研究目的
To develop a high-resolution radiation imaging detector using LaGPS scintillator combined with a PSPMT and evaluate its performance, including the capability for pulse shape discrimination to separate different types of radiations such as alpha particles, beta particles, and gamma photons.
研究成果
The developed LaGPS imaging detector achieves high spatial resolution for alpha particles (better than 0.31 mm FWHM), beta particles (~0.6 mm FWHM), gamma photons (better than 0.6 mm FWHM), and X-ray (~0.8 mm FWHM). It successfully separates different radiation types using pulse shape discrimination based on decay time differences (143 ns for alpha, 124 ns for beta, 119 ns for gamma). This detector is promising for applications such as plutonium particle detection and environmental monitoring, offering simultaneous imaging and discrimination capabilities.
研究不足
The thickness of the LaGPS scintillator is fixed at 0.5 mm, which may not be optimal for all applications; producing thinner crystals is difficult. The study did not explore variations in scintillator thickness or other materials. The pulse shape discrimination method may have limitations in environments with very high background radiation.
1：Experimental Design and Method Selection:
The study involved designing a radiation imaging detector using a LaGPS scintillator plate optically coupled to a position-sensitive photomultiplier tube (PSPMT). Pulse shape discrimination was employed to differentiate radiation types based on decay time differences.
2：Sample Selection and Data Sources:
A LaGPS plate of dimensions 20 mm × 20 mm ×
3：5 mm thick was used. Radiation sources included Am-241 (alpha particles), Sr-Y-90 (beta particles), Co-57 (gamma photons), and Cs-137 (X-ray). List of Experimental Equipment and Materials:
Equipment included a PSPMT (R8900-100-C12, Hamamatsu Photonics), voltage divider (E7514, Hamamatsu Photonics), digital oscilloscope (DLM2052, Yokogawa), data acquisition system with weight summing boards and A-D converters, and personal computer. Materials included LaGPS plate, silicone rubber (KE420, Shin-etsu Silicone), aluminized Mylar sheet, and tungsten slit masks.
4：Experimental Procedures and Operational Workflow:
The detector was assembled by optically coupling the LaGPS plate to the PSPMT. Decay times were measured using a PMT and oscilloscope. Imaging experiments involved irradiating the detector with different radiation sources through slit masks, acquiring data in list mode, and processing to form images and energy spectra. Pulse shape discrimination was applied by calculating the ratio of partial to full integration values.
5：Data Analysis Methods:
Data were analyzed using FPGA for position calculation and software for image formation, energy spectrum analysis, and pulse shape spectrum calculation. Exponential fitting was done with spreadsheet software for decay time evaluation.
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