Bismuth-fission detectors for high energy nucleons: I. Registration characteristics

There is considerable current interest in the detection of high energy nucleons around accelerators, spallation sources, and in cosmic rays. A detector that has its principal response at nucleon-energy above 50 MeV is provided by the fission of Bi-209. The problem of limited sensitivity has been solved by: a) spark counting large detector areas, b) reducing the detector background by special counting procedures, c) using many replicates of a thin track detector between two ²⁰⁹Bi-radiators. Finally, the registration efficiency has been evaluated and determined experimentally using proton beams with energies of 100, 150, and 250 MeV.