Abstract
Measurements of dose rate and penetration in water have been made for neutron beams produced by 30-75 MeV protons on beryllium. The effects of polythene filters added on the target side of the collimator have also been studied. A neutron beam comparable with a photon beam from a 4-8 MeV linear accelerator can be produced with p/Be neutrons plus 5 cm polythene filtration, with protons in the range 50-75 MeV. This is a more economical method than use of the d/Be reaction.