Enhancing the detection sensitivity of a high-resolution β - γ coincidence spectrometer

Area of Science:

• Nuclear physics and analytical chemistry.
• Nuclear non-proliferation and treaty verification.

Background:

• The Comprehensive Nuclear-Test-Ban Treaty (CTBT) relies on detecting radioxenon isotopes.
• Existing laboratory systems face challenges in detecting specific isotopes in complex mixtures.

Purpose of the Study:

• To establish and calibrate a high-resolution beta-gamma coincidence spectrometry system for enhanced radioxenon isotope analysis.
• To improve the detection sensitivity and lower the detection limits for radioxenon isotopes indicative of nuclear explosions.

Main Methods:

• Setup and calibration of a novel coincidence spectrometry system using high purity germanium (HPGe) and PIPSBox detectors.
• Utilizing an ultra-low-background lead shield and new software to combine signals from four detectors.
• Measurement of radioxenon isotope samples and background acquisitions to determine detection limits.

Main Results:

• Achieved detection limits of 1.3 mBq for 133Xe and ≤0.3 mBq for 131mXe and 133mXe.
• Demonstrated high detection sensitivity even with interfering signals from other radioxenon isotopes.
• Showcased improved detectability of metastable isomers (131mXe, 133mXe) compared to current systems.

Conclusions:

• The developed high-resolution coincidence system significantly enhances the capability to detect radioxenon signatures of nuclear explosions.
• This advanced system offers improved performance for re-measuring samples from the CTBT International Monitoring System (IMS).
• The system provides crucial advancements for nuclear non-proliferation efforts by improving the detection of critical radioxenon isotopes.