HIPPO: A supersonic helium jet gas target for nuclear astrophysics

A high density supersonic helium jet gas target has been developed for the newly installed St. George Recoil Mass Separator, at the Nuclear Science Laboratory, University of Notre Dame. The jet's properties for both helium and nitrogen have been studied by means of elastic scattering and energy loss experiments. The helium jet's full width at half maximum was found to be 2.1 mm, assuming axially symmetric gas expansion with a maximum target thickness of (2.67±0.16)×1017 atoms/cm2 at 1500 mbar of inlet pressure, and well confined within the jet region.