A compensated coaxial Faraday cup for absolute bunched proton beam current determination

To measure the time structure and absolutely accurate amplitude of charged pulse particle beam for a Faraday cup is a challenge. To address this issue, we develop a Compensated Coaxial Fast Faraday Cup (CCFFC) which preserves the high-frequency component of the electrical signal generated by the pulsed charged particles. The CCFFC is designed to measure the absolute amplitude of the pulsed proton beam current. We discuss the compensation principle of the detector and evaluate its accuracy. The experimental results show a good agreement with the nominal beam current, with the difference less than 3% for the proton energy ranging from 2.5 to 10 MeV. The response time of the CCFFC is 128 ps.