Alteration of natural ³⁷Ar activity concentration in the subsurface by gas transport and water infiltration

High ³⁷Ar activity concentration in soil gas is proposed as a key evidence for the detection of underground nuclear explosion by the Comprehensive Nuclear Test-Ban Treaty. However, such a detection is challenged by the natural background of ³⁷Ar in the subsurface, mainly due to Ca activation by cosmic rays. A better understanding and improved capability to predict ³⁷Ar activity concentration in the subsurface and its spatial and temporal variability is thus required. A numerical model integrating ³⁷Ar production and transport in the subsurface is developed, including variable soil water content and water infiltration at the surface. A parameterized equation for ³⁷Ar production in the first 15 m below the surface is studied, taking into account the major production reactions and the moderation effect of soil water content. Using sensitivity analysis and uncertainty quantification, a realistic and comprehensive probability distribution of natural ³⁷Ar activity concentrations in soil gas is proposed, including the effects of water infiltration. Site location and soil composition are identified as the parameters allowing for a most effective reduction of the possible range of ³⁷Ar activity concentrations. The influence of soil water content on ³⁷Ar production is shown to be negligible to first order, while ³⁷Ar activity concentration in soil gas and its temporal variability appear to be strongly influenced by transient water infiltration events. These results will be used as a basis for practical CTBTO concepts of operation during an OSI.

Technical consideration on survival measures and reduction of casualties /

"Health and Safety."

Biological blast effects /

"Progress report AEC Contract no. AT(29-1)-1242."

Scope of chemical explosive cratering experiment /

"Issued: Aug.,1963"--Cover : "May 15, 1963"--Title page.

Base surge analysis /

"September 1, 1963"--Title page.

Engineering geology of Buckboard Mesa, Nevada test site : interim report /

"July 1964."

Mass distribution and throwout studies /

"Issued: August 6, 1963"--Cover ; "May 1963"--Title page.

Influence of a cratering device on close-in populations of lizards /

"PNE-224F."

Stability of crater slopes /

"Issued: October 2, 1964"--Cover ; "March 1964"--Title page.

Food-chain relationships of radiostrontium in the Sedan fallout field /

"Nuclear explosions - Peaceful Applications (TID-4500, 42nd ed.)."

Timing and firing : preliminary report /

"Nuclear explosions - peaceful applications."

Design, testing and field pumping of grout mixtures : final report /

U.S. Atomic Energy Commission Plowshare Program.

Nuclear fusion from Coulomb explosions of deuterated methane clusters subjected to ultraintense femtosecond laser pulses

This paper reports that Coulomb explosions taken place in the experiment of heteronuclear deuterated methane clusters ((CD4)(n)) in a gas jet subjected to intense femtosecond laser pulses (170 mJ, 70 fs) have led to table-top laser driven DD nuclear fusion. The clusters produced in supersonic expansion had an average energies of deuterons produced in the laser-cluster interaction were 60 and 1.5 KeV, respectively. From DD collisons of energetic deuterons, a yield of 2.5(+/-0.4)x10(4) fusion neutrons of 2.45 MeV per shot was realized, giving rise to a neutron production efficiency of about 1.5 x 10(5) per joule of incident laser pulse energy. Theoretical calculations were performed and a fairly good agreement of the calculated neutron yield with that obtained from the present experiment was found.