Composition Of Xenon Research Articles

Double beta decay of tellurium-130

The isotopic composition of xenon is reported in four, neutron-irradiated tellurium minerals — tellurobismuthite from Boliden, Sweden, native tellurium from the Good Hope Mine of Gunnison County, Colorado, altaite from the Kirkland Lake area, Ontario, and altaite from the Mattagami Lake area, Quebec. From the amount of radiogenic 130Xe and pile-produced 131Xe in these samples, it is concluded that the half-life of 130Te for ββ-decay is ≲ 1 × 10 21 y based on measured values of (1.0 ± 0.3) × 10 21 y and higher. Our results demonstrate that there has been no significant partial leakage of radiogenic 130Xe from these minerals over geologic time. Larger values of T 1 2 as indicated from some of the analysis reported here and in other studies, are attributed to recrystallization of the soft telluride minerals and complete resetting of the TeXe system after mineralization. The value obtained here for the half-life of 130Te is substantiated by recent measurements on xenon in tellurides from Kalgoorlie, Western Australia.

Isotopic composition of xenon in the solar system.

Xenon in the solar system can be divided into two groups: (a) primordial xenon, whose isotopic composition can be approximated by that of the atmospheric xenon and (b) xenon, whose isotopic composition was severely altered by high energy proton and neutron reactions which took place during the T-Tauri phase of our Sun. The isotopic compositions of the SUCOR (surface correlated) xenon found in lunar fines and the CCFX xenon, corrected for mass fractionation and spallation effects, belong to the group (a) and the AVCC xenon and the so-called s-type xenon found in the Murchison meteorite belong to the group (b). Some of the xenon fractions recently isolated from the Allende and Belgica meteorites appear to be more ‘primordial’ than the atmospheric xenon.

The case for a martian origin of the shergottites: nitrogen and noble gases in EETA 79001

Nitrogen and noble gases were measured in samples of a glass inclusion and the surrounding basaltic matrix from the antarctic shergottite EETA 79001. A nitrogen component trapped in the glass, but not present in the matrix, has a δ 15N value at least as high as +190‰. Ratios of 40Ar/ 14N and 15N/ 14N in the glass are consistent with dilution of a martian atmospheric component ( δ 15N = 620 ± 160‰, 40Ar/ 14N= 0.33 ± 0.03 ) by either terrestrial atmosphere adsorbed on the samples or by indigenous nitrogen from the minerals of the rock. Trapped noble gases in the glass reproduce, within error, the elemental and isotopic compositions measured in Mars' atmosphere by Viking, and are in general agreement with previous measurements except for much lower abundances of neutron-generated krypton and xenon isotopes. The most reasonable explanation at the present time for the noble gas pattern and the isotopically heavy nitrogen is that a sample of martian atmosphere has been trapped in the EETA 79001 glass, and that this meteorite, and thus the shergottites and probably the nakhlites and chassignites as well, originated on Mars. Nitrogen in the non-glassy matrix of EETA 79001 amounts to less than 0.5 ppm and has a spallation-corrected δ 15N value in the range 0 to −20‰; it may reflect indigenous nitrogen in the basalt or a mixture of indigenous and adsorbed terrestrial nitrogen. Spallogenic noble gases yield single-stage exposure ages between 400,000 and 900,000 years, depending on irradiation geometry. Trapped argon may have an unusually low 36Ar/ 38Ar ratio. Trapped krypton, except for a small excess at 80Kr, is smoothly mass-fractionated with respect to either terrestrial or chondritic Kr. The trapped xenon composition is consistent with addition of neutron-capture, radiogenic and fissiogenic isotopes to a base composition resembling terrestrial atmospheric Xe. The elemental 84Kr/ 132Xe ratio of 25 is close to the terrestrial value and very different from the chondritic ratio.

Shock disturbance of the I‐XE system

Three separate samples of the meteorite Bjurbole were artificially shocked at pressures of 70 kb, 200 kb, and 400 kb. Analysis of xenon released in stepwise heating shows that the I‐Xe system of the 400 kb sample is substantially altered by the shock loading and it is no longer possible to infer an age or trapped xenon composition for that sample. The 200 kb and 70 kb samples display isotopic structures progressively less altered demonstrating the gradations in shock disturbance likely to be found in natural systems. Interpretations of the I‐Xe and 40Ar‐39Ar systems for several naturally shocked meteorites are also presented. New data for Arapahoe do not confirm the previously reported age and trapped xenon composition, demonstrating instead that its I‐Xe structure has been strongly disturbed by shock.

Excess 129Xe in a terrestrial sample as measured in a pristine system

The isotopic composition of xenon from CO 2 gas from the Bueyeros Field, Harding County, New Mexico (U.S.A.) has been redetermined in a brand new mass spectrometer and sample system into which no previous sample had ever been inserted except for small calibration samples of air. The large excess found for 129Xe agrees perfectly with earlier work on this sample and thus can in no way be attributed to meteoritic contamination of the measuring systems. An important constraint on the thermal history of the Earth implied by this result is valid as far as the experimental observations are concerned.

Isotopic compositions of xenon and krypton in Belgian Congo pitchblende.

Isotopic compositions of xenon and krypton released from a sample of Belgian Congo pitchblende were measured mass-spectrometrically in stepwise heating experiments. Relative contributions from spontaneous fission of 238U, thermal neutron-induced fission of 235U and fast neutron-induced fission of 238U, to the production of fissiogenic xenon found in the ore were calculated to be 64.1, 18.8 and 17.1 percent, respectively.

Anomalous isotope composition of xenon and krypton in minerals of the natural nuclear reactor

Anomalous isotope composition of xenon and krypton in minerals of the natural nuclear reactor

Xenon isotope anomalies in the carbonaceous chondrite murray

The isotopic compositions have been measured mass spectrometrically for xenon fractions released from the carbonaceous chondrite Murchison in stepwise heating experiments. Variation of the isotopic ratios was found to be relatively small: for example, the 136Xe/132Xe ratio in the 600°C fraction was 0.328 (the atmospheric ratio is 0.330), and the ratio in the 1500°C fraction was 0.310 (the Sucor ratio is 0.301), whereas the ratios observed in other temperature fractions had intermediate values. It appears that these variations can best be explained as being due to the fact that reservoirs of two isotopically distinct gases (solar and planetary) exist in the meteorite and that mixtures of these gases in various proportions are being released at different temperatures. The major difference in the isotopic compositions of solar and planetary xenon can be attributed to a mass-dependent fractionation process, but the solar xenon contains excesses of xenon isotopes at mass numbers 128, 130, 131, and 132 that appear to have been produced by neutron capture processes that took place in the sun during its deuterium-burning stage. The solar xenon must have been transported from the sun to the meteorites in the form of solar wind. The relative abundances of the light isotopes of xenon in carbonaceous chondrites are appreciably altered by the cosmic ray irradiation process. The decay products of 129I and 244Pu further modify the isotopic compositions of xenon fractions released from the carbonaceous chondrites. According to this interpretation, it is unnecessary to assume the existence of the so-called Renazzo-type fission xenon component (CCF or xenon X) in the carbonaceous chondrites.

Solar wind xenon in some carbonaceous chondrites

A table shows the isotopic composition of xenon from several carbonaceous chondrites in which the presence of solar xenon can be demonstrated. The data suggest the presence of a solar xenon component in these carbonaceous chondrites, but solar xenon in these meteorites can be more clearly demonstrated through correlation plots. It is argued that the incorporation of the solar type of noble gases must have occurred during the early history of meteoritic matter when this material consisted of fine-grained particles.

Xenon isotopes in tellurobismuthite, Boliden, Sweden

The isotopic composition of xenon is reported in four different samples of tellurobismuthite, Boliden, Sweden, of varying tellurium content. It is observed that excess 129Xe, 130Xe and 131Xe, vary proportionately to the tellurium content of the sample. From the excess 130Xe measurement, the half-life for double beta decay of 130Te is calculated to be 2·51 × 10 21 yr. From the observed excess of 128Xe in the most tellurium rich sample, the half-life for the double beta decay of 128Te is estimated to be greater than 2·7 × 10 23 yr. It is shown that solar neutrino induced reactions on 128Te and 130Te do not contribute significantly to the observed excesses of 128Xe and 130Xe. The isotopic composition of xenon in a pyrite sample from the Boliden mine and in two samples of the cesium-rich mineral, pollucite, are used to examine previous hypotheses for the origin of excess 129Xe and 131Xe in tellurium ores. It is shown that these two xenon isotopes are produced in situ by nuclear reactions on tellurium.

Mass Fractionation and the Isotopic Anomalies of Xenon and Krypton in Ordinary Chondrites

The abundance and isotopic composition of all noble gases are reported in the Wellman chondrite, and the abundance and isotopic composition of xenon and krypton are reported in the gases released by stepwise heating of the Tell and Scurry chondrites. Major changes in the isotopic composition of Xe result from radiogenic Xe129 and from variations in the isotopic mass fractionation pattern in the different temperature fractions. The isotopic composition of trapped krypton in the different temperature fractions of the Tell and Scurry chondrites displays smaller fractional changes than xenon, but the isotopic composition of these two gases covary in the manner expected from mass dependent fractionation

Isotopic Composition of Xenon from a Greenland Anorthosite

FOLLOWING a study of the data resulting from the lunar α-scattering experiment of Turkevich et al.1, Olsen2 pointed out that the rocks in the Mare Tranquillitatus region were similar in oxide composition to certain terrestrial anorthosites. When lunar rocks became available for examination after the Apollo 11 mission, O'Hara3 drew attention to the possibility that terrestrial anorthosites might be re-worked slices of the Earth's primordial crust. Windley4, in particular, supported this view proposing that early Pre-Cambrian Group III anorthosites are fragments of layered differentiates formed early in the evolution of the Earth. Romey5, on the other hand, does not like the comparison between lunar and terrestrial anorthosites and suggests that theories of lunar petrogenesis are developing too fast.

Isotopic composition of xenon and krypton in the lunar soil and in the solar wind

Xe and Kr analyses of three lunar samples, the Murray meteorite and Xe from the terrestrial atmosphere are presented. The isotopic compositions of surface-correlated (solar wind?) and lunar soil spallation xenon and krypton are derived from the lunar soil data alone. The lunar soil spallation Xe is similar to that in lunar rocks and meteorites, but the lunar soil spallation Kr has higher ( 84Kr/ 83Kr) and 82Kr/ 83Kr). We have no adequate explanation for this Kr spectrum, although independent evidence for such a component comes from stepwise heating data. The surface-correlated Xe (SUCOR) is distinct from both AVCC and terrestrial Xe. However, SUCOR Xe cannot be directly identified with the solar wind, but may contain an admixture of gases from the lunar atmosphere implanted on the grain surfaces by ion pumping processes. The general fractionation trend in SUCOR Xe relative to the atmosphere presumably reflects the solar wind composition. SUCOR Kr appears to be totally ascribable to the solar wind. Solar wind and terrestrial Kr are related by fractionation, but opposite to that of Xe.

Physical Sciences: Rare Gas Anomalies and Intense Muon Fluxes in the Past

SEVERAL explanations1–4 of the excess 129Xe and 131Xe in terrestrial tellurium ores have been proposed. Takagi et al.2 pointed out that the observed 129Xe/131Xe ratios are well explained by muon interactions on tellurium isotopes. The intense muon flux necessary for the production of the observed amount of the xenon isotopes was considered to have been produced through the resonant scattering of high energy electron antineutrinos emitted by the explosion of our galaxy. Since that paper there has been some further analytical data on the isotopic composition of xenon in tellurides4, which essentially seem to be consistent with the explosion mechanism.

Solar-Type Xenon: A New Isotopic Composition of Xenon in the Pesyanoe Meteorite

Xenon in the Pesyanoe meteorite is a mixture of several componenits. Solar-type xenon is a new component deficient in the neutron-rich isotopes as compared to both trapped chondritic and terrestrial atmospheric xenon.

Xenon and Krypton from the Spontaneous Fission of Californium-252

The isotopic composition of xenon and krypton was measured in aluminum foils which had been exposed to \ensuremath{\sim}${10}^{10}$ fissions of ${\mathrm{Cf}}^{252}$. Relative to ${\mathrm{Xe}}^{136}$, observed yields are ${\mathrm{Kr}}^{83}$: ${\mathrm{Kr}}^{84}$: ${\mathrm{Kr}}^{85}$: ${\mathrm{Kr}}^{86}$: ${\mathrm{Xe}}^{131}$: ${\mathrm{Xe}}^{132}$: ${\mathrm{Xe}}^{134}$: ${\mathrm{Xe}}^{136}$ = 0.010:0.017:0.0049:0.032:0.35:0.52:0.90:1.000. These results show a higher relative yield at mass 134 and less fine structure in the 83-86 mass region than reported from energy-versus-time-of-flight studies on single fission fragments. Our results do not confirm the sharp minimum in the fine structure at mass 136, as suggested from radiochemical studies in the mirror mass region.

Xenon in the inclusions of Canyon Diablo and Toluca iron meteorites

The concentration and isotopic composition of xenon is reported in two samples of Canyon Diablo graphite and in three coexisting mineral phases from a silicate inclusion of Toluca. The existence of large 129rXe anomalies in iron meteorites is confirmed. Formation intervals of about 200 m.y. after an initial 129I/ 127I = 3 × 10 −3 are calculated. Within the limits of experimental error the xenon appears to be a mixture of atmospheric and average-carbonaceous-chondrite-type xenon. No fissiogenic xenon could be identified.

Isotopic composition of xenon, krypton, and argon emitted by Cm244 oxide

Isotopic composition of xenon, krypton, and argon emitted by Cm244 oxide

Spallation yield of xenon from 730 MeV proton irradiation of barium

The isotopic composition of xenon produced by 730 MeV proton bombardment of BaCl 2 was measured to be: 124Xe : 126Xe : 127Xe : 128Xe : 129Xe : 130Xe : 131Xe : 132Xe : 134Xe corresponding to 72 : ≡ 100 : 102 : 116 : 111 : 72 : 183 : 52 : 4.6, respectively. The cross section observed for 126Xe production was 0.140 barn. The agreement between these measured yields and the yields calculated by means of the spallation systematics of Rudstam is in general quite good: striking discrepancies occur, however, at 130Xe and 132Xe. These findings confirm the relative yield found from meteoritic spallation xenon which shows similar discrepancies at 130Xe and 132Xe. The discrepancy at 129Xe between the meteoritic data reported by Rowe and spallation systematics is not confirmed in this work.

Isotopic anomalies of krypton and xenon in Canyon Diablo graphite

The abundance and isotopic composition of xenon and krypton have been determined in Canyon Diablo graphite. Large excesses of 80Kr, 82Kr and 128Xe are attributed to neutron capture on bromine and iodine. The graphite contains one of the largest excesses of 129Xe observed in meteoritic xenon. The xenon spectra do not display the ‘general anomaly pattern’ which characterizes xenon in chondrites.