Beryllium-boron relative sensitivity factors for melilitic glasses measured with a NanoSIMS ion microprobe

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The short-lived radionuclide ¹⁰Be (t_1/2 = 1.4 Myr) present in the Early Solar System (ESS) provides important information about the astrophysical environment in which the solar system formed. However, the origin of ¹⁰Be in the ESS remains controversial. To reveal its origin, it is important to determine precise and accurate ¹⁰Be abundances in meteoritic components. The initial ¹⁰Be/⁹Be ratio can be estimated using ion microprobe analysis and a ¹⁰B/¹¹B-⁹Be/¹¹B correlation. The relative sensitivities for Be and B must be determined to obtain ⁹Be/¹¹B ratios of unknowns. Here, we report Be/B relative sensitivities for synthetic melilitic glasses and silica-rich NIST SRM 610 glass measured with a NanoSIMS ion microprobe. The Be/B relative sensitivities for melilitic glasses are identical to that of the NIST 610 glass within uncertainties, which suggests that the matrix effects, at least between the NIST 610 glass and melilite, are not significant with respect to Be-B measurements. The present results confirm that the observed variations in the ¹⁰Be/⁹Be ratios for CV calcium-aluminum-rich inclusions (CAIs) are real and the origin of ¹⁰Be must be attributed to irradiation by the active early sun. It is also inferred that the ¹⁰Be/⁹Be ratios of fractionation and unidentified nuclear effect (FUN) CV CAIs are not significantly lower than those for normal (non-FUN) CV CAIs, suggesting similar formation conditions.