CURRENT MEASUREMENT ON MEV ENERGY ION-BEAMS

It is a crucial problem to obtain the number of incident particles in MeV energy ion beam techniques. To solve this problem a simple but powerful method, the transmission Faraday cup is suggested. A rotating beam chopper periodically detects the beam current. To eliminate the disturbing current of the secondary electrons it is surrounded on both sides by a Faraday cup. Additional mechanical shields as well as electrostatic and magnetic fields keep away the charged particles different from the ions of the incident beam. The (p, γ) reaction and He RBS test measurements show that the particle number reproducibility is better than 1% and 2%, respectively. The reproducibility in the charge measurement was found to be ~ 0.6%. © 1990.