Measurement of the Beam Energy Distribution of a Medical Cyclotron with a Multi-Leaf Faraday Cup

摘要

Accurate knowledge of the beam energy distribution is crucial for particle accelerators,compact medical cyclotrons for the production of radioisotopes in particular. For this purpose,a compact instrument was developed, based on a multi-leaf Faraday cup made of thin aluminum foilsinterleaved with plastic absorbers. The protons stopping in the aluminum foils produce a measurablecurrent that is used to determine the range distribution of the proton beam. On the basis of the protonrange distribution, the beam energy distribution is assessed by means of stopping-power MonteCarlo simulations. In this paper, we report on the design, construction, and testing of this apparatus,as well as on the first measurements performed with the IBA Cyclone 18-MeV medical cyclotron inoperation at the Bern University Hospital.