Real-Time Measurement of Ion Energies for Heavy Ions

Abstract

A real-time position detection system is developed for measuring heavy ions with low fluence and energy of several hundred MeV, which are generated from an azimuthally varying field (AVF) cyclotron accelerator. We investigate the photoluminescence of α-Al2O3 single crystals implanted with Eu (Al2O3:Eu), which is used in the detection system. The Al2O3:Eu scintillators with a fluence of 3.0 × 1016 cm−2 are annealed at 500–900°C. The annealing conditions required for the Al2O3:Eu scintillators to obtain the maximum luminescence are 0.5 h at 600°C. The scintillator is placed on the AVF cyclotron target stage under atmospheric pressure and is irradiated by 260-MeV Ne. An inverted confocal microscope with a ×10 objective lens is positioned behind the Al2O3:Eu scintillator, and the luminescent images during ion irradiation are obtained by a position-sensitive camera unit with a 512 × 512 pixel electron multiplying charge-coupled device. The images indicate that our online measurement system has a sufficient spatial resolution, since the luminous diameter induced by irradiation with 190 ions /s is almost the same as that of the microbeam.