a b s t r a c tInorganic scintillators are very important in medical and industrial measuring systems in the detection and measurement of ionizing radiation. In addition to Ce 3 þ , a widely used dopant ion in oxide scintillators, divalent Europium (Eu 2 þ ) has shown promise as a high-luminescence, fast-response luminescence center useful in the detection of ionizing radiation. In this research, aluminum oxide (Al 2 O 3 ) was studied as a host material for the divalent europium ion. Polycrystalline samples of Eu 2 þ -doped translucent Al 2 O 3 were fabricated, and room temperature luminescence behavior was observed. Al 2 O 3 ceramics doped with 0.1 at% Eu 2 þ were fabricated with a relative density of 99.75% theoretical density and in-line transmittance of 22% at a wavelength of 800 nm. The ceramics were processed by a gel-casting method, followed by sintering under high vacuum. The gelling agent, a copolymer of isobutylene and maleic anhydride, is marketed under the commercial name ISOBAM, and has the advantage of simultaneously acting as both a gelling agent and as a dispersant. The microstructure and composition of the vacuum-sintered Eu 2 þ :Al 2 O 3 were characterized by Scanning Electric Microscopy (SEM), Transmission Electron Microscopy (TEM), and Energy-dispersive X-ray spectroscopy (EDS). The phase composition was determined by X-ray diffraction measurements (XRD) combined with Rietveld analysis. The photoluminescence behavior of the Eu 2 þ :Al 2 O 3 was characterized using UV light as the excitation source, which emitted blue emission at 440 nm. The radio-luminescence of Eu 2 þ :Al 2 O 3 was investigated by illumination with X-ray radiation, showing three emission bands at 376 nm, 575 nm and 698 nm. Multiple level traps at different depths were detected in the Eu 2 þ :Al 2 O 3 by employing thermoluminescence measurements.
Tl2LiYCl6:Ce (TLYC) is a recently discovered
dual mode gamma-ray and neutron scintillator. So far small crystals
of this composition have been studied, but for practical applications
with affordable price, large-scale crystals are required. In this
work, we present successful efforts to grow crack-free single crystals
with sizes up to ⌀1″ × 5.5″. A variety of
experimental techniques were employed to investigate the scintillation
properties. A ⌀1″ × 1.2″ TLYC cylinder has
a light yield of 25,000 ph/MeV, and its energy resolution is better
than 4% at 662 keV. The gamma equivalent energy (GEE) produced by
thermal neutron is 1.89 MeVee, along with a neutron induced light
yield of 47,000 ph/n. Pulse shape discrimination (PSD) between gamma-rays
and neutrons has been successfully shown with a current Figure-of-Merit
(FOM) of 2.4. This article explores the crystal growth, scintillation
properties, and potential applications of TLYC.
The detection of ionizing radiation is important in numerous applications related to national security ranging from the detection and identification of fissile materials to the imaging of cargo containers. A key performance criterion is the ability to reliably identify the specific gamma-ray signatures of radioactive elements, and energy resolution approaching 2% at 662 keV is required for this task. In this work, we present discovery and development of new high energy resolution scintillators for gamma-ray detection. The new ternary halide scintillators belong to the following compositional families: AM 2 X 5 :Eu, AMX 3 , and A 2 MX 4 :Eu (A = Cs, K; M = Ca, Sr, Ba; X = Br, I) as well as mixed elpasolites Cs 2 NaREBr 3 I 3 :Ce (RE = La, Y). Using thermal analysis, we confirmed their congruent melting and determined crystallization and melting points. Using the Bridgman technique, we grew 6, 12 and 22 mm diameter single crystals and optimized the Eu concentration to obtain the best scintillation performance. Pulse-height spectra under gamma-ray excitation were recorded in order to measure scintillation light output, energy resolution and light output nonproportionality. The KSr 2 I 5 :Eu 4% showed the best combination of excellent crystal quality obtained at fast pulling rates and high light output of ~95,000 photons/MeV with energy resolution of 2.4% at 662 keV.
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