Helium Targets for Low-Energy Deuteron Bombardment

The $^{\mathrm{3}}$He(d,p)$\alpha $ reaction can produce protons with energies in excess of 20 MeV at deuteron bombarding energies of 3 MeV. This makes it a useful accelerator-based reaction for calibrating CR-39 plastic detectors with high energy protons. Helium targets are most frequently made via ion implantation. This approach confines the Helium in the inner atomic structure of a thin Palladium getter. The getter is produced by evaporating Pd at 2963 $^{\circ}$C on a glass slide treated in a releasing agent and carbon substrate. The 4 $\mu$m thickness film is then placed in a pure Helium environment and heated to 300 $^{\circ}$C for 4 hours. The targets were bombarded with 3 MeV protons generated by SUNY Geneseo's 1.7 MV Pelletron Accelerator. Analysis of the elastically scattered Helium ion was used to determine the concentration of Helium as a function of the beam heating and vacuum chamber evaporation.