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The Application of Full Spectrum Analysis to NaI(Tl) Gamma Spectrometry for the Determination of Burial Dose Rates Cover

The Application of Full Spectrum Analysis to NaI(Tl) Gamma Spectrometry for the Determination of Burial Dose Rates

Geochronometria
Volume 48 (2021): Issue 1 (January 2021)
By: Minqiang Bu,  Andrew S. Murray,  Myungho Kook,  Jan-Pieter Buylaert and  Kristina J. Thomsen  
Open Access
|Dec 2021

Figures & Tables

Fig. 1

Drift correction reference spectrum KUTh mix, and drift-corrected spectra from 40K, 238U and 232Th calibration standards and background.

Fig. 2

Illustration of the agreement of a calculated fitted spectrum with the original sample spectrum, together with fitting residuals in each channel.

Fig. 3

(a–c) Minimum detection limits (MDLs) for activities of 40K, 238U and 232Th, respectively, defined as random uncertainty approaching 30%, when random uncertainty is expressed as a function of expected activity (AEXP); (d–f) Comparison of measured 40K, 238U and 232Th activity concentration (AMEAS) and expected activity concentration (AEXP), showing the accuracy of measurement and FSA analysis. The error bars in panels (d-f) shows the random uncertainty.

Fig. 4

Normalized deviations between those activity concentrations for 40K, 238U and 232Th (a–c), and total (β + γ) dose rates (d) determined by the NaI(Tl) spectrometer and those determined by an HPGe spectrometer, for 20 geological samples. The shaded regions represent ±5% deviation in panels (a–c), and ±4% deviation in panel (d). The standard deviation for 20 data in each subpanel show a high measurement precision on NaI(Tl) spectrometer. All error bars in panel (a-c) and in panel (d) are derived from the total uncertainties of ACNaI and ACHPGe, and total uncertainties of DRNaI and DRHPGe, respectively.

Fig. 5

Activity concentrations (a-c) and total dose rate (d) of a natural sample (LD962) counted with different counting time on NaI(Tl spectrometer. The horizontal dashed line in the centre of shaded region in each subpanel represents the activity concentration (a-c) and total dose rate (d) from HPGe spectrometer. All error bars in panel (a-c) and in panel (d) denote the total uncertainties of ACNaI, and total uncertainties of DRNaI, respectively.

Fig. 6

Dependence of relative total dose rate uncertainty on counting time, for a sample containing 235, 8.6, and 8.3 Bq·kg−1 of 40K, 238U and 232Th, respectively and a total dose rate of 1.09 Gy·ka−1.

Average ratios of ACNaI/ACHPGe and DRNaI/DRHPGe (n = 20)_

Average ratio
40K0.995 ± 0.005
238U0.984 ± 0.005
232Th1.005 ± 0.006
Total dose rate0.993 ± 0.004

Updated 40K, 238U and 232Th activity concentration per ppm for dose rate derivation_

RadionuclideActivity concentration (Bq·kg−1)Uncertainty (Bq·kg−1)
40K3173
238U12.9220.025
232Th4.0610.029

Comparison of MDLs (Bq·kg−1) from different studies_

NuclideNaI(Tl) spectrometer (Sample weight: 0.23 kg)HPGe spectrometer (Sample weight: 0.25 kg)
FSA (This study)3-Window (Bu et al., 2018)(Murray et al., 2018)
40K4.8210.6
238U0.44.00.04
232Th0.32.10.03
DOI: https://doi.org/10.2478/geochr-2020-0009 | Journal eISSN: 1897-1695
Journal RSS Feed
Language: English
Page range: 161 - 170
Submitted on: Feb 15, 2019
|
Accepted on: Oct 28, 2019
|
Published on: Dec 31, 2021
Published by: Sciendo
In partnership with: Paradigm Publishing Services
Publication frequency: 1 issue per year
Keywords:
NaI(Tl) detector,
scintillation gamma spectrometry,
full spectrum analysis (FSA),
minimum detection limit (MDL),
burial dose rate measurement,
OSL dating
Related subjects:
Geosciences,
Geosciences, other

© 2021 Minqiang Bu, Andrew S. Murray, Myungho Kook, Jan-Pieter Buylaert, Kristina J. Thomsen, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

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