Viability of long-lived fission products as signatures in forensic radiochemistry

Forensic radiochemistry refers to studies on special nuclear materials, related to nonproliferation and anti-smuggling efforts. AMS (accelerator mass spectroscopy) measurement of long-lived fission products and U and Pu isotopes has the potential to significantly aid the field of forensic radiochemistry by providing new or more sensitive signatures and improving on the speed with which they can be determined. Expanding the suite of signatures obtainable form an illicit sample of special nuclear material increases the likelihood that its point of origin can be positively identified, leveraging LLNL`s impact on policy decisions regarding national security

Can the magnetic moment contribution explain the A_y puzzle?

We evaluate the full one-photon-exchange Born amplitude for $Nd$ scattering. We include the contributions due to the magnetic moment of the proton or neutron, and the magnetic moment and quadrupole moment of the deuteron. It is found that the inclusion of the magnetic-moment interaction in the theoretical description of the $Nd$ scattering observables cannot resolve the long-standing $A_y$ puzzle.Comment: 7 pages, 2 Postscript figures; to appear in Phys.Rev.

Nucleon-deuteron elastic scattering as a tool to probe properties of three-nucleon forces

Faddeev equations for elastic Nd scattering have been solved using modern NN forces combined with the Tucson-Melbourne two-pion exchange three-nucleon force, with a modification thereof closer to chiral symmetry and the Urbana IX three-nucleon force. Theoretical predictions for the differential cross section and several spin observables using NN forces only and NN forces combined with three-nucleon force models are compared to each other and to the existing data. A wide range of energies from 3 to 200 MeV is covered. Especially at the higher energies striking three-nucleon force effects are found, some of which are supported by the still rare set of data, some are in conflict with data and thus very likely point to defects in those three-nucleon force models.Comment: 30 pages, 14 Postscript figures; now minor changes in figures and reference

A new form of three-body Faddeev equations in the continuum

We propose a novel approach to solve the three-nucleon (3N) Faddeev equation which avoids the complicated singularity pattern going with the moving logarithmic singularities of the standard approach. In this new approach the treatment of the 3N Faddeev equation becomes essentially as simple as the treatment of the two-body Lippmann-Schwinger equation. Very good agreement of the new and old approaches in the application to nucleon-deuteron elastic scattering and the breakup reaction is found.Comment: 20 pages, 3 eps figure

Technetium-99 and strontium-90: Abundance determination at ultratrace sensitivity by AMS as signatures of undeclared nuclear reprocessing activity

The purpose of this White Paper is to examine the use of the ultratrace technique Accelerator Mass Spectrometry (AMS) to lower detection limits for {sup 99}Tc and {sup 90}Sr, and to examine the utility of these isotopes as signatures of a convert reprocessing facility. The International Atomic Energy Agency (IAEA) has committed to improving the effectiveness of the IAEA Safeguards System. This is in some degree a result of the discovery in 1991 of an undeclared Iraqi EMIS program. Recommendations from the March 1993 Consultants Group Meeting have resulted in several studies and follow on field trials to identify environmental signatures from covert nuclear fuel reprocessing activity. In particular, the April, 1993 reports of the Standing Advisory Group on Safeguards Implementation (SAGSI) identified the long-lived radioisotopes Technetium-99 and strontium-90 as two reliable signatures of fuel reprocessing activity. This report also suggested pathways in the chemical processing of irradiated fuel where these elements would be volatilized and potentially released in amounts detectable with ultratrace sensitivity techniques. Based on measured {sup 99}Tc background levels compiled from a variety of sources, it is estimated that AMS can provide 10% measurements of environmental levels of {sup 99}Tc in a few minutes using modestly sized samples: a few grams for soils, plants, or animal tissues; one to several liters for rain or seawater samples; and tens to hundreds of cubic meters for air sampling. Small sample sizes and high sample throughput result in significant increases in feasibility, cost effectiveness, and quality of data for a regional monitoring program. Similar results are expected for {sup 90}Sr

Toxikologische Beurteilung von Daemmstoffen aus kuenstlichen Mineralfasern

Available from TIB Hannover: RN 7632(112) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Biological sample preparation and 41Ca AMS measurement at LLNL

Calcium metabolism in biology may be better understood by the use of 41Ca tracer, although requiring detection by accelerator mass spectrometry (AMS). Methodologies for preparation of urine samples and subsequent AMS measurement were investigated. Novel attempts at preparing CaH2 were unsuccessful, but CaF2 of sufficient purity could be produced by precipitation of calcium from urine as oxalate, followed by separation of calcium by cation exchange chromatography and washing the CaF2 precipitate. The presence of some remaining impurities could be compensated for by selecting the appropriate accelerated ion charge state for AMS. The use of projectile X-rays for isobar discrimination was explored as an alternative to the conventional detector

The LLNL AMS facility

The AMS facility at Lawrence Livermore National Laboratory (LLNL) routinely measures the isotopes 3H, 7Be, 10Be, 14C, 26Al, 36Cl, 41Ca, and 129I. During the past two years, over 30000 research samples have been measured. Of these samples, approximately 30% were for 14C bioscience tracer studies, 45% were 14C samples for archaeology and the geosciences, and the other isotopes constitute the remaining 25%. During the past two years at LLNL, a significant amount of work has gone into the development of the Projectile X-ray AMS (PXAMS) technique. PXAMS uses induced characteristic X-rays to discriminate against competing atomic isobars. PXAMS has been most fully developed for 63Ni but shows promise for the measurement of several other long lived isotopes. During the past year LLNL has also conducted an 129I interlaboratory comparison exercise. Recent hardware changes at the LLNL AMS facility include the installation and testing of a new thermal emission ion source, a new multi-anode gas ionization detector for general AMS use, re-alignment of the vacuum tank of the first of the two magnets that make up the high energy spectrometer, and a new cryo-vacuum system for the AMS ion source. In addition, we have begun design studies and carried out tests for a new high-resolution injector and a new beamline for heavy element AMS

Neutron-induced 63Ni in copper samples from Hiroshima and Nagasaki: A comprehensive presentation of results obtained at the Munich Maier-Leibnitz Laboratory.

Those inhabitants of Hiroshima and Nagasaki who were affected by the A-bomb explosions, were exposed to a mixed neutron and gamma radiation field. Few years later about 120,000 survivors of both cities were selected, and since then radiation-induced late effects such as leukemia and solid tumors are being investigated in this cohort. When the present study was initiated, the fast neutron fluences that caused the neutron doses of these survivors had never been determined experimentally. In principle, this would have been possible if radioisotopes produced by fast neutrons from the A-bomb explosions had been detected in samples from Hiroshima and Nagasaki at distances where the inhabitants survived. However, no suitable radioisotope had so far been identified. As a contribution to a large international effort to re-evaluate the A-bomb dosimetry, the concentration of the radionuclide (63)Ni (half-life 100.1 years) has been measured in copper samples from Hiroshima and Nagasaki. These measurements were mainly performed at the Maier-Leibnitz-Laboratory in Munich, Germany, by means of accelerator mass spectrometry. Because the (63)Ni had been produced in these samples by fast A-bomb neutrons via the reaction (63)Cu(n,p)(63)Ni, these measurements allow direct experimental validation of calculated neutron doses to the members of the LSS cohort, for the first time. The results of these efforts have already been published in a compact form. A more detailed discussion of the methodical aspects of these measurements and their results are given in the present paper. Eight copper samples that had been significantly exposed to fast neutrons from the Hiroshima A-bomb explosion were investigated. In general, measured (63)Ni concentrations decreased in these samples with increasing distance to the hypocenter, from 4 x 10(6 ) (63)Ni nuclei per gram copper at 391 m, to about 1 x 10(5 ) (63)Ni nuclei per gram copper at about 1,400 m. Additional measurements performed on three large-distant copper samples from Hiroshima (distance to the hypocenter 1,880-7,500 m) and on three large-distant copper samples from Nagasaki (distance to the hypocenter 3,931-4,428 m) that were not exposed significantly to A-bomb neutrons, suggest a typical background concentration of about 8 x 10(4 ) (63)Ni nuclei per gram copper. If the observed background is accounted for, the results are consistent with state-of-the-art neutron transport calculations for Hiroshima, in particular for those distances where the victims survived and were included in the life span study cohort