학술논문

Maximum Likelihood Spectrum Decomposition for Isotope Identification and Quantification
Document Type
Periodical
Source
IEEE Transactions on Nuclear Science IEEE Trans. Nucl. Sci. Nuclear Science, IEEE Transactions on. 69(6):1212-1224 Jun, 2022
Subject
Nuclear Engineering
Bioengineering
Detectors
Isotopes
Standards
Calibration
Monitoring
Government
Inverse problems
Gamma-ray detection
gamma-ray detectors
gamma-ray spectroscopy
isotope identification
maximum likelihood expectation maximization (MLEM)
Monte Carlo methods
nuclear measurements
nuclide identification
radioactive decay
semiconductor radiation detectors
spectral analysis
spectral decomposition
Language
ISSN
0018-9499
1558-1578
Abstract
A spectral decomposition method has been implemented to identify and quantify isotopic source terms in high-resolution gamma-ray spectroscopy in static geometry and shielding scenarios. Monte Carlo simulations were used to build the response matrix of a shielded high-purity germanium detector monitoring an effluent stream with a Marinelli configuration. The decomposition technique was applied to a series of calibration spectra taken with the detector using a multi-nuclide standard. These results are compared with decay-corrected values from the calibration certificate. For most nuclei in the standard ( 241 Am, 109 Cd, 137 Cs, and 60 Co), the deviations from the certificate values were generally no more than 6% with a few outliers as high as 10%. For 57 Co, the radionuclide with the lowest activity, the deviations from the standard reached as high as 25%, driven by the meager statistics in the calibration spectra. In addition, a complete treatment of error propagation for the technique is presented.