New neutron‐rich isotopes of several rare‐eath elements have been identified using the 252Cf‐based ISOL facility at the INEL. New isotopes observed to date, with values of their half‐lives in parentheses, are 153Pr (4.28±0.11 s), 155Nd (8.9±0.2 s), 156Nd (5.47±0.11 s), 157Pm (10.50±0.12 s), 158Pm (4.8±0.5 s), 162Eu (10.6±1.0 s) and 164Gd (45±3 s). Also, new half‐life values have been measured for 151Pr (18.90±0.07 s), 152Pr (3.7±0.2 s), 153Nd (28.9±0.4 s), 154Nd (25.9±0.2 s), 153Pm (315±1 s), 155Pm (41.5±0.2 s), 156Pm (26.70±0.10 s), 157Sm (483±2 s), 158SM (318±2 s), 159Sm (11.37±0.15 s), 160Sm (9.6±0.3 s) and 161Eu (24±4 s). The half‐life values are compared to the results of theoretical predictions.

A three-step method has been developed for extracting trace amounts of selenium from biological samples for neutron activation analysis /NAA/. After acid digestion, the sample is first extracted with lead diethyldithiocarbamate at pH 4 to remove a number of interfering elements. Next, selenium is extracted with sodium diethyldithiocarbamate into chloroform at pH 1.5. Finally, selenium is back-extracted with concentrated nitric acid for NAA. Analysis of selenium extracted from four standard reference materials resulted in excellent agreement with the certified values of selenium concentration. A detection limit of 0.05 μg has been achieved.

The independent isomer yield ratio for /sup 90/Rb from thermal neutron fission of /sup 235/U has been measured by use of a new technique involving a pulsed reactor and an on-line mass spectrometer facility. The apparent isomer yield ratio was measured for different ion collection time intervals and extrapolated to zero collection time to eliminate interference from /sup 90/Kr decay. The observed isomer yield ratio of 8.7 +- 1.0 is one of the largest ratios measured for a low energy fission process. However, a statistical model analysis shows that the average angular momentum ( = 4.5) deduced from this isomer yield ratio is consistent with average angular momentum for other products from low energy fission. 7 refs.

The decay rate of chemically purified 241Pu source material was determined by observation of the in-growth of the 59.5-keV γ-ray from the decay of the 241Am daughter over a period of 154 days. From the resulting source calibration and measurements of γ intensities, emission probabilities were determined for four γ-rays from the decay of 241Pu and for eight γ-rays from the decay of its 237U daugther. The uncertainties in the emission probabilities were less than 1% for the 148-keV γ-ray from 241Pu, and for the 65-, 165-, 208-, and 268-keV γ-rays from 237U. Uncertainties for the remaining γ-rays were between 1.0 and 4.2%. The applicability of the various transitions to the quantitative assay of 241Pu is discussed.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSolvent extraction of molybdenum from biological samples and from coal fly ash for neutron activation analysisW. M. Mok, Henry. Willmes, and C. M. WaiCite this: Anal. Chem. 1984, 56, 13, 2623–2624Publication Date (Print):November 1, 1984Publication History Published online1 May 2002Published inissue 1 November 1984https://doi.org/10.1021/ac00277a086RIGHTS & PERMISSIONSArticle Views67Altmetric-Citations13LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (295 KB) Get e-Alerts Get e-Alerts