On the Study of Energy Spectra and Angular Distributions of the Neutrons Emitted from a Beryllium Target Bombarded with 4-MeV Protons for Neutron Capture Therapy

Abstract

Due to the recent advancement of the technologies in high-current proton accelerators, neutron sources based on 2.5 MeV proton bombarding a lithium (Li) target have been vigorously studied in the past few years^1,2 and was thought to be feasible for neutron capture therapy (NCT). Neutrons are generated based on the ⁷Li(p,n)⁷Be reactions and then moderated with beryllia (BeO) or heavy water (D₂O). For a treatment time of 1 hour it was determined that a proton current of 30 mA might be necessary. This intense proton beam is achievable with the newly available radio-frequency quadrupole (RFQ) accelerator³. However, because Li has a low melting point (179°C) and a low thermal conductivity (45 W/m°C), the removal of the immense heat (75 kW) from the Li target imposes a big challenge on the target design. In addition, Li is very reactive chemically, and it thus further complicates the target design in order to provide proper access for system maintenance⁴.