Development of transparent ceramic Ce-doped gadolinium garnet gamma spectrometers

Abstract

Abstract-Transparent polycrystalline ceramic scintillators based on the garnet structure and incorporating gadolinium for high stopping power are being developed for use in gamma spectrometers. Optimization of energy resolution for gamma spectroscopy involves refining the material composition for high stopping and high light yield, developing ceramics fabrication methodology for material homogeneity, as well as selecting the size and geometry of the scintillator to match the photodetector characteristics and readout electronics. We have demonstrated energy resolution of 4% at 662 keV for 0.05 cm 3 GYGAG(Ce) ceramics with photodiode readout, and 4.9% resolution at 662 keV for 18 cm 3 GYGAG(Ce) ceramics and PMT readout. Comparative gamma spectra acquired with GYGAG(Ce) and NaI(Tl) depict the higher resolution of GYGAG(Ce) for radioisotope identification applications. Light yield nonproportionality of garnets fabricated following different methods reveal that the fundamental shapes of the light yield dependence on energy are not intrinsic to the crystal structure, but may instead depend on trap state distributions. With exposure to 9 MeV Brehmsstrahlung radiation, we also find that GYGAG(Ce) ceramics exhibit excellent radiation hardness.

Nonproportionality of Scintillator Detectors. V. Comparing the Gamma and Electron Response

“…4 we compare the calculated and measured resolution values where in the case of the GYGAG(Ce) scintillation response as measured with a PMT, and it is apparent that photon statistics play a much larger role in the determination of the resolution, in this case incorporated with . In passing we note that the poorer photon statistics are due to the shift in the emission to longer wavelengths peaking at 550 nm for GYGAG(Ce) [15], [16] compared to (Eu) near to 440 nm where the PMT is much more sensitive. As expected, when the resolution for a small GYGAG(Ce) ceramic on a silicon photodiode is measured, the resolution is 3.5%, in contrast to the PMT-based value of 4.6%.…”

Highly transparent ZrO2-doped (Ce,Gd)3Al3Ga2O12 ceramics prepared via oxygen sintering

“…4. The difference between the refractive indices of ZrO 2 and GAGG phase is significant (2.2 for ZrO 2 and 1.9 for GAGG [25] in the 400-700 nm range) and is sufficient to cause light scattering at grain boundaries due to Rayleigh or Mie scattering. The EDS analysis of Y site confirms that the Zr 4+ ions have partially dissolved into GAGG base material.…”

Preliminary investigation of scintillator materials properties: SrI2:Eu, CeBr3 and GYGAG:Ce for gamma rays up to 9 MeV

“…The development of ceramic scintillator materials offers the possibility to have high-resolution gamma-ray spectroscopy at low cost. Transparent ceramic scintillators, such as GYGAG:Ce, allow gamma-ray spectroscopy performance superior to the most common scintillators [29][30][31][32][33][34]. For high energy gamma spectroscopy, large volume scintillators are required.…”