GEnerating extreme NEutrons for achieving controlled r-process nucleosyntheSIS

ended

The project aim is to perform the first direct measurements of neutron capture and beta-decay rates related to the “r-process” of nucleosynthesis. This process, based on squeezing at once multiple neutrons in a nucleus, is presently thought to be the main mechanism that forms the heaviest elements in our Solar System and in stars. At present, there are large discrepancies between the observed element abundances in stars and those found from simulations. It is speculated that this problem stems from the uncertainties in nuclear parameters, particularly in the plasma environment. These nuclear parameters have not been experimentally verified due to the too-low flux of current neutron facilities and the lack of means to create on-site hot and dense plasmas. Lasers are not the first thing that comes to mind as a neutron source, but with the upcoming ultra high-power laser facilities (Apollon in 2018 and ELI-NP in 2019), high-density and high-energy protons can be generated. Through spallation, these can then produce neutrons with the needed flux, a flux comparable to that found in Supernovae. To further emulate the astrophysical scenario, auxiliary lasers can be used to turn the target material into a plasma. In practice, this project will aim to measure neutron capture and beta-decay rates, as well as yields and abundances of the products of nucleosynthesis obtained by exposing heavy-ion targets to laser-produced extreme neutron fluxes. These targets will be either in a plasma or a solid state. In plasmas, we will investigate the effect of excited nuclear states, created by the plasma photons and electrons, on neutron capture. In solid targets, we will take advantage of the unique possibility of generating on-site unstable nuclei, and then re-expose them to the neutron beam in order to measure double neutron capture.