Development of a beam-profile monitor for cyclotron MC50

Abstract

A current sensor module was designed and fabricated to measure the beam profile of the cyclotron MC50 at Korea Institute of Radiological & Medical Sciences (KlRAMS). The sensors were made of tungsten wire, and they were assembled into an array. The sensor wires were placed in parallel with the incident beam whereas, in the convention method, they are placed in a direction perpendicular to the incident beam. The current output of each sensor was amplified using a trans-resistance amplifier. The front-end stage of this amplifier was implemented using discrete circuit elements and could measure input currents in the range of 1pA to 1 mu A. The amplifier had a resolution of similar to 20 fA, a temperature drift of similar to 0.5 pA/degrees C, and a signal-to-noise ratio greater than 80 dB. Various test results of the amplifier and sensor module assembly are given in this paper. The measured current profiles of the cyclotron beam line at KIRAMS are also given.