Ionisation Chambers Containing Boron as Neutron Detectors in Mixed Radiation Fields

The paper presents a newly designed ionisation chambers containing boron, operated in the initial recombination regime. The chambers were either filled with BF₃ or the chamber electrodes were covered with B₄C. The chambers can be placed in paraffin moderators. The sensitivity of the chambers was investigated depending on gas pressure, moderator thickness and polarizing voltage. The results showed that it was possible to obtain nearly the same sensitivity of the chamber to H* (10) for photons and neutrons in restricted energy range, however further investigations are needed to make an optimum design. The examples of applications for dosimetric measurements in mixed radiation fields near medical linear accelerator and in the vicinity of high-energy proton accelerator are presented.