapillary region in an attempt to induce resolution of the retinal detachment. The subretinal fluid resolved after laser therapy in four of the patients. In the fifth, the retinal detachment was successfully treated with pars

W. Annesley; G. Brown; J. Bolling; R. Goldberg; D. Fischer

1987-01-01

283

Dielectric and adsorption isotherms of adsorbed krypton and xenon on boron nitride  

NASA Astrophysics Data System (ADS)

We present simultaneous measurements of adsorption isotherms and dielectric isotherms for krypton and xenon on boron nitride. Dielectric measurements give a good characterization of monolayer formation and completion, and provide new information on the dielectric properties evolution from a two-dimensional system towards the bulk.

Laheurte, J. P.; Noiray, J. C.; Obadia, M.; Romagnan, J. P.

1982-11-01

284

Continuous imaging of regional myocardial blood flow in dogs using krypton-81m.  

PubMed

The unique physical properties of the freely diffusible gas krypton-81 m allowed continuous imaging of regional myocardial blood flow in dogs when infused into the aortic root. Regional changes in myocardial perfusion related to transient coronary artery occlusion were demonstrated both as high resolution gamma camera images and as a quantitative strip chart record. PMID:954025

Turner, J H; Selwyn, A P; Jones, T; Evans, T R; Raphael, M J; Lavender, J P

1976-05-01

285

COURBES D'IONISATION DANS LE KRYPTON ET LE XNON PURS RELATIVES AUX RAYONS 03B1 DU POLONIUM  

E-print Network

COURBES D'IONISATION DANS LE KRYPTON ET LE X?NON PURS RELATIVES AUX RAYONS 03B1 DU POLONIUM Par R polonium dans le krypton et le xénon purs. Les parcours trouvés sont : RKr = 3,03 ± 0,01 cm; RXe = 2,17 ± 0 sont d'environ 30 pour 100 dans le krypton et de 40 pour 100 dans le xénon. Dans l'air la perte par

Paris-Sud XI, Université de

286

Histopathology of vascular anomalies.  

PubMed

Vascular anomalies may be appropriately classified into two broad categories, vascular tumors and vascular malformations, which are distinguished by the presence of cellular proliferation in contrast to aberrations in morphogenesis, respectively. This system of classification is based upon histological features that may in large part be differentiating, but nevertheless, may show morphological overlap. Advances in immunophenotyping allow for more precise diagnoses as well as further delineation of cell origins. In the discussion, we present the clinical, histological, and, when applicable, the immunophenotypic presentation of vascular anomalies commonly seen in infancy and early childhood. PMID:23188681

Aboutalebi, Amir; Jessup, Chad J; North, Paula E; Mihm, Martin C

2012-12-01

287

Normal Zirconium Isotopic Composition in Murchison Hibonite 13-13  

Microsoft Academic Search

Murchison hibonite 13-13 has a special place in isotopic astronomy because it has the largest isotopic anomalies in Ca and Ti as yet measured with delta ^48Ca at +105 per mil and delta ^50Ti at +273 per mil [1]. It has been suggested that these anomalies are the result of nucleosynthesis in neutron-rich supernova ejecta [2] and Ca and Ti

T. R. Ireland

1993-01-01

288

Isotopic Biogeochemistry  

NASA Technical Reports Server (NTRS)

An overview is provided of the biogeochemical research. The funding, productivity, personnel and facilities are reviewed. Some of the technical areas covered are: carbon isotopic records; isotopic studies of banded iron formations; isotope effects in microbial systems; studies of organic compounds in ancient sediments; and development in isotopic geochemistry and analysis.

Hayes, J. M.

1985-01-01

289

Antler anomalies in tule elk  

USGS Publications Warehouse

Antler anomalies were evident in tule elk (Cervus elaphus nannodes) within 1 yr of reintroduction to Point Reyes, California (USA). These anomalies are consistent with previously described mineral deficiency-induced anomalies in cervids. The elk were judged deficient in copper. Low levels of copper in soils and vegetation at the release site, exacerbated by possible protein deficiency due to poor range conditions, are postulated as likely causes of the antler anomalies.

Gogan, Peter J.P.; Jessup, David A.; Barrett, Reginald H.

1988-01-01

290

Global Climate Highlights and Anomalies  

NSDL National Science Digital Library

NOAA's Global Climate Highlights and Anomalies page offers weekly summaries of global climate highlights and anomalies (warm, cold, wet, dry). Areas experiencing climate anomalies are color-marked on a global map, followed by written summaries of each region's climate conditions. All weeks are posted for the year 2000 (to present), and a link points users to the complete 1999 archive.

291

Performance of a continuous-wave forsterite laser with krypton ion, Ti:sapphire, and Nd:YAG pump lasers  

Microsoft Academic Search

The authors characterize continuous-wave operation of a chromium-doped forsterite (Cr4+:Mg2SiO4) laser using krypton ion, Ti:sapphire, and Nd:YAG lasers as pump sources. Measurements were made pumping at 647 nm and 676 nm with the krypton ion laser, between 690 and 1010 nm with the Ti:sapphire laser, and at 1.06 ?m with the Nd:YAG laser. Threshold pump powers and slope efficiencies are

Timothy J. Carrig; Clifford R. Pollock

1993-01-01

292

Isotopic distributions.  

PubMed

Isotopic information determined by mass spectrometry can be used in a wide variety of applications. Broadly speaking these could be classified as "passive" applications, meaning that they use naturally occurring isotopic information, and "active" applications, meaning that the isotopic distributions are manipulated in some way. The classic passive application is the determination of chemical composition by comparing observed isotopic patterns of molecules to theoretically calculated isotopic patterns. Active applications include isotope exchange experiments of a variety of types, as well as isotope labeling in tracing studies and to provide references for quantitation. Regardless of the type of application considered, the problem of theoretical calculation of isotopic patterns almost invariably arises. This paper reviews a number of application examples and computational approaches for isotopic studies in mass spectrometry. PMID:23666722

Rockwood, Alan L; Palmblad, Magnus

2013-01-01

293

High-accuracy mass measurements of neutron-rich Kr isotopes  

SciTech Connect

The atomic masses of the neutron-rich krypton isotopes {sup 84,86-95}Kr have been determined with the tandem Penning trap mass spectrometer ISOLTRAP with uncertainties ranging from 20 to 220 ppb. The masses of the short-lived isotopes {sup 94}Kr and {sup 95}Kr were measured for the first time. The masses of the radioactive nuclides {sup 89}Kr and {sup 91}Kr disagree by 4 and 6 standard deviations, respectively, from the present Atomic-Mass Evaluation database. The resulting modification of the mass surface with respect to the two-neutron separation energies as well as implications for mass models and stellar nucleosynthesis are discussed.

Delahaye, P.; Kellerbauer, A. [ISOLDE, CERN, Physics Department, CH-1211 Geneva 23 (Switzerland); Audi, G.; Lunney, D. [CSNSM-CNRS-IN2P3, F-91405 Orsay (France); Blaum, K.; George, S. [Johannes Gutenberg-Universitaet, Institut fuer Physik, D-55099 Mainz (Germany); Gesellschaft fuer Schwerionenforschung GSI, D-64291 Darmstadt (Germany); Carrel, F.; Herfurth, F.; Yazidjian, C. [Gesellschaft fuer Schwerionenforschung GSI, D-64291 Darmstadt (Germany); Herlert, A.; Schweikhard, L. [Ernst-Moritz-Arndt-Universitaet, Institut fuer Physik, D-17487 Greifswald (Germany); Kluge, H.-J. [Gesellschaft fuer Schwerionenforschung GSI, D-64291 Darmstadt (Germany); Ruprecht-Karls-Universitaet Heidelberg, Physikalisches Institut, D-69120 Heidelberg (Germany)

2006-09-15

294

Yearly Arctic Temperature Anomaly  

NSDL National Science Digital Library

This animation shows the yearly temperature anomaly over the Arctic region from 1981-82 through 2002-03. Years run from August 1 through July 31. Blue hues indicate cooling regions; red hues depict warming. Light regions indicate less change while darker regions indicate more. The temperature scale used ranges from -7.0 to +7.0 degrees Celsius in increments of .25 degrees. (See color bar below)

Cindy Starr

2003-10-23

295

Electron capture from the krypton M-shell by MeV protons S. Andriamonje (*), J. F. Chemin (*), J. Roturier (*), B. Saboya (*), J. N. Scheurer (*),  

E-print Network

349 Electron capture from the krypton M-shell by MeV protons S. Andriamonje (*), J. F. Chemin, accepté le 1 G novembre 1984 ) Résumé. 2014 La capture électronique dans un jet gazeux de krypton par des capture a lieu préférentiellement depuis la sous-couche 3d du krypton. Une analyse est faite du rôle joué

Paris-Sud XI, Université de

296

Shape of the two-photon-continuum emission from the 1s2s 1 S0 state in He-like krypton  

E-print Network

Shape of the two-photon-continuum emission from the 1s2s 1 S0 state in He-like krypton R. Ali,* I of the 1s2s 1 S0 level in heliumlike krypton. In the experiment, a beam of Kr34 ions was excited using of the continuum radiation from the two-photon decay of the 1s2s 1 S0 level in He-like krypton see Fig. 1

Cheng, Song

297

Neon isotopes in submarine basalts  

Microsoft Academic Search

Very large neon isotopic anomalies have been accurately measured in mid-ocean ridge basalt glassy samples from diverse locations worldwide. Values for 20Ne\\/22Ne range up to ~ 13 and 21Ne\\/22Ne values range up to ~ 0.07 (present atmospheric values are 20Ne\\/22Ne = 9.8 and 21Ne\\/22Ne = 0.029). The data are highly correlated in the 20Ne\\/22Ne-21Ne\\/22Ne diagram, independent of sample location. Loihi

Philippe Sarda; Thomas Staudacher; Claude J. Allgre

1988-01-01

298

Elemental and isotopic composition of the galactic cosmic rays  

Microsoft Academic Search

It is now established that there are important differences in elemental and isotopic abundance between the source matter of galactic cosmic rays and the solar system matter. These large differences (more than a factor of 2 in some cases, in contrast to less than or equal to1% for isotopic anomalies in solar system matter) may become essential clues to the

J A Simpson

1983-01-01

299

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

SciTech Connect

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.

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

2013-08-23

300

Single-frequency oscillation of a wide-aperture krypton laser  

SciTech Connect

The parameters of a high-current krypton discharge in tubes of an increased diameter (5 - 7 mm) are studied and optimised. Increased lasing power on the lines of singly and doubly charged krypton ions is achieved: 14 W (647 - 676 nm) and 6 W (407 - 415 nm). One transverse and one longitudinal mode are selected with efficiencies of 85 and 70 % using a convex - concave resonator and a Fabry - Perot etalon, respectively. The shape of the Lamb dip at the 676-nm line is studied in the single-frequency oscillation mode. It is shown that, in accordance with the theory, the dip broadens by a factor of 2.6 due to Coulomb ion - ion collisions at an achieved electron concentration N{sub e} {approx} 5 x 10{sup 14} cm{sup -3}. (active media. lasers)

Babin, S A; Khorev, S V [Institute of Automation and Electrometry, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

2003-09-30

301

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

PubMed

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

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

2013-12-12

302

AA stacking, tribological and electronic properties of double-layer graphene with krypton spacer.  

PubMed

Structural, energetic, and tribological characteristics of double-layer graphene with commensurate and incommensurate krypton spacers of nearly monolayer coverage are studied within the van der Waals-corrected density functional theory. It is shown that when the spacer is in the commensurate phase, the graphene layers have the AA stacking. For this phase, the barriers to relative in-plane translational and rotational motion and the shear mode frequency of the graphene layers are calculated. For the incommensurate phase, both of the barriers are found to be negligibly small. A considerable change of tunneling conductance between the graphene layers separated by the commensurate krypton spacer at their relative subangstrom displacement is revealed by the use of the Bardeen method. The possibility of nanoelectromechanical systems based on the studied tribological and electronic properties of the considered heterostructures is discussed. PMID:24160531

Popov, Andrey M; Lebedeva, Irina V; Knizhnik, Andrey A; Lozovik, Yurii E; Potapkin, Boris V; Poklonski, Nikolai A; Siahlo, Andrei I; Vyrko, Sergey A

2013-10-21

303

Soft X-Ray Images of Krypton Gas-Puff Z-Pinches  

Microsoft Academic Search

A series of experiments has been carried out on Qiang-guang I generator to study the dynamics of krypton gas-puff Z-pinches. The generator was operated at a peak current of 1.5 MA with a rise-time of 80 ns. The specific linear mass of gas liner was about 20 mug\\/cm in these experiments. In the diagnostic system, a four-frame x-ray framing camera

Meng-tong Qiu; Bin Kuai; Zheng-zhong Zeng; Min Lu; Kui-lu Wang; Ai-ci Qiu; Mei Zhang; Jian-hui Luo

2002-01-01

304

High-Power Krypton Hall Thruster Technology Being Developed for Nuclear-Powered Applications  

NASA Technical Reports Server (NTRS)

The NASA Glenn Research Center has been performing research and development of moderate specific impulse, xenon-fueled, high-power Hall thrusters for potential solar electric propulsion applications. These applications include Mars missions, reusable tugs for low-Earth-orbit to geosynchronous-Earth-orbit transportation, and missions that require transportation to libration points. This research and development effort resulted in the design and fabrication of the NASA-457M Hall thruster that has been tested at input powers up to 95 kW. During project year 2003, NASA established Project Prometheus to develop technology in the areas of nuclear power and propulsion, which are enabling for deep-space science missions. One of the Project-Prometheus-sponsored Nuclear Propulsion Research tasks is to investigate alternate propellants for high-power Hall thruster electric propulsion. The motivation for alternate propellants includes the disadvantageous cost and availability of xenon propellant for extremely large scale, xenon-fueled propulsion systems and the potential system performance benefits of using alternate propellants. The alternate propellant krypton was investigated because of its low cost relative to xenon. Krypton propellant also has potential performance benefits for deep-space missions because the theoretical specific impulse for a given voltage is 20 percent higher than for xenon because of krypton's lower molecular weight. During project year 2003, the performance of the high-power NASA-457M Hall thruster was measured using krypton as the propellant at power levels ranging from 6.4 to 72.5 kW. The thrust produced ranged from 0.3 to 2.5 N at a discharge specific impulse up to 4500 sec.

Jacobson, David T.; Manzella, David H.

2004-01-01

305

Tomography of regional ventilation and perfusion using krypton 81m in normal subjects and asthmatic patients  

Microsoft Academic Search

Single photon emission computed tomography, a rotating gamma camera, and continuous inhalation or infusion of krypton 81m (half life 13 seconds) were used to measure regional ventilation (V), perfusion (Q), and ventilation-perfusion (V\\/Q) ratios in five normal subjects in supine, prone, and lateral decubitus postures and in three asthmatic patients (supine posture only) before and after inhalation of 2.5 mg

D Orphanidou; J M Hughes; M J Myers; A R Al-Suhali; B Henderson

1986-01-01

306

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

SciTech Connect

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.

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

307

Thermodynamic and molecular properties of gas hydrates from mixtures containing methane, argon, and krypton  

Microsoft Academic Search

Because hydrate formation in pipelines, processing operations, and reservoirs is generally undesirable, studies of gas-hydrate thermodynamics, particularly examinations of conditions where a second hydrate phase or a hydrocarbon-rich phase exists in addition to the water, hydrate, and gas phases, are important to the natural gas industry. In this study, analysts used experimental methane-krypton and methane-argon hydrate data to generate chemical-potential,

G. D. Holder; G. Corbin; K. D. Papadopoulos

1980-01-01

308

Renormalization-group treatment of a Potts lattice gas for krypton adsorbed onto graphite  

Microsoft Academic Search

Krypton atoms adsorbed in submonolayer quantities onto the basal graphite surface may be represented by a triangular lattice gas with nearest-neighbor exclusion and further-neighbor attraction decreasing with separation. We view this as a three-state Potts model with thermodynamic vacancies which are controlled by a chemical potential. A position-space renormalization-group treatment is performed by adapting Migdal's approximate recursion to the triangular

A. N. Berker; S. Ostlund; F. A. Putnam

1978-01-01

309

Krypton81 m and 5-?m radioaerosol images in asymptomatic asthma: a blind marking assessment  

Microsoft Academic Search

Gamma camera images recorded during tidal breathing of krypton-81m (81mKr) and after slow inhalation of 99mTc-labelled monodisperse 5-m polystyrene particles were assessed by three independent observers. Results from 20 symptom-free asthmatic subjects, all with a forced expiratory volume in 1 s (FEV1) at least equal to 75% of the predicted value, were compared with those from 16 healthy non-smoking volunteers.

J. E. Agnew; E. J. Wood; P. P. Sutton; J. R. M. Bateman; D. Pavia; S. W. Clarke

1984-01-01

310

Electron-Photon Polarization Correlation Study of Neon, Argon and Krypton Excitation by Electron Impact  

Microsoft Academic Search

The electron impact excitation of the 3s ^' (1\\/2) ^0_1 state in neon, the 4s^' (1\\/2) ^0_1 state in argon and the 5s (3\\/2) ^0_1 state in krypton have been studied using the electron-photon polarization correlation technique. The two linear coherence parameters P_1 and P_2 have been measured and the alignment angle gamma and the linear polarization P ^+_{rm lin}

Shuanghai Zheng

1993-01-01

311

Energy transfer studies in krypton-xenon mixtures excited in a cooled DC discharge  

Microsoft Academic Search

The VUV spectrum of gaseous mixtures of krypton with a small amount of xenon added was investigated in the range 115200 nm.\\u000a The mixtures were excited in a capillary DC discharge where the capillary could be cooled by using liquid nitrogen. The mixed\\u000a molecule band around the Xe I resonance line at ? = 147 nm and the mixed molecule

B. Krylov; G. Gerasimov; A. Morozov; A. Arnesen; R. Hallin; F. Heijkenskjold

2000-01-01

312

Configuration interaction calculation for the isotope shift in Mg I  

E-print Network

We present an ab initio method of calculation of isotope shift in atoms with a few valence electrons, based on the configuration-interaction calculation of energy. The main motivation for developing the method comes from the need to analyze whether differences in isotope abundance in early universe can contribute to the observed anomalies in quasar absorption spectra. The current best explanation for these anomalies is the assumption that the fine structure constant, alpha, was smaller at early epoch. We show that we can calculate the isotope shift in magnesium with good accuracy.

Berengut, J C; Flambaum, V V; Kozlov, M G

2003-01-01

313

Isotopic composition and concentration of sulfur in carbonaceous chondrites  

NASA Technical Reports Server (NTRS)

New sulfur isotopic ratio measurements are reported for seven carbonaceous chondrites. Newly developed procedures permit measurement of delta S-33, delta S-34, and delta S-36 at precisions significantly greater than previously reported. A search for S-36 nucleosynthetic anomalies coproduced with anomalies in, for example, Ti-50 and Ca-48 was negative. The high endemic sulfur concentration probably dilutes any S-36 anomaly, and separation of individual sulfur phases may be needed to identify S-36 carrier phases. Large internal isotopic variations are observed, deriving from parent body and possibly nebular processes. Chondrule separates from Allende demonstrate isotopic compositions which vary as a function of diameter. High-temperature gas-solid exchange and a two-component mixing model may account for the observations. High-resolution isotopic data and structural information are reported for organic sulfur compounds separated by chemical extractions. The insoluble organics appear to be of either aliphatic or alicyclic structure and are dominant phases.

Gao, Xia; Thiemens, Mark H.

1993-01-01

314

Groundwater age structure and palaeo hydrogeology over a 500 kyr time scale revealed from Krypton 81and a multiple tracer study: Great Artesian Basin  

NASA Astrophysics Data System (ADS)

We report on the most comprehensive set of krypton -81 data to be analysed so far. Our study site is on the western margin of the Great Artesian Basin (GAB). The study area is focused on the western margin of the GAB between the Finke River system in the Northern Territory and the iconic Dalhousie springs in South Australia. This represents the direction of groundwater flow from recharge to discharge through the Dalhousie spring complex. Because of its vast size and the potential for large regional flow systems to occur, the GAB has been considered an ideal basin to test emerging groundwater dating techniques such as Cl-36 and He-4. However both of these techniques are subjected to large degrees of uncertainty, as they require a detailed understanding of different sources and sinks of these two isotopes. Contrasting this Kr-81 is considered to be an ideal tracer as it contains only one source, the atmosphere with no or at most minimal sub surface production. For the first time we have provided a comprehensive suite of analyse not only of Cl-36, He-4, C-14, Ar-39, stable isotopes of the water molecule and noble gases but also, Kr-85 and Kr-81. Our results indicate a spectrum of 'groundwater ages' ranging from modern as indicated by thermonuclear C-14 and Ar-39 up to hundreds of thousands of years as indicated by Kr-81, Cl-36 and He-4. The data set indicates a wide range of stable isotopes of the water molecule as well as variability in noble gas recharge temperatures that suggest that not only has this region been subjected to changes in climate in the recharge zone but also testaments to a changes in the dominate direction of rainfall indicated by a change in recharge mechanism at the beginning of the Holocene. As suggested previously this groundwater flow transect may represent an ideal 'type section' for testing new and emerging environmental tracers in hydrogeology.

Love, A. J.; Purtschert, R.; Jiang, W.; Lu, Z.; Tosaki, Y.; Fulton, S.; Wohling, D.; Shand, P.; Broder, L.; Aeschbach, W.; Rousseau=Gueutin, P.

2013-12-01

315

Deuterium excess anomaly of precipitation in Svalbard  

NASA Astrophysics Data System (ADS)

The isotopic composition of precipitation and melt-water lakes in Svalbard was studied. The IAEA precipitation record of monthly precipitation data from Ny Alesund reveals a much stronger and regular seasonal variability of deuterium excess compared to oxygen-18 and deuterium. The seasonal amplitude of deuterium excess in Ny Alesund is more pronounced than in stations of similar latitude in Greenland and Iceland. Ratios of 18O/16O and 2H/H vary between single events and do not show a clear seasonal pattern. These principle observations have been applied to the investigation of melt-water lakes in Svalbard using the stable isotopes of water. For each melt-water lake samples have been taken of the uppermost layer of the surrounding snow pack, of melt-water inflow(s), the lake water itself and the existing outflow. Samples have been analyzed for 18O/16O and 2H/H with laser ring-down spectrometry. Based on observed topological and geomorphometric data the mean residence time was estimated indicating turnover within days to few weeks. Kinetic isotope fractionation by evaporation was observed only in the inflow of the lowest lake. The isotopic data from melt-water lakes reflects the deuterium excess anomaly observed in the precipitation data from Svalbard. The hydrological input to the melt-water lakes from snow-melt and groundwater could be identified. While the hydrological regime of most lakes is dominated by melt-water, significant groundwater inflow could be detected in specific lakes. In this environment the investigation of hydrological processes and properties of hydrological systems can be improved by using the information content of deuterium excess seasonality. Deuterium excess results from ocean-atmosphere interactions and reflects moisture conditions and temperature gradients during evaporation in the source region of atmospheric moisture. In high-latitude environments deuterium excess seasonality and variability contains information about changes in circulation patterns that can be traced through hydrological systems.

Kuells, C. J.; Ritter, M.

2010-12-01

316

The XXXXY Chromosome Anomaly  

PubMed Central

The majority of abnormal sex chromosome complexes in the male have been considered to be variants of Klinefelter's syndrome but an exception should probably be made in the case of the XXXXY individual who has distinctive phenotypic features. Clinical, radiological and cytological data on three new cases of XXXXY syndrome are presented and 30 cases from the literature are reviewed. In many cases the published clinical and radiological data were supplemented and re-evaluated. Mental retardation, usually severe, was present in all cases. Typical facies was observed in many; clinodactyly of the fifth finger was seen in nearly all. Radiological examination revealed abnormalities in the elbows and wrists in all the 19 personally evaluated cases, and other skeletal anomalies were very frequent. Cryptorchism is very common and absence of Leydig's cells may differentiate the XXXXY chromosome anomaly from polysomic variants of Klinefelter's syndrome. The relationship of this syndrome to Klinefelter's syndrome and to Down's syndrome is discussed. ImagesFig. 1Fig. 2Fig. 3Fig. 4Fig. 5Fig. 6Fig. 7Fig. 8Fig. 9Fig. 10Fig. 11Fig. 12Fig. 13Fig. 14Fig. 15 PMID:4222822

Zaleski, Witold A.; Houston, C. Stuart; Pozsonyi, J.; Ying, K. L.

1966-01-01

317

Lunar Orbit Anomaly  

NASA Astrophysics Data System (ADS)

Independent experiments show a large anomaly in measurements of lunar orbital evolution, with applications to cosmology and the speed of light. The Moon has long been known to be slowly drifting farther from Earth due to tidal forces. The Lunar Laser Ranging Experiment (LLRE) indicates the Moon's semimajor axis increasing at 3.82 .07 cm/yr, anomalously high. If the Moon were today gaining angular momentum at this rate, it would have coincided with Earth less than 2 Gyr ago. Study of tidal rhythmites indicates a rate of 2.9 0.6 cm/yr. Historical eclipse observations independently measure a recession rate of 2.82 .08 cm/yr. Detailed numerical simulation of lunar orbital evolution predicts 2.91 cm/yr. LLRE differs from three independent experiments by over12 sigma. A cosmology where speed of light c is related to time t by GM=tc^3 has been suggested to predict the redshifts of Type Ia supernovae, and a 4.507034% proportion of baryonic matter. If c were changing in the amount predicted, lunar orbital distance would appear to increase by an additional 0.935 cm/yr. An anomaly in the lunar orbit may be precisely calculated, shedding light on puzzles of 'dark energy'. In Planck units this cosmology may be summarized as M=R=t.Lunar Recession Rate;

Riofrio, L.

2012-12-01

318

Automated anomaly detection processor  

NASA Astrophysics Data System (ADS)

Robust exploitation of tracking and surveillance data will provide an early warning and cueing capability for military and civilian Law Enforcement Agency operations. This will improve dynamic tasking of limited resources and hence operational efficiency. The challenge is to rapidly identify threat activity within a huge background of noncombatant traffic. We discuss development of an Automated Anomaly Detection Processor (AADP) that exploits multi-INT, multi-sensor tracking and surveillance data to rapidly identify and characterize events and/or objects of military interest, without requiring operators to specify threat behaviors or templates. The AADP has successfully detected an anomaly in traffic patterns in Los Angeles, analyzed ship track data collected during a Fleet Battle Experiment to detect simulated mine laying behavior amongst maritime noncombatants, and is currently under development for surface vessel tracking within the Coast Guard's Vessel Traffic Service to support port security, ship inspection, and harbor traffic control missions, and to monitor medical surveillance databases for early alert of a bioterrorist attack. The AADP can also be integrated into combat simulations to enhance model fidelity of multi-sensor fusion effects in military operations.

Kraiman, James B.; Arouh, Scott L.; Webb, Michael L.

2002-07-01

319

Einstein, Entropy and Anomalies  

NASA Astrophysics Data System (ADS)

This paper strengthens and defends the pluralistic implications of Einstein's successful, quantitative predictions of Brownian motion for a philosophical dispute about the nature of scientific advance that began between two prominent philosophers of science in the second half of the twentieth century (Thomas Kuhn and Paul Feyerabend). Kuhn promoted a monistic phase-model of scientific advance, according to which a paradigm driven `normal science' gives rise to its own anomalies, which then lead to a crisis and eventually a scientific revolution. Feyerabend stressed the importance of pluralism for scientific progress. He rejected Kuhn's model arguing that it fails to recognize the role that alternative theories can play in identifying exactly which phenomena are anomalous in the first place. On Feyerabend's account, Einstein's predictions allow for a crucial experiment between two incommensurable theories, and are an example of an anomaly that could refute the reigning paradigm only after the development of a competitor. Using Kuhn's specification of a disciplinary matrix to illustrate the incommensurability between the two paradigms, we examine the different research strategies available in this peculiar case. On the basis of our reconstruction, we conclude by rebutting some critics of Feyerabend's argument.

Sirtes, Daniel; Oberheim, Eric

2006-11-01

320

Influence of krypton atoms on the structure of hydrogenated amorphous carbon deposited by plasma enhanced chemical vapor deposition  

SciTech Connect

Hydrogenated amorphous carbon (a-C:H) films were prepared by plasma enhanced chemical vapor deposition using methane (CH{sub 4}) plus krypton (Kr) mixed atmosphere. The depositions were performed as function of the bias voltage and krypton partial pressure. The goal of this work was to study the influence of krypton gas on the physical properties of a-C:H films deposited on the cathode electrode. Krypton concentration up to 1.6 at. %, determined by Rutherford Back-Scattering, was obtained at high Kr partial pressure and bias of -120 V. The structure of the films was analyzed by means of optical transmission spectroscopy, multi-wavelength Raman scattering and Fourier Transform Infrared spectroscopy. It was verified that the structure of the films remains unchanged up to a concentration of Kr of about 1.0 at. %. A slight graphitization of the films occurs for higher concentration. The observed variation in the film structure, optical band gap, stress, and hydrogen concentration were associated mainly with the subplantation process of hydrocarbons radicals, rather than the krypton ion energy.

Oliveira, M. H. Jr. [Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas-UNICAMP, C. P. 6165, Campinas, Sao Paulo 13083-970 (Brazil); Institut de Ciencia dels Materials, Universitat de Valencia, E-46071 Valencia (Spain); Viana, G. A.; Marques, F. C. [Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas-UNICAMP, C. P. 6165, Campinas, Sao Paulo 13083-970 (Brazil); Lima, M. M. Jr. de; Cros, A.; Cantarero, A. [Institut de Ciencia dels Materials, Universitat de Valencia, E-46071 Valencia (Spain)

2010-12-15

321

System for closure of a physical anomaly  

DOEpatents

Systems for closure of a physical anomaly. Closure is accomplished by a closure body with an exterior surface. The exterior surface contacts the opening of the anomaly and closes the anomaly. The closure body has a primary shape for closing the anomaly and a secondary shape for being positioned in the physical anomaly. The closure body preferably comprises a shape memory polymer.

Bearinger, Jane P; Maitland, Duncan J; Schumann, Daniel L; Wilson, Thomas S

2014-11-11

322

PII S0016-7037(02)00965-1 A method for precise measurement of argon 40/36 and krypton/argon ratios in trapped air  

E-print Network

PII S0016-7037(02)00965-1 A method for precise measurement of argon 40/36 and krypton/argon ratios,000 years ago. The krypton/argon ratio can provide a diagnostic of argon leakage out of the bubbles, which

Severinghaus, Jeffrey P.

323

Genetics of lymphatic anomalies  

PubMed Central

Lymphatic anomalies include a variety of developmental and/or functional defects affecting the lymphatic vessels: sporadic and familial forms of primary lymphedema, secondary lymphedema, chylothorax and chylous ascites, lymphatic malformations, and overgrowth syndromes with a lymphatic component. Germline mutations have been identified in at least 20 genes that encode proteins acting around VEGFR-3 signaling but also downstream of other tyrosine kinase receptors. These mutations exert their effects via the RAS/MAPK and the PI3K/AKT pathways and explain more than a quarter of the incidence of primary lymphedema, mostly of inherited forms. More common forms may also result from multigenic effects or post-zygotic mutations. Most of the corresponding murine knockouts are homozygous lethal, while heterozygotes are healthy, which suggests differences in human and murine physiology and the influence of other factors. PMID:24590274

Brouillard, Pascal; Boon, Laurence; Vikkula, Miikka

2014-01-01

324

Modern test of chiral anomalies  

SciTech Connect

Chiral anomalies are calculated using an effective Lagrangian technique introduced for anomalies by Wess and Zumino and recently reformulated by Witten. Anomalous amplitudes for vector currents decaying into three pseudoscalars are tested by comparison with K/sub l4/ decay and eta ..-->.. ..pi../sup +/..pi../sup -/..gamma... 12 references.

Kramer, G.; Palmer, W.F.; Pinsky, S.S.

1984-01-01

325

Graph anomalies in cyber communications  

Microsoft Academic Search

Enterprises monitor cyber traffic for viruses, intruders and stolen information. Detection methods look for known signatures of malicious traffic or search for anomalies with respect to a nominal reference model. Traditional anomaly detection focuses on aggregate traffic at central nodes or on user-level monitoring. More recently, however, traffic is being viewed more holistically as a dynamic communication graph. Attention to

Scott A Vander Wiel; Curtis B Storlie; Gary Sandine; Aric A Hagberg; Michael Fisk

2011-01-01

326

Magnetic Anomalies from Satellite Magnetometer  

Microsoft Academic Search

Proton magnetometer measurements were made from the USSR satellite Cosmos 49 during the period October 24 to November 3, 1964. A selected number of the 18,000 observations were fitted to a special field model; residual anomalies were less than 100 gammas and appear to be consistent with belts of broad anomalies that are known from surface and nearsurface magnetic measurements.

Isidore Zietz; Gordon E. Andreasen; Joseph C. Cain

1970-01-01

327

Design and construction of a cryogenic distillation device for removal of krypton for liquid xenon dark matter detectors.  

PubMed

Liquid xenon (Xe) is one of the commendable detecting media for the dark matter detections. However, the small content of radioactive krypton-85 ((85)Kr) always exists in the commercial xenon products. An efficient cryogenic distillation system to remove this krypton (Kr) from commercial xenon products has been specifically designed, developed, and constructed in order to meet the requirements of the dark matter experiments with high- sensitivity and low-background. The content of krypton in regular commercial xenon products can be reduced from 10(-9) to 10(-12), with 99% xenon collection efficiency at maximum flow rate of 5 kg/h (15SLPM). The purified xenon gases produced by this distillation system can be used as the detecting media in the project of Panda X, which is the first dark matter detector developed in China. PMID:24517821

Wang, Zhou; Bao, Lei; Hao, Xihuan; Ju, Yonglin

2014-01-01

328

Isotope-shift calculations for atoms with one valence electron  

SciTech Connect

This work presents a method for the ab initio calculation of isotope shift in atoms and ions with one valence electron above closed shells. As a zero approximation, we use relativistic Hartree-Fock and then calculate correlation corrections. The main motivation for developing the method comes from the need to analyze whether different isotope abundances in early universe can contribute to the observed anomalies in quasar absorption spectra. The current best explanation for these anomalies is the assumption that the fine-structure constant {alpha} was smaller at early epoch. We test the isotope-shift method by comparing the calculated and experimental isotope shift for the alkali-metal and alkali-metal-like atoms Na, Mg II, K, Ca II and Ba II. The agreement is found to be good. We then calculate the isotope shift for some astronomically relevant transitions in Si II and Si IV, Mg II, Zn II, and Ge II.

Berengut, J. C.; Dzuba, V. A.; Flambaum, V. V. [School of Physics, University of New South Wales, Sydney 2052, (Australia)

2003-08-01

329

Measurement of the Cotton-Mouton effect in nitrogen, oxygen, carbon dioxide, argon, and krypton with the Q & A apparatus  

E-print Network

Experiments for vacuum birefringence and vacuum dichroism have been set up with high-finesse high magnetic experimental apparatuses, which seem to be ideal for small gaseous Cotton-Mouton effect (CME) measurements. PVLAS Collaboration has measured CMEs in krypton, xenon and neon at the wavelength of 1064 nm. In this Letter, we report on our measurement of CMEs in nitrogen, oxygen, carbon dioxide, argon, and krypton at the same wavelength in a magnetic field B = 2.3 T at pressure P = 0.5-300 Torr and temperature T = 295-298 K. Our results agree with the PVLAS results in the common cases.

Hsien-Hao Mei; Wei-Tou Ni; Sheng-Jui Chen; Sheau-shi Pan

2009-02-11

330

Measurement of the Cotton-Mouton effect in nitrogen, oxygen, carbon dioxide, argon, and krypton with the Q & A apparatus  

E-print Network

Experiments for vacuum birefringence and vacuum dichroism have set up high-finesse high magnetic experimental apparatuses which are ideal for gaseous Cotton-Mouton effect measurements. PVLAS Collaboration has recently measured Cotton-Mouton effects in krypton, xenon and neon at the wavelength of 1064 nm. In this Letter, we report on our measurement of Cotton-Mouton effects in nitrogen, oxygen, carbon dioxide, argon, and krypton at pressure P = 0.5-300 Torr, temperature T = 295-298 K, and laser wavelength of 1064 nm in a magnetic field B = 2.3 T, using our Q & A experimental setup, which are in agreement with the PVLAS results.

Mei, Hsien-Hao; Chen, Sheng-Jui; Pan, Sheau-shi

2008-01-01

331

Time-and-energy resolved measurement of the cascaded Auger decay in krypton  

Microsoft Academic Search

The cascaded Auger decay following ionization or excitation with 94 eV soft-X-ray pulses from the 3d subshell in krypton has been energy-and-time-resolved for the first time. The decay time of the 4s\\u000a ?14p\\u000a ?2\\u000a nl ? 4p\\u000a ?3 + e and\\/or 4s\\u000a ?14p\\u000a ?1\\u000a nl ? 4p\\u000a ?2 + e transition is measured to be 74 20 fs. Furthermore,

A. J. Verhoef; A. V. Mitrofanov; X. T. Nguyen; M. Krikunova; S. Fritzsche; N. M. Kabachnik; M. Drescher; A. Baltuska

2011-01-01

332

Cryogenic system with GM cryocooler for krypton, xenon separation from hydrogen-helium purge gas  

NASA Astrophysics Data System (ADS)

In the thorium molten salt reactor (TMSR), fission products such as krypton, xenon and tritium will be produced continuously in the process of nuclear fission reaction. A cryogenic system with a two stage GM cryocooler was designed to separate Kr, Xe, and H2 from helium purge gas. The temperatures of two stage heat exchanger condensation tanks were maintained at about 38 K and 4.5 K, respectively. The main fluid parameters of heat transfer were confirmed, and the structural heat exchanger equipment and cold box were designed. Designed concentrations after cryogenic separation of Kr, Xe and H2 in helium recycle gas are less than 1 ppb.

Chu, X. X.; Zhang, M. M.; Zhang, D. X.; Xu, D.; Qian, Y.; Liu, W.

2014-01-01

333

A REMPI study of indene and its clusters with argon and krypton  

NASA Astrophysics Data System (ADS)

The S 0 ? S 1 transition of indene was studied in a supersonic jet by resonance enhance multiphoton ionization and assigned with the help of an ab initio calculation. Experimental results are also reported for argon and krypton clusters of indene, from which the dissociation energies of the 1:1 clusters were estimated in both S 0 and S 1 states. Two-color two-photon ionization spectroscopy was used to determine the ionization potential and dissociation energy of the indene-argon cluster ion. The data are compared with results obtained for styrene, whose electronic structure is similar, but has much lower frequency out-of-plane vibrational modes.

Kendler, S.; Zilberg, S.; Haas, Y.

1995-08-01

334

Effects of three-body interactions on the structure and thermodynamics of liquid krypton  

E-print Network

Large-scale molecular dynamics simulations are performed to predict the structural and thermodynamic properties of liquid krypton using a potential energy function based on the two-body potential of Aziz and Slaman plus the triple-dipole Axilrod-Teller (AT) potential. By varying the strength of the AT potential we study the influence of three-body contribution beyond the triple-dipole dispersion. It is seen that the AT potential gives an overall good description of liquid Kr, though other contributions such as higher order three-body dispersion and exchange terms cannot be ignored.

N. Jakse; J. M. Bomont; J. L. Bretonnet

2002-03-07

335

Angular distribution of Auger electrons due to 3d-shell ionization of krypton  

NASA Technical Reports Server (NTRS)

Cross sections for electron impact ionization of krypton due to ejection of a 3rd shell electron have been calculated using screened hydrogenic and Hartree-Slater wave functions for target atom. While the total ionization cross sections in the two approximations are within 10% of each other, the Auger electron angular distribution, related to cross sections for specific magnetic quantum numbers of the 3rd electrons, is widely different in the two approximations. The angular distribution due to Hartree-Slater approximation is in excellent agreement with measurement. The physical reason for the discrepancies in the two approximations is explained.

Omidvar, K.

1977-01-01

336

Angular distribution of Auger electrons due to 3d-shell impact ionization of krypton  

NASA Technical Reports Server (NTRS)

Cross sections for electron impact ionization of krypton due to ejection of a 3d-shell electron have been calculated using screened hydrogenic and Hartree-Slater wavefunctions for the target atom. While the total ionization cross sections in the two approximations are within 10% of each other, the Auger electron angular distribution, related to cross sections for specific magnetic quantum numbers of the 3d electrons, are widely different in the two approximations. The angular distribution due to the Hartree-Slater approximation is in excellent agreement with measurement. The physical reason for the discrepancies in the two approximations is explained.

Omidvar, K.

1977-01-01

337

Cryogenic system with GM cryocooler for krypton, xenon separation from hydrogen-helium purge gas  

SciTech Connect

In the thorium molten salt reactor (TMSR), fission products such as krypton, xenon and tritium will be produced continuously in the process of nuclear fission reaction. A cryogenic system with a two stage GM cryocooler was designed to separate Kr, Xe, and H{sub 2} from helium purge gas. The temperatures of two stage heat exchanger condensation tanks were maintained at about 38 K and 4.5 K, respectively. The main fluid parameters of heat transfer were confirmed, and the structural heat exchanger equipment and cold box were designed. Designed concentrations after cryogenic separation of Kr, Xe and H{sub 2} in helium recycle gas are less than 1 ppb.

Chu, X. X.; Zhang, D. X.; Qian, Y.; Liu, W. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800 (China); Zhang, M. M.; Xu, D. [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China)

2014-01-29

338

Anomalies and graded coisotropic branes  

NASA Astrophysics Data System (ADS)

We compute the anomaly of the axial U(1) current in the A-model on a Calabi-Yau manifold, in the presence of coisotropic branes discovered by Kapustin and Orlov. Our results relate the anomaly-free condition to a recently proposed definition of graded coisotropic branes in Calabi-Yau manifolds. More specifically, we find that a coisotropic brane is anomaly-free if and only if it is gradable. We also comment on a different grading for coisotropic submanifolds introduced recently by Oh.

Li, Yi

2006-03-01

339

Gravitational anomaly and transport phenomena.  

PubMed

Quantum anomalies give rise to new transport phenomena. In particular, a magnetic field can induce an anomalous current via the chiral magnetic effect and a vortex in the relativistic fluid can also induce a current via the chiral vortical effect. The related transport coefficients can be calculated via Kubo formulas. We evaluate the Kubo formula for the anomalous vortical conductivity at weak coupling and show that it receives contributions proportional to the gravitational anomaly coefficient. The gravitational anomaly gives rise to an anomalous vortical effect even for an uncharged fluid. PMID:21797593

Landsteiner, Karl; Megas, Eugenio; Pena-Benitez, Francisco

2011-07-01

340

Shape evolution in Yttrium and Niobium neutron-rich isotopes  

E-print Network

The isotopic evolution of the ground-state nuclear shapes and the systematics of one-quasiproton configurations are studied in neutron-rich odd-A Yttrium and Niobium isotopes. We use a selfconsistent Hartree-Fock-Bogoliubov formalism based on the Gogny energy density functional with two parametrizations, D1S and D1M. The equal filling approximation is used to describe odd-A nuclei preserving both axial and time reversal symmetries. Shape-transition signatures are identified in the N=60 isotopes in both charge radii and spin-parities of the ground states. These signatures are a common characteristic for nuclei in the whole mass region. The nuclear deformation and shape coexistence inherent to this mass region are shown to play a relevant role in the understanding of the spectroscopic features of the ground and low-lying one-quasiproton states. Finally, a global picture of the neutron-rich A=100 mass region from Krypton up to Molybdenum isotopes is illustrated with the systematics of the nuclear charge radii isotopic shifts.

R. Rodriguez-Guzman; P. Sarriguren; L. M. Robledo

2011-03-22

341

Evidence of magnetic isotope effects during thermochemical sulfate reduction  

PubMed Central

Thermochemical sulfate reduction experiments with simple amino acid and dilute concentrations of sulfate reveal significant degrees of mass-independent sulfur isotope fractionation. Enrichments of up to 13 for 33S are attributed to a magnetic isotope effect (MIE) associated with the formation of thiol-disulfide, ion-radical pairs. Observed 36S depletions in products are explained here by classical (mass-dependent) isotope effects and mixing processes. The experimental data contrasts strongly with multiple sulfur isotope trends in Archean samples, which exhibit significant 36S anomalies. These results support an origin other than thermochemical sulfate reduction for the mass-independent signals observed for early Earth samples. PMID:21997216

Oduro, Harry; Harms, Brian; Sintim, Herman O.; Kaufman, Alan J.; Cody, George; Farquhar, James

2011-01-01

342

Lunar and Planetary Science XXXV: Isotopes in Meteorites  

NASA Technical Reports Server (NTRS)

The session"Isotopes in Meteorites" consisted of the following presentations:The Common Property of Isotopic Anomalies in Meteorites; Revised Production Rates for 22Na and 54Mn in Meteorites Using Cross Sections Measured for Neutron-induced Reactions; Modeling of 14C and 10Be Production Rates in Meteorites and Lunar Samples; Investigating Xenon Isotopic Fractionation During Rayleigh-type Distillation; The Mean Life Squared Relationship for Abundances of Extinct Radioactivities; and Magnesium Isotopic Fractionation of Forsterite During Evaporation from Different Crystallographic Surfaces.

2004-01-01

343

Tracing the ozone isotopic anomaly transferred to other atmospheric  

E-print Network

by oceans Far from pollution sources Strong seasonal variations (Temp, light) Antarctic Ice sheet Ice core 2008 #12;The polar regions: Interests Ocean surrounded by continent Close to pollution sources Strong seasonal variations (Temp, light) Greenland Ice sheet Ice core site Arctic Antarctic Continent surrounded

Einat, Aharonov

344

Probing the Isotopic Composition of Surface Waters Across Isotopic Extremes of Cryogenian Carbonates  

NASA Astrophysics Data System (ADS)

Neoproterozoic carbonate strata record unusually large and positive carbon isotope values (?13Ccarb from 4 to 10 per mil), and stratigraphically extensive large negative carbon isotope excursions (?13Ccarb < -5 per mil). Mechanisms that account for the magnitude, the facies distribution and the global abundance of these isotopically extreme carbonates in Neoproterozoic successions remain poorly understood. Little is also known about organisms and metabolisms that cycled carbon in these carbonate strata, because they rarely contain well-preserved organic-rich fossils. To better understand the cycling of carbon during the deposition of the 715-635 Ma Tayshir member of the Tsagaan Oloom Formation, Mongolia, we analyzed ?13Cfossil of two types of organic fossils that occur in 13C- enriched carbonates (+ 5 to 9.9 per mil) and within 13C-depleted carbonates of the Tayshir anomaly (-3 to -6 per mil). Because these organic microfossils are remarkably similar to the tests of modern planktonic, herbivorous tintinnid ciliates and benthic macroscopic red algae, respectively, they can be used as tracers of organic matter production in surface waters. Fossil tests were extracted by acid maceration, cleaned and analyzed morphologically and microscopically. Their carbon isotopic composition was measured using a nano-scaled elemental analyzer inlet (nano-EA-IRMS), with 1 per mil analytical precision. To date, we analyzed 12 samples of 100-150 organic tests, representing 3 different fossiliferous parts of the Tayshir anomaly (?13Ccarb < -3 per mil) and 3 different strata predating the Tayshir anomaly (?13Ccarb > +5 per mil), respectively. More samples, including those of fossil algae and tests from the carbonate strata overlying the Tayshir anomaly, are currently being analyzed. Initial data reveal a rather constant isotopic composition of organic carbon in fossil tests (?13Cfossil), with values of -23 1 per mil both within 13C-enriched and 13C-depleted carbonates. The isotopic difference between ?13Cfossil and 13C-enriched carbonates is 28 to 30 per mil, suggesting maximal isotopic fractionation by primary producers, and little environmental (or diagenetic) processing of primary photosynthetic carbon. The carbonates of the Tayshir anomaly preserve two organic materials: matrix or bulk carbon characterized by a ?13Corg that covaries with ?13Ccarb, and a small, but morphologically diagnostic component whose ?13Cfossil values do not covary with ?13Ccarb. The stratigraphic thickness (~ 50 m) and isotopic heterogeneity of the organic matter within the Tayshir anomaly (~ 50 m) suggest a prolonged and large contribution of organic carbon remineralization.

Bosak, T.; Matys, E. D.; Bird, L. R.; Macdonald, F. A.; Freeman, K. H.

2012-12-01

345

First-principles calculations of the stability and incorporation of helium, xenon and krypton in uranium  

NASA Astrophysics Data System (ADS)

While metallic fuels have a long history of reactor use, their fundamental physical and thermodynamic properties are not well understood. Many metallic nuclear fuels are body-centered cubic alloys of uranium that swell under fission conditions, creating fission product gases such as helium, xenon and krypton. In this paper, helium, xenon, and krypton point defects are investigated in the ? and ? phases of metallic uranium using first principles calculations. A density functional theory (DFT) framework is utilized with projector augmented-wave (PAW) pseudopotentials. Formation and incorporation energies of He, Xe, and Kr are calculated at various defect positions for the prediction of fission gas behavior in uranium. In most cases, defect energies follow a size effect, with helium incorporation and formation energies being the smallest. The most likely position for the larger Xe and Kr atoms in uranium is the substitutional site. Helium atoms are likely to be found in a wide variety of defect positions due to the comparable formation energies of all defect configurations analyzed. This is the first detailed study of the stability and incorporation of fission gases in uranium.

Beeler, B.; Good, B.; Rashkeev, S.; Deo, C.; Baskes, M.; Okuniewski, M.

2012-06-01

346

Short wavelength laser calculations for electron pumping in neon-like krypton (Kr XXVII)  

NASA Technical Reports Server (NTRS)

Calculations of electron impact collision strengths and spontaneous radiative decay rates are made for neon-like krypton (Kr XXVII) for the 2s2 2p6, 2s2 2p5 3s, 2s2 2p5 3p, and 2s2 2p5 3d configurations. From these atomic data, the level populations as a function of the electron density are calculated at two temperatures, 1 x 10 to the 7th K and 3 x 10 to the 7th K. An analysis of level populations reveals that a volume of krypton in which a significant number of the ions are in the Kr XXVII degree of ionization can produce a significant gain in transition between the 2s2 2p5 3s and 2s2 2p5 3p configurations. At an electron density of 1 x 10 to the 19th/cu cm the plasma length has to be of the order of 1 m; at a density of 1 x 10 to the 21st/cu cm the length is reduced to approximately 0.5 cm; and at an electron density of 1 x 10 to the 22nd/cu cm the length of the plasma is further reduced to approximately 1 mm.

Feldman, U.; Bhatia, A. K.; Suckewer, S.

1983-01-01

347

First-principles calculations of the stability and incorporation of helium, xenon and krypton in uranium  

SciTech Connect

While metallic fuels have a long history of reactor use, their fundamental physical and thermodynamic properties are not well understood. Many metallic nuclear fuels are body-centered cubic alloys of uranium that swell under fission conditions, creating fission product gases such as helium, xenon and krypton. In this paper, helium, xenon, and krypton point defects are investigated in the a and ? phases of metallic uranium using first principles calculations. A density functional theory (DFT) framework is utilized with projector augmented-wave (PAW) pseudopotentials. Formation and incorporation energies of He, Xe, and Kr are calculated at various defect positions for the prediction of fission gas behavior in uranium. In most cases, defect energies follow a size effect, with helium incorporation and formation energies being the smallest. The most likely position for the larger Xe and Kr atoms in uranium is the substitutional site. Helium atoms are likely to be found in a wide variety of defect positions due to the comparable formation energies of all defect configurations analyzed. This is the first detailed study of the stability and incorporation of fission gases in uranium.

B. Beeler; B. Good; S. Rashkeev; M. Baskes; M. Okuniewski

2012-06-01

348

Diagnosis of high-temperature implosions using low- and high-opacity Krypton lines  

SciTech Connect

High-temperature laser target implosions can be achieved by using relatively thin-shell targets, and they can be. diagnosed by doping the fuel with krypton and measuring K-shell and L-shell lines. Electron temperatures of up to 5 keV at modest compressed densities ({approximately}1-5g/cm{sup 3}) are predicted for such experiments, with ion temperatures peaking above 10 keV at the center. It is found that the profiles of low-opacity (optically thin) lines in the expected density range are dominated by the Doppler broadening and can provide a measurement of the ion temperature if spectrometers of spectral resolution {Delta}{lambda}/{lambda} {ge} 1000 are used. For high-opacity lines, obtained with a higher krypton fill pressure, the measurement of the escape factor can yield the {rho}R of the compressed fuel. At higher densities, Stark broadening of low-opacity lines becomes important and can provide a density measurement, whereas lines of higher opacity can be used to estimate the extent of mixing.

Yaakobi, B.; Epstein, R. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Hooper, C.F. Jr.; Haynes, D.A. Jr. [Univ. of Florida, Gainesville, FL (United States)] [and others

1996-04-01

349

Unintentional fatal intoxications with mitragynine and O-desmethyltramadol from the herbal blend Krypton.  

PubMed

The leaves of Kratom, a medicinal plant in Southeast Asia, have been used as an herbal drug for a long time. At least one of the alkaloids present in Kratom, mitragynine, is a mu-receptor agonist. Both Kratom and an additional preparation called Krypton are available via the internet. It seems to consist of powdered Kratom leaves with another mu-receptor agonist, O-desmethyltramadol, added. O-Desmethyltramadol is an active metabolite of tramadol, a commonly prescribed analgesic. We present nine cases of intoxication, occurring in a period of less than one year, where both mitragynine and O-desmethyltramadol were detected in the postmortem blood samples. Neither tramadol nor N-desmethyltramadol was present in these samples, which implies that the ingested drug was O-desmethyltramadol. The blood concentrations of mitragynine, determined by ultra-performance liquid chromatography-tandem mass spectrometry, ranged from 0.02 to 0.18 ?g/g, and O-desmethyltramadol concentrations, determined by gas chromatography with nitrogen-specific detection, ranged from 0.4 to 4.3 ?g/g. We believe that the addition of the potent mu-receptor agonist O-desmethyltramadol to powdered leaves from Kratom contributed to the unintentional death of the nine cases presented and conclude that intake of Krypton is not as harmless as it often is described on internet websites. PMID:21513619

Kronstrand, Robert; Roman, Markus; Thelander, Gunilla; Eriksson, Anders

2011-05-01

350

Kohn anomalies in graphene nanoribbons  

E-print Network

The quantum corrections to the energies of the ? point optical phonon modes (Kohn anomalies) in graphene nanoribbons (NRs) are investigated. We show theoretically that the longitudinal optical (LO) modes undergo a Kohn ...

Dresselhaus, Mildred

351

Classifying sex biased congenital anomalies  

SciTech Connect

The reasons for sex biases in congenital anomalies that arise before structural or hormonal dimorphisms are established has long been unclear. A review of such disorders shows that patterning and tissue anomalies are female biased, and structural findings are more common in males. This suggests different gender dependent susceptibilities to developmental disturbances, with female vulnerabilities focused on early blastogenesis/determination, while males are more likely to involve later organogenesis/morphogenesis. A dual origin for some anomalies explains paradoxical reductions of sex biases with greater severity (i.e., multiple rather than single malformations), presumably as more severe events increase the involvement of an otherwise minor process with opposite biases to those of the primary mechanism. The cause for these sex differences is unknown, but early dimorphisms, such as differences in growth or presence of H-Y antigen, may be responsible. This model provides a useful rationale for understanding and classifying sex-biased congenital anomalies. 42 refs., 7 tabs.

Lubinsky, M.S. [Medical College of Wisconsin and Children`s Hospital, Milwaukee, WI (United States)] [Medical College of Wisconsin and Children`s Hospital, Milwaukee, WI (United States)

1997-03-31

352

Spacecraft environmental anomalies expert system  

NASA Astrophysics Data System (ADS)

An expert system has been developed by The Aerospace Corporation, Space and Environment Technology Center for use in the diagnosis of satellite anomalies caused by the space environment. The expert system is designed to determine the probable cause of an anomaly from the following candidates: surface charging, bulk charging, single-event effects, total radiation dose, and space-plasma effects. Such anomalies depend on the orbit of the satellite, the local plasma and radiation environment (which is highly variable), the satellite-exposure time, and the hardness of the circuits and components in the satellite. The expert system is a rule-based system that uses the Texas Instrument's Personal Consultant Plus expert-system shell. The expert system's knowledgebase includes about 200 rules, as well as a number of databases that contain information on spacecraft and their orbits, previous spacecraft anomalies, and the environment.

Koons, Harry C.; Groney, David J.

1994-02-01

353

Pacific Temperature Anomalies with Graph  

NSDL National Science Digital Library

This animation shows the El Nino-La Nina Sea Surface Temperature Anomaly from January 1997 through July 1999. A graph inset shows the global average sea surface temperature fluctuation during this time period.

Greg Shirah

2003-08-30

354

Triangle Anomalies, Thermodynamics, and Hydrodynamics  

E-print Network

We consider 3+1-dimensional fluids with U(1)^3 anomalies. We use Ward identities to constrain low-momentum Euclidean correlation functions and obtain differential equations that relate two and three-point functions. The solution to those equations yields, among other things, the chiral magnetic conductivity. We then compute zero-frequency functions in hydrodynamics and show that the consistency of the hydrodynamic theory also fixes the anomaly-induced conductivities.

Kristan Jensen

2012-04-11

355

Anomaly detection on cup anemometers  

NASA Astrophysics Data System (ADS)

The performances of two rotor-damaged commercial anemometers (Vector Instruments A100 LK) were studied. The calibration results (i.e. the transfer function) were very linear, the aerodynamic behavior being more efficient than the one shown by both anemometers equipped with undamaged rotors. No detection of the anomaly (the rotors damage) was possible based on the calibration results. However, the Fourier analysis clearly revealed this anomaly.

Vega, Enrique; Pindado, Santiago; Martnez, Alejandro; Meseguer, Encarnacin; Garca, Luis

2014-12-01

356

Holographic description of gravitational anomalies  

NASA Astrophysics Data System (ADS)

The holographic duality can be extended to include quantum theories with the broken coordinate invariance leading to the appearance of the gravitational anomalies. On the gravity side one adds the gravitational Chern-Simons term to the bulk action which is gauge invariant only up to the boundary terms. We analyze in detail how the gravitational anomalies originate from the modified Einstein equations in the bulk. As a side observation, we find that the gravitational Chern-Simons functional has the interesting conformal properties. It is invariant under the conformal transformations. Moreover, its metric variation produces a conformal tensor which is a generalization of the Cotton tensor to dimension d+1 = 4k-1, kinZ. We calculate the modification of the holographic stress-energy tensor that is due to the Chern-Simons term and use the bulk Einstein equations to find its divergence and thus reproduce the gravitational anomaly. The explicit calculation of the anomaly is carried out in dimensions d = 2 and d = 6. The result of the holographic calculation is compared with that of the descent method and an agreement is found. The gravitational Chern-Simons term originates by the Kaluza-Klein mechanism from a one-loop modification of M-theory action. This modification is discussed in the context of the gravitational anomaly in the six-dimensional (2,0) theory. The agreement with the earlier conjectured anomaly is found.

Solodukhin, Sergey N.

2006-07-01

357

Transport of electron beams and stability of optical windows in high-power e-beam-pumped krypton fluoride lasers  

Microsoft Academic Search

Two of the key issues of a krypton fluoride (KrF) laser driver for inertial fusion energy are the development of long life, high transparency pressure foils (to isolate vacuum in the electron beam diode from a working gas in the laser chamber), and the development of durable, stable, optical windows. Both of these problems have been studied on the single-pulse

V. D. Zvorykin; S. V. Arlantsev; V. G. Bakaev; O. V. Rantsev; P. B. Sergeev; G. V. Sychugov; A. Yu. Tserkovnikov

2001-01-01

358

Neutron and Charged-Particle Induced Cross Sections for Radiochemistry in the Region of Bromine and Krypton  

SciTech Connect

We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron and proton induced nuclear reaction cross sections in the mass region of bromine and krypton (34 {le} Z {le} 37, 40 {le} N {le} 47).

Hoffman, R; Dietrich, F; Bauer, R; Kelley, K; Mustafa, M

2004-07-23

359

A comparative study of argon laser and krypton laser in the treatment of diabetic optic disc neovascularisation  

Microsoft Academic Search

A comparative study of the relative efficacy of the krypton and argon lasers in the treatment of disc new vessels in diabetic retinopathy was made. Resolution of the disc new vessels was achieved in both instances. There were clinical differences in the use and effects of the 2 lasers.

W E Schulenburg; A M Hamilton; R K Blach

1979-01-01

360

Study of emission of a volume nanosecond discharge plasma in xenon, krypton and argon at high pressures  

Microsoft Academic Search

The emission properties of a volume nanosecond discharge plasma produced in xenon, krypton and argon at high pressures in a discharge gap with a cathode having a small radius of curvature are studied. Spectra in the range 120850 nm and amplitudetime characteristics of xenon emission at different regimes and excitation techniques are recorded and analysed. It is shown that upon

E Kh Baksht; Mikhail I Lomaev; D V Rybka; Viktor F Tarasenko

2006-01-01

361

Transport of atmospheric trace gases to the water table: Implications for groundwater dating with chlorofluorocarbons and krypton 85  

Microsoft Academic Search

Chlorofluorocarbons and krypton 85 are trace gases whose atmospheric concentrations have been increasing over the past few decades. As they are soluble in water, they have been used as groundwater age indicators over timescales ranging from a few years to a few decades. In this paper we show that the time lag for transport of these atmospheric trace gases through

P. G. Cook; D. K. Solomon

1995-01-01

362

The Viscosity and Thermal Conductivity Coefficients for Dense Gaseous and Liquid Argon, Krypton, Xenon, Nitrogen, and Oxygen  

Microsoft Academic Search

Data for the viscosity and thermal conductivity coefficients of argon, nitrogen, and oxygen have been critically evaluated. A functional form to represent the data has been proposed. The function is basically the same for both coefficients. The critical point enhancement in the thermal conductivity coefficient is included. Transport properties of krypton and xenon are calculated by means of the principle

H. J. M. Hanley; R. D. McCarty; W. M. Haynes

1974-01-01

363

Hydration of krypton and consideration of clathrate models of hydrophobic effects from the perspective of quasi-chemical theory  

Microsoft Academic Search

Ab initio molecular dynamics (AIMD) results on a kryptonwater liquid solution are presented and compared to recent XAFS results for the radial hydration structure for a Kr atom in liquid water solution. Though these AIMD calculations have important limitations of scale, the comparisons with the liquid solution results are satisfactory and significantly different from the radial distributions extracted from the

Henry S. Ashbaugh; D. Asthagiri; Lawrence R. Pratt; Susan B. Rempe

2003-01-01

364

An evaluation of Technegas as a ventilation agent compared with krypton-81 m in the scintigraphic diagnosis of pulmonary embolism.  

PubMed

A ventilation agent that provides good quality lung images, which is cheap, easy to use and non-toxic, with a low radiation dose, has long been sought. Technegas, an ultrafine aerosol of technetium-99m-labelled carbon, was developed with these qualities in mind. We have studied Technegas in a clinical setting to evaluate some of these qualities. Twenty-five patients referred with a diagnosis of suspected pulmonary embolism were investigated during the same study using both krypton-81 m and Technegas as ventilation agents in conjunction with 99mTc-macroaggregated albumin as a perfusion agent. Technegas provided images which were of satisfactory quality. Images were obtained relatively easily and without discomfort to the patient, and Technegas has the advantage of always being available. A semi-quantitative regional assessment was employed which showed a good correlation (r = 0.499, P less than 0.001) between Technegas and krypton-81 m ventilation. We report on an effect not previously found to be significant, that is lung regions were better ventilated with Technegas than with krypton-81 m. This altered the diagnostic probability rating of pulmonary embolism in a number of patients (n = 3, 12%) compared with krypton-81 m. This effect was also noted in a further 8 patients (32%) without a change in the diagnostic probability. We offer possible explanations for this phenomenon. PMID:1327796

Cook, G; Clarke, S E

1992-01-01

365

In situ measurements of Krypton in Xenon gas with a quadrupole mass spectrometer following a cold-trap at a temporarily reduced pumping speed  

E-print Network

A new method for measuring trace amounts of krypton in xenon using a cold trap with a residual gas analyzer has been developed, which achieves an increased sensitivity by temporarily reducing the pumping speed while expending a minimal amount of xenon. By partially closing a custom built butterfly valve between the measurement chamber and the turbomolecular pump, a sensitivity of 40 ppt has been reached. This method has been tested on an ultra-pure gas sample from Air Liquide with an unknown intrinsic krypton concentration, yielding a krypton concentration of $330 \\pm 200$ ppt.

Brown, Ethan; Huhmann, Christian; Weinheimer, Christian; Kettling, Hans

2012-01-01

366

In situ measurements of Krypton in Xenon gas with a quadrupole mass spectrometer following a cold-trap at a temporarily reduced pumping speed  

E-print Network

A new method for measuring trace amounts of krypton in xenon using a cold trap with a residual gas analyzer has been developed, which achieves an increased sensitivity by temporarily reducing the pumping speed while expending a minimal amount of xenon. By partially closing a custom built butterfly valve between the measurement chamber and the turbomolecular pump, a sensitivity of 40 ppt has been reached. This method has been tested on an ultra-pure gas sample from Air Liquide with an unknown intrinsic krypton concentration, yielding a krypton concentration of $330 \\pm 200$ ppt.

Ethan Brown; Stephan Rosendahl; Christian Huhmann; Christian Weinheimer; Hans Kettling

2012-12-20

367

MAGSAT anomaly map and continental drift  

NASA Technical Reports Server (NTRS)

Anomaly maps of high quality are needed to display unambiguously the so called long wave length anomalies. The anomalies were analyzed in terms of continental drift and the nature of their sources is discussed. The map presented confirms the thinness of the oceanic magnetized layer. Continental magnetic anomalies are characterized by elongated structures generally of east-west trend. Paleomagnetic reconstruction shows that the anomalies found in India, Australia, and Antarctic exhibit a fair consistency with the African anomalies. It is also shown that anomalies are locked under the continents and have a fixed geometry.

Lemouel, J. L. (principal investigator); Galdeano, A.; Ducruix, J.

1981-01-01

368

The Palladium Isotopic Composition in Iron Meteorites  

NASA Technical Reports Server (NTRS)

Ru, Mo and Pd are very useful indicators for the identification of nucleosynthetic components. We have developed techniques for Pd isotopes, in an effort to check the extent of isotopic effects in this mass region and for a Pt-group element which is less refractory than Ru. Stable Pd isotopes are produced by the process only (102Pd), the s-process only (104Pd), the process only (Pd-110) and by both the r- and s-processes (Pd-105, Pd-106, Pd-108). Kelly and Wasserburg reported a hint of a shift in 102Pd (approx. 25(epsilon)u; 1(epsilon)u (triple bonds) 0.01%) in Santa Clara. Earlier searches for Mo and Ru isotopic anomalies were either positive or negative.

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

2005-01-01

369

Isotope spectroscopy  

NASA Astrophysics Data System (ADS)

The measurement of isotopic ratios provides a privileged insight both into nucleosynthesis and into the mechanisms operating in stellar envelopes, such as gravitational settling. In this article, we give a few examples of how isotopic ratios can be determined from high-resolution, high-quality stellar spectra. We consider examples of the lightest elements, H and He, for which the isotopic shifts are very large and easily measurable, and examples of heavier elements for which the determination of isotopic ratios is more difficult. The presence of 6Li in the stellar atmospheres causes a subtle extra depression in the red wing of the 7Li 670.7 nm doublet which can only be detected in spectra of the highest quality. But even with the best spectra, the derived 6Li abundance can only be as good as the synthetic spectra used for their interpretation. It is now known that 3D non-LTE modelling of the lithium spectral line profiles is necessary to account properly for the intrinsic line asymmetry, which is produced by convective flows in the atmospheres of cool stars, and can mimic the presence of 6Li. We also discuss briefly the case of the carbon isotopic ratio in metal-poor stars, and provide a new determination of the nickel isotopic ratios in the solar atmosphere.

Caffau, E.; Steffen, M.; Bonifacio, P.; Ludwig, H.-G.; Monaco, L.; Lo Curto, G.; Kamp, I.

2014-01-01

370

Anomaly in the optical potential for deformed nuclei  

NASA Astrophysics Data System (ADS)

Elastic scattering of 65 MeV polarized protons from Sm isotopes, 164Dy, and 172Yb has been measured. The volume integrals of the real central part and the spin-orbit part of the optical potential show anomalously low values for deformed nuclei. The origins of these anomalies are discussed. NUCLEAR REACTIONS 144Sm, 148Sm, 150Sm, 152Sm, 154Sm, 164Dy, 172Yb(p,p), 164Dy(p,p'), E=65 MeV; measured ?(?), A(?) deduced optical-model parameters, coupled channel parameters, volume integrals for the real central potential, volume integrals for the real spin-orbit potential.

Ohtani, F.; Sakaguchi, H.; Nakamura, M.; Noro, T.; Sakamoto, H.; Ogawa, H.; Ichihara, T.; Yosoi, M.; Kobayashi, S.

1983-07-01

371

A primitive plume neon component in MORB: The Shona ridge-anomaly, South Atlantic (5152S)  

Microsoft Academic Search

We report on He and Ne isotopes in basaltic glasses from eight dredge stations occupied over the Shona gravity and topographic anomaly high on the Mid-Atlantic Ridge around 5152S. The results indicate the presence of a primitive, little degassed, 3He-rich mantle component. 3He4He ratios correlate positively with the bathymetric and gravity anomaly, with values ranging from 12.5 to 6.4 times

Manuel Moreira; Thomas Staudacher; Philippe Sarda; Jean-Guy Schilling; Claude Jean Allgre

1995-01-01

372

Stable platinum isotope measurements in presolar nanodiamonds by TEAMS  

NASA Astrophysics Data System (ADS)

Nanodiamonds are stardust grains commonly found in primitive meteorites. They survived the formation of the solar system and kept their own individuality. Measurements of trace-element isotopic signatures in these grains will help understanding heavy element nucleosynthesis in massive stars and dust formation from their ejecta. We have continued previous attempts to search for stable Pt isotope anomalies in nanodiamonds via trace element accelerator mass spectrometry (TEAMS). The installation of a new injector beam line at the VERA facility allowed studying low traces of stable elements in different materials. Moreover, recent experiments showed that VERA provides the required measurement precision together with a low Pt machine background. Here, we observed for the first time an indication for enhancements of 198Pt/195Pt isotope ratios in two diamond residues prepared by different chemical separation techniques from the Allende meteorite. Variations in other isotopic ratios were within analytical uncertainty, and no anomaly was identified in a third diamond fraction.

Wallner, A.; Melber, K.; Merchel, S.; Ott, U.; Forstner, O.; Golser, R.; Kutschera, W.; Priller, A.; Steier, P.

2013-01-01

373

Stable platinum isotope measurements in presolar nanodiamonds by TEAMS  

PubMed Central

Nanodiamonds are stardust grains commonly found in primitive meteorites. They survived the formation of the solar system and kept their own individuality. Measurements of trace-element isotopic signatures in these grains will help understanding heavy element nucleosynthesis in massive stars and dust formation from their ejecta. We have continued previous attempts to search for stable Pt isotope anomalies in nanodiamonds via trace element accelerator mass spectrometry (TEAMS). The installation of a new injector beam line at the VERA facility allowed studying low traces of stable elements in different materials. Moreover, recent experiments showed that VERA provides the required measurement precision together with a low Pt machine background. Here, we observed for the first time an indication for enhancements of 198Pt/195Pt isotope ratios in two diamond residues prepared by different chemical separation techniques from the Allende meteorite. Variations in other isotopic ratios were within analytical uncertainty, and no anomaly was identified in a third diamond fraction. PMID:23565017

Wallner, A.; Melber, K.; Merchel, S.; Ott, U.; Forstner, O.; Golser, R.; Kutschera, W.; Priller, A.; Steier, P.

2013-01-01

374

Stable platinum isotope measurements in presolar nanodiamonds by TEAMS.  

PubMed

Nanodiamonds are stardust grains commonly found in primitive meteorites. They survived the formation of the solar system and kept their own individuality. Measurements of trace-element isotopic signatures in these grains will help understanding heavy element nucleosynthesis in massive stars and dust formation from their ejecta. We have continued previous attempts to search for stable Pt isotope anomalies in nanodiamonds via trace element accelerator mass spectrometry (TEAMS). The installation of a new injector beam line at the VERA facility allowed studying low traces of stable elements in different materials. Moreover, recent experiments showed that VERA provides the required measurement precision together with a low Pt machine background. Here, we observed for the first time an indication for enhancements of (198)Pt/(195)Pt isotope ratios in two diamond residues prepared by different chemical separation techniques from the Allende meteorite. Variations in other isotopic ratios were within analytical uncertainty, and no anomaly was identified in a third diamond fraction. PMID:23565017

Wallner, A; Melber, K; Merchel, S; Ott, U; Forstner, O; Golser, R; Kutschera, W; Priller, A; Steier, P

2013-01-01

375

[Right ventricular function in patients with chronic obstructive pulmonary disease measured by krypton-81m].  

PubMed

Right ventricular function was assessed at rest and during exercise in patients with chronic obstructive pulmonary disease (COPD). Right ventricular ejection fraction (RVEF) was measured by first-pass radionuclide angiography using ultrashort-lived radionuclide krypton-81m. The half-life of this nuclide is only 13 sec, and it is completely expired from the lungs. These properties allow measurement of RVEF without correcting for background activity. In 30 patients with cardiac or pulmonary disease, RVEF was first measured by krypton-81 m scintigraphy (Kr-RVEF), then by technetium-99m (Tc-RVEF), without changing the patients' positions. In eight of the 30 cases, right ventricular cineangiography (RVG) was performed within 72 hrs after the radionuclide study, and RVEF was measured according to the Chapman's rule (RVG-RVEF). Kr-RVEF correlated significantly with Tc-RVEF (r = 0.87), and also with RVG-RVEF (r = 0.80). In 10 patients with stable COPD, who had severe hypoxemia (PaO2 less than or equal to 60 mmHg) and pulmonary hypertension [mean pulmonary arterial pressure (mean PAP) greater than or equal to 20 mmHg], and in seven normal control subjects, radionuclide angiographic and hemodynamic monitoring were performed at rest and during supine ergometer exercise. Kr-RVEF at rest was 47.6 +/- 5.4% (mean +/- SD) in patients with COPD and was 54.1 +/- 4.8% in normal subjects. Kr-RVEF during exercise was 51.8 +/- 7.3% in the patients, and 62.3 +/- 3.2% in the normal subjects. Hemodynamically, mean PAP and pulmonary vascular resistance (PVR) increased significantly during exercise, but the RV end-diastolic volume index (RVEDVI) did not change. There was inverse correlation between Kr-RVEF and mean PAP (r = -0.51) or PVR (r = -0.47) as an index of RV afterload. However, there was no correlation between Kr-RVEF and RVEDVI as an expression of RV preload. These findings suggest that a poor response by RVEF during exercise in patients with COPD is associated with elevation of afterload. Thus, right ventricular imaging techniques using the ultrashort-lived nuclide krypton-81 m allow noninvasive, serial and accurate assessments of right ventricular function in patients with COPD. PMID:3429914

Ishibashi, Y; Sano, K; Murakami, R; Murakami, Y; Ikuma, I; Yoshikane, H; Nakazawa, Y; Matsuno, Y; Shimada, T; Morioka, S

1987-03-01

376

Hyperfine Field and Hyperfine Anomalies of Copper Impurities in Iron  

E-print Network

A new value for the hyperfine magnetic field of copper impurities in iron is obtained by combining resonance frequencies from experiments involving {\\beta}-NMR on oriented nuclei on 59-Cu, 69-Cu, and 71-Cu with magnetic moment values from collinear laser spectroscopy measurements on these isotopes. The resulting value, i.e., Bhf(CuFe) = -21.794(10) T, is in agreement with the value adopted until now but is an order of magnitude more precise. It is consistent with predictions from ab initio calculations. Comparing the hyperfine field values obtained for the individual isotopes, the hyperfine anomalies in Fe were determined to be 59{\\Delta}69=0.15(9)% and 71{\\Delta}69=0.07(11)%.

V. V. Golovko; F. Wauters; S. Cottenier; M. Breitenfeldt; V. De Leebeeck; S. Roccia; G. Soti; M. Tandecki; E. Traykov; S. Van Gorp; D. Zkouck; N. Severijns

2011-07-29

377

Structural, chemical, and isotopic microanalytical investigations of graphite from supernovae  

Microsoft Academic Search

We report the results of coordinated ion microprobe and transmission electron microscope (TEM) studies of presolar graphites from the KE3 separate (1.651.72 g\\/cm3) of the Murchison CM2 meteorite. Isotopic analysis of individual graphites (112 ?m) with the ion microprobe shows many to have large 18O excesses combined with large silicon isotopic anomalies, indicative of a supernova (SN) origin. Transmission electron

T. Kevin Croat; Thomas Bernatowicz; Sachiko Amari; Scott Messenger; FRANK J. STADERMANN

2003-01-01

378

Shape evolution in Yttrium and Niobium neutron-rich isotopes  

E-print Network

The isotopic evolution of the ground-state nuclear shapes and the systematics of one-quasiproton configurations are studied in neutron-rich odd-A Yttrium and Niobium isotopes. We use a selfconsistent Hartree-Fock-Bogoliubov formalism based on the Gogny energy density functional with two parametrizations, D1S and D1M. The equal filling approximation is used to describe odd-A nuclei preserving both axial and time reversal symmetries. Shape-transition signatures are identified in the N=60 isotopes in both charge radii and spin-parities of the ground states. These signatures are a common characteristic for nuclei in the whole mass region. The nuclear deformation and shape coexistence inherent to this mass region are shown to play a relevant role in the understanding of the spectroscopic features of the ground and low-lying one-quasiproton states. Finally, a global picture of the neutron-rich A=100 mass region from Krypton up to Molybdenum isotopes is illustrated with the systematics of the nuclear charge radii is...

Rodriguez-Guzman, R; Robledo, L M

2011-01-01

379

Graph anomalies in cyber communications  

SciTech Connect

Enterprises monitor cyber traffic for viruses, intruders and stolen information. Detection methods look for known signatures of malicious traffic or search for anomalies with respect to a nominal reference model. Traditional anomaly detection focuses on aggregate traffic at central nodes or on user-level monitoring. More recently, however, traffic is being viewed more holistically as a dynamic communication graph. Attention to the graph nature of the traffic has expanded the types of anomalies that are being sought. We give an overview of several cyber data streams collected at Los Alamos National Laboratory and discuss current work in modeling the graph dynamics of traffic over the network. We consider global properties and local properties within the communication graph. A method for monitoring relative entropy on multiple correlated properties is discussed in detail.

Vander Wiel, Scott A [Los Alamos National Laboratory; Storlie, Curtis B [Los Alamos National Laboratory; Sandine, Gary [Los Alamos National Laboratory; Hagberg, Aric A [Los Alamos National Laboratory; Fisk, Michael [Los Alamos National Laboratory

2011-01-11

380

Spacecraft environmental anomalies expert system  

NASA Technical Reports Server (NTRS)

A microcomputer-based expert system is being developed at the Aerospace Corporation Space Sciences Laboratory to assist in the diagnosis of satellite anomalies caused by the space environment. The expert system is designed to address anomalies caused by surface charging, bulk charging, single event effects and total radiation dose. These effects depend on the orbit of the satellite, the local environment (which is highly variable), the satellite exposure time and the hardness of the circuits and components of the satellite. The expert system is a rule-based system that uses the Texas Instruments Personal Consultant Plus expert system shell. The completed expert system knowledge base will include 150 to 200 rules, as well as a spacecraft attributes database, an historical spacecraft anomalies database, and a space environment database which is updated in near real-time. Currently, the expert system is undergoing development and testing within the Aerospace Corporation Space Sciences Laboratory.

Koons, H. C.; Gorney, D. J.

1988-01-01

381

Generalized oscillator strengths for 5s, 5s{sup '}, and 5p excitations of krypton  

SciTech Connect

The absolute generalized oscillator strengths (GOSs) for 5s, 5s{sup '}, 5p [5/2]{sub 3,2}, 5p [3/2]{sub 1,2}, and 5p [1/2]{sub 0} transitions of krypton have been determined in a large K{sup 2} region at a high electron-impact energy of 2500 eV. The positions of the minima and maxima of these GOSs have been determined. The present results show that the angular resolution and pressure effect have great influence on the position and the amplitude of the minimum for the GOS of 5s+5s{sup '} transitions. When these effects are considered, the measured minimum position for the GOS of 5s+5s{sup '} transitions is in excellent agreement with the calculation of Chen and Msezane [J. Phys. B 33, 5397 (2000)].

Li Wenbin; Zhu Linfan; Yuan Zhensheng; Sun Jianmin; Cheng Huadong; Xu Kezun [Laboratory of Bond-Selective Chemistry, Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui, 230027 (China); Zhong Zhiping [Department of Physics, the Graduate School of the Chinese Academy of Sciences, P.O. Box 3908, Beijing 100039 (China); Liu Xiaojing

2003-06-01

382

Computation of thermodynamic and transport properties to predict thermophoretic effects in an argon-krypton mixture  

NASA Astrophysics Data System (ADS)

Thermophoresis is the movement of molecules caused by a temperature gradient. Here we report the results of a study of thermophoresis using non-equilibrium molecular dynamics simulations of a confined argon-krypton fluid subject to two different temperatures at thermostated walls. The resulting temperature profile between the walls is used along with the Soret coefficient to predict the concentration profile that develops across the channel. We obtain the Soret coefficient by calculating the mutual diffusion and thermal diffusion coefficients. We report an appropriate method for calculating the transport coefficients for binary systems, using the Green-Kubo integrals and radial distribution functions obtained from equilibrium molecular dynamics simulations of the bulk fluid. Our method has the unique advantage of separating the mutual diffusion and thermal diffusion coefficients, and calculating the sign and magnitude of their individual contributions to thermophoresis in binary mixtures.

Miller, Nicholas A. T.; Daivis, Peter J.; Snook, Ian K.; Todd, B. D.

2013-10-01

383

High-pressure equation of state for solid krypton from interatomic potentials  

SciTech Connect

The pressure-volume isotherm for krypton at 300 K is evaluated by the Monte Carlo method using pair and three-body potentials. The pair potentials used are that of Aziz and Salman and a slightly modified version of their potential which gives better agreement with high-energy scattering data. The three-body potentials considered are the Axilrod-Teller interaction and the first-order three-body exchange interaction as parametrized by Loubeyre. The results are compared with recent measurements at pressures up to 300 kbar and the implications of the comparison are discussed. The best agreement with experiment is found using the Axilrod-Teller interaction as the only many-body interaction, indicating that the three-body exchange interaction is to a large extent canceled by higher many-body interactions, at least in the highly symmetrical environment of the crystal.

Barker, J.A.

1988-09-01

384

The Upgrade of the Control System for the CERN/NA62 Liquid Krypton Detector  

E-print Network

The NA62 experiment is a continuation of the CERN kaon research program and particularly of the NA48 experiment which was designed in the early 90s to measure the direct CP violation with a very high precision. An important component of the experimental setup is an electromagnetic calorimeter filled with 9000 liters of high-purity liquid krypton at 120 K. Its associated cryogenic system aims at providing a very high reliability and stable thermal conditions with temperature stabilization better than 0.1 K. The upgrade of the cryogenic control system was motivated by the need of ensuring its durability and standardization for the long term fixed-target physics program at the CERN Super Proton Synchrotron (SPS). This paper describes the adopted technical solutions to minimize the control shutdown and emphasizes the related safety issues.

Moraux, A; Falaleev, V; Gonidec, A; Passardi, Giorgio; Pezzetti, M

2009-01-01

385

Theory of Attosecond Transient Absorption Spectroscopy of Krypton for Overlapping Pump and Probe Pulses  

E-print Network

We present the first fully ab initio calculations for attosecond transient absorption spectroscopy of atomic krypton with overlapping pump and probe pulses. Within the time-dependent configuration interaction singles (TDCIS) approach, we describe the pump step (strong-field ionization using a near-infrared pulse) as well as the probe step (resonant electron excitation using an extreme- ultraviolet pulse) from first principles. We extent our TDCIS model and account for the spin-orbit splitting of the occupied orbitals. We discuss the spectral features seen in a recent attosecond transient absorption experiment [A. Wirth et al., Science 334, 195 (2011)]. Our results support the concept that the transient absorption signal can be directly related to the instantaneous hole population even during the ionizing pump pulse. Furthermore, we find strong deformations in the absorption lines when the overlap of pump and probe pulses is maximum. These deformations can be described by relative phase shifts in the oscillati...

Pabst, Stefan; Moulet, Antoine; Wirth, Adrian; Goulielmakis, Eleftherios; Santra, Robin

2012-01-01

386

Double shock front formation in cylindrical radiative blast waves produced by laser irradiation of krypton gas  

SciTech Connect

Radiative blast waves were created by irradiating a krypton cluster source from a supersonic jet with a high intensity femtosecond laser pulse. It was found that the radiation from the shock surface is absorbed in the optically thick upstream medium creating a radiative heat wave that travels supersonically ahead of the main shock. As the blast wave propagates into the heated medium, it slows and loses energy, and the radiative heat wave also slows down. When the radiative heat wave slows down to the transonic regime, a secondary shock in the ionization precursor is produced. This paper presents experimental data characterizing both the initial and secondary shocks and numerical simulations to analyze the double-shock dynamics.

Kim, I.; Quevedo, H. J.; Feldman, S.; Bang, W.; Serratto, K.; McCormick, M.; Aymond, F.; Dyer, G.; Bernstein, A. C.; Ditmire, T. [Center for High Energy Density Science, Department of Physics, The University of Texas at Austin, C1510, Austin, Texas 78712 (United States)] [Center for High Energy Density Science, Department of Physics, The University of Texas at Austin, C1510, Austin, Texas 78712 (United States)

2013-12-15

387

Semiclassical description of high-order-harmonic spectroscopy of the Cooper minimum in krypton  

NASA Astrophysics Data System (ADS)

The Cooper minimum has recently been observed in the high-order-harmonic spectrum issued from the interaction of a short and intense laser pulse with krypton atoms [A. D. Shiner et al., J. Phys. B 45, 074010 (2012), 10.1088/0953-4075/45/7/074010]. Here we compare this observation to a semiclassical description using the single-active electron approximation. Particular attention is paid to the description of the interaction of the active valence electron with the ionic core in the framework of a mean-field approach. The computed harmonic spectrum presents a minimum at about 83 eV, which does not show up so clearly in the measurements probably because of second-order diffraction of the grating used to disperse the harmonic spectrum.

Cloux, F.; Fabre, B.; Pons, B.

2015-02-01

388

Computation of thermodynamic and transport properties to predict thermophoretic effects in an argon-krypton mixture.  

PubMed

Thermophoresis is the movement of molecules caused by a temperature gradient. Here we report the results of a study of thermophoresis using non-equilibrium molecular dynamics simulations of a confined argon-krypton fluid subject to two different temperatures at thermostated walls. The resulting temperature profile between the walls is used along with the Soret coefficient to predict the concentration profile that develops across the channel. We obtain the Soret coefficient by calculating the mutual diffusion and thermal diffusion coefficients. We report an appropriate method for calculating the transport coefficients for binary systems, using the Green-Kubo integrals and radial distribution functions obtained from equilibrium molecular dynamics simulations of the bulk fluid. Our method has the unique advantage of separating the mutual diffusion and thermal diffusion coefficients, and calculating the sign and magnitude of their individual contributions to thermophoresis in binary mixtures. PMID:24116632

Miller, Nicholas A T; Daivis, Peter J; Snook, Ian K; Todd, B D

2013-10-14

389

Statistical analysis of the electrical breakdown time delay distributions in krypton  

SciTech Connect

The statistical analysis of the experimentally observed electrical breakdown time delay distributions in the krypton-filled diode tube at 2.6 mbar is presented. The experimental distributions are obtained on the basis of 1000 successive and independent measurements. The theoretical electrical breakdown time delay distribution is evaluated as the convolution of the statistical time delay with exponential, and discharge formative time with Gaussian distribution. The distribution parameters are estimated by the stochastic modelling of the time delay distributions, and by comparing them with the experimental distributions for different relaxation times, voltages, and intensities of UV radiation. The transition of distribution shapes, from Gaussian-type to the exponential-like, is investigated by calculating the corresponding skewness and excess kurtosis parameters. It is shown that the mathematical model based on the convolution of two random variable distributions describes experimentally obtained time delay distributions and the separation of the total breakdown time delay to the statistical and formative time delay.

Maluckov, Cedomir A.; Karamarkovic, Jugoslav P.; Radovic, Miodrag K.; Pejovic, Momcilo M. [Technical Faculty in Bor, University of Belgrade, Vojske Jugoslavije 24, 19210 Bor (Serbia and Montenegro); Faculty of Civil Engineering and Architecture, University of Nis, Beogradska 14, 18000 Nis (Serbia and Montenegro); Faculty of Sciences and Mathematics, University of Nis, P.O. Box 224, 18001 Nis (Serbia and Montenegro); Faculty of Electronic Engineering, University of Nis, P.O. Box 73, 18001 Nis (Serbia and Montenegro)

2006-08-15

390

Configuration-interaction calculation for the isotope shift in Mg I  

Microsoft Academic Search

We present an ab initio method of calculation of isotope shift in atoms with a few valence electrons, based on the configuration-interaction calculation of energy. The main motivation for developing the method comes from the need to analyze whether differences in isotope abundance in early universe can contribute to the observed anomalies in quasar absorption spectra. The current best explanation

J. C. Berengut; V. A. Dzuba; V. V. Flambaum; M. G. Kozlov

2004-01-01

391

UNCORRECTEDPROOF 2 The effect of rising atmospheric oxygen on carbon and sulfur isotope  

E-print Network

UNCORRECTEDPROOF 1 2 The effect of rising atmospheric oxygen on carbon and sulfur isotope 3 90089, United States 8 Accepted 8 June 2006 9 10 Editor: P. Deines 11 Abstract 12 Carbonates within a remarkable negative carbon isotope anomaly to a nadir of near -11 that accompanies a dramatic rise

Kaufman, Alan Jay

392

PhotoIonization of Krypton Between 300 and 1500 eV. Relative Subshell Cross Sections and Angular Distributions of Photoelectrons  

Microsoft Academic Search

Energy spectra of electrons ejected from M and N subshells of krypton by characteristic x rays of 300 to 1500 eV energy have been measured with an electrostatic analyzer. Krypton was irradiated in the gas phase and electrons were detected perpendicular to the x-ray beam. From these spectra, relative subshell contributions to the photo-ionization cross section were obtained for single-electron

Manfred O. Krause

1969-01-01

393

Phase behavior of mixed submonolayer films of krypton and xenon on graphite  

NASA Astrophysics Data System (ADS)

Using the results of extensive Monte Carlo simulations in the canonical and grand canonical ensembles, we discuss the phase behavior of mixed submonolayer films of krypton and xenon adsorbed on the graphite basal plane. The calculations have been performed using two- and three-dimensional models of the systems studied. It has been demonstrated that out-of-plane motion does not affect the properties of the films as long as the total density is well below the monolayer completion and at moderate temperatures. For the total densities close to the monolayer completion, the promotion of particles to the second layer considerably affects the film properties. Our results are in a reasonable agreement with the available experimental data. The melting point of submonolayer films has been shown to exhibit non-monotonous changes with the film composition, and reaches minimum for the xenon concentration of about 50%. At the temperatures below the melting point, the structure of solid phases depends upon the film composition and the temperature; one can also distinguish commensurate and incommensurate phases. Two-dimensional calculations have demonstrated that for the xenon concentration between about 15% and 65% the adsorbed film exhibits the formation of a superstructure, in which each Xe atom is surrounded by six Kr atoms. This superstructure is stable only at very low temperatures and transforms into the mixed commensurate (?{3} ?{3})R30 phase upon the increase of temperature. Such a superstructure does not appear when a three-dimensional model is used. Grand canonical ensemble calculations allowed us to show that for the xenon concentration of about 3% the phase diagram topology of monolayer films changes from the krypton-like (with incipient triple point) to the xenon-like (with ordinary triple point).

Patrykiejew, A.; Soko?owski, S.

2012-04-01

394

Review on possible gravitational anomalies  

E-print Network

This is an updated introductory review of 2 possible gravitational anomalies that has attracted part of the Scientific community: the Allais effect that occur during solar eclipses, and the Pioneer 10 spacecraft anomaly, experimented also by Pioneer 11 and Ulysses spacecrafts. It seems that, to date, no satisfactory conventional explanation exist to these phenomena, and this suggests that possible new physics will be needed to account for them. The main purpose of this review is to announce 3 other new measurements that will be carried on during the 2005 solar eclipses in Panama and Colombia (Apr. 8) and in Portugal (Oct.15).

Xavier Amador

2008-09-03

395

Review on possible gravitational anomalies  

NASA Astrophysics Data System (ADS)

This is an updated introductory review of 2 possible gravitational anomalies that has attracted part of the Scientific community: the Allais effect that occur during solar eclipses, and the Pioneer 10 spacecraft anomaly, experimented also by Pioneer 11 and Ulysses spacecrafts. It seems that, to date, no satisfactory conventional explanation exist to these phenomena, and this suggests that possible new physics will be needed to account for them. The main purpose of this review is to announce 3 other new measurements that will be carried on during the 2005 solar eclipses in Panama and Colombia (Apr. 8) and in Portugal (Oct.15).

Amador, Xavier E.

2005-01-01

396

[Summary of 2004 Chinese National Conference on oral and maxillofacial vascular anomalies].  

PubMed

Congenital vascular anomalies have been the subject of much controversy and confusion over the years, many remain to be investigated and resolved. Authorized by the Managing Director Board of Chinese Stomatological Association (CSA), 2004 Chinese National Conference on Oral and Maxillofacial Vascular Anomalies was successfully held on July 15 to 18, 2004 in Shenzhen Grand Hotel. The conference was sponsored by Chinese Society of Oral and Maxillofacial Surgery (CSOMS), and undertaken by the Second People's Hospital of Shenzhen city. Professor ZHANG Zhen-kang, president of CSA, Professor QIU Wei-liu, president of CSOMS and academician of Chinese Academy of Engineers, and Professor LIU Bao-lin, vice president of CSOMS were present and made important speech at the meeting. More than 120 delegates nationwide attended this conference. Through a 3-day of oral presentation and discussion, the terminology, classification, treatment selection and outcome measurement of oral and maxillofacial hemangioma and vascular malformations were concerted among the delegates. Hemangiomas and vascular malformations have been recognized as distinct diseases that exhibit unique properties and behavior that demand an appropriately tailored treatment plan. The classification of Waner and Suen was adopted and different treatment modalities were reviewed and advocated for different lesions. Delegates were most interested in intralesional injection of Pingyangmycin for venous malformations, Krypton laser photodynamic therapy of venular malformations, Nd:YAG laser therapy for deep head and neck venous malformations after surgical exposure of the lesions, as well as "double" embolization of large venous malformations reported by Professor QIN Zhong-ping. The conference witnessed the foundation of the Division of Vascular Anomalies, Chinese Society of Oral and Maxillofacial Surgery. PMID:15349690

Zheng, Jia-Wei; Zhang, Zhi-Yuan; Zheng, Cang-Shang; Zhou, Qi

2004-08-01

397

Monitoring smartphones for anomaly detection  

Microsoft Academic Search

In this paper we demonstrate how to monitor a smartphone running Symbian OS in order to extract features that de- scribe the state of the device and can be used for anomaly detection. These features are sent to a remote server, be- cause running a complex intrusion detection system (IDS) on this kind of mobile device still is not feasible,

Aubrey-derrick Schmidt; Frank Peters; Florian Lamour; Sahin Albayrak

2008-01-01

398

Coral can have growth anomalies  

EPA Science Inventory

Coral growth anomalies (GAs) are changes in the coral cells that deposit the calcium carbonate skeleton. They usually appear as raised areas of the skeleton and tissue that are different from the surrounding normal areas on the same colony. The features include abnormal shape a...

399

Lunar rocks and thermal anomalies  

Microsoft Academic Search

Recent microwave and infrared spectral observations of several of the large bright-rayed craters on the moon suggest that the thermal anomalies in these craters are produced by large rocks, boulders, and exposed rock strata. The data for the crater Tycho can be simulated by a surface consisting of 16% loose rocks of I-meter size and 4% exposed rock strata. A

David Buhl

1971-01-01

400

Prenatal diagnosis of congenital anomalies  

PubMed Central

Up till the early 1970s, prenatal diagnosis of congenital anomalies was primarily aimed at detecting chromosomal abnormalities by amniocentesis.1. Over the last two decades, prenatal diagnosis has greatly benefited from advances in ultrasound technology and in our ability to detect microscopic and submicroscopic chromosome abnormalities as well as single gene disorders, leading to substantive improvements in detection of such congenital anomalies.2 At present, invasive prenatal diagnosis continues to be the gold standard for pregnancies at increased risk for chromosomal anomaly or other genetic disease, with chorionic villus sampling being the procedure of choice for the first trimester,3 whereas mid-trimester amniocentesis continues to be the most common form of invasive procedure for prenatal diagnosis.4 Still, invasive techniques are restricted to subgroups at risk for anomalies, for whom such time-consuming procedures are believed to be cost-effective, also accounting for procedure-related abortive risks. In the low-risk population prenatal diagnosis generally consists of screening procedures by means of ultrasound and maternal serum biochemistry. PMID:22368596

Todros, T; Capuzzo, E; Gaglioti, P

2001-01-01

401

Development anomalies of the occiput  

Microsoft Academic Search

Four patients with classical features of bathrocephalism are described. Three further patients with developmental anomalies of the occiput are described and these are contrasted with those having classical bathrocephalism. The distinction between the two groups is emphasised. Reference is made to cases described in the pediatric literature which appears at times to depart from the traditional norms and classical notation.

J. Wickenhauser; O. Hochberg

1974-01-01

402

Gravitational Anomaly and Transport Phenomena  

Microsoft Academic Search

Quantum anomalies give rise to new transport phenomena. In particular, a magnetic field can induce an anomalous current via the chiral magnetic effect and a vortex in the relativistic fluid can also induce a current via the chiral vortical effect. The related transport coefficients can be calculated via Kubo formulas. We evaluate the Kubo formula for the anomalous vortical conductivity

Karl Landsteiner; Eugenio Megas; Francisco Pena-Benitez

2011-01-01

403

Archaeological Anomalies in the Bahamas  

Microsoft Academic Search

Controversial claims have been made for the presence of anom- alous underwater archaeological sites in the Bahamas by a number of in- vestigators. The proponents emphasize extraordinary explanations for the anomalies and tend to bypass the scientific journals in favor of popular presentations with little scientific rigor. The skeptics debunk selected claims for some of the sites, do not adequately

DOUGLAS G. RICHARDS

1988-01-01

404

Configuration-interaction calculation for the isotope shift in Mg I  

SciTech Connect

We present an ab initio method of calculation of isotope shift in atoms with a few valence electrons, based on the configuration-interaction calculation of energy. The main motivation for developing the method comes from the need to analyze whether differences in isotope abundance in early universe can contribute to the observed anomalies in quasar absorption spectra. The current best explanation for these anomalies is the assumption that the fine structure constant {alpha} was smaller at early epoch. We show that we can calculate the isotope shift in magnesium with good accuracy.

Berengut, J.C.; Dzuba, V.A.; Flambaum, V.V.; Kozlov, M.G. [School of Physics, University of New South Wales, Sydney 2052 (Australia); School of Physics, University of New South Wales, Sydney 2052 (Australia); Institute for Advanced Study, Einstein Drive, Princeton, New Jersey 08540 (United States); Petersburg Nuclear Physics Institute, Gatchina, 188300 (Russian Federation); Queen's University of Belfast, Belfast BT71NN (United Kingdom)

2004-04-01

405

Osmium isotope evidence for an s-process carrier in primitive chondrites.  

PubMed

Osmium extracted from unequilibrated bulk chondrites has isotope anomalies consistent with an insoluble s-process carrier, termed Os(i) here. Osmium from metamorphosed bulk chondrites does not have isotope anomalies, implying that the Os(i) carrier was destroyed by metamorphism. The isotopic homogeneity of metamorphosed bulk chondrites is consistent with extremely effective mixing of presolar grains from varied sources in the nebula. Osmium in the Os(i) carrier is likely from nucleosynthetic sites with a neutron density about two to four times as high as that of the average solar s-process Os. PMID:16109878

Brandon, A D; Humayun, M; Puchtel, I S; Leya, I; Zolensky, M

2005-08-19

406

Molybdenum Evidence for Inherited Planetary Scale Isotope Heterogeneity of the Protosolar Nebula  

E-print Network

Isotope anomalies provide important information about early solar system evolution. Here we report molybdenum isotope abundances determined in samples of various meteorite classes. There is no fractionation of molybdenum isotopes in our sample set within 0.1 permil and no contribution from the extinct radionuclide 97Tc at mass 97 (97Tc/92Momolybdenum must have been inherited from the interstellar environment where the sun was born, illustrating the concept of ``cosmic chemical memory''. The presence of molybdenum anomalies is used to discuss the filiation between planetesimals.

N. Dauphas; B. Marty; L. Reisberg

2001-09-28

407

Congenital anomalies of the male urethra  

Microsoft Academic Search

The spectrum of congenital anomalies of the male urethra is presented. The embryologic basis of each anomaly, when known,\\u000a is discussed. Clinical and imaging features of each entity are presented.

Terry L. Levin; Bokyung Han; Brent P. Little

2007-01-01

408

Anomaly constraints on monopoles and dyons  

SciTech Connect

Fermions with magnetic charges can contribute to anomalies. We derive the axial anomaly and gauge anomalies for monopoles and dyons, and find eight new gauge anomaly cancellation conditions in a general theory with both electric and magnetic charges. As a by-product, we also extend the Zwanziger two-potential formalism to include the {theta} parameter, and elaborate on the condition for CP invariance in theories with fermionic dyons.

Csaki, Csaba [Institute for High Energy Phenomenology Newman Laboratory of Elementary Particle Physics, Cornell University, Ithaca, New York 14853 (United States); Shirman, Yuri [Department of Physics, University of California, Irvine, California 92697 (United States); Terning, John [Department of Physics, University of California, Davis, California 95616 (United States); CERN, Physics Department, Theory Unit, Geneva (Switzerland)

2010-06-15

409

Investigation of the combined adsorption of krypton, xenon, and water vapor of the off-gas of atomic power stations  

Microsoft Academic Search

A radiochromatogra phic system of purifying the off-gas from the short-lived krypton, xenon, and iodine nuclides is presently used in Russian atomic power stations and in foreign atomic power stations equipped with the aid of the USSR. The basic elements of the system are filter-adsorbers filled with activated carbon and a drying unit [1-3]. Dynamic adsorption and radioactive decay in

I. E. Nakhutin; D. V. Ochkin; S. A. Tret'yak

1980-01-01

410

Conclusions on plutonium separation from atmospheric krypton-85 measured at various distances from the Karlsruhe reprocessing plant  

Microsoft Academic Search

For wide-area atmospheric monitoring, krypton-85 is the best indicator for clandestine plutonium separations. The detection and false alarm rates were determined from weekly samples at five different distances from the Karlsruhe reprocessing plant between 1985 and 1988. The detection rate for the separation of 4 kg of plutonium per week was found to be as high as 8090% at a

Martin B. Kalinowski; Hartmut Sartorius; Stefan Uhl; Wolfgang Weiss

2004-01-01

411

Monitoring of kratom or Krypton intake in urine using GC-MS in clinical and forensic toxicology.  

PubMed

The Thai medicinal plant Mitragyna speciosa (kratom) is misused as a herbal drug. Besides this, a new herbal blend has appeared on the drugs of abuse market, named Krypton, a mixture of O-demethyltramadol (ODT) and kratom. Therefore, urine drug screenings should include ODT and focus on the metabolites of the kratom alkaloids mitragynine (MG), paynantheine (PAY), speciogynine (SG), and speciociliatine (SC). The aim of this study was to develop a full-scan gas chromatography-mass spectrometry procedure for monitoring kratom or Krypton intake in urine after enzymatic cleavage of conjugates, solid-phase extraction, and trimethylsilylation. With use of reconstructed mass chromatography with the ions m/z 271, 286, 329, 344, 470, 526, 528, and 586, the presence of MG, 16-carboxy-MG, 9-O-demethyl-MG, and/or 9-O-demethyl-16-carboxy-MG could be indicated, and in case of Krypton, with m/z 58, 84, 116, 142, 303, 361, 393, and 451, the additional presence of ODT and its nor metabolite could be indicated. Compounds were identified by comparison with their respective reference spectra. Depending on the plant type, dose, administration route, and/or sampling time, further metabolites of MG, PAY, SG, and SC could be detected. The limits of detection (signal-to-noise ratio of 3) were 100 ng/ml for the parent alkaloids and 50 ng/ml for ODT. As mainly metabolites of the kratom alkaloids were detected in urine, the detectability of kratom was tested successfully using rat urine after administration of a common user's dose of MG. As the metabolism in humans was similar, this procedure should be suitable to prove an intake of kratom or Krypton. PMID:21153588

Philipp, Anika A; Meyer, Markus R; Wissenbach, Dirk K; Weber, Armin A; Zoerntlein, Siegfried W; Zweipfenning, Peter G M; Maurer, Hans H

2011-04-01

412

On the spectra of highly-ionized krypton, strontium, zirconium and rhodium excited in the plasma of the TFR tokamak  

Microsoft Academic Search

Storntium, zirconium and rhodium have been injected into TFR tokamak plasmas by using the laser blow-off technique, and their spectra recorded either photographically (Zr, 10-92 ) or photoelectrically (all three elements, 10-330 ). Line identifications for several isoelectronic sequences from sodium-like to gallium-like are reported. Additionally, isoelectronic regularities observed for these three elements have allowed to identify a few krypton

J. F. Wyart

1988-01-01

413

Minor Physical Anomalies, Intelligence, and Cognitive Decline  

Microsoft Academic Search

Background\\/Study Context: Minor physical anomalies are thought to be markers of development and increased frequency of such anomalies has been linked to lower levels of intelligence. Here the authors examine a finger curvature anomaly, and evaluate its potential as a marker of the causes of cognitive aging.Methods: Participants were members of the Lothian Birth Cohort 1921 (LBC 1921). Intelligence was

David Hope; Timothy Bates; Alan J. Gow; John M. Starr; Ian J. Deary

2012-01-01

414

Anomaly Resolution in the International Space Station  

NASA Technical Reports Server (NTRS)

Topics include post flight 2A status, groundrules, anomaly resolution, Early Communications Subsystem anomaly and resolution, Logistics and Maintenance plan, case for obscuration, case for electrical short, and manual fault isolation, and post mission analysis. Photographs from flight 2A.1 are used to illustrate anomalies.

Evans, William A.

2000-01-01

415

Limb Body Wall Complex: A Rare Anomaly  

PubMed Central

We present autopsy findings of a case of limb body wall complex (LBWC). The fetus had encephalocele, genitourinary agenesis, skeletal anomalies and body wall defects. The rare finding in our case is the occurrence of both cranial and urogenital anomalies. The presence of complex anomalies in this fetus, supports embryonal dysplasia theory of pathogenesis for LBWC. PMID:24014975

Chikkannaiah, Panduranga; Dhumale, Hema; Kangle, Ranjit; Shekar, Rosini

2013-01-01

416

Diagnosing network-wide traffic anomalies  

Microsoft Academic Search

Anomalies are unusual and significant changes in a network's traffic levels, which can often span multiple links. Diagnosing anomalies is critical for both network operators and end users. It is a difficult problem because one must extract and interpret anomalous patterns from large amounts of high-dimensional, noisy data.In this paper we propose a general method to diagnose anomalies. This method

Anukool Lakhina; Mark Crovella; Christophe Diot

2004-01-01

417

Safeguarding SCADA Systems with Anomaly Detection  

Microsoft Academic Search

This paper will show how the accuracy and security of SCADA systems can be improved by using anomaly detection to identify bad values caused by attacks and faults. The performance of invariant induction and n- gram anomaly-detectors will be compared and this paper will also outline plans for taking this work further by integrating the output from several anomaly- detecting

John Bigham; David Gamez; Ning Lu

2003-01-01

418

Progress update on IUPAC Project 2009-046-2-200: Terminology and definition of quantities related to the isotope distribution in elements with more than two stable isotopes  

NASA Astrophysics Data System (ADS)

The objective of IUPAC Project 2009-046-2-200 (http://www.iupac.org/web/ins/2009-046-2-200) is to define terminology and to identify the most suitable definitions of quantities that characterise the isotope distribution in elements with more than two stable isotopes, including so-called mass-independent fractionation, non-mass dependent fractionation, isotope anomaly, 17O excess, etc. Most atmospheric oxygen-bearing species show deviations in their triple oxygen isotope ratios from mass-dependent fractionation (MDF) relationships predicted by the theories of Urey, Bigeleisen and Mayer. Similar deviations have also been found in sulphur and other elements with more than two stables isotopes (e.g. Hg, Cd, Zn), often preserved in non-atmospheric reservoirs, including rocks, minerals, soils, ice and waters. Despite the ubiquity of this type of isotope anomaly, there has never been an attempt to clearly define the terminology and physical quantities used to measure these anomalies and the processes that lead to their formation. Terms like mass-independent fractionation, non-mass dependent fractionation, isotope anomaly, isotope excess etc. have been used in the historic and recent literature, but are often not carefully distinguished. The realisation that MDF comprises a range of possible relationships between the isotopes of one element led to further complications because it meant that apparent isotope anomalies could be created by a combination of different MDF processes. At the moment, at least four different definitions to quantify isotope anomalies are being used. Furthermore, coefficients used in these definitions vary, which makes the comparison of data from different sources very difficult, even for experts. A consistent set of recommendations on how to express and quantify the isotope distribution in elements with more than two stable isotopes is highly warranted. From our experience as academic teachers, we are woefully aware how impenetrable the field is for young researchers at the moment because of the lack of consistency and the lack of understanding between different groups. This project seeks to alleviate this.

Kaiser, Jan; Angert, Alon; Bergquist, Bridget; Brand, Willi; Ono, Shuhei; Rckmann, Thomas; Savarino, Jol

2014-05-01

419

Development and Congenital Anomalies of the Pancreas  

PubMed Central

Understanding how the pancreas develops is essential to understand the pathogenesis of congenital pancreatic anomalies. Recent studies have shown the advantages of investigating the development of frogs, mice, and chickens for understanding early embryonic development of the pancreas and congenital anomalies, such as choledochal cysts, anomalous pancreaticobiliary junction, annular pancreas, and pancreas divisum. These anomalies arise from failure of complete rotation and fusion during embryogenesis. There are many theories in the etiology of congenital anomalies of the pancreas. We review pancreas development in humans and other vertebrates. In addition, we attempt to clarify how developmental failure is related to congenital pancreatic anomalies. PMID:22567291

Tadokoro, Hiroyuki; Takase, Masaru; Nobukawa, Bunsei

2011-01-01

420

The origin of the 'FUN' anomalies and the high temperature inclusions in the Allende meteorite. [Fractionation and Unknown Nuclear processes  

NASA Technical Reports Server (NTRS)

The discovery of isotopic anomalies in white inclusions of the meteorite Allende has led to fundamental questions concerning the origin of these anomalies and of the white inclusions themselves. An analysis of the 'FUN' anomalies in the inclusions C1 and EK1-4-1 demonstrates that these isotopic anomalies may be decomposed into individual nucleosynthetic components, which have been subjected to separate mass and component fractionations. There is no evidence that any freshly-synthesized material injected into the primitive solar nebula was of abnormal isotopic composition, or that the FUN anomalies were due to an injection of unusual material. Rather, they show the effects of large mass fractionations and an unusual mixture of normal nucleosynthetic material, likely to be in the form of interstellar grains whose size or chemistry served as a memory for the nucleosynthetic origins of their constituent atoms. Giant gaseous protoplanets, as described for the early solar nebula by Cameron (1978), are a potential site for achieving both mass and component fractionations, and for producing white inclusions in general.

Consolmagno, G. J.; Cameron, A. G. W.

1980-01-01

421

Anomalies and Discrete Chiral Symmetries  

SciTech Connect

The quantum anomaly that breaks the U(1) axial symmetry of massless multi-flavored QCD leaves behind a discrete flavor-singlet chiral invariance. With massive quarks, this residual symmetry has a close connection with the strong CP-violating parameter theta. One result is that if the lightest quarks are degenerate, then a first order transition will occur when theta passes through pi. The resulting framework helps clarify when the rooting prescription for extrapolating in the number of flavors is valid.

Creutz, M.

2009-09-07

422

Monitoring Smartphones for Anomaly Detection  

Microsoft Academic Search

In this paper we demonstrate how to monitor a smartphone running Symbian operating system and Windows Mobile in order to extract\\u000a features for anomaly detection. These features are sent to a remote server because running a complex intrusion detection system\\u000a on this kind of mobile device still is not feasible due to capability and hardware limitations. We give examples on

Aubrey-derrick Schmidt; Frank Peters; Florian Lamour; Christian Scheel; Seyit Ahmet amtepe; Sahin Albayrak

2009-01-01

423

Columbus Payloads Flow Rate Anomalies  

NASA Technical Reports Server (NTRS)

The Columbus Active Thermal Control System (ATCS) is the main thermal bus for the pressurized racks working inside the European laboratory. One of the ATCS goals is to provide proper water flow rate to each payload (P/L) by controlling actively the pressure drop across the common plenum distribution piping. Overall flow measurement performed by the Water Pump Assembly (WPA) is the only flow rate monitor available at system level and is not part of the feedback control system. At rack activation the flow rate provided by the system is derived on ground by computing the WPA flow increase. With this approach, several anomalies were raised during these 3 years on-orbit, with the indication of low flow rate conditions on the European racks FSL, BioLab, EDR and EPM. This paper reviews the system and P/Ls calibration approach, the anomalies occurred, the engineering evaluation on the measurement approach and the accuracy improvements proposed, the on-orbit test under evaluation with NASA and finally discusses possible short and long term solutions in case of anomaly confirmation.

Quaranta, Albino; Bufano, Gaetana; DePalo, Savino; Holt, James M.; Szigetvari, Zoltan; Palumberi, Sergio; Hinderer, S.

2011-01-01

424

Satellite GN and C Anomaly Trends  

NASA Technical Reports Server (NTRS)

On-orbit anomaly records for satellites launched from 1990 through 2001 are reviewed to determine recent trends of un-manned space mission critical failures. Anomalies categorized by subsystems show that Guidance, Navigation and Control (GN&C) subsystems have a high number of anomalies that result in a mission critical failure when compared to other subsystems. A mission critical failure is defined as a premature loss of a satellite or loss of its ability to perform its primary mission during its design life. The majority of anomalies are shown to occur early in the mission, usually within one year from launch. GN&C anomalies are categorized by cause and equipment type involved. A statistical analysis of the data is presented for all anomalies compared with the GN&C anomalies for various mission types, orbits and time periods. Conclusions and recommendations are presented for improving mission success and reliability.

Robertson, Brent; Stoneking, Eric

2003-01-01

425

Pristine extraterrestrial material with unprecedented nitrogen isotopic variation  

PubMed Central

Pristine meteoritic materials carry light element isotopic fractionations that constrain physiochemical conditions during solar system formation. Here we report the discovery of a unique xenolith in the metal-rich chondrite Isheyevo. Its fine-grained, highly pristine mineralogy has similarity with interplanetary dust particles (IDPs), but the volume of the xenolith is more than 30,000 times that of a typical IDP. Furthermore, an extreme continuum of N isotopic variation is present in this xenolith: from very light N isotopic composition (?15NAIR = ?310 20), similar to that inferred for the solar nebula, to the heaviest ratios measured in any solar system material (?15NAIR = 4,900 300). At the same time, its hydrogen and carbon isotopic compositions exhibit very little variation. This object poses serious challenges for existing models for the origin of light element isotopic anomalies. PMID:19528640

Briani, Giacomo; Gounelle, Matthieu; Marrocchi, Yves; Mostefaoui, Smail; Leroux, Hugues; Quirico, Eric; Meibom, Anders

2009-01-01

426

The Emergence of a Coherent Explanation for Anomalies Observed in D/Pd and H/Pd Systems  

NASA Astrophysics Data System (ADS)

Numerous observations have been made of apparent anomalies in carefully performed experimental studies of D/Pd and H/Pd systems. Such anomalies include: prompt emission of electrons and charged particles; unexplained heat in excess of known input sources; the residual presence of light elements (notably tritium, helium-3 and helium-4); the possible occurrence of isotope anomalies in higher mass elements (including the host metal); unusual conductance effects both stable and transient. The features which unify these apparently disparate observations are the common elements of the needed experimental stimuli, and the requirement for extended lattice coherent processes in any obvious explanation. An attempt will be made in this paper to compare and characterize the results of a range of experiments performed at SRI in terms of these two principals: the commonality of conditions and stimulus; the reasonable requirement for and expectation of coherent processes involving electrons and lattice trapped hydrogen isotopic entities.

McKubre, Michael C. H.; Tanzella, Francis L.; Tripodi, Paolo; Hagelstein, Peter

2000-03-01

427

1. Isotope Definitions and terms a) Isotopes and isotope ratios.  

E-print Network

discrimination in C3 plants b) C3 vs C4 photosynthesis and the distinction in isotopes c) Measuring isotopic and fixation at night Why C4 plants? Problems with C3 photosynthesis Increase in photorespiration - in hot dry fractionation c) Simple illustration with the water cycle 2. CO2 isotopes in photosynthesis a) Photosynthetic

Saleska, Scott

428

Effect of Grain Boundaries on Krypton Segregation Behavior in Irradiated Uranium Dioxide  

NASA Astrophysics Data System (ADS)

Fission products, such as krypton (Kr), are known to be insoluble within UO2, segregating toward grain boundaries and eventually leading to a lowering in thermal conductivity and fuel swelling. Recent computational studies have identified that differences in grain boundary structure have a significant effect on the segregation behavior of fission products. However, experimental work supporting these simulations is lacking. Atom probe tomography was used to measure the Kr distribution across grain boundaries in UO2. Polycrystalline depleted UO2 samples were irradiated with 0.7 MeV and 1.8 MeV Kr-ions and annealed to 1000C, 1300C, and 1600C for 1 h to produce a Kr-bubble dominated microstructure. The results of this work indicate a strong dependence of Kr concentration as a function of grain boundary structure. Temperature also influences grain boundary chemistry with greater Kr concentration evident at higher temperatures, resulting in a reduced Kr concentration in the bulk. Although Kr segregation takes place at elevated temperatures, no change in grain size or texture was observed in the irradiated UO2 samples.

Valderrama, Billy; He, Lingfeng; Henderson, Hunter B.; Pakarinen, Janne; Jaques, Brian; Gan, Jian; Butt, Darryl P.; Allen, Todd R.; Manuel, Michele V.

2014-12-01

429

Space Telescope Imaging Spectrograph Observations of Interstellar Oxygen and Krypton in Translucent Clouds  

NASA Astrophysics Data System (ADS)

We have obtained high-resolution Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) observations of O I ?1356 and Kr I ?1236 absorption in 11 sight lines characterized by high extinction, large H I column densities, and/or long path lengths. Previous Goddard High Resolution Spectrograph (GHRS) measurements of these weak features in seven relatively nearby diffuse clouds have shown no evidence for density-dependent depletion of either oxygen or krypton and have yielded a weighted mean gas-phase abundance ratio of log[N(O)/N(Kr)]GHRS=5.56+/-0.04. Our STIS measurements yield a lower weighted mean of log[N(O)/N(Kr)]STIS=5.48 the difference is due primarily to several translucent sight lines in the STIS data set that diverge from the GHRS value. These translucent cloud sight lines pass near dense, star-forming regions, notably the ? Oph, Orion, and Taurus molecular clouds. Since Kr, as a noble gas, should not be depleted much into grains, these cases suggest a trend toward the enhanced oxygen depletion predicted for denser ISM clouds. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555.

Cartledge, Stefan I. B.; Meyer, David M.; Lauroesch, J. T.; Sofia, U. J.

2001-11-01

430

Effect of Grain Boundaries on Krypton Segregation Behavior in Irradiated Uranium Dioxide  

SciTech Connect

Fission products, such as krypton (Kr), are known to be insoluble within UO2, segregating towards grain boundaries, eventually leading to a lowering of the thermal conductivity and fuel swelling. Recent computational studies have identified that differences in grain boundary structure have a significant effect on the segregation behavior of fission products. However, experimental work supporting these simulations is lacking. Atom probe tomography was used to measure the Kr distribution across grain boundaries in UO2. Polycrystalline depleted-UO2 samples was irradiated with 0.7 and 1.8 MeV Kr-ions and annealed to 1000, 1300, and 1600C for 1 hour to produce a Kr-bubble dominated microstructure. The results of this work indicate a strong dependence of Kr concentration as a function of grain boundary structure. Temperature also influences grain boundary chemistry with greater Kr concentration evident at higher temperatures, resulting in a reduced Kr concentration in the bulk. While Kr migration is active at elevated temperatures, no changes in grain size or texture were observed in the irradiated samples.

Billy Valderrama; Lingfeng He; Hunter B. Henderson; Janne Pakarinen; Brian Jaques; Jian Gan; Darryl P. Butt; Todd R. Allen; Michele V. Manuel

2015-01-01

431

Velocity selective bipolarization spectroscopy for laser cooling of metastable krypton atoms  

NASA Astrophysics Data System (ADS)

We report a velocity selective bi-polarization spectroscopy (VS-BPS) technique to generate a background-free, dispersion-like reference signal which is tunable over a wide range of frequency. In this technique, a pair of linearly polarized weak probe beams passing through a gas cell of metastable Krypton (Kr*) atoms, overlaps with a pair of counter-propagating circularly polarized strong pump beams derived from an independently tunable control laser. The polarization spectroscopy signals from the two probe beams, after subtraction, result in VS-BPS signal. The spectral shifting in VS-BPS signal can be achieved by tuning the frequency of the control laser. The dependence of the amplitude and slope of the VS-BPS signal on the RF power used for excitation of Kr atoms in the gas cell and on the power of pump beams has been studied. The frequency stability of a diode laser locked with VS-BPS signal has been found to be better than the frequency stability of the laser locked with a saturated absorption spectroscopy (SAS) signal. The VS-BPS signal is finally used for stabilization and tuning of the cooling laser frequency for a magneto-optical trap (MOT) for Kr* atoms.

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

2014-11-01

432

Interstellar Krypton Abundances: The Detection of Kiloparsec-scale Differences in Galactic Nucleosynthetic History  

E-print Network

We present an analysis of Kr I 1236 line measurements from 50 sight lines in the Hubble Space Telescope Space Telescope Imaging Spectrograph and Goddard High Resolution Spectrograph data archives that have sufficiently high resolution and signal-to-noise ratio to permit reliable krypton-to-hydrogen abundance ratio determinations. The distribution of Kr/H ratios in this sample is consistent with a single value for the ISM within 5900 pc of the Sun, log(Kr/H) = -9.02+/-0.02, apart from a rough annulus from between about 600 and 2500 pc distant. The Kr/H ratio toward stars within this annulus is elevated by approximately 0.11 dex, similar to previously noted elevations of O/H and Cu/H gas-phase abundances beyond about 800 pc. A significant drop in the gas-phase N/O ratio in the same region suggests that this is an artifact of nucleosynthetic history. Since the physical scale of the annulus' inner edge is comparable to the radius of the Gould Belt and the outer limit of heliocentric distances where the D/H abundance ratio is highly variable, these phenomena may be related to the Gould Belt's origins.

Stefan I. B. Cartledge; J. T. Lauroesch; David M. Meyer; U. J. Sofia; Geoffrey C. Clayton

2008-08-06

433

Multielectron coincidence study of the double Auger decay of 3d-ionized krypton  

SciTech Connect

Multielectron coincidence data for triple ionization of krypton have been recorded above the 3d ionization threshold at two photon energies (140 and 150 eV). Three principal transition pathways have been observed, two involving double Auger transitions from Kr{sup +}, and one involving single Auger transitions from Kr{sup 2+} created by direct single-photon double ionization. The decay of the 3d{sup 9} {sup 2}D{sub 5/2,3/2} states in Kr{sup +} has been analyzed in some detail and is found to be strongly dominated by cascade processes where two electrons with well-defined energies are emitted. The decay paths leading to the 4s{sup 2}4p{sup 3} {sup 4}S, {sup 2}D, and {sup 2}P states of Kr{sup 3+} are analyzed and energies of seven intermediate states in Kr{sup 2+} are given. A preliminary investigation of the decay paths from Kr{sup +} 3d{sup 9}4p{sup 5}nl shake-up states has also been carried out.

Andersson, E.; Hedin, L.; Rubensson, J.-E.; Karlsson, L.; Feifel, R. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Fritzsche, S. [Department of Physics, P.O. Box 3000, Fin-90014 University of Oulu (Finland); GSI Helmholtzzentrum fuer Schwerionenforschung, D-64291 Darmstadt (Germany); Linusson, P. [Department of Physics, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm (Sweden); Eland, J. H. D. [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ (United Kingdom)

2010-10-15

434

Effects of copper nanoparticle inclusions on pressure-induced fluid-polynanocrystalline structural transitions in krypton  

NASA Astrophysics Data System (ADS)

The dependence of nanoscale crystal formation from a noble element fluid on the rate of hydrodynamic compression was explored using molecular dynamics. Results were obtained for pure krypton samples as well as ones containing a cubic- or spherical-shaped fcc copper nanocrystal inclusion for compression rates of 1, 10, and 20 MPa/ps. In the absence of Cu, Kr crystals nucleate with apparently random locations and orientations in the sample; slower compression leads to larger nanocrystal size. The effect of the Cu inclusion is to partially mediate the location, orientation, and size of the formed crystals. The effect is larger for the slower compression rate and when the inclusion is cubic rather than spherical in shape. For sufficiently slow compression, the stress state in the cubic Cu inclusion changes from hydrostatic to non-hydrostatic as a consequence of the formation of extended orthotropic hcp/fcc nanostructures in the Kr. The mechanism of the dynamic stress-induced nanostructural transition is explained qualitatively in terms of known geometric effects on the quasi-static indentation response of crystalline materials.

Chen, Zhen; Jiang, Shan; Sewell, Thomas D.; Gan, Yong; Oloriegbe, Suleiman Y.; Thompson, Donald L.

2014-12-01

435

Velocity selective bi-polarization spectroscopy for laser cooling of metastable Krypton atoms  

E-print Network

We report a velocity selective bi-polarization spectroscopy (VS-BPS) technique to generate a background-free, dispersion-like reference signal which is tunable over a wide range of frequency. In this technique, a pair of linearly polarized weak probe beams passing through a gas cell of metastable Krypton (Kr*) atoms, overlaps with a pair of counter-propagating circularly polarized strong pump beams derived from an independently tunable control laser. The polarization spectroscopy signals from the two probe beams, after subtraction, result in VS-BPS signal. The spectral shifting in VS-BPS signal can be achieved by tuning the frequency of the control laser. The dependence of the amplitude and slope of the VS-BPS signal on the RF power used for excitation of Kr atoms in the gas cell and on the power of pump beams has been studied. The frequency stability of a diode laser locked with VS-BPS signal has been found to be better than the frequency stability of the laser locked with a saturated absorption spectroscopy...

Kale, Y B; Singh, S; Mishra, S R; Rawat, H S

2014-01-01

436

Pulsed power considerations for electron beam pumped krypton fluoride lasers for inertial confinement fusion applications  

SciTech Connect

The Los Alamos National Laboratory inertial confinement fusion (ICF) program is developing the krypton-fluoride excimer laser for use as an ICF driver. The KrF laser has a number of inherent characteristics that make it a promising driver candidate, such as short wavelength (0.25 {mu}m), broad bandwidth to target (>100 cm{sup {minus}1}), pulse-shaping with high dynamic range, and the potential for high overall efficiency (>5%) and repetitive operation. The large KrF laser amplifiers needed for ICF drivers are electron-beam pumped. A key issue for all laser ICF drivers is cost, and a leading cost component of a KrF laser driver is associated with the pulsed power and electron diode. Therefore, the efficient generation of electron beams is a high priority. The Los Alamos ICF program is investigating pulsed-power and diode designs and technologies to further the development of affordable KrF laser ICF drivers. 12 refs., 8 figs.

Rose, E.A.; McDonald, T.E.; Rosocha, L.A.; Harris, D.B.; Sullivan, J.A. (Los Alamos National Lab., NM (USA)); Smith, I.D. (Pulse Sciences, Inc., San Leandro, CA (USA))

1991-01-01

437

Multilayer adsorption of xenon, krypton, and argon on graphite: An ellipsometric study  

NASA Astrophysics Data System (ADS)

We present ellipsometric measurements of multilayer adsorption of xenon, krypton, and argon on highly oriented pyrolytic graphite along numerous isotherms spanning the coverage range from completion of the first layer to about twelve layers and the temperature range from below the melting of the top layer to above the bulk adsorbate melting point Tm. The three adsorbates have very similar phase diagrams, and all show reentrant first-order layering. The top layer of three-layer and thicker films disorders at 0.81Tm-0.83Tm. For films thicker than three layers, first-order layer condensation reappears at shifted coverages and chemical potentials in the range 0.83Tm-0.87Tm to 0.92Tm-0.94Tm. The solid adsorbate films reach a limiting thickness of about 12 layers at saturation, but the limiting thickness increases rapidly just below Tm and reaches the equivalent of about 24 layers in the liquid region. We discuss implications of these results for roughening and melting of the adsorbate (111) surfaces. Chemical potentials for layer condensation are compared to a simple Frankel-Halsey-Hill theory.

Youn, H. S.; Meng, X. F.; Hess, G. B.

1993-11-01

438

The nature and role of the gold-krypton interactions in small neutral gold clusters.  

PubMed

We investigate the nature and role of krypton embedding in small neutral gold clusters. For some of these clusters, we observe a particular site-dependent character of the Kr binding that does not completely follow the criterion of binding at low-coordinated sites, widely accepted for interaction of a noble gas with closed-shell metal systems such as metal surfaces. We aim at understanding the effect of low dimensionality and open-shell electronic structure of the odd-numbered clusters on the noble gas-metal cluster interaction. First, we investigate the role of attractive and repulsive forces, and the frontier molecular orbitals. Second, we investigate the Au-Kr interaction in terms of reactivity and bonding character. We use a reactivity index derived from Fukui formalism, and criteria provided by the electron localization function (ELF), in order to classify the type of bonding. We carry out this study on the minimum energy structures of neutral gold clusters, as obtained using pseudo potential plane-wave density functional theory (DFT). A model is proposed that includes the effect of attractive electrostatic, van der Waals and repulsive forces, together with effects originating from orbital overlap. This satisfactorily explains minimum configurations of the noble gas-gold cluster systems, the site preference of the noble gas atoms, and changes in electronic properties. PMID:25742369

Mancera, Luis A; Benoit, David M

2015-03-26

439

Status of the Level 0 Trigger Processor of the NA62 Liquid Krypton Electromagnetic Calorimeter  

NASA Astrophysics Data System (ADS)

The NA62 experiment at the CERN SPS aims to measure the Branching Ratio of the ultra-rare decay K^+ rightarrow ?^+?bar?, collecting about 100 events in two years of data taking with a signal to background ratio of 10:1. A hermetic photon veto system has been designed to efficiently reject the ?0 background, one of the main background sources, and the 20-ton liquid krypton calorimeter is a fundamental component of such system in the angular acceptance region 1-10 mrad. In this paper, we present the design of the Level 0 trigger processor that is able to identify electromagnetic clusters in the calorimeter providing information on time, position and energy reconstruction for each cluster. In particular, it is composed of 36 readout boards (TEL62), organized in a three layer parallel system, 108 mezzanines and 215 high-performance FPGAs. The system has been designed to sustain an instantaneous hit rate of 40 MHz, to process data with a latency of about 100 ?s, and to achieve a time resolution of 1.5 ns on the single cluster. Performance and functionality test results of a trigger slice, together with an updated status report of the whole level 0 trigger project, will be presented.

Bonaiuto, V.; de Simone, N.; Federici, L.; Sargeni, F.; Badoni, D.; Fucci, A.; Paoluzzi, G.; Salamon, A.; Salina, G.; Santovetti, E.; Checcucci, B.; Papi, A.; Piccini, M.; Bizzarri, M.; Venditti, S.

2014-06-01

440

Comparison between radioactive aerosol, technegas and krypton for ventilation imaging in healthy calves.  

PubMed

The use of lung scintigraphy in calves necessitates the validation of a ventilation (V) imaging agent compatible with clinical applications. This study aimed at defining the value of an inhaled radioactive aerosol (99mTc-DTPA) and a 'pseudogas' (Technegas) in the assessment of regional V in healthy conscious calves by comparing 99mTc-DTPA and Technegas deposition (D) images to V(V) images obtained from the steady-state inhalation of the short half-life krypton 81 (81mKr) gas. Images were compared by analysis of radioactivity distribution in computer-generated regions of interest within the right lung and D to V ratio images were generated in order to highlight areas of mismatching between 99mTc-DTPA or Technegas and 81mKr distributions. Results of this analysis showed that the 99mTc-DTPA aerosol droplets were unable to reach the lung parenchyma because of significant particle impaction in the major conducting airways. Better definition of the ventilated lung was obtained when using Technegas because of minimal deposition in conducting airways. Furthermore, the Technegas and 81mKr distribution patterns were highly equivalent. PMID:10950132

Coghe, J; Votion, D; Lekeux, P

2000-07-01

441

[Right ventricular function assessed by scintigraphy using continuous infusion of krypton-81 m].  

PubMed

Scintigraphy using continuous infusion of krypton-81m, (81mKr) is a reproducible, noninvasive method for determining right ventricular ejection fraction (RVEF). Radionuclide determinations of RVEF by 81mKr scintigraphy were compared with those by the technetium-99m (99mTc) first-pass technique in 25 patients; the results obtained by both methods correlated well (r = 0.86, p less than 0.005). In 20 additional patients, the RVEF determined by 81mKr was compared with the RVEF as measured by multislice ECG-gated cardiac X-ray computed tomography, and there was good correlation between RVEFs obtained by the two methods (r = 0.76, p less than 0.005). Furthermore, the RVEF by the 81mKr technique and the LVEF by the 99mTc gated blood pool technique were compared with hemodynamic measurements. There was a significant inverse correlation between RVEF and pulmonary artery pressure or total pulmonary resistance. Other determinants of right ventricular systolic function were the presence of proximal right coronary artery disease, reduced left ventricular function and associated tricuspid regurgitation. PMID:3722880

Miyamoto, A; Sakuma, I; Kanamori, K; Kobayashi, T; Yasuda, H

1986-01-01

442

Space Weather, Cosmic Rays, and Satellite Anomalies  

NASA Astrophysics Data System (ADS)

Results are presented of the Satellite Anomaly Project, which aims to improve the methods of safeguarding satellites in the Earths magnetosphere from the negative effects of the space environment. Anomaly data from the USSR and Russian Kosmos series satellites in the period 1971-1999 are combined into one database, together with similar information on other spacecraft. This database contains, beyond the anomaly information, various characteristics of space weather: geomagnetic activity indices (Ap, AE and Dst), fluxes and fluencies of electrons and protons at different energies, high energy cosmic ray variations and other solar, interplanetary and solar wind data. A comparative analysis of the distribution of each of these parameters relative to satellite anomalies was carried out for the total number of anomalies (about 6000 events), and separately for high altitude orbit satellites ( 5000 events) and low altitude (about 800 events). No relation was found between low and high altitude satellite anomalies. Daily numbers of satellite anomalies, averaged by a superposed epoch method around sudden storm commencements and proton event onsets for high (>1500 km) and low (<1500 km) altitude orbits revealed a big difference in behavior. Satellites were divided into several groups according to their orbital characteristics (altitude and inclination). The relation of satellite anomalies to the environmental parameters was found to be different for various orbits, and this should be taken into account when developing anomaly frequency models. The preliminary anomaly frequency models are presented.

Lev, Dorman

443

Developing a new, passive diffusion sampler suite to detect helium anomalies associated with volcanic unrest  

NASA Astrophysics Data System (ADS)

Helium (He) concentration and 3He/4He anomalies in soil gas and spring water are potentially powerful tools for investigating hydrothermal circulation associated with volcanism and could perhaps serve as part of a hazards warning system. However, in operational practice, He and other gases are often sampled only after volcanic unrest is detected by other means. A new passive diffusion sampler suite, intended to be collected after the onset of unrest, has been developed and tested as a relatively low-cost method of determining He-isotope composition pre- and post-unrest. The samplers, each with a distinct equilibration time, passively record He concentration and isotope ratio in springs and soil gas. Once collected and analyzed, the He concentrations in the samplers are used to deconvolve the time history of the He concentration and the 3He/4He ratio at the collection site. The current suite consisting of three samplers is sufficient to deconvolve both the magnitude and the timing of a step change in in situ concentration if the suite is collected within 100 h of the change. The effects of temperature and prolonged deployment on the suite's capability of recording He anomalies have also been evaluated. The suite has captured a significant 3He/4He soil gas anomaly at Horseshoe Lake near Mammoth Lakes, California. The passive diffusion sampler suite appears to be an accurate and affordable alternative for determining He anomalies associated with volcanic unrest.

Dame, Brittany E.; Solomon, D. Kip; Evans, William C.; Ingebritsen, Steven E.

2015-03-01

444

Isotope Shifts  

NASA Astrophysics Data System (ADS)

A three parameter formula (3P) for isotope shifts r^2(n)= n C +n)n-1)/2A+[n/2]B is related to he staggering parameter G= 2 [r^2(n+1)-r^2(n)]/[r^(n+2)-r^2(n)] If A+B=0 then G=1 (no staggering). If A=0 there is no n dependence to the staggering.One can get G to almost be plus or minus infinity for certain n,but this does not necessarily mean that there are major changes in the nuclear structure. We consider Potassium and Argon isotopes. We also consider quadrupole and monopole core polarization with a delta interaction. We vary the oscillator length parameter of the valence particle but keep the core values fixed. We find for both modes the amount of core polarization decreases as we increase the radius of the valence particle relative to that of the core (for small deviations from the case where the core and valence length parameters are the same).

Zamick, Larry

2010-11-01

445

Anomaly detection for internet surveillance  

NASA Astrophysics Data System (ADS)

Many threats in the real world can be related to activity of persons on the internet. Internet surveillance aims to predict and prevent attacks and to assist in finding suspects based on information from the web. However, the amount of data on the internet rapidly increases and it is time consuming to monitor many websites. In this paper, we present a novel method to automatically monitor trends and find anomalies on the internet. The system was tested on Twitter data. The results showed that it can successfully recognize abnormal changes in activity or emotion.

Bouma, Henri; Raaijmakers, Stephan; Halma, Arvid; Wedemeijer, Harry

2012-06-01

446

Hot Flow Anomalies at Venus  

NASA Technical Reports Server (NTRS)

We present a multi-instrument study of a hot flow anomaly (HFA) observed by the Venus Express spacecraft in the Venusian foreshock, on 22 March 2008, incorporating both Venus Express Magnetometer and Analyzer of Space Plasmas and Energetic Atoms (ASPERA) plasma observations. Centered on an interplanetary magnetic field discontinuity with inward convective motional electric fields on both sides, with a decreased core field strength, ion observations consistent with a flow deflection, and bounded by compressive heated edges, the properties of this event are consistent with those of HFAs observed at other planets within the solar system.

Collinson, G. A.; Sibeck, David Gary; Boardsen, Scott A.; Moore, Tom; Barabash, S.; Masters, A.; Shane, N.; Slavin, J.A.; Coates, A.J.; Zhang, T. L.; Sarantos, M.

2012-01-01

447

Congenital anomalies of the breast.  

PubMed

Poland syndrome is a combination of chest wall deformity and absent or hypoplastic pectoralis muscle and breast associated with shortening and brachysyndactyly of the upper limb. Clinical presentation varies widely; therefore, reconstructive procedures have to be adapted to the deformity, ranging from chest wall stabilization or augmentation, dynamic muscle transfer, nipple and areola repositioning, and breast augmentation using prosthesis or autologous tissue transfer. Other congenital breast anomalies include supernumerary nipple and areola (polythelia) and breast (polymastia), which can generally be found on the embryonic mammary ridge. Absence of the nipple, areola (athelia), or the breast tissue (amastia) is less frequent. PMID:24872738

Caouette-Laberge, Louise; Borsuk, Daniel

2013-02-01

448

Congenital Anomalies of the Breast  

PubMed Central

Poland syndrome is a combination of chest wall deformity and absent or hypoplastic pectoralis muscle and breast associated with shortening and brachysyndactyly of the upper limb. Clinical presentation varies widely; therefore, reconstructive procedures have to be adapted to the deformity, ranging from chest wall stabilization or augmentation, dynamic muscle transfer, nipple and areola repositioning, and breast augmentation using prosthesis or autologous tissue transfer. Other congenital breast anomalies include supernumerary nipple and areola (polythelia) and breast (polymastia), which can generally be found on the embryonic mammary ridge. Absence of the nipple, areola (athelia), or the breast tissue (amastia) is less frequent. PMID:24872738

Caouette-Laberge, Louise; Borsuk, Daniel

2013-01-01

449

Sea level anomalies exacerbate beach erosion  

NASA Astrophysics Data System (ADS)

Sea level anomalies are intra-seasonal increases in water level forced by meteorological and oceanographic processes unrelated to storms. The effects of sea level anomalies on beach morphology are unknown but important to constrain because these events have been recognized over large stretches of continental margins. Here, we present beach erosion measurements along Onslow Beach, a barrier island on the U.S. East Coast, in response to a year with frequent sea level anomalies and no major storms. The anomalies enabled extensive erosion, which was similar and in most places greater than the erosion that occurred during a year with a hurricane. These results highlight the importance of sea level anomalies in facilitating coastal erosion and advocate for their inclusion in beach-erosion models and management plans. Sea level anomalies amplify the erosive effects of accelerated sea level rise and changes in storminess associated with global climate change.

Theuerkauf, Ethan J.; Rodriguez, Antonio B.; Fegley, Stephen R.; Luettich, Richard A.

2014-07-01

450

Triple oxygen isotope variations in sedimentary rocks  

NASA Astrophysics Data System (ADS)

Relatively large (?0.2) 17O anomalies in the geologic record have been used to recognize atmospheric processes such as photochemical reactions and to trace changes in the partial pressures of O2 and CO2 in Earths atmosphere through time. However, recent oxygen isotope measurements of terrestrial rocks, minerals and waters also reveal common, smaller (but statistically significant) deviations from a single mass-dependent fractionation line. These subtle anomalies have been explained through differences in mass-dependent isotopic fractionations for various equilibrium and kinetic mechanisms. Here we present triple oxygen isotope data on sedimentary silica and oxides, including Archean and Phanerozoic cherts, and iron formations. The distribution of data reflects the mass fractionation laws of low-temperature precipitation reactions during growth of authigenic minerals, variation in ?17O of the waters from which sedimentary minerals precipitate, and equilibrium exchange after initial authigenic formation. We use these results to illustrate the potential for small, mass-dependent variations in ?17O values of sedimentary rocks to provide constraints on the environmental and climatic conditions in which they formed.

Levin, Naomi E.; Raub, Timothy D.; Dauphas, Nicolas; Eiler, John M.

2014-08-01

451

Congenital hand anomalies: etiology, classification, and treatment.  

PubMed

Congenital hand anomalies have a wide range of presentations and functional consequences. Understanding and treatment of these deformities require an understanding of embryology of upper-extremity development. In this report, common anomalies of the hand and upper extremity have been reviewed according to the International Federation for Societies for Surgery of the Hand classification system. We examine the epidemiology, etiology, functional consequences, and current treatments available for each anomaly. PMID:24406593

Gishen, Kriya; Askari, Morad

2014-01-01

452

The Mars Rover Spirit FLASH anomaly  

NASA Technical Reports Server (NTRS)

The Mars Exploration Rover 'Spirit' suffered a debilitating anomaly that prevented communication with Earth for several anxious days. With the eyes of the world upon us, the anomaly team used each scrap of information, our knowledge of the system, and sheer determination to analyze and fix the problem, then return the vehicle to normal operation. This paper will discuss the Spirit FLASH anomaly, including the drama of the investigation, the root cause and the lessons learned from the experience.

Reeves, Glenn E.; Neilson, Tracy C.

2005-01-01

453

Chiral and gravitational anomalies in any dimension  

SciTech Connect

Gravitational contributions to the chiral anomaly in 4N space-time dimensions as well as the purely gravitational anomaly in 4N-2 dimensions are expressed in terms of the Riemann--Christoffel tensor. Using this formula, we give a simple proof that if N > or = 4 there is no way to cancel the gravitational anomalies using fields of spin- 1/2 , - (3)/(2) , and -1.

Delbourgo, R.; Matsuki, T.

1985-06-01

454

Magnetic anomalies northeast of Shatsky Plateau  

E-print Network

MAGNETIC ANOMALIES NORTHEAST OF SHATSKY PLATEAU A Thesis by DAVID LAWRENCE RISCH Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE May 1982 Major Subject...: Oceanography MAGNETIC ANOMALIES NORTHEAST OF SHATSKY PLATEAU A Thesis by DAVID LAWRENCE RISCH Approved as to style and content by: C rman Committee Member Member Head of Department May 198Z ABSTRACT Magnetic Anomalies Northeast of Shatsky Plateau...

Risch, David Lawrence

1982-01-01

455

Anomaly Intrusion Detection Based on System Call  

Microsoft Academic Search

(Abstract)Monitoring program behavior is one of the highlighted research topics of host-based anomaly detection recently. The key is to construct a program behavior-based anomaly detection model. Some existing anomaly detection techniques based on system call sequences are analyzed and discussed in this paper. They are compared from three dimensions: the information extracted from system call, the system call level used

LI Hongjiao; LI Jianhua; ZHU Hongwen

2007-01-01

456

Red krypton and blue-green argon panretinal laser photocoagulation for proliferative diabetic retinopathy: a laboratory and clinical comparison.  

PubMed Central

The effects of PRP with red krypton laser are essentially identical to those produced with blue-green argon laser. Burns of the rabbit retina produced with these two different lasers are almost the same. In a prospective and randomized clinical trial of proliferative diabetic retinopathy treatment there was no significant difference between PRP using these two different lasers. The characteristic changes of rabbit fundi 3, 7, and 30 days after PRP with red krypton laser were almost the same as those following blue-green argon laser. Both types of treatment frequently produced small vitreous hemorrhages and exudative retinal detachments, but choroidal thickening occurred more frequently with argon treatment. These changes were transient and had resolved within 30 days of treatment. The microscopic changes consisted of pigment epithelial disruption with pigment migration into the retina, heat coagulation of the photoreceptors, disruption of the outer and inner nuclear layers with atrophy of the nuclei, and temporary swelling of the nerve fiber layer. The untreated retina and choroid between burns was not involved and appeared normal at each period. Thirty days after treatment, the scarring produced by these two types of burns was identical. Seventy-one eyes with proliferative diabetic retinopathy having three or four retinopathy risk factors were treated with panretinal laser photocoagulation, and followed in a prospective study for 6 months. Thirty-six eyes were randomly selected for blue-green argon treatment, and 35 were randomly selected for red krypton treatment. The incidence of undesired side effects during the first 2 weeks following treatment was almost identical between the two groups. However, by 1 month the majority of eyes in both groups had visual acuities equal to or better than the pretreatment acuities and complete regression of NVD. Six months after treatment, the majority of eyes in both groups continued to have visual acuities equal to or better than the pretreatment acuities with fewer cases having larger losses of vision in the krypton treated group. Loss of peripheral visual field was equal with the two types of treatment having a minimal decrease with the IV-4e isopter, but substantial loss with the I-4e isopter. Additional vitreous hemorrhage rarely occurred in either group, but was slightly more frequent in those treated with krypton. Complete regression was accomplished in most eyes with pretreatment disc and/or NVE in both groups, but persistence of neovascularization was more frequent in those treated with krypton. Overall, the wavelength used seemingly had little effect on the result.(ABSTRACT TRUNCATED AT 400 WORDS) Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 7 FIGURE 8 FIGURE 9 FIGURE 10 FIGURE 11 FIGURE 12 FIGURE 13 FIGURE 14 FIGURE 15 FIGURE 16 FIGURE 17 PMID:2438841

Blankenship, G W

1986-01-01

457

A New Isotope Effect and Its Possible Role in the Production of Excess Meteoritic 33S and Carbonaceous Material (Q?)  

NASA Astrophysics Data System (ADS)

There are several observations of sulfur isotopic anomalies in meteoritic material. This includes excess ^33S in Allende acid residues, oldhamite from Norton County and bulk ureilites. The source of these observed isotopic anomalies is at present, unresolved. Recently, excess ^33S has been observed in an organic extract from Murchison (methane sulfonic acid). This molecule also possesses deuterium excesses ranging from 660 to 2,730 per mil. Since sulfur, like oxygen, may be subject to symmetry dependent reaction chemistry, investigations exploring isotopic fractionations in astronomically relevant molecules may be of utility.

Thiemens, M. H.; Xu, X.; Colman, J.; Trogler, W. C.

1996-03-01

458

The magnetic anomaly of the Ivreazone  

NASA Technical Reports Server (NTRS)

A magnetic field survey was made in the Ivreazone in 1969/70. The results were: significant anomaly of the vertical intensity is found. It follows the basic main part of the Ivrea-Verbano zone and continues to the south. The width of the anomaly is about 10 km, the maximum measures about +800 gamma. The model interpretation shows that possibly the anomaly belongs to an amphibolitic body, which in connection with the Ivrea-body was found by deep seismic sounding. Therefore, the magnetic anomaly provides further evidence for the conception that the Ivrea-body has to be regarded as a chip of earthmantle material pushed upward by tectonic processes.

Albert, G.

1979-01-01

459

Anomaly-free sets of fermions  

SciTech Connect

We present new techniques for finding anomaly-free sets of fermions. Although the anomaly cancellation conditions typically include cubic equations with integer variables that cannot be solved in general, we prove by construction that any chiral set of fermions can be embedded in a larger set of fermions which is chiral and anomaly-free. Applying these techniques to extensions of the Standard Model, we find anomaly-free models that have arbitrary quark and lepton charges under an additional U(1) gauge group.

Batra, Puneet; /Argonne; Dobrescu, Bogdan A.; /Fermilab; Spivak, David; /UC, Berkeley, Math. Dept.

2005-10-01

460

Anomaly polynomial of general 6D SCFTs  

NASA Astrophysics Data System (ADS)

We describe a method to determine the anomaly polynomials of general 6D mathcal {N}={(2,0)} and mathcal {N}={(1,0)} superconformal field theories (SCFTs), in terms of the anomaly matching on their tensor branches. This method is almost purely field theoretical, and can be applied to all known 6D SCFTs. We demonstrate our method in many concrete examples, including mathcal {N}={(2,0)} theories of arbitrary type and the theories on M5 branes on asymptotically locally Euclidean (ALE) singularities, reproducing the N^3 behavior. We check the results against the anomaly polynomials computed M-theoretically via the anomaly inflow.

Ohmori, Kantaro; Shimizu, Hiroyuki; Tachikawa, Yuji; Yonekura, Kazuya

2014-10-01

461

Large S-33 Anomalies in Late Archean Carbonacous Shales  

NASA Astrophysics Data System (ADS)

Multi-sulfur isotope ratios (34S/33S/32S) were determined on sulfides extracted from two late Archean carbonaceous shale units, the Mt. McRae shale (~2.5 Ga) and the Jeerinah formation (~2.7 Ga), from the Hamersley Basin, Western Australia by using the CO2-laser fluorination line at the Geophisical Laboratory. We have measured the largest ?33S anomaly yet reported for a terrestrial sample on sulfides from 22 m core section of the Mt McRae shale. The large positive ?33S, up to +6.9 , is found in the lower part of the core section; the ?33S shifts to negative upward in the section to as low as -1.9 . The age of the Mt. McRae shale is bracketed by 2470 and 2561 Ma. Therefore, the observed isotopic shift represents the maximum duration of 91 million years, but most likely less than 30 million years by assuming a constant sedimentation rate for the Mt. McRae shale that has average thickness of 60 m in the area. Sulfide sulfur from the Jeerinah formation also yield large ?33S anomalies ranging from -0.1 to +4.4 . Our model fundamentally follows the one proposing a strong atmospheric influence in the Archean sulfur cycle by Farquhar et al. (2000). Our new data show the large and systematic variation between ?33S and ?34S. This allows us to further speculate the isotopic compositions of Archean sulfur reservoirs and the manner in which the atmospheric signature was transferred to sediments. Our data are consistent with the late Archean seawater sulfate reservoir that has a negative ?33S of ~ -2 . Thus, pyrite formed via microbial sulfate reduction shows variable ?34S and negative ?33S. The large positive ?33S of + 6.9 is likely to be a signature of deposition of sulfur aerosol, probably elemental sulfur. Our sulfur isotope data is best explained by mixing of those two components. Atmospheric deposition of elemental sulfur requires an anoxic atmosphere, and subsequent burial and preservation of the signature into pelagic sediments would have been favored in an anoxic and iron-rich ocean in the late Archean Earth.

Ono, S.; Rumble, D.; Pavlov, A.; Kharecha, P.; Kasting, J. F.

2002-12-01

462

Solvation of fluoroform and fluoroform-dimethylether dimer in liquid krypton: a theoretical cryospectroscopic study.  

PubMed

A hybrid, sequential statistical physics-quantum mechanical electronic-quantum mechanical nuclei approach has been applied to study the C-H stretching frequencies of bare fluoroform dissolved in liquid krypton under cryogenic conditions (at ~130 K), as well as upon blue shifting hydrogen bonding interactions with dimethylether in the same solvent. The structure of the liquid at 130 K was generated by Monte Carlo simulations of cryogenic Kr solutions containing either fluoroform or fluoroform and dimethylether molecules. Statistically uncorrelated configurations were appropriately chosen from the equilibrated MC runs and supermolecular clusters containing solute and solvent molecules (either standalone or embedded in the "bulk" part of the solvent treated as a polarizable continuum) were subjected to quantum mechanical electronic (QMel) and subsequent quantum mechanical nuclei (QMnuc) calculations. QMel calculations were implemented to generate the in-liquid 1D intramolecular C-H stretching vibrational potential of the fluoroform moiety and subsequently in the QMnuc phase the corresponding anharmonic C-H stretching frequency was computed by diagonalization techniques. Finally, the constructed vibrational density of states histograms were compared to the experimental Raman bands. The calculated anharmonic vibrational frequency shifts of the fluoroform C-H stretching mode upon interaction with dimethylether in liquid Kr are in very good agreement with the experimental data (20.3 at MP2 level vs. 16.6 cm(-1) experimentally). Most of this relatively large frequency blue shift is governed by configurations characterized by a direct C-HO contact between monomers. The second population detected during MC simulations, characterized by reversed orientation of the monomers, has a minor contribution to the spectral appearance. The experimentally observed trend in the corresponding bandwidths is also correctly reproduced by our theoretical approach. Solvation of the fluoroform monomer, according to experiment, results in small C-H stretching frequency red shift (~-2 cm(-1)), while our approach predicts a blue shift of about 10 cm(-1). By a detailed analysis of the anharmonic C-H stretching frequency dependence on the position of the nearest solvent krypton atom and also by analyzing the vibrational Stark effect induced by the local fluctuating field component parallel to the C-H axis, we have derived several conclusions related to these observations. The frequency vs. CKr distance dependence shows appreciable fluctuations and even changes in sign at R values close to the maximum of the CKr radial distribution function, so that most of the first-shell Kr atoms are located at positions at which the CH frequency shifts acquire either small negative or small positive values. It so happens, therefore, that even the actual sign of the frequency shift is strongly dependent on the correct description of the first solvation shell around CF3H by the Monte Carlo method, much more than the other in-liquid properties calculated by similar approaches. PMID:23927267

Kohls, Emilija; Mishev, Anastas; Pejov, Ljup?o

2013-08-01

463

Total projectile electron loss cross sections of U28 + ions in collisions with gaseous targets ranging from hydrogen to krypton  

NASA Astrophysics Data System (ADS)

Beam lifetimes of stored U28 + ions with kinetic energies of 30 and 50 MeV /u , respectively, were measured in the experimental storage ring of the GSI accelerator facility. By using the internal gas target station of the experimental storage ring, it was possible to obtain total projectile electron loss cross sections for collisions with several gaseous targets ranging from hydrogen to krypton from the beam lifetime data. The resulting experimental cross sections are compared to predictions by two theoretical approaches, namely the CTMC method and a combination of the DEPOSIT code and the RICODE program.

Weber, G.; Herdrich, M. O.; DuBois, R. D.; Hillenbrand, P.-M.; Beyer, H.; Bozyk, L.; Gassner, T.; Grisenti, R. E.; Hagmann, S.; Litvinov, Yu. A.; Nolden, F.; Petridis, N.; Sanjari, M. S.; Winters, D. F. A.; Sthlker, Th.

2015-03-01

464

Laser isotope separation  

Microsoft Academic Search

The present state of the art is reviewed and developments on the horizon are sketched. Major chapter headings are: isotope shift and optical spectrum; present state of the art in laser isotope separation (LIS); future trends in research on laser isotope separation. Isotope shift data on nuclides and molecules of interest are tabulated. Published LIS methods are reviewed (LIS of

M. Yamashita; H. Kashiwagi

1976-01-01

465

Stable isotope studies  

SciTech Connect

The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs.

Ishida, T.

1992-01-01

466

Analysis of neutral active particle loss in afterglow in krypton at 2.6 mbar pressure  

SciTech Connect

This paper presents the analysis of the surface recombination and/or de-excitation of neutral active particles in two different volume krypton-filled tubes at pressure of 2.6 mbar with 1 ppm oxygen impurities. The analysis was performed on the basis of secondary electron emission from the cathode induced by positive ions and neutral active particles using the experimental data of electrical breakdown time delay mean value t{sub d} as a function of afterglow period {tau} ('memory curve'). It was shown that the main channel of neutral active particles' loss in afterglow is their recombination and/or de-excitation on the bulb walls. The loss rate increases with the increase of available wall surface per unit of gas volume. It was also shown that in early afterglow (15 ms for the tube with smaller bulb volume and 30 ms for the tube with bigger bulb volume) positive ions are formed in the mutual collisions of neutral active particles, and these ions dominantly influence the secondary electron emission from the cathode. In late afterglow (to 30 s for the tube with smaller bulb volume and to 150 s for the tube with bigger bulb volume) neutral active particles have dominant role in secondary electron emission from the cathode. The probability for this process decreases with the increase of afterglow period as a consequence of the decrease of the concentration of neutral active particles in gas, and this probability is smaller for the tube with smaller bulb volume. The influence of additional electron yield in the electrode gap caused by gamma radiation on breakdown initiation is also analyzed. It is shown that the influence of the neutral active particles in the process of secondary electron emission in the case of gamma radiation is also significant in both early and late afterglow.

Pejovic, Momcilo M.; Karamarkovic, Jugoslav P.; Ristic, Goran S.; Pejovic, Milic M. [Faculty of Electronic Engineering, University of Nis, P.O. Box 73, 18001 Nis (Serbia); Faculty of Civil Engineering and Architecture, University of Nis, A. Medvedeva 14, 18001 Nis (Serbia); Faculty of Electronic Engineering, University of Nis, P.O. Box 73, 18001 Nis (Serbia)

2008-01-15

467

Tomography of regional ventilation and perfusion using krypton 81m in normal subjects and asthmatic patients.  

PubMed Central

Single photon emission computed tomography, a rotating gamma camera, and continuous inhalation or infusion of krypton 81m (half life 13 seconds) were used to measure regional ventilation (V), perfusion (Q), and ventilation-perfusion (V/Q) ratios in five normal subjects in supine, prone, and lateral decubitus postures and in three asthmatic patients (supine posture only) before and after inhalation of 2.5 mg nebulised salbutamol. Vertical and horizontal gradients of V, Q, and V/Q were examined at three levels in each lung in regions of 1.9 cm3 size. In normal subjects V and Q increased along the axis of gravity in all postures and at all levels in the lung except for V in the prone position. Smaller horizontal gradients were found with an increase in V and Q from caudal to cranial--again except in the prone posture, where the gradient was slightly reversed. Constraint to outward motion of the ventral chest and abdominal wall is the most likely explanation for the different behaviour in the prone posture. In chronic asthma the vertical gradients of V and V/Q were the reverse of normal, but the Q gradient was normal. Bronchodilator treatment did not affect the vertical or horizontal gradients significantly, but analysis of individual regions showed that, relatively, V/Q worsened in 42% of them; this was associated in two thirds with an increase in fractional Q. After inhalation of beta agonist local vasodilatation may influence V/Q ratios in some units more than bronchodilatation. Images PMID:3491441

Orphanidou, D; Hughes, J M; Myers, M J; Al-Suhali, A R; Henderson, B

1986-01-01

468

Studies on the photochemical and thermal dissociation synthesis of krypton difluoride  

SciTech Connect

Like dioxygen difluoride (O{sub 2}F{sub 2}), KrF{sub 2} can be produced by thermal dissociation or photochemical synthesis from the elements; however, the yields are invariably much less than those obtained for O{sub 2}F{sub 2}. For example, while irradiation of liquid O{sub 2}/F{sub 2} mixtures at {minus}196{degrees}C through a sapphire window with an unfiltered 1,000W uv lamp provides in excess of 3g of O{sub 2}F{sub 2} per hour, the yield of KrF{sub 2} under identical circumstances is approximately 125 mg/hr. In this report, the yield of KrF{sub 2} in quartz and Pyrex{trademark} photochemical reactors has been examined as a function of irradiation wavelength, irradiation power, and Kr: F{sub 2} mole ratio. The uv-visible spectrum of KrF{sub 2} has also been recorded for comparison with earlier work, and the quantum yield for photodissociation at two wavelengths determined. The synthesis of KrF{sub 2} using large thermal gradients has also been examined using resistively heated nickel filaments to thermally dissociate the F{sub 2} in close proximity to liquid nitrogen-cooled metal surfac