Download or read book 230Th 234U Age Dating Uranium by Mass Spectrometry written by and published by . This book was released on 2012 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the standard operating procedure used by the Isotope Ratio Mass Spectrometry Group of the Chemical Sciences Division at LLNL for the preparation of a sample of uranium oxide or uranium metal for 23°Th-234U age-dating. The method described here includes the dissolution of a sample of uranium oxide or uranium metal, preparation of a secondary dilution, spiking of separate aliquots for uranium and thorium isotope dilution measurements, and purification of uranium and thorium aliquots for mass spectrometry. This SOP may be applied to uranium samples of unknown purity as in a nuclear forensic investigation, and also to well-characterized samples such as, for example, U3O and U-metal certified reference materials. The sample of uranium is transferred to a quartz or PFA vial, concentrated nitric acid is added and the sample is heated on a hotplate at approximately 100 C for several hours until it dissolves. The sample solution is diluted with water to make the solution approximately 4 M HNO3 and hydrofluoric acid is added to make it 0.05 M HF. A secondary dilution of the primary uranium solution is prepared. Separate aliquots for uranium and thorium isotope dilution measurements are taken and spiked with 233U and 229Th, respectively. The spiked aliquot for uranium isotope dilution analysis is purified using EiChrom UTEVA resin. The spiked aliquot for thorium isotope dilution analysis is purified by, first, a 1.8 mL AG1x8 resin bed in 9 M HCl on which U adsorbs and Th passes through; second, adsorbing Th on a 1 mL AG1x8 resin bed in 8 M HNO3 and then eluting it with 9 M HCl followed by 0.1 M HCl + 0.005 M HF; and third, by passing the Th through a final 1.0 mL AG1x8 resin bed in 9 M HCl. The mass spectrometry is performed using the procedure 'Th and U Mass Spectrometry for 23°Th-234U Age Dating'.
Download or read book Round robin 230Th 234U Age Dating of Bulk Uranium for Nuclear Forensics written by and published by . This book was released on 2015 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: We report that in an inter-laboratory measurement comparison study, four laboratories determined 230Th-234U model ages of uranium certified reference material NBL U050 using isotope dilution mass spectrometry. The model dates determined by the participating laboratories range from 9 March 1956 to 19 October 1957, and are indistinguishable given the associated measurement uncertainties. These model ages are concordant with to slightly older than the known production age of NBL U050.
Download or read book Uranium Age Determination by Measuring the 230Th written by and published by . This book was released on 2004 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: A radiochemical isotope dilution mass spectrometry method has been developed to determine the age of uranium materials. The amount of 230Th activity, the first progeny of 234U, that had grown into a small uranium metal sample was used to determine the elapsed time since the material was last radiochemically purified. To preserve the sample, only a small amount of oxidized uranium was removed from the surface of the sample and dissolved. Aliquots of the dissolved sample were spiked with 233U tracer and radiochemically purified by anion-exchange chromatography. The 234U isotopic concentration was then determined by thermal ionization mass spectrometry. Additional aliquots of the sample were spiked with 229Th tracer, and the thorium was purified using two sequential anion-exchange chromatography separations. The isotopic concentrations of 230Th and 232Th were determined by TIMS. The lack of any 232Th confirmed the assumption that all thorium was removed from the uranium sample at the time of purification. The 230Th and 234U mass concentrations were converted to activities and the 230Th/234U ratio for the sample was calculated. The experimental 230Th/234U ratio showed the uranium in this sample was radiochemically purified in about 1945. Isotope dilution thermal ionization mass spectrometry has sufficient sensitivity to determine the age of 100 samples of uranium. This method could certainly be employed as a nuclear forensic method to determine the age of small quantities of uranium metal or salts. Accurate determination of the ultra-trace 230Th radiochemically separated from the uranium is possible due to the use of 229Th as an isotope dilution tracer. The precision in the experimental age of the uranium could be improved by making additional replicate measurements of the 230Th/234U isotopic ratio or using a larger initial sample.
Download or read book Round robin 230Th u2013 234U Age Dating of Bulk Uranium for Nuclear Forensics written by and published by . This book was released on 2015 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: We report that in an inter-laboratory measurement comparison study, four laboratories determined 230Th–234U model ages of uranium certified reference material NBL U050 using isotope dilution mass spectrometry. The model dates determined by the participating laboratories range from 9 March 1956 to 19 October 1957, and are indistinguishable given the associated measurement uncertainties. These model ages are concordant with to slightly older than the known production age of NBL U050.
Download or read book 230Th 234U Model Ages of Some Uranium Standard Reference Materials written by and published by . This book was released on 2009 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 'age' of a sample of uranium is an important aspect of a nuclear forensic investigation and of the attribution of the material to its source. To the extent that the sample obeys the standard rules of radiochronometry, then the production ages of even very recent material can be determined using the 23°Th-234U chronometer. These standard rules may be summarized as (a) the daughter/parent ratio at time=zero must be known, and (b) there has been no daughter/parent fractionation since production. For most samples of uranium, the 'ages' determined using this chronometer are semantically 'model-ages' because (a) some assumption of the initial 23°Th content in the sample is required and (b) closed-system behavior is assumed. The uranium standard reference materials originally prepared and distributed by the former US National Bureau of Standards and now distributed by New Brunswick Laboratory as certified reference materials (NBS SRM = NBL CRM) are good candidates for samples where both rules are met. The U isotopic standards have known purification and production dates, and closed-system behavior in the solid form (U3O) may be assumed with confidence. We present here 23°Th-234U model-ages for several of these standards, determined by isotope dilution mass spectrometry using a multicollector ICP-MS, and compare these ages with their known production history.
Download or read book Encyclopedia of Modern Coral Reefs written by David Hopley and published by Springer Science & Business Media. This book was released on 2010-11-26 with total page 1226 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coral reefs are the largest landforms built by plants and animals. Their study therefore incorporates a wide range of disciplines. This encyclopedia approaches coral reefs from an earth science perspective, concentrating especially on modern reefs. Currently coral reefs are under high stress, most prominently from climate change with changes to water temperature, sea level and ocean acidification particularly damaging. Modern reefs have evolved through the massive environmental changes of the Quaternary with long periods of exposure during glacially lowered sea level periods and short periods of interglacial growth. The entries in this encyclopedia condense the large amount of work carried out since Charles Darwin first attempted to understand reef evolution. Leading authorities from many countries have contributed to the entries covering areas of geology, geography and ecology, providing comprehensive access to the most up-to-date research on the structure, form and processes operating on Quaternary coral reefs.
Download or read book Studies of Cave Sediments written by Ira D. Sasowsky and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: John E. Mylroie and Ira D. Sasowsky' Caves occupy incongruous positions in both our culture and our science. The oldest records of modem human culture are the vivid cave paintings from southern France and northern Spain, which are in some cases more than 30,000 years old (Chauvet, et ai, 1996). Yet, to call someone a "caveman" is to declare them primitive and ignorant. Caves, being cryptic and mysterious, occupied important roles in many cultures. For example, Greece, a country with abundant karst, had the oracle at Delphi and Hades the god of death working from caves. People are both drawn to and mortified by caves. Written records ofcave exploration exist from as early as 852 BC (Shaw, 1992). In the decade of the 1920's, which was rich in news events, the second biggest story (as measured by column inches of newsprint) was the entrapment of Floyd Collins in Sand Cave, Kentucky, USA. This was surpassed only by Lindbergh's flight across the Atlantic (Murray and Brucker, 1979).
Download or read book Chronometric Dating in Archaeology written by R.E. Taylor and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since World War II, there has been tremendous success in the development of new methods for dating artifacts; the so-called `radiocarbon revolution' was only the first such discovery. The increasing accuracy of the various new techniques has brought about major changes in archaeological research strategies. This important new text compiles the work of some of today's most innovative archaeologists who summarize progress in their respective techniques over the last 30 years - with an emphasis on developments of the last five - and the status of current research.
Download or read book REIMEP 22 written by Célia Venchiarutti and published by . This book was released on 2015 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: The REIMEP-22 inter-laboratory comparison (ILC) "U Age Dating - Determination of the production date of a uranium certified test sample" was organised by JRC-IRMM as support to the Nuclear Forensics International Technical Working Group (ITWG) This ILC was organised prior to the release of the candidate certified reference material IRMM-1000, produced in cooperation with JRC-ITU. The aim of REIMEP-22 was to determine the production date of the uranium certified test sample (i.e. the last chemical separation date of the material) using the disequilibrium between the 230Th-234U and 231Pa-235U nuclides as chronometers. The first was compulsory, the latter optional. Participants in REIMEP-22 received either a 20 mg or 50 mg low-enriched uranium sample of known age in solid uranyl nitrate form, depending on the type of analytical technique they used.^Participating laboratories were asked to measure and report either the isotope amount ratio n(230Th)/n(234U) for the 20 mg uranium samples or the activity ratio A(230Th)/A(234U) for the 50 mg uranium samples and to report the calculated production date of the certified test samples. The participants were asked to apply their standard analytical procedures and report the results with the associated uncertainties. REIMEP-22 was announced to participants in June 2013 and fourteen laboratories registered for REIMEP-22 by October 2013. The shipment of the samples to the participants took place between December 2013 and late January 2014. Finally, by May 2014, nine laboratories reported results for the 20 mg uranium sample (using mass spectrometry and reporting amount ratios) and four laboratories for the 50 mg uranium sample (using a-spectrometry and reporting activity ratios).^The reported measurement results have been evaluated against the certified reference value by means of zeta-scores in compliance with international guidelines. In general the REIMEP-22 participants' results were satisfactory. This report presents the REIMEP-22 participants' results; including the evaluation of the questionnaire.
Download or read book REIMEP 22 written by and published by . This book was released on 2015 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: The REIMEP-22 inter-laboratory comparison (ILC) "U Age Dating - Determination of the production date of a uranium certified test sample" was organised by JRC-IRMM as support to the Nuclear Forensics International Technical Working Group (ITWG) This ILC was organised prior to the release of the candidate certified reference material IRMM-1000, produced in cooperation with JRC-ITU. The aim of REIMEP-22 was to determine the production date of the uranium certified test sample (i.e. the last chemical separation date of the material) using the disequilibrium between the 230Th-234U and 231Pa-235U nuclides as chronometers. The first was compulsory, the latter optional. Participants in REIMEP-22 received either a 20 mg or 50 mg low-enriched uranium sample of known age in solid uranyl nitrate form, depending on the type of analytical technique they used.^Participating laboratories were asked to measure and report either the isotope amount ratio n(230Th)/n(234U) for the 20 mg uranium samples or the activity ratio A(230Th)/A(234U) for the 50 mg uranium samples and to report the calculated production date of the certified test samples. The participants were asked to apply their standard analytical procedures and report the results with the associated uncertainties. REIMEP-22 was announced to participants in June 2013 and fourteen laboratories registered for REIMEP-22 by October 2013. The shipment of the samples to the participants took place between December 2013 and late January 2014. Finally, by May 2014, nine laboratories reported results for the 20 mg uranium sample (using mass spectrometry and reporting amount ratios) and four laboratories for the 50 mg uranium sample (using a-spectrometry and reporting activity ratios).^The reported measurement results have been evaluated against the certified reference value by means of zeta-scores in compliance with international guidelines. In general the REIMEP-22 participants' results were satisfactory. This report presents the REIMEP-22 participants' results; including the evaluation of the questionnaire.
Download or read book Uranium series Geochemistry written by Bernard Bourdon and published by Walter de Gruyter GmbH & Co KG. This book was released on 2018-12-17 with total page 676 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume 52 of Reviews in Mineralogy and Geochemistry updates our knowledge of U-series geochemistry, offer an opportunity for non-specialists to understand its basic principles, and give us a view of the future of this active field of research. In this volume, for the first time, all the methods for determining the uranium and thorium decay chain nuclides in Earth materials are discussed. It was prepared in advance of a two-day short course (April 3-4, 2003) on U-series geochemistry, jointly sponsored by GS and MSA and presented in Paris, France prior to the joint EGS/AGU/EUG meeting in Nice.
Download or read book Encyclopedia of Scientific Dating Methods written by W. Jack Rink and published by Springer. This book was released on 2015-08-15 with total page 978 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume provides an overview of (1) the physical and chemical foundations of dating methods and (2) the applications of dating methods in the geological sciences, biology, and archaeology, in almost 200 articles from over 200 international authors. It will serve as the most comprehensive treatise on widely accepted dating methods in the earth sciences and related fields. No other volume has a similar scope, in terms of methods and applications and particularly time range. Dating methods are used to determine the timing and rate of various processes, such as sedimentation (terrestrial and marine), tectonics, volcanism, geomorphological change, cooling rates, crystallization, fluid flow, glaciation, climate change and evolution. The volume includes applications in terrestrial and extraterrestrial settings, the burgeoning field of molecular-clock dating and topics in the intersection of earth sciences with forensics. The content covers a broad range of techniques and applications. All major accepted dating techniques are included, as well as all major datable materials.
Download or read book Separation of U Th and Ra from Silicates for Uranium Series Dating by Thermal Ionisation Mass Spectrometry written by Robert G. Ditchburn and published by . This book was released on 1995 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Age Determination of Young Rocks and Artifacts written by Günther A. Wagner and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dating the Quaternary, which covers approximately the last 2 million years, has experienced considerable progress over the past few decades. On the one hand, this resulted from the necessity to obtain a valid age concept for this period which had seen tremendous environmental changes and the advent of the genus Homo. On the other hand, instrumental improvements, such as the introduction of highly sensitive analytical techniques, gave rise to physical and chemical innovations in the field of dating. This rapid methodological development is still in full progress. The broad spectrum of chronometric methods applicable to young rocks and artifacts also becomes increasingly intricate to the specialist. Hence, it is my goal to present a comprehensive, state-of-the-art sum mary of these methods. This book is essentially designed as an aid for scientists who feel a demand for dating tasks falling into this period, i. e., Quaternary geologists and archaeologists in the broadest sense. Since it has been developed from a course of lectures for students of geological and archaeological sciences, held at the University of Heidelberg, it certainly shall serve as an introduction for students of these disciplines.
Download or read book Science Based Dating in Archaeology written by M.J. Aitken and published by Routledge. This book was released on 2014-02-25 with total page 295 pages. Available in PDF, EPUB and Kindle. Book excerpt: Archaeologists and archaeology students have long since needed an authoritative account of the techniques now available to them, designed to be understood by non-scientists. This book fills the gap and it offers a two-tier approach to the subject. The main text is a coherent introduction to the whole field of science-based dating, written in plain langauge for non-scientists. Additional end-notes, however, offer a a more technical understanding, and cater for those who have a scientific and mathematical background.
Download or read book The New Nuclear Forensics written by Vitaly Fedchenko and published by Oxford University Press. This book was released on 2015 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nuclear material changes its form and properties as it moves through the nuclear fuel cycle, from one facility to another. Each step of the fuel cycle or each use of the material will inevitably leave its mark. The science of determining the history of a sample of nuclear material through the study of these characteristics is known as nuclear forensics. While nuclear forensic analysis has normally been associated with investigations and prosecutions in the contextof trafficking of nuclear materials or nuclear terrorism, it had wider applications in in national security contexts, such as nuclear non-proliferation, disarmament, and arms control. The New Nuclear Forensics is the first book to give a definitive guide to this broader definition of nuclear forensic analysis. This book describes the various methods used in nuclear forensics, giving first a broad introduction to the process followed by details of relevant measurement techniques and procedures. In each case, the advantages and limitations are outlined. To put these methods in context, the book also recounts the history of the discipline anddescribes the diverse contemporary applications of nuclear forensics.
Download or read book Uranium series Disequalibrium Dating Using Energy filtered ICP Magnetic Sector Multiple Collector Mass Spectrometry written by Xiaozhong Luo and published by . This book was released on 1999 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt:
