Measuring the ⁸⁸Sr(α, n)⁹¹Zr reaction cross section with Accelerator Mass Spectrometry

Supernovae, the explosive conclusion to nuclear burning in massive stars, dominate contributions to the early galactic abundance of the elements. Different astrophysical scenarios, under which supernovae seed the early galaxy with elements heavier than iron, are still being investigated. Of particular interest are the lighter heavy elements from Sr to Ag with their origin being placed in the neutrino-driven ejecta in core-collapse supernovae. While the s- and r- process have been perceived for years as the dominant mechanisms for the formation of heavier elements, more recent studies support that in particular the elements from Sr to Ag are synthesized via (α, n)-reactions or the so-called “weak” r-process. Sensitivity studies have shown that (α, n) reaction rates of these lighter heavy nuclei indeed play a crucial role in predicting their abundances, suggesting the need of experimental data to constrain the uncertainties on those rates and thus the abundance predictions. The ⁸⁸Sr(α, n)⁹¹Zr reaction has been identified among the key processes that impact these abundances with no experimental data currently available. At the Center for Accelerator Mass Spectrometry of Lawrence Livermore National Laboratory, we measure this reaction using a combination of target irradiation and Accelerator Mass Spectrometry (AMS). This talk focuses on the development of the experimental methods and the preliminary data obtained.