Neutron-Induced Reactions in Inertial Confinement Fusion experiments and the Curious Case of the 42Ar Nuclide

Michael Paul (Racah Institute of Physics, Hebrew University of Jerusalem)

Inertial confinement fusion experiments at the National Ignition Facility (NIF), Lawrence Livermore National Laboratory, are the closest laboratory analog of explosive nucleosynthesis sites in terms of their thermodynamic properties. Neutron densities in the range of 10^22-24 n/cm³ achieved in deuterium-tritium (DT) implosions are similar to those believed present in stellar sites of rapid (r-) process. We investigated neutron-induced reactions on ⁴⁰Ar seeds doped in a DT-filled capsule imploded at NIF, namely the fast-neutron reaction ⁴⁰Ar(n,2n)³⁹Ar (t_1/2 = 268 yr) and the neutron capture reaction ⁴⁰Ar(n,γ)⁴¹Ar (110 min); we specifically searched also for ⁴²Ar(33 yr) possibly produced by a rapid two-neutron capture ⁴⁰Ar(2n,γ)⁴²Ar process. While ³⁹Ar and ⁴¹Ar production is observed with yields consistent with simulations, the measured ⁴²Ar yield is much larger than expected from two-neutron rapid captures. The seminar will describe the experiments, the detection technique for the three Ar isotopes and our present understanding of ⁴²Ar production.