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High-quantity and large-size β-Ga2O3 single crystals were grown by the optimal edge-defined film-fed method. Under the excitation of 241Am α-ray, the scintillation light yields of the as-grown and after-annealed β-Ga2O3 single crystal are estimated to be 4797 and 6788 ph/5.5 MeV-α, respectively. The energy resolutions of the as-grown and after-annealed β-Ga2O3 single crystal are 21.8% and 19.1%, respectively. Annealing in the air can eliminate some color centers and decrease the concentration of free electrons, which can lead to the near-infrared absorption. The light yield and the energy resolution are some slightly worse than that of the commercial Bi4Ge3O12 (BGO) scintillator. However, the fast component with the time constant of 7 ns for the as-grown and after-annealed β-Ga2O3 single crystal reaches 25% of the total yield, suggesting that the β-Ga2O3 single crystal grown by the present method is a promising fast scintillator, which could be used in the ultrafast timing resolution detection systems. [ABSTRACT FROM AUTHOR]

A detector based on the plastic scintillator film with large-area photonic crystals has been designed and demonstrated for measuring pulsed neutron flux. Compared with the reference detector, the neutron sensitivity and the gamma sensitivity of the detector using the scintillator film with photonic crystals were enhanced by more than 20%, which is attributed to the improved light extraction efficiency and the controllable angular profile of scintillation light by the photonic crystal. The application of the photonic crystals is beneficial to the improvement of the signal-to-noise ratio of the detector in the calibration experiment, thus expanding the lower limit of the measurable neutron flux without sacrificing the ratio of the neutron sensitivity to the gamma sensitivity. This research indicates that photonic crystals play an important role in the fields where scintillation photons need to be extracted and collected as many as possible. [ABSTRACT FROM AUTHOR]

Phosphorescence is a fascinating photoelectronic phenomenon usually observed in rare-earth-doped inorganic crystals and organic molecular crystals, owning great potential in optical information storage, color display and biological dosimetry. Here, we present an ultralong intrinsic phosphorescence (>20,000 seconds) in AlN single-crystal scintillator through X-ray excitation. We suggest that the long afterglow emission originates from the intra-band transition related to native nitrogen vacancy. Some excited states formed by absorbing X-ray photons cannot satisfy the parity difference between initial and final states required by transition selection rule, so they cannot return to the ground state directly through radiation transitions but through several phonon-assisted intra-band transitions slowly. During this process, a long-term broad-spectra phosphorescence emission is formed. Investigating the X-ray excited phosphorescence emission in the AlN is of great significance to understanding the mechanism of phosphorescence in inorganic materials, and to realizing the practical applications in high-energy ray dosimetry. Phosphorescence emission from extrinsic rare-earth element and organic component remains a challenge. Here, the authors demonstrate an ultraviolet ultralong intrinsic phosphorescence (UIP, >20,000 seconds) in aluminum nitride (AlN) single-crystal scintillator through X-ray excitation. [ABSTRACT FROM AUTHOR]

This paper describes the change of the luminescent properties of GS20 irradiated by X-rays and alpha particles at different low temperatures with a wide range from 60 K to about 310 K. The light yield (LY) of GS20 declines with the drop of the temperature of GS20 when either X-rays or alpha particles irradiate the GS20. Under the excitation of X-rays, the LY of GS20 nearly does not change until the temperature is lower than 180 K and the shape of the luminescent spectra does not change with the drop in temperature. However, the LY of GS20 irradiated by alpha particles gradually declines below 180 K as the temperature drops, and declines faster than that under the excitation of X-rays. Due to the principles of GS20 detecting neutrons and γ -rays, the results obtained by alpha particles and X-rays can reflect the temperature dependence of the GS20 response to neutrons and γ -rays, respectively. Therefore, we can infer that the low temperature is disadvantageous in neutron/gamma discrimination. This study is useful for reference in applications of GS20 at low temperatures and necessary for other peers to understand the luminescent mechanism of this amorphous scintillator better. [ABSTRACT FROM AUTHOR]

To acquire the direct time response of ZnO crystals to high energy particles, a dual-channels single photon correlation (DCSPC) system based on the measurement of the autocorrelation function of the fluoresce temporal profile was employed. The measuring resolution of the DCSPC system calibrated by Cerenkov luminescence is 46 ps. With this DCSPC system, the fast decay time constants of ZnO:Ga, ZnO:In and ZnO:Sc under charged particle alpha and beta excitation were successfully measured, which are 1.56 ns, 0.48 ns, 0.12 ns, and 1.11 ns, 0.40 ns, 0.10 ns, respectively. For all the three samples, it is found that the decay time constants under beta excitation are faster than those under alpha excitation, indicating that ZnO crystal is a fast scintillation material with pulse shape discrimination (PSD) ability. This would be applied in selective detection of mixed radiation field, particularly where high counting rate is required. [ABSTRACT FROM AUTHOR]

In this investigation, β -Ga 2 O 3 single crystals were grown by the Floating Zone method. At room temperature, the X-ray excited emission spectrum includes ultraviolet and blue emission bands. The scintillation light output is comparable to the commercial BGO scintillator. The scintillation decay times are composed of the dominant ultra-fast component of 0.368 ns and a small amount of slightly slow components of 8.2 and 182 ns. Such fast component is superior to most commercial inorganic scintillators. In contrast to most semiconductor crystals prepared by solution method such as ZnO, β -Ga 2 O 3 single crystals can be grown by traditional melt-growth method. Thus we can easily obtain large bulk crystals and mass production. [ABSTRACT FROM AUTHOR]

We have demonstrated that the scintillation light output of CsI(Na) crystals can be enhanced by photonic crystals consisting of arrays of nanospheres. The photonic crystals on the surfaces of the CsI(Na) crystals were prepared by a dry-transfer technology which is a suitable method for hygroscopic scintillators. Under the excitation of X-ray, compared with a reference sample, a 2.79-fold wavelength-integrated enhancement has been obtained for the optimal photonic crystal parameters. The increased light output could improve the performance of scintillator-based detectors. • Photonic crystals were prepared on the hygroscopic CsI(Na) scintillators. • Photonic crystals can enhance the light output of CsI(Na). • Increased light output can improve the performance of detectors. [ABSTRACT FROM AUTHOR]

We report a method for the preparation of fast scintillation composite material based on CsI(Na) micron-scale particles. The composite material was prepared by solidifying CsI(Na) micron-scale particles in an epoxy resin adhesive. The scintillation properties under X-ray excitation were investigated. The luminescence time characteristic of the CsI(Na) composite material is significantly improved, with the fall time range of 15.6–19.6 ns, over 20 times faster than that of bulk single crystal CsI(Na). Furthermore, the deliquescence property of CsI(Na) is overcome. The luminescence spectra show that the Na-related luminescence and self-trapped excitons luminescence of the composite material are strongly concentration-dependent. This kind of composite material could be a promising scintillator used in fast pulse X-ray detection. [ABSTRACT FROM AUTHOR]