A Negative Pion Beam Transport Channel for Radiobiology and Radiation Therapy at TRIUMF

A five quadrupole, two bending magnet negative pion beam transport channel has been designed to deliver a physical dose of 0.2 rad/sec into a volume of 10 cm × 10 cm × 8 cm thick located at a mean depth of 24 cm. The dose as a function of depth will be varied by a momentum-defining slit which will travel during the irradiation; a second slit in the system will be used to give a sharp lateral cut-off in the dose. Beam size will be varied by appropriately choosing the distances from the second bend to the last quadrupole and from the last quadrupole to the irradiation location. The changes in beam properties due to second-order terms and their correction by sextupole magnets and pole edge curvatures will be described.