A scintillator detector for beam tuning of low-energy single electron accelerator

Abstract

Nine scintillator detectors were developed for beam tuning of low-energy single electron accelerator instead of the picoammeter and Faraday cup, both of which will be insensitive to the weak-current beam lower than picoampere. The detectors are based on plastic scintillator and photomultiplier tube (PMT) and the beam is 100 Hz pulsed electrons in the energy range of 0.1 to 50 MeV. The beam flux was tuned from about 10 $$^7$$ to quasi-single electron for each bunch according to the measurement results of these detectors installed along the beam pipe and after slits. In order to determine the number of electrons in a bunch, the gains of each PMT were finely calibrated, and the energy response of each detector was calibrated with $$^{207}$$ Bi radioactive source. Moreover, the deposited energy in the plastic scintillator, the electron detection efficiency and light collection efficiency, as a function of electron incident energy, were also simulated in detail by Geant4. Nine detectors worked well at a gain of $$0.6\times 10^6$$ after installation in the beam pipe, and the number of electrons in a bunch could be measured at each detector position. The single electron peak was seen when the beam reached the final detector. The commissioning result shows that the beam was tuned to quasi-single electron level successfully and the scintillator detector is an effective method to measure the weak-current beam lower than picoampere.