Determination of 131m Xe and 133m Xe in the presence of 133gXe via combined beta-spectroscopy and delayed coincidence

• Published in: Journal of radioanalytical and nuclear chemistry Vol. 248; no. 3
• Main Authors: Reeder, Paul L., Bowyer, Ted W., McIntyre, Justin I., Pitts, W. K.
• Format: Journal Article
• Language: English
• Published: United States 06.01.2001
• Subjects: BETA SPECTROSCOPY; beta-gama coincidence counting; COINCIDENCE METHODS; CTBTO; PLASTIC SCINTILLATORS; RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; Radioxenon; SCINTILLATION COUNTERS; XENON 131; XENON 133; XENON 135
• ISSN: 0236-5731; 1588-2780
• DOI: 10.1023/A:1010668006840

The International Monitoring System for the Comprehensive Nuclear-Test-Ban Treaty will include measurements of Xe fission products. Pacific Northwest National Laboratory has developed an automated system for separating Xe from air which detects Xe fission products using a beta-gamma counting system for 131mXe, 133mXe, 133Xe, and 135Xe. Betas and conversion electrons are detected in a plastic scintillation cell containing the Xe sample. Gamma and X-rays are detected in a NaI(Tl) scintillation detector which surrounds the plastic scintillator sample cell. Two-dimensional pulse height spectra of gamma energy versus beta energy are obtained. The plastic scintillator spectrum in coincidence with the 31-keV X-rays from 131mXe. 133mXe, and 133Xe is a complex mixture of conversion electrons and betas. A new technique to simultaneously measure the delayed coincidence (t1/2 = 6.27 ns) between beta particles from 133Xe and conversion electrons depopulating the 81-keV state in 133Cs is being developed. This technique will allow separation of the 133Xe spectrum from the conversion electrons due to 131mXe and 133mXe and will uniquely quantify all three nuclides.