Novel measurement of Zr-88 cross section supports value orders of magnitude larger than predicted*

The cross section of nuclei - linked to the likelihood of their accepting neutrons at a certain energy - is an essential value for understanding nuclear reactions, as nuclei with higher cross sections absorb more neutrons. Accordingly most nuclei have well-documented cross section spectra, typically obtained through the activation method, where the sample is bombarded with neutrons and the unique gamma emissions of the new isotope are measured to find the rate of nuclear conversion, from which is found the cross section. Due to the nature of this method, radioisotopes prove much harder to measure, as their radioactivity obscures the gamma rays needed for the measurement. Because of these difficulties, predictive models were typically used in place of spectrum data for radioisotopes. When Zr-88 was measured in 2019 by Schusterman et al., the value they obtained was a shocking five orders of magnitude greater than predicted by the model. Here we support this result with our finding also being far larger than the predicted value of around 10 barns: the 2019 finding was 861,000 +/- 69,000 barns and our finding 1,102,000 +/- 167,000 . Our results support the notion that Zr-88’s cross section is far larger than originally supposed, and the discrepancy between our result and Schusterman’s suggests this is still in need of more study. The magnitude of this finding is relevant to almost all areas of nuclear science, as radioisotope cross sections are just beginning to be studied, and isotopes with large cross sections are highly useful in medical and reactor physics.