Beam dynamic design and study of a linac with variable output energy for an AB-BNCT facility

Abstract

The Accelerator-based Boron Neutron Capture Therapy (AB-BNCT) is being established worldwide as a future modality to start an era of in-hospital facilities. The most popular reaction for AB-BNCT is 7Li(p, n)7Be and high-flux neutron beams can be produced by bombarding lithium targets with low-energy proton beams. We chose the combined acceleration structure of Radio Frequency Quadrupole linac (RFQ) and Cross-bar H-mode DTL (CH-DTL) considering the compactness of the structure and the adjustment of output energy. The CW proton beam could be accelerated to 1.8 MeV by one RFQ cavity, and then to the final energy by one CH-DTL cavity. The output beam energy can be adjusted in the range of 2.2 MeV to 3.0 MeV with small beam loss and high beam quality, which could be achieved by controlling the feed power and RF phase of the CH-DTL. The variation of beam energy can meet requirements of the BNCT in treating tumors of different depths without adjusting structure of beam shaping assembly (BSA). The beam dynamics of the RFQ and DTL were completed to meet all requirements and the energy stability and adjustment method of output beam were investigated. In addition, we also performed the start-to-end beam tracking and error sensitivity analysis at last.