Radiogenic Xenon and Argon in 14318 and Implications

Geochimica et Cosmochimica Acta, 1994

This is a report on the nature of isotopically anomalous xenon, which has been detected in two Ca-Al-rich inclusions of the Allende carbonaceous chondrite. It is extremely enriched in 13'Xe, lz9Xe, and to a lesser extent in 13'Xe. Similar large excesses of 13'Xe as well as of "'Xe, '34Xe, and lz9Xe have previously been found in material processed in a natural nuclear reactor (Oklo phenomenon). Excess of these isotopes had also been encountered in MORB-glasses, in an ancient Greenland anorthosite. Thus, this Xe-type, which had previously been termed "alien" (JORDAN et al., 1980a) does not seem to be unique. To determine the origin of "alien" Xe, we analysed Xe (a) in neutron irradiated pitchblende and in the irradiation capsule, (b) in non-irradiated extremely fine-grained pitchblende (so-called Colorado-type deposit), and (c) in sandstone taken from the epicentre of an atomic explosion. In addition, the isotopic composition of xenon released by stepwise degassing and after selective dissolving of rocks from the Oklo natural reactor was determined. The results of these dedicated experiments demonstrate that the formation of alien Xe is due to the migration of the radioactive precursors of the stable isotopes '34Xe, 13*Xe, 13'Xe, and '29Xe. Due to this reason we now call it CFF-Xe-Chemically Fractionated Fission Xenon. Prerequisites for its formation are the simultaneous prevalence of two conditions: (1) fission (of 238U, 235U, and/ or 244Pu) and (2) a physicochemical environment (temperature, pressure, fluidity) at which the precursors of xenon (mainly Te and I) are mobile. Taking into account the occurrence of xenon in meteorites and terrestrial rocks, not all excesses of '29Xe in mantle rocks and natural gases are necessarily connected with the decay of primordial 12'?

Chinese Science Bulletin, 1997

Pure and Applied Geophysics

Isotopic ratios of radioxenons sampled in the atmosphere or subsurface can be used to verify the occurrence of an underground nuclear explosion (UNE). Differences in the half-lives of radioactive xenon precursors and their decay-chain networks produce different time-dependent concentration profiles of xenon isotopes allowing isotopic ratios to be used for tracking UNE histories including estimating the time of detonation. In this study, we explore the potential effects of post-detonation cavity processes: precipitation of iodine precursors, gas seepage, and prompt venting on radioxenon isotopic evolution which influences UNE histories. Simplified analytical models and closed-form solutions yielding a potentially idealized radioactive decay/ingrowth chain in a closed and well-mixed system typically have limited application by not including the partitioning of the radionuclide inventory between a gas phase and rock melt created by the detonation and by ignoring gas transport from the ...

Science, 1971

The mass spectrum of xenon from spontaneous fission in a laboratory sample of plutonium-244 is precisely what meteoriticists predicted it would be; this discovery completes a web of proof that this nuclide is a bona fide extinct radioactivity of galactic origin, that r-process nucleosynthesis was ongoing in the galaxy at the time of the birth of the sun, and that the early meteoritic abundances of plutonium-244, heretofore tentative, can be utilized with confidence in models for the chronology of galactic nucleosynthesis. The search for an explanation for anomalous fission-like xenon in carbonaceous chondrites can now be narrowed.

Journal of Geophysical Research, 1967

Following the discovery by Rowe and Kuroda that there are striking excesses of the xenon ratios 134/132 and 136/132 in the Pasamonte achondrite, we performed stepwise heating experiments with this meteorite. Xenon results from three experimental systems were concordant. The ratio 124/130 is linearly correlated with the ratio 126/130, showing a (cosmogenic) spallation component. Ratios reported by other laboratories for total xenon from various achondrites and a mesosiderite fall on this correlation line. The ratio 134/132 is linearly correlated with the ratio 136/132, showing a component presumed to be from fission. The line so defined is a gross but accurate extrapolation of the 'Pepin line,' which is now seen to be applicable to both chondrites and achondrites. Our Pasamonte data, taken alone, permit calculation of the isotopic composition of the fission and spallation components which are: fission, 131/132/134/136 _-0.285/1.00/1.06/1.13; spallation, 124/126/130/131/132 (assumed zero)-0.285/0.995/1.00/ 4.48/0. Our Pasamonte data combined with Berne data for the highly cosmogenic Stannern achondrite provide an alternative but similar set of values: fission, 131/132/

We investigate radioactivity from the decay sequence of 44Ti in a young supernova remnant SN 1987A. We perform Monte-Carlo simulations of degradation of the nuclear lines to explain a late-time bolometric luminosity which is estimated from optical and near-infrared observation at 3600 days after the explosion. Assuming the distance to LMC in between 45.5 and 52.1 kpc, we have obtained the initial 44Ti mass of (0.82-2.3) 10^{-4} solar mass within the current uncertainty of the physical quantities. The resulting fluxes of gamma- and hard X-rays emerged from the 44Ti decay are estimated and compared with the line sensitivity of the INTEGRAL/SPI on board and that of NeXT X-ray satellite planned to be launched in 2010. The effect of 44Ti ionization on the estimated fluxes is briefly remarked. Comment: 6 pages, 2 figures; Invited talk, in Proceedings of Tours Symposium on Nuclear Physics V (Tours2003), Tours, France, August 2003, eds. H. Utsunomiya et al., AIP Conference Series, in press

Pure and Applied Geophysics, 2010

Pure and Applied Geophysics, 2014

Both radioxenon and radioiodine are possible indicators for a nuclear explosion. Therefore, they will be, together with other relevant radionuclides, globally monitored by the International Monitoring System in order to verify compliance with the Comprehensive Nuclear-Test-Ban Treaty once the treaty has entered into force. This paper studies the temporal development of radioxenon and radioiodine activities with two different assumptions on fractionation during the release from an underground test. In the first case, only the noble gases are released, in the second case, radioiodine is released as well while the precursors remain underground. For the second case, the simulated curves of activity ratios are compared to prompt and delayed atmospheric radioactivity releases from underground nuclear tests at Nevada as a function of the time of atmospheric air sampling for concentration measurements of 135 I, 133 I and 131 I. In addition, the effect of both fractionation cases on the isotopic activity ratios is shown in the four-isotope-plot (with 135 Xe, 133m Xe, 133 Xe and 131m Xe) that can be utilized for distinguishing nuclear explosion sources from civilian releases.

Zeitschrift f�r Physik A Atoms and Nuclei, 1985

Evaporation residues from the heavy-ion fusion reaction 5~ on 2~ were investigated. They were separated from the projectile beam by the velocity filter SHIP and identified after implantation into an array of position-sensitive surface-barrier detectors by analyzing their a-decay chains. Spontaneous fission was also observed. A A+0.9 S), 257105 = Four new ~ emitters, 258105 (T1/2 ..... 0.6 (T1/2 =1"4-+~ S), 254Lr (T1/2 13_ +3 s), and 253Lr +0.6 (T1/2 = 1.3 0.3 s) could be identified. For the isotope 257105 we obtained a spontaneous-fission branch of about 20%. A spontaneous-fission activity with a halflife comparable to that for the e decay of 258105 was explained as fission of 258104, formed by electron capture from 258105. An excitation function for evaporation-residue production was measured for bombarding energies in the range of EcM= 184.4 MeV to EcM= 196.6 MeV. Nearly all evaporation residues we observed, could be attributed to the In and 2n deexcitation channels. The maximum cross sections were ~r(1 n) = c/2.9_+ 0.3) nbarn, and a(2n) = c/2.1 _ 0.8) nbarn, respectively. We could measure the total kinetic energy of the fission fragments of 258104 to be TKE = (220+_ 15)MeV, a value that fits into empirical systematics based on a Z2/A ~/3 dependence.

Journal of Geophysical Research, 1965

Unambiguous evidence for fission-produced nuclides in meteorites has been shown in the abundance pattern of the Xe isotopes from the Pasamonte meteorite. Calculation of the age of the meteorite from fissiogenic Xe •6 and uranium contents of the meteorite yields a value of T'-:2 X 10 •ø years, which seems far too large. The result of this calculation leads to the conclusion that part of the fissiogenic Xe in Pasamonte must have been produced by other fissionable nuclide(s), such as Pu 2•, in addition to U •. Assuming that the fissiogenic Xe • in Pasamonte is produced from spontaneous fission of U • and extinct Pu 24•, then •, the time interval between the cessation of nucleosynthesis and formation of the meteorite, is estimated to be •300 m.y.