Low level radioactivity measurements with phoswich detectors using coincident techniques and digital pulse processing...

Area of Science:

• Nuclear physics and instrumentation.
• Environmental monitoring and radiation detection.

Background:

• The Nuclear Test Ban Treaty (NTBT) necessitates monitoring low levels of gaseous fission products from underground nuclear explosions.
• Existing methods for detecting low radioactivity levels of fission products and actinides can be complex and require radiochemical separation.

Purpose of the Study:

• To develop and present a novel system for the sensitive detection of low radioactivity levels of fission products and actinides.
• To enable simultaneous identification of transuranic nuclides in environmental samples without radiochemical separation.

Main Methods:

• Utilized a phoswich detector for alpha/beta/gamma-ray recognition coupled with a fast digital card for electronic pulse analysis.
• Employed coincidence techniques, specifically alpha/gamma coincidence, to identify specific nuclides.
• Integrated liquid scintillators and a high-resolution low-energy germanium detector to enhance system sensitivity.

Main Results:

• The developed system successfully identifies coincidence events, determining the energy and type of coincident particles.
• Achieved a minimum detectable activity of 0.01 Bq kg(-1) for 0.1 kg of soil with a 1000-minute counting time.
• Demonstrated the capability to simultaneously identify transuranic nuclides in environmental samples via alpha/gamma coincidence.

Conclusions:

• The new system offers improved sensitivity and specificity for detecting low radioactivity levels.
• This technology is valuable for verifying the Nuclear Test Ban Treaty and for environmental radiological analysis.
• The ability to perform simultaneous detection without radiochemical separation significantly advances the field.