1. Degradation of 81 keV 133Xe gamma-rays into the 31 keV X-ray peak in CsI scintillators.
- Author
-
Keillor, Martin E., Cooper, Matthew W., Hayes, James C., and McIntyre, Justin I.
- Subjects
- *
XENON isotopes , *GAMMA ray detectors , *BETA rays , *SCINTILLATORS , *CESIUM , *SIMULATED annealing , *MONTE Carlo method - Abstract
Pacific Northwest National Laboratory uses beta-gamma coincidence detectors in a number of xenon sampling and measurement systems to enable simultaneous, sensitive measurements of 131Xe, 133Xe, 133mXe, and 135Xe for treaty monitoring applications. In recent years, a new style of beta–gamma detector was developed to improve upon the detector module used in the Automated Radioxenon Sampler/Analyzer. The results of an MCNP5 Monte Carlo simulation of the new detector cell are presented, with particular emphasis on the identification of an energy deposition sequence with the potential to introduce significant error into the detector efficiency calibration. This sequence occurs when an 81 keV gamma from 133Xe is absorbed in an inactive region of the CsI(Na) scintillator, followed by emission of a 31 keV X-ray from cesium (or possibly a 28.5 keV X-ray from iodine). These X-rays add excess counts into the 31 keV peak observed in the decay of 133Xe. The impact of this effect on different efficiency calibration techniques is discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF