研究目的
To introduce light power spectra as a new tool for relative light yield determinations, providing a reliable measurement method for low-yield scintillators.
研究成果
The power derivative procedure combined with the LS-6500 spectrometer enables reliable light yield measurements down to 2% of high-yield scintillators using small samples in a laboratory. Results for LAB+PPO systems fit a two-exponential model of light evolution, suggesting efficient excitation transfer followed by self-quenching. The method is applicable to water-based scintillators, though with larger errors at very low yields, and supports further development in low-yield scintillator research.
研究不足
The method may be affected by sample positioning variations relative to the source, leading to correlated errors in Ntot and Ptot. The two-photon trigger in the LS-6500 cuts off spectra at low channels, potentially distorting measurements for very low-yield materials. Oxygen quenching in samples is not fully accounted for, though relative measurements mitigate this. The procedure assumes ideal conditions that may not hold for all scintillator types.
1：Experimental Design and Method Selection:
The study uses Compton scattering of gamma rays from a 137Cs source to excite scintillator samples, with light collected, digitized, and stored. A power derivative method is applied to transform event spectra into power spectra for analysis.
2：Sample Selection and Data Sources:
Samples include liquid scintillators with varying PPO concentrations in LAB, toluene-based scintillators, pure LAB, water-based liquid scintillators (WbLS-1 and WbLS-5), and instrument blanks (e.g., black vial, empty vial, vial with water).
3：List of Experimental Equipment and Materials:
Beckman LS-6500 Scintillation Spectrometer, 137Cs gamma-ray source, standard 20-ml Pyrex scintillation vials, samples of LAB, PPO, MSB, toluene, water, and WbLS formulations.
4：Experimental Procedures and Operational Workflow:
Samples are placed in vials and analyzed sequentially by the LS-6500 in quench mode with a fixed 137Cs source. Data acquisition time is 30 minutes per sample, with spectra digitized and stored. Event and power spectra are derived and smoothed, and derivatives are calculated to find marker positions.
5：Data Analysis Methods:
Spectra are smoothed using a polynomial function, derivatives are computed, and Gaussian fits are applied to derivative peaks. Light yields are determined from derivative maxima, and total events (Ntot) and total power (Ptot) are integrated. Statistical analysis includes Gaussian fits and Pearson's correlation coefficient.
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