A high resolution radiation imaging detector using a ceramic YGAG scintillator plate

Ce doped (YGd)3(GaAl)5O12:Ce (YGAG) is a ceramic scintillator originally developed for X-ray computed tomography (CT). It has high light output and is also a promising candidate for high resolution event-by-event radiation imaging detectors. Thus we developed a radiation imaging detector using a YGAG plate combined with a position sensitive photomultiplier tube (PSPMT) and evaluated the performance. The spatial resolution for Am-241 alpha particles (5.5 MeV) was ~0.4 mm FWHM and the energy resolution was 12 % FWHM. The spatial resolution for Sr-Y-90 beta particles, Am-241 gammas (60 keV) and Cs-137 X-ray (~35 keV) was 0.8 mm FWHM, 1.6 mm FWHM and 2.0 mm FWHM, respectively. The decay time difference of YGAG between 5.5 MeV alpha particles and 662 keV Cs-137 gammas was 37 ns and the pulse shape spectra for 5.5 MeV alpha particles and 662 keV Cs-137 gammas were separated without overlap with the figure of merit (FOM) of 1.14. It was possible to separate the alpha particle and gamma photon images using pulse shape discrimination. Using pulse shape discrimination, it was also possible to separate the alpha particles and gamma photons in the electrostatically collected radon daughters on the imaging detector. We conclude that the developed YGAG imaging detector is useful for high resolution radiation detector with pulse shape discrimination capability to discriminate the different types of radiations.