Developing a high-energy density plasma platform for studying nuclear reactions relevant to the CNO cycle

The CNO cycle dominates energy production in massive stars, and the CNO neutrino flux, which provides insight into the solar core’s metallicity, depends on rates of the CNO cycle reactions that have significant uncertainties at solar temperatures. Traditionally, these nuclear reactions have been studied using accelerators at energies far from the stellar-relevant range. An alternative approach to investigate these reactions involves high-energy density plasmas, which can closely mimic stellar interiors. As a first step toward studying CNO reactions in such environments, the D + ¹³C reaction is used as a surrogate, which has a relatively high cross section at temperatures achievable at OMEGA and has been recently investigated in experiments. However, measured yields were significantly lower than expected. Discrepancies in past accelerator data suggest possible inaccuracies in the ENDF cross section. Two parallel efforts are now underway to resolve this: Experiments at the MIT linear accelerator will investigate whether the problem lies with inaccuracies in the ENDF cross-section data, and an upcoming CNO shot day will help determine whether the low yields are due to errors in detecting protons from the D + ¹³C reaction or due to suppression of the reaction by the HED platform itself. The long term goal of these efforts is to study CNO-relevant reactions in the plasma environment.

This work is supported by NSF under grant number 2409369.