  The Department of Nuclear Engineering, University of California Berkeley
built a D-D neutron generator called the High Flux Neutron Generator (HFNG). It
operates in the range of 100-125 keV of accelerating voltage. The generator
produces neutron current of about 10^8 per second. These neutrons have energies
between 2.2-2.8 MeV. We report here the results of a measurement of the
scattered vs unscattered neutron fluence on polyethylene determined via neutron
activation of multiple natural indium foils from a D-D neutron generator. Both
the angle-integrated spectrum and the angle differential results are consistent
with the predictions of the Monte Carlo N-Particle Transport (MCNP) code, using
the ENDF/B-VII.1. This supports shielding calculations in the fast energy
region with high density polyethylene (HDPE). To the best of our knowledge no
integral benchmark experiment has been performed on polyethylene using
D(D,n)alpha neutron spectrum.
