Time-domain based evaluation of detection efficiency in liquid scintillation counting

Area of Science:

• Nuclear Physics
• Analytical Chemistry
• Instrumentation

Background:

• Liquid scintillation counting (LSC) is a primary technique for measuring radioactivity.
• Traditional LSC analysis focuses on pulse height and shape, with less attention paid to signal timing.
• Understanding signal timing can provide additional information for improving LSC accuracy.

Purpose of the Study:

• To explore the information content of the time interval distribution between photomultiplier tube (PMT) signals in LSC.
• To develop a theoretical model for the cross-correlation distribution of PMT signals.
• To validate the model and assess its utility for improving LSC measurements.

Main Methods:

• Derivation of a theoretical model for the cross-correlation distribution of PMT signals.
• Monte Carlo simulations to validate the theoretical model.
• Experimental validation using low-energy beta-emitting and electron-capture radionuclides with LSC systems and cocktails.

Main Results:

• The cross-correlation distribution contains information about scintillation event detection probability.
• The derived model accurately describes the cross-correlation distribution.
• Parameters like peak height and kurtosis of the distribution serve as effective detection efficiency estimators and quenching indicators.
• Experimental results with various radionuclides confirm the model's predictions.

Conclusions:

• The time domain and cross-correlation distribution offer significant potential for improving LSC applications, particularly for low-energy emitters.
• This approach can enhance activity determination and provide better quenching assessment.
• The findings pave the way for developing novel LSC systems with improved performance.