[en] The IAB iron meteorites may be related to the chondrites; siderophile elements in the metal matrix have chondritic abundances, and the abundant silicate inclusions are chondritic both in mineralogy and in chemical composition. Silicate and troilite (FeS) and IAB irons were analyzed by the I-Xe technique. Four IAB silicate samples gave well-defined I-Xe ages [in millions of years relative to Bjurboele; the monitor error (+-2.5 m.y.) is not included]: -3.7 +- 0.3 for Woodbine, -0.7 +- 0.6 for Mundrabilla, +1.4 +- 0.7 for Copiapo, and +2.6 +- 0.6 for Landes. The (₁₂₉Xe/₁₃₂Xe)_trapped ratios are consistent with previous values for chondrites, with the exception of Landes which has an extraordinary trapped ratio of 3.5 +- 0.2. Both analyses of silicate from Pitts gave anomalous I-Xe patterns: intermediate-temperature points defined good correlations but higher-temperature (greater than or equal to 1400₀C) points lay above (extra ₁₂₉Xe) these lines. The two correlations have different slopes, so it cannot be assigned a definite I-Xe age to Pitts silicate. Troilite samples from Mundrabilla and Pitts were also analyzed: Pitts troilite gave a complex I-Xe pattern, which suggests an age of +17 m.y.; Mundrabilla troilite defined a good I-Xe correlation, which after correction for neutron capture on ₁₂₈Te an age of -10.8 +- 0.7 m.y. Thus, surprisingly, low-melting troilite substantially predates high-melting silicate in Mundrabilla. Abundances of Ga, Ge, and Ni in metal from these meteorites are correlated with I-Xe ages of the silicate (referred to henceforth as the metal-silicate correlation). After exploring possible relationships between the I-Xe ages and other properties of the IAB group, it was concluded that the metal-silicate correlation, the old Mundrabilla troilite, and other results favor a nebular formation model (e.g. Wasson, 1970a)

[en] In this paper a synopsis is presented of the second ITWG (Nuclear Smuggling International Technical Working Group) meeting that was held in Obninsk, Russia, on December 2-4, 1996, at the Institute of Physics and Power Engineering

[en] The Nuclear Smuggling International Technical Working Group (ITWG) is an international body of nuclear forensic experts that cooperate to deter the illicit trafficking of nuclear materials. The objective of the ITWG is to provide a common approach and effective technical solutions to governments who request assistance in nuclear forensics. The ITWG was chartered in 1996 and since that time more than 28 nations and organizations have participated in 9 international meetings and 2 analytical round-robin trials. Soon after its founding the ITWG adopted a general framework to guide nuclear forensics investigations that includes recommendations for nuclear crime scene security and analysis, the best application of radioanalytical methods, the conduct of traditional forensic analysis of contaminated materials, and effective data analysis to interpret the history of seized nuclear materials. This approach has been adopted by many nations as they respond to incidents of illicit nuclear trafficking

[en] This paper presents the personal perspectives of the authors on the early development of nuclear forensics, beginning with the early 1990s. Independently, we started to work on nuclear forensics, recognizing that we were addressing a new set of questions. In 1995 an “International Conference on Nuclear Smuggling Forensics Analysis” was held at Lawrence Livermore National Laboratory, which ended by forming a International Technical Working Group (ITWG) as a forum for international technical cooperation on nuclear forensics. This conference also marked the start of our working relationship. Some of the early work of the ITWG is highlighted, notably the development of a “model action plan” and the execution of exercises in which scientists learned from one another. In the 2000s a number of countries and organizations started programs to make technical progress in developing nuclear forensics. Signatures are at the heart of the technical development, as they are crucially important for drawing technical interpretations from measurements. Some examples of cooperative research projects that include multiple countries will be described. Finally, based on our experience in the early evolution of nuclear forensics, we present some lessons learned regarding the development of a new field like nuclear forensics. (author)

[en] We present a matrix of 60 possible forensic tools. If the specifics of the types of materials and analytical techniques are included, the number becomes vastly greater. Accordingly, the prioritization and discretion is addressed that should be utilized to select the most useful tools

[en] The goal of the U.S. Department of Homeland Security (DHS) Nuclear and Radiological Forensics and Attribution Program is to develop the technical capability for the nation to rapidly, accurately, and credibly attribute the origins and pathways of interdicted or collected materials, intact nuclear devices, and radiological dispersal devices. A robust attribution capability contributes to threat assessment, prevention, and deterrence of nuclear terrorism; it also supports the Federal Bureau of Investigation (FBI) in its investigative mission to prevent and respond to nuclear terrorism. Development of the capability involves two major elements: (1) the ability to collect evidence and make forensic measurements, and (2) the ability to interpret the forensic data. The Program leverages the existing capability throughout the U.S. Department of Energy (DOE) national laboratory complex in a way that meets the requirements of the FBI and other government users. At the same time the capability is being developed, the Program also conducts investigations for a variety of sponsors using the current capability. The combination of operations and R and D in one program helps to ensure a strong linkage between the needs of the user community and the scientific development

[en] Theft, illegal possession, smuggling, or attempted unauthorized sale of nuclear and radiological materials remains a worldwide problem. The Nuclear Smuggling International Technical Working Group (ITWG) has adopted a model action plan to guide investigation of these cases through a systematic approach to nuclear forensics. The model action plan was recently documented and provides recommendations concerning incident response, collection of evidence in conformance with required legal standards, laboratory sampling and distribution of samples, radioactive materials analysis, including categorization and characterization of samples, forensics analysis of conventional evidence, and case development including interpretation of forensic signatures

[en] Average Ti isotopic patterns are derived for each class of carbonaceous chondrite from a chemically characterized suite of whole-rock samples. There is a well-resolved excess of ⁵⁰Ti in a subset of CI meteorites. Mean values of the ⁵⁰Ti excess for the four classes span a range of only 2 ε-units, with an apparent positive correlation with Al content. Previous evidence for anomalies in chondrules is augmented here by demonstrating that: (1) the more pristine Ca-Al-rich inclusions (CAIs) in Efremovka show the same isotopic pattern as the typical Allende CAI; and, (2) CM and CV matrix carry ⁵⁰Ti excesses of about 2 ε-units. The distribution of Ti isotopic anomalies among matrix, chondrules, and CAIs suggests a model in which all three constituents formed from precursor-assemblages in which some chemical memories were still intact; the isotopic differences reflect fractionations among the carrier phases of the different isotopic components. Chondrules formed by a mostly closed-system melting of their precursors, and thus provide a recording of the extent of nebular heterogeneity on the mg-size scale. The larger anomalies in CAIs, compared to matrix and most (but not all) chondrules, are attributed primarily to an open- rather than closed-system processing of the CAI precursors. Precursors of both FUN and normal CAIs experienced an episode of intense processing, perhaps partial melting, that created the FUN characteristics, but for normal CAIs the FUN effects were erased by subsequent isotopic equilibration and exchange

[en] Discussions of isotopic anomalies usually focus on the several known FUN inclusions of Allende since most analyzed-elements in these samples show isotopic anomalies. In contrast, this review will consider only the anomalies which are commonly present in refractory Allende inclusions. Other than oxygen, such ubiquitous anomalies are presently resolved only in Ca, Ti, and Cr. The isotopic patterns in all 3 elements are consistent with a relative enrichment of the heaviest isotope. Smaller Ti anomalies are also found in whole-rock samples of most carbonaceous chondrites and in many of the chondrules from Allende, and in some chondrules from ordinary chondrites. The dominant anomalies at the neutron-rich isotopes indicate a single exotic component. The most likely source is neutron-rich hydrostatic burning at densities and temperatures found near the cores of massive stars. It is far from clear, though, how these nuclei are transported from the star through the ISM and then inhomogeneously distributed in solar system matter. Important factors are probably a refractory carrier phase for these neutron-rich isotopes and a chemical memory in the solar nebula whereby the dust component retains memories of its various nucleosynthetic origins and its subsequent history in the ISM

[en] Silicate from two unusual iron-rich meteorites were analyzed by the I-Xe and ₄₀Ar-₃₉Ar techniques. Enon, an anomalous iron meteorite with chondritic silicate, shows no loss of radiogenic ₄₀Ar at low temperature, and gives a plateau age of 4.59 +- 0.03 Ga. Although the Xe data fail to define an I-Xe correlation the inferred Pu/U ratio is more than 2 σ above the chondritic value, and the Pu abundance derived from the concentration of Pu-fission Xe is 6 times greater than the abundance inferred for CI meteorites. These findings for Enon, coupled with data for IAB iron meteorites, suggest that presence of chondritic silicate in an iron-rich meteorite is diagnostic of an old radiometric age with little subsequent thermal disturbance. The Eagle Station pallasite, the most ₁₆O-rich meteorite known, gives a complex ₄₀Ar-₃₉Ar age pattern which suggests a recent severe thermal disturbance. The absence of excess ₁₂₉Xe, and the low trapped Ar and Xe contents, are consistent with this interpretation. The similarity between ₄₀Ar-₃₉Ar data for Eagle Station and for the olivine-rich meteorite Chassigny lends credence to the previous suggestion of a connection between Chassigny and pallasites. (author)