The Experts below are selected from a list of 168 Experts worldwide ranked by ideXlab platform
Jamie D Gilmour - One of the best experts on this subject based on the ideXlab platform.
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Combined Palladium-Silver and Iodine-Xenon Isotope Systematics for Allegan (H5) and Dhofar 125 (Acapulcoite)
2013Co-Authors: K J Theis, Maria Schönbächler, Sarah Crowther, Jamie D GilmourAbstract:Allegan (H5 OC) yields an I-Xe age of 4565.8 My for pyroxenes suggesting a closure temperature higher than 800?875 oC. Dhofar 125 (acapulcoite) yields an I-Xe age of 4557.9 My, consistent with related lodranites and older than Pd-Ag age of 4549 My.
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Xenon Isotope Composition of Shergottite RBT 04262
2008Co-Authors: J A Cartwright, Sarah Crowther, Ray Burgess, Jamie D GilmourAbstract:Xenon Isotope systematics of mineral separates from RBT 04262 suggest a significant contribution from the terrestrial atmosphere, overprinting a martian signature similar to that of the basaltic shergottites.
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Characteristics and applications of RELAX, an ultrasensitive resonance ionization mass spectrometer for Xenon
Journal of Analytical Atomic Spectrometry, 2008Co-Authors: S A Crowther, R. K. Mohapatra, Grenville Turner, D. J. Blagburn, K. Kehm, Jamie D GilmourAbstract:RELAX is an ultra sensitive, time of flight, resonance ionization mass spectrometer specifically for measuring Xenon Isotope ratios. RELAX combines a resonance ionization source, a cryogenic sample concentrator and a time of flight mass spectrometer. It is the most sensitive instrument currently available for determining Xenon Isotope ratios. We report recent modifications to the spectrometer and discuss the properties and performance of the instrument in its current configuration. We also present the first data from attempted analyses of individual presolar SiC grains from the Murchison meteorite. The lifetime against ionization of Xenon atoms in the spectrometer is about 100 s. Isotope ratios for the major Xenon Isotopes can be determined more precisely than 1.5 ‰. The detection limit (3σ over the blank) is 950 atoms 132Xe, and is limited only by variations in the blank, which is currently about 1000 atoms of 132Xe. At peak sensitivity, sample sizes are restricted to less than ∼106 atoms. Thus to achieve precise measurements of Isotope ratios it is necessary to take an average from multiple analyses. Repeat analyses of air calibration samples are reproducible to 1 ‰ for the major Xenon Isotopes over several weeks, allowing us to determine precise and accurate Isotope ratios of large samples by averaging multiple analyses.
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Constraints on Nucleosynthesis from Xenon Isotopes in Presolar Material
The Astrophysical Journal, 2007Co-Authors: Jamie D Gilmour, Grenville TurnerAbstract:By applying theoretical constraints to three-dimensional fits of Xenon Isotope data from presolar grains, we show that they strongly suggest a nucleosynthesis process that produces "r-process" Isotopes without producing s-process Isotopes (128Xe, 130Xe) and without producing the conventional r-process Isotope 136Xe. It is one of three distinct nucleosynthetic sources that are necessary and sufficient to explain the gross variation in Xenon isotopic data across all presolar material. The other source contributing r-process Isotopes is responsible for the heavy Isotope signature identified in nanodiamonds, which is also present in presolar SiC, and is associated with light Isotope enrichment. The relative enrichments of heavy and light Isotopes in this component in nanodiamonds and SiC grains are different, implying that the parent nucleosynthetic processes are not inextricably linked. Because minor variations in the isotopic compositions of Xenon trapped in nanodiamonds show that two distinct sites contributed nanodiamonds to the early solar system within the average grain lifetime, it is suggested that Type IIa supernovae (SNe IIa) are not the source of the nanodiamonds. The s-process signature derived is consistent with that derived from mixing lines between grain subpopulations for Isotopes on the s-process path. This implies that a pure end-member is present in the grains (although not approached in analyses). Our approach is more general and provides a less restrictive set of numerical constraints to be satisfied by proposed theoretical treatments of nucleosynthesis.
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Characteristics and Applications of RELAX, an Ultrasensitive, Resonance Ionization Mass Spectrometer for Xenon
2005Co-Authors: S A Crowther, R. K. Mohapatra, Grenville Turner, D. J. Blagburn, Jamie D GilmourAbstract:We report the features and characteristics of RELAX -- Refrigeration Enhanced Laser Analyser for Xenon -- the most sensitive resonance ionisation mass spectrometer currently available for determination of Xenon Isotope ratios.
Paul R Renne - One of the best experts on this subject based on the ideXlab platform.
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when the dust settles stable Xenon Isotope constraints on the formation of nuclear fallout
Journal of Environmental Radioactivity, 2014Co-Authors: William S Cassata, S G Prussin, Brett H Isselhardt, Kim B. Knight, Ian D. Hutcheon, Paul R RenneAbstract:Abstract Nuclear weapons represent one of the most immediate threats of mass destruction. In the event that a procured or developed nuclear weapon is detonated in a populated metropolitan area, timely and accurate nuclear forensic analysis and fallout modeling would be needed to support attribution efforts and hazard assessments. Here we demonstrate that fissiogenic Xenon Isotopes retained in radioactive fallout generated by a nuclear explosion provide unique constraints on (1) the timescale of fallout formation, (2) chemical fractionation that occurs when fission products and nuclear fuel are incorporated into fallout, and (3) the speciation of fission products in the fireball. Our data suggest that, in near surface nuclear tests, the presence of a significant quantity of metal in a device assembly, combined with a short time allowed for mixing with the ambient atmosphere (seconds), may prevent complete oxidation of fission products prior to their incorporation into fallout. Xenon Isotopes thus provide a window into the chemical composition of the fireball in the seconds that follow a nuclear explosion, thereby improving our understanding of the physical and thermo-chemical conditions under which fallout forms.
Bernard Marty - One of the best experts on this subject based on the ideXlab platform.
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chondritic Xenon in the earth s mantle
Nature, 2016Co-Authors: Antonio Caracausi, Guillaume Avice, P Burnard, Evelyn Furi, Bernard MartyAbstract:Noble gas Isotopes are powerful tracers of the origins of planetary volatiles, and the accretion and evolution of the Earth. The compositions of magmatic gases provide insights into the evolution of the Earth's mantle and atmosphere. Despite recent analytical progress in the study of planetary materials and mantle-derived gases, the possible dual origin of the planetary gases in the mantle and the atmosphere remains unconstrained. Evidence relating to the relationship between the volatiles within our planet and the potential cosmochemical end-members is scarce. Here we show, using high-precision analysis of magmatic gas from the Eifel volcanic area (in Germany), that the light Xenon Isotopes identify a chondritic primordial component that differs from the precursor of atmospheric Xenon. This is consistent with an asteroidal origin for the volatiles in the Earth's mantle, and indicates that the volatiles in the atmosphere and mantle originated from distinct cosmochemical sources. Furthermore, our data are consistent with the origin of Eifel magmatism being a deep mantle plume. The corresponding mantle source has been isolated from the convective mantle since about 4.45 billion years ago, in agreement with models that predict the early isolation of mantle domains. Xenon Isotope systematics support a clear distinction between mid-ocean-ridge and continental or oceanic plume sources, with chemical heterogeneities dating back to the Earth's accretion. The deep reservoir now sampled by the Eifel gas had a lower volatile/refractory (iodine/plutonium) composition than the shallower mantle sampled by mid-ocean-ridge volcanism, highlighting the increasing contribution of volatile-rich material during the first tens of millions of years of terrestrial accretion.
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Chondritic Xenon in the Earth’s mantle
Nature, 2016Co-Authors: Antonio Caracausi, Guillaume Avice, P Burnard, Evelyn Furi, Bernard MartyAbstract:Noble gas Isotopes are powerful tracers of the origins of planetary volatiles, and the accretion and evolution of the Earth. The compositions of magmatic gases provide insights into the evolution of the Earth’s mantle and atmosphere. Despite recent analytical progress in the study of planetary materials and mantle-derived gases, the possible dual origin of the planetary gases in the mantle and the atmosphere remains unconstrained. Evidence relating to the relationship between the volatiles within our planet and the potential cosmochemical end-members is scarce5. Here we show, using high-precision analysis of magmatic gas from the Eifel volcanic area (in Germany), that the light Xenon Isotopes identify a chondritic primordial component that differs from the precursor of atmospheric Xenon. This is consistent with an asteroidal origin for the volatiles in the Earth’s mantle, and indicates that the volatiles in the atmosphere and mantle originated from distinct cosmochemical sources. Furthermore, our data are consistent with the origin of Eifel magmatism being a deep mantle plume. The corresponding mantle source has been isolated from the convective mantle since about 4.45 billion years ago, in agreement with models that predict the early isolation of mantle domains. Xenon Isotope systematics support a clear distinction between mid-ocean-ridge and continental or oceanic plume sources6, with chemical heterogeneities dating back to the Earth’s accretion. The deep reservoir now sampled by the Eifel gas had a lower volatile/refractory (iodine/plutonium) composition than the shallower mantle sampled by mid-ocean-ridge volcanism, highlighting the increasing contribution of volatile-rich material during the first tens of millions of years of terrestrial accretion.
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Reply to comment on “Chondritic-like Xenon trapped in Archean rocks: A possible signature of the ancient atmosphere” by Pujol, M., Marty, B., Burgess, R., Earth and Planetary Science Letters 308 (2011) 298–306 by Pepin, R.O.
Earth and Planetary Science Letters, 2013Co-Authors: Magali Pujol, Bernard Marty, Ray BurgessAbstract:We thank Pepin (2013) for pointing-out an interesting issue concerning the interpretation of the Xenon Isotope data that we recently published (Pujol et al., 2011). We have analyzed noble gases trapped in quartz fluid inclusions from the 3.5 Ga-old Dresser Formation (Western Australia). Ar–Ar dating of the quartz yielded an age of 3.0±0.2 Ga, slightly younger than the formation age, but still clearly within the Archean eon. This study focused on the Xe isotopic signature of these fluids: the non-fissiogenic Isotopes of Xenon appear isotopically fractionated, with about 1% amu−1 enrichment in light Isotopes. This isotopic mass fractionation was interpreted to represent an intermediate stage of atmosphere evolution.
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Reply to comment on "Chondritic-like Xenon trapped in Archean rocks: A possible signature of the ancient atmosphere" by Pujol, M., Marty, B., Burgess, R., Earth and Planetary Science Letters 308 (2011) 298-306 by Pepin, R.O.
Earth and Planetary Science Letters, 2013Co-Authors: Magali Pujol, Bernard Marty, Ray BurgessAbstract:We thank Pepin (2013) for pointing-out an interesting issue concerning the interpretation of the Xenon Isotope data that we recently published (Pujol et al., 2011). We have analyzed noble gases trapped in quartz fluid inclusions from the 3.5 Ga-old Dresser Formation (Western Australia). Ar–Ar dating of the quartz yielded an age of 3.0±0.2 Ga, slightly younger than the formation age, but still clearly within the Archean eon. This study focused on the Xe isotopic signature of these fluids: the non-fissiogenic Isotopes of Xenon appear isotopically fractionated, with about 1% amu−1 enrichment in light Isotopes. This isotopic mass fractionation was interpreted to represent an intermediate stage of atmosphere evolution.
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Xenon Isotope constraints on the thermal evolution of the early Earth
Chemical Geology, 2009Co-Authors: Nicolas Coltice, Bernard Marty, Reika YokochiAbstract:Abstract The thermal regime of the Earth's interior during the Hadean (the first 700 My after the birth of the solar system) is subject to debate. Evidence for a hotter mantle stems from the abundance of magnesian lavas (komatiites) in the Archean, although their generation might have also resulted from different (hydrous) melting conditions. In this contribution, the present-day mantle abundances of Xenon Isotopes contributed by extinct and extant radioactivities are used to constrain thermal and magmatic evolution models of the early Earth. Results show that, in the Hadean, heat could escape at a rate much faster than Today. Heat loss from the mantle was driven by magmatism rather than by conduction through the lithospheric lid, precluding modern style plate tectonics. Around the Hadean–Archean transition, a drastic change in the thermal regime led to a secular cooling rate comparable to the modern one, in probable relation to the onset of plate tectonics. Our model also suggests that solid-state convection started later than 50 My after the formation of the solar system, a view consistent with proposed ages for the Moon-forming impact.
Grenville Turner - One of the best experts on this subject based on the ideXlab platform.
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Characteristics and applications of RELAX, an ultrasensitive resonance ionization mass spectrometer for Xenon
Journal of Analytical Atomic Spectrometry, 2008Co-Authors: S A Crowther, R. K. Mohapatra, Grenville Turner, D. J. Blagburn, K. Kehm, Jamie D GilmourAbstract:RELAX is an ultra sensitive, time of flight, resonance ionization mass spectrometer specifically for measuring Xenon Isotope ratios. RELAX combines a resonance ionization source, a cryogenic sample concentrator and a time of flight mass spectrometer. It is the most sensitive instrument currently available for determining Xenon Isotope ratios. We report recent modifications to the spectrometer and discuss the properties and performance of the instrument in its current configuration. We also present the first data from attempted analyses of individual presolar SiC grains from the Murchison meteorite. The lifetime against ionization of Xenon atoms in the spectrometer is about 100 s. Isotope ratios for the major Xenon Isotopes can be determined more precisely than 1.5 ‰. The detection limit (3σ over the blank) is 950 atoms 132Xe, and is limited only by variations in the blank, which is currently about 1000 atoms of 132Xe. At peak sensitivity, sample sizes are restricted to less than ∼106 atoms. Thus to achieve precise measurements of Isotope ratios it is necessary to take an average from multiple analyses. Repeat analyses of air calibration samples are reproducible to 1 ‰ for the major Xenon Isotopes over several weeks, allowing us to determine precise and accurate Isotope ratios of large samples by averaging multiple analyses.
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Constraints on Nucleosynthesis from Xenon Isotopes in Presolar Material
The Astrophysical Journal, 2007Co-Authors: Jamie D Gilmour, Grenville TurnerAbstract:By applying theoretical constraints to three-dimensional fits of Xenon Isotope data from presolar grains, we show that they strongly suggest a nucleosynthesis process that produces "r-process" Isotopes without producing s-process Isotopes (128Xe, 130Xe) and without producing the conventional r-process Isotope 136Xe. It is one of three distinct nucleosynthetic sources that are necessary and sufficient to explain the gross variation in Xenon isotopic data across all presolar material. The other source contributing r-process Isotopes is responsible for the heavy Isotope signature identified in nanodiamonds, which is also present in presolar SiC, and is associated with light Isotope enrichment. The relative enrichments of heavy and light Isotopes in this component in nanodiamonds and SiC grains are different, implying that the parent nucleosynthetic processes are not inextricably linked. Because minor variations in the isotopic compositions of Xenon trapped in nanodiamonds show that two distinct sites contributed nanodiamonds to the early solar system within the average grain lifetime, it is suggested that Type IIa supernovae (SNe IIa) are not the source of the nanodiamonds. The s-process signature derived is consistent with that derived from mixing lines between grain subpopulations for Isotopes on the s-process path. This implies that a pure end-member is present in the grains (although not approached in analyses). Our approach is more general and provides a less restrictive set of numerical constraints to be satisfied by proposed theoretical treatments of nucleosynthesis.
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Characteristics and Applications of RELAX, an Ultrasensitive, Resonance Ionization Mass Spectrometer for Xenon
2005Co-Authors: S A Crowther, R. K. Mohapatra, Grenville Turner, D. J. Blagburn, Jamie D GilmourAbstract:We report the features and characteristics of RELAX -- Refrigeration Enhanced Laser Analyser for Xenon -- the most sensitive resonance ionisation mass spectrometer currently available for determination of Xenon Isotope ratios.
S A Crowther - One of the best experts on this subject based on the ideXlab platform.
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i xe and other Xenon Isotope systematics in irradiated gra 06129
In: Lunar and Planetary Science XLII; The Woodlands Texas. 2011. p. Abstract #2127., 2011Co-Authors: J L Claydon, S A Crowther, C K Shearer, J D GilmourAbstract:Xe Isotopes produced from I, Ba and U are released together in four high T ranges, implying distinct host phases associated with plagioclase. Peak 129Xe/132Xe data are consistent with previous analyses, but no I-Xe correlation is observed.
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Characteristics and applications of RELAX, an ultrasensitive resonance ionization mass spectrometer for Xenon
Journal of Analytical Atomic Spectrometry, 2008Co-Authors: S A Crowther, R. K. Mohapatra, Grenville Turner, D. J. Blagburn, K. Kehm, Jamie D GilmourAbstract:RELAX is an ultra sensitive, time of flight, resonance ionization mass spectrometer specifically for measuring Xenon Isotope ratios. RELAX combines a resonance ionization source, a cryogenic sample concentrator and a time of flight mass spectrometer. It is the most sensitive instrument currently available for determining Xenon Isotope ratios. We report recent modifications to the spectrometer and discuss the properties and performance of the instrument in its current configuration. We also present the first data from attempted analyses of individual presolar SiC grains from the Murchison meteorite. The lifetime against ionization of Xenon atoms in the spectrometer is about 100 s. Isotope ratios for the major Xenon Isotopes can be determined more precisely than 1.5 ‰. The detection limit (3σ over the blank) is 950 atoms 132Xe, and is limited only by variations in the blank, which is currently about 1000 atoms of 132Xe. At peak sensitivity, sample sizes are restricted to less than ∼106 atoms. Thus to achieve precise measurements of Isotope ratios it is necessary to take an average from multiple analyses. Repeat analyses of air calibration samples are reproducible to 1 ‰ for the major Xenon Isotopes over several weeks, allowing us to determine precise and accurate Isotope ratios of large samples by averaging multiple analyses.
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Characteristics and Applications of RELAX, an Ultrasensitive, Resonance Ionization Mass Spectrometer for Xenon
2005Co-Authors: S A Crowther, R. K. Mohapatra, Grenville Turner, D. J. Blagburn, Jamie D GilmourAbstract:We report the features and characteristics of RELAX -- Refrigeration Enhanced Laser Analyser for Xenon -- the most sensitive resonance ionisation mass spectrometer currently available for determination of Xenon Isotope ratios.
