Static, Mixed-Array Total Evaporation for Improved Quantitation of Plutonium Minor Isotopes in Small Samples

Abstract

Abstract. Actinide isotope measurements are a critical signature capability in the modern nuclear forensics Btoolbox^, especially when interrogating anthropogenic constituents in realworld scenarios. Unfortunately, established methodologies, such as traditional total evaporation via thermal ionization mass spectrometry, struggle to confidently measure low abundance isotope ratios (<10 -6 ) within already limited quantities of sample. Herein, we investigate the application of static, mixed array total evaporation techniques as a straightforward means of improving plutonium minor isotope measurements, which have been resistant to enhancement in recent years because of elevated radiologic concerns. Results are presented for small sample (~20 ng) applications involving a well-known plutonium isotope reference material, CRM-126a, and compared with traditional total evaporation methods.

Isotopic analysis of sub‐nanogram neodymium loads using new ATONA™ amplifiers

“…Second, when the value of the amplification resistor in the feedback circuit is increased to allow for the measurement of smaller ion beams, the dynamic range of the Faraday cup‐RTIA combination is reduced, limiting the maximum ion beam current that can be measured on a given RTIA 8,9 . This problem can be overcome for some isotope systems by using a mixed array of amplifiers 2,10–12 with larger ion beams measured on lower value (10 10 Ω or 10 11 Ω) RTIAs and smaller ion beams measured on higher value RTIAs (10 12 Ω or 10 13 Ω). However, a mixed value RTIA array introduces issues of variable settling times associated with different value amplifiers and challenges with gain calibration and drift for resistors of different values.…”

“…7 Second, when the value of the amplification resistor in the feedback circuit is increased to allow for the measurement of smaller ion beams, the dynamic range of the Faraday cup-RTIA combination is reduced, limiting the maximum ion beam current that can be measured on a given RTIA. 8,9 This problem can be overcome for some isotope systems by using a mixed array of amplifiers 2,[10][11][12] with larger ion beams measured on lower value (10 10 Ω or 10 11 Ω)…”

Investigation of the crucial factors affecting accurate measurement of strontium isotope ratios by total evaporation thermal ionization mass spectrometry

“…Theoretically, if the sample loaded on the filament is totally exhausted and the ion currents are integrated, the mass‐dependent bias will be completely avoided, which is the basic concept of total evaporation thermal ionization mass spectrometry (TE‐TIMS), first described by Callis et al By using TE‐TIMS, the repeatability and accuracy of isotopic analysis can be significantly improved without additional internal normalization or external normalization using certified reference materials (CRMs) . Therefore, its applications quickly expanded from U and Pu to other elements such as Ra, Nd, B, Re, Cr, Zr, Eu, Yb, etc. More attractively, with reliable method verification and proper uncertainty evaluation, TE‐TIMS has the potential to be an absolute method for the assignment of certified values of isotopic reference materials.…”

Improved Uranium Isotope Ratio Analysis in Liquid Sampling–Atmospheric Pressure Glow Discharge/Orbitrap FTMS Coupling through the Use of an External Data Acquisition System

“…TIMS instruments are large, complex, and expensive while having low throughput as a result of often-tedious sample preparation processes. 1,5,6 Extensive chemical separations are required in most cases to minimize chemical matrix effects in the form of ionization large capital input, both in up-front costs and consumables, requiring argon flow rates of up to 14 L min −1 . While the sample preparation for ICP-MS is not as extensive as for TIMS, chemical separations are often necessary to alleviate isobaric interferences, even in the case of high resolution (m/ Δm ≈ 10000) sector-field instruments.…”

“…Thermal ionization mass spectrometry (TIMS) and inductively coupled plasma-mass spectrometry (ICP-MS), particularly on multicollector, sector-field platforms, have long been the gold standards for isotope ratio (IR) analysis due to their abilities to obtain high precision measurements. − Unfortunately, whereas these instruments provide high precision measurements, each method is not without its drawbacks. TIMS instruments are large, complex, and expensive while having low throughput as a result of often-tedious sample preparation processes. ,, Extensive chemical separations are required in most cases to minimize chemical matrix effects in the form of ionization suppression and complex-ion formation as well as to alleviate potential isobaric interferences. ICP-MS instruments require large capital input, both in up-front costs and consumables, requiring argon flow rates of up to 14 L min –1 .…”