Precise and accurate uranium isotope analysis by modified total evaporation using 10¹³ ohm current amplifiers

This study presents analytical advances in thermal ionization mass spectrometry for uranium isotope analysis involving minor isotopes. The potential of 10¹³ ohm current amplifiers for detecting minor isotope ion beams down to the 10 kcps range during modified total evaporation analyses is assessed on sub-microgram U loads, which is one order of magnitude less material than typical. Sub-‰ to ‰ precision and accuracy may be achieved for uranium isotopic ratios in the 10^-5 to 10^-4 range. This is 1.2-2.9 times better than expected from scaling down the performance achieved on microgram loads using 10¹² ohm current amplifiers. (author)