Development of embedded-helium nanoparticle targets for nuclear physics

Nuclear reactions involving helium are important for understanding how the chemical elements are produced in stellar explosions and for exploring the fundamental interactions of protons and neutrons inside the nucleus. However helium is a gas at room temperature, and unlike hydrogen, does not form compounds. It is therefore difficult to make targets containing helium. In this project, we address these issues by trapping helium at high density in the porous structures of nanoparticle-assembled thin films. By controlling the size of the nanoparticles, generated by sputtering atoms of silicon, we will be able to finely tune the porosity, thickness and helium density of the resulting targets. The target characteristics will be studied using state of the art microscopes in York, and at the Ion Beam Centre in Surrey before bombardment tests are performed with our collaborators at Argonne National Lab, USA.