Cryogenic Scintillation Properties of Lead-Free Cs3Cu2I5 Single Crystals.

Perovskite scintillators have become increasingly popular in recent years because of their simple production and high sensitivity to X-ray. Due to large Stokes shifts, high light yield, eco-friendly fabrication, and good stability, the lead-free Cu-based perovskites have gained much attention. In this paper, we prepared the Cs3Cu2I5 single crystals (SCs) by the solution-processed method. At room temperature, we measured the emission band at 440 nm with an average decay time of 595 ns under X-ray excitation. Under 137Cs γ-ray excitation, we determined that the light yield of Cs3Cu2I5 SCs was 23 000 photons/MeV. Notably, under alpha particle excitation by 241Am, the light yield of Cs3Cu2I5 SCs is approximately 3.2 times higher than that of the commercial scintillator LYSO(Ce). In addition, we systematically investigated the cryogenic scintillation properties of Cs3Cu2I5 SCs at the temperature range of 60-300 K. With decreasing temperature, the intensity of the emission band at 440 nm significantly increases, and an additional emission band at 336 nm emerges below 100 K. Meanwhile, the temperature-dependent decay times were determined. The fast and slow decay time of Cs3Cu2I5 SCs are estimated to be 221 and 1193 ns, respectively, at 60 K. Our findings highlight the great potential for Cs3Cu2I5 SCs to be a cryogenic scintillator.

High-Performance X-ray Detector Based on Single-Crystal ß-Ga2O3:Mg.

X-ray detection plays an important role in medical imaging, scientific research, and security inspection. Recently, the ß-Ga2O3 single-crystal-based X-ray detector has attracted extensive attention due to its excellent intrinsic properties such as good absorption for X-ray photons, a high breakdown electric field, high stability, and low cost. However, developing a high-performance ß-Ga2O3-based X-ray detector remains a challenge because of the large dark current and the high oxygen vacancy concentration in the crystals. In this paper, we report a high-performance Mg-doped ß-Ga2O3 single-crystal-based X-ray detector with a sandwich structure. The reduced dark current enables the detector to have a high sensitivity of 338.9 µC Gy-1 cm-2 under 50 keV X-ray irradiation with a dose rate of 69.5 µGy/s. The sensitivity is 16-fold higher than that of the commercial amorphous selenium detector. Furthermore, the reduced oxygen vacancy concentration can improve the response speed (<0.2 s) of the detector. The present studies provide a promising method to obtain the high performances for the X-ray detector based on ß-Ga2O3 single crystals.

Recoil-proton track imaging as a new way for neutron spectrometry measurements.

Recoil-proton track imaging (RPTI) is an attractive technique to optically record the tracks of recoil protons in scintillation gas by using realtime imaging devices. For the first time, its use as an online nuclear track detector for neutron spectrometry measurements (NSM) is explored. Based on the RPTI methodology for NSM, a very basic detector system is designed, consisting of the neutron-to-proton recoil system and proton track imaging system. Satisfactory performance of the RPTI neutron spectrometer has been examined with a series of Monte Carlo simulations. Moreover, using well-defined line-proton sources from a tandem accelerator, the capability of the detector for imaging proton tracks at the single-particle level in real time has been validated in preliminary experiments. From the clear single proton tracks in the images, the proton ranges were easily distinguished, and precise proton energy spectra were unfolded, laying a solid experimental foundation for the future implementation of NSM.

Transient Radiation Imaging Based on a ZnO:Ga Single-Crystal Image Converter.

A ZnO:Ga single crystal with an applicable size of φ40 × 1 mm was prepared using the hydro-thermal method. The crystal exhibits good crystallinity and scintillation properties with a 63.94-arcsec full-width at half-maximum (FWHM) in the X-ray rocking curve (XRC) spectrum, 8% luminous non-uniformity, emission at 389 nm in the X-ray excited luminescence spectrum, fast response and 5.5% BGO luminous intensity. Furthermore, an X-ray pinhole imaging system of nanosecond temporal resolution with a ZnO:Ga single-crystal image converter was established to diagnose the cathode electron emission spatial distribution of an intense current diode. Results for shutter times of 4 µs and 5 ns were obtained, which directly represent the cathode electron spatial distribution throughout the entire pulse duration and during a certain moment of the pulse, respectively. The results demonstrate that the large ZnO:Ga single crystal can diagnose the spatial distribution of cathode electron emission in an intense current diode with high temporal resolution and provide new solutions for high-temporal-resolution diagnosis of a pulse radiation field.