Characterization of the Mixed Radiation Fields for BNCT

Mixed radiation fields are normally encountered in the treatment of tumors with ionizing radiations in Boron Neutron Capture Therapy (BNCT). The present thesis describes the characterization and the application of the Bonner sphere spectrometer of university of Pisa (BSS-UNIPI), based on 6LiI (Eu), as neutron spectrometer in investigating neutron beam in mixed fields, as found in BNCT. The shadow cone technique was optimized and applied for the evaluation of the scattered neutrons. The BSS set and shadow cones were used to characterize the 9Be (p, xn) reaction with 5 MeV proton beam, in the framework of TRASCO-BNCT project at the INFN-LNL. Different angles of neutron emission (0°, 40°, 80°, and 120°) were considered. Evaluation of the response matrix for the BSS was carried out by using a Monte Carlo code in the neutron energy range from 1E -8 to 100 MeV. The neutron spectrum was obtained by a proper unfolding code applying to the experimental BSS data and the response function matrix. The BSS-UNIPI was coupled with the shadow cone technique. The result showed satisfactory agreement with other authors. BSS-UNIPI coupled with the shadow cone technique can be used for determination of neutron spectra in BNCT facility and other mixed fields.