Inductively coupled plasma-mass spectrometry (ICP-MS) was used to concurrently determine multiple long-lived (t_ > 104 y) actinide isotopes in soil samples. Ultrasonic nebulization was found to maximize instrument sensitivity. Instrument detection limits for actinides in solution ranged from 50 mBq L-I (ngPu) to 2 _Bq L-I (23SU). Hydride adducts of n2Th and 238U interfered with the determinations of 233U and 239pu; thus, extraction chromatography was used to eliminate the sample matrix, concentrate the analytes, and separate uranium from the other actinides. Alpha spectrometric determinations of 23°Th, ngPu, and the 234U/nsU activity ratio in soil leachates compared well with ICP-MS determinations; however, there were some small systematic differences (ca. 10%) between ICP-MS and _-spectrometric determinations of 234U and 238U activities.
Refractive x-ray lenses have been fabricated using deep x-ray lithography. Lenses were produced directly in 1-to 6-mm-thick sheets of polymethylmethacrylate (PMMA) with as many as 100 cylindrical lenses along the optical axis. The fabrication process consists of exposing the PMMA sheets to highenergy synchrotron radiation through a mask of 50-micron-thick gold on silicon and subsequent development in ketone. The lenses are suitable for use in synchrotron radiation from a bending magnet at the Advanced Photon Source in the energy range of 8-16 keV. Results of measurements of focus quality, flux density gain, and scatter are presented and discussed with regard to the quality of lens material and fabrication method. Means for improving the performance of the lenses is discussed.
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