Optimisation of neodymium hydroxide micro-precipitation of polonium-210 for alpha spectrometry source preparation

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South Pacific Environmental Radioactivity Association
Co-precipitation of actinides with lanthanide hydroxides is a suitable technique to prepare high resolution sources for alpha spectrometry. One such technique has been adapted and optimised for co-precipitation of 210Po with Nd(OH)3. Chemical recovery greater than 90%, with a resolution less than 40 keV at full-with-half-maximum (FWHM) was achieved. The method can be faster, less expensive and less labour intensive than routine techniques using auto-deposition of Po onto Ag. Owing to co-precipitation of several metals with Nd(OH)3, including Fe and alpha emitting radionuclides, radiochemical separation of 210Po from the sample matrix is required for this method to be effective. The technique, however, does effectively separate Po from Cu, and is thus highly suited to samples where complete radiochemical separation from Cu is difficult to achieve, such as copper concentrates. The method also achieves 94±2% separation of 210Po from Pb. A common technique for measurement of 210Pb uses an initial separation of 210Pb from 210Po and then allows time for ingrowth of 210Po. A second radiochemical separation is then performed for 210Po, measurement of which is used to infer the initial activity concentration of 210Pb. Effective separation of 210Po and 210Pb using Nd(OH)3 co-precipitation can therefore simultaneously radiochemically separate these two isotopes and prepare 210Po for alpha spectrometry. Thus, reducing radiochemical processing for 210Pb analysis when measured through ingrowth of 210Po. As Bi is also co-precipitated with Nd(OH)3 with this method, a correction factor for contribution from 210Bi to the 210Po activity measured may be required. Biological samples were processed using microwave-assisted digestion followed by radiochemical separation for 210Pb and 210Po. Co-precipitation of 210Po with Nd(OH)3 was done on the 210Po fraction from both separated fractions, a delay after radiochemical separation for the 210Pb fraction was allowed for ingrowth of 210Po. Results from these measurements will be presented.
Neodymium hydroxides, Polonium 210, Alpha spectroscopy, Neodymium, keV range, Separation processes, Precipitation
Medley, P., Patterson, S., Howell, N., & Froehlich, M. (2022). Optimisation of neodymium hydroxide micro-precipitation of polonium-210 for alpha spectrometry source preparation. Paper presented to SPERA 2022 - Connecting people, developing solutions for a changing environment, Christchurch, New Zealand, 28-30 November 2022, (pp. 33). Retrieved from: https://au-admin.eventscloud.com/file_uploads