Otwarty dostęp

Accounting for Overcounting Induced by 222Rn Contamination in 14C Measurements Performed with Liquid Scintillation Counting

Maksymilian Jędrzejowski
Maksymilian Jędrzejowski
, 
Danuta J. Michczyńska
Danuta J. Michczyńska
, 
Adam Michczyński
Adam Michczyński
, 
Marzena Kłusek
Marzena Kłusek
 oraz 
Konrad Tudyka
Konrad Tudyka
   | 15 gru 2023
Geochronometria's Cover Image
O artykule
Poprzedni artykuł
Następny artykuł
Zacytuj
Data publikacji: 15 gru 2023
Zakres stron: 91 - 99
Otrzymano: 25 cze 2023
Przyjęty: 03 lis 2023
DOI: https://doi.org/10.2478/geochr-2023-0007
Słowa kluczowe
© 2023 Maksymilian Jędrzejowski et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Fig 1.

Alpha and beta particle spectra of radioactive nuclides in a Quantulus 1220™ liquid scintillation counter with counting windows used at the Gliwice Laboratory (Poland). In most cases, peak from 210Pb would not be observed in radiocarbon dating due to its low probability.
Alpha and beta particle spectra of radioactive nuclides in a Quantulus 1220™ liquid scintillation counter with counting windows used at the Gliwice Laboratory (Poland). In most cases, peak from 210Pb would not be observed in radiocarbon dating due to its low probability.

Fig 2.

Counts spectra for the GdS-4657 sample with counting windows used at the Gliwice Laboratory.
Counts spectra for the GdS-4657 sample with counting windows used at the Gliwice Laboratory.

Fig 3.

Exponential function fitted into (A) – radon and daughter products window, (B) – combined 14C and radon and daughter products window. Fitted functions are shown with a 68.3% confidence band.
Exponential function fitted into (A) – radon and daughter products window, (B) – combined 14C and radon and daughter products window. Fitted functions are shown with a 68.3% confidence band.

Fig 4.

The results of the solved system of equations for the GdS-4657 sample. (A) – Equation corresponding to the radon and daughter products window. (B) – Equation corresponding to the combined 14C and radon and daughter products window. The fitted functions for both equations are shown with a 68.3% confidence band.
The results of the solved system of equations for the GdS-4657 sample. (A) – Equation corresponding to the radon and daughter products window. (B) – Equation corresponding to the combined 14C and radon and daughter products window. The fitted functions for both equations are shown with a 68.3% confidence band.

Fig 5.

Evolution of determined count rate, with a χ2 value versus χcrit2 \chi _{crit}^2 at α = 0.05. Each data point represents a hypothetical scenario where measurements were terminated after a specific cycle, starting from the 10th cycle for the first point, the 11th cycle for the second point, the 12th cycle for the third point, and so on. (A) – Subtraction approach. (B) – System of equations approach.
Evolution of determined count rate, with a χ2 value versus χcrit2 \chi _{crit}^2 at α = 0.05. Each data point represents a hypothetical scenario where measurements were terminated after a specific cycle, starting from the 10th cycle for the first point, the 11th cycle for the second point, the 12th cycle for the third point, and so on. (A) – Subtraction approach. (B) – System of equations approach.

Subsequent decays of the uranium series from 226Ra to 210Pb.

Parent isotope Decay mode Daughter isotope Percentage of decay mode (%) Half-life T1/2 Weighted mean β− decay energy, keV Q value (max energy), keV Major decay branches (>0.5%)
Mean β−energy, keV End-point energy, keV Branching percentages (%)
14C β− 14N 100 5700(30) year 49.47(10) 156.475(4) 49.47(10) 156.475(4) 100
226Ra α 222Rn 100 1600(7) year – 4870.62(25) 4601(1) – 6.16(3)
4784.34(25) 93.84(11)
222Rn α 218Po 100 3.8222(9) day – 5590.4(3) 5489.48(30) – 99.920(10)
218Po α 214Pb 99.980(2) 3.097(12) min – 6114.75(9) 6002.55(10) – 99.9789(20)
218Po β− 218At 0.020(2) 3.097(12) min – 259(12) – – –
218At α 214Bi 99.95(5) 1.27(6) s – 6876.1(26) 6654(5) – 6.90(10)
6693(3) 92.7(5)
218At β− 218Rn 0.05(5) 1.27(6) s – 2883(12) – – –
218Rn α 214Po 100 33.75(15) ms – 7262.5(19) 7129.1(19) – 99.870(4)
214Pb β− 214Bi 100 27.06(7) min 224(5) 1018(11) 48.0(32) 179(11) 2.75(8)
142.8(37) 484(11) 1.063(18)
205.1(39) 666(11) 44.5(7)
225.3(40) 723(11) 39.0(5)
334.5(42) 1018(11) 12.7(9)
214Bi β− 214Po 99.9790(13) 19.71(2) min 641(6) 3269(11) 161.4(38) 540(11) 0.542(22)
247.8(40) 787(11) 1.28(4)
260.5(41) 821(11) 2.78(6)
317.8(42) 976(11) 0.563(16)
351.8(42) 1065(11) 5.56(5)
356.1(43) 1076(11) 0.866(12)
384.7(43) 1150(11) 4.33(4)
424.2(44) 1252(11) 2.459(15)
426.7(44) 1258(11) 1.433(11)
433.1(44) 1274(11) 1.192(21)
474.5(44) 1379(11) 1.589(17)
491.6(44) 1422(11) 8.16(5)
524.9(43) 1504(11) 16.90(11)
539.0(45) 1539(11) 17.55(10)
566.8(45) 1608(11) 0.57(5)
614.9(46) 1726(11) 3.09(4)
667.6(46) 1854(11) 0.90(5)
683.3(46) 1891(11) 7.22(8)
1007.1(47) 2660(11) 0.55(8)
1268.4(48) 3269(11) 19.2(4)
214Bi α 210Tl 0.0210(13) 19.9(4) min – 5621(3) 5273(9) – 5.8(5) a
5452(3) 54(4) a
5516(3) 39(3) a
214Po α 210Pb 100 163.6(3) µs – 7833.46(6) 7686.82(7) – 99.9895(6)
210Tl β− 210Pb 100 1.30(3) min 1.18(16)∙103 5482(12) 477(13) 1380(30) 2.0(10)
568(14) 1600(30) 7.0(20)
674(10) 1860(24) 24(5)
743(11) 2020(30) 10(3)
877.1(69) 2413(17) 10(3)
1635(18) 4210(40) 30(6)
1762.6(54) 4386(12) 20.0(20)
210Pb β− 210Bi 100 22.20(22) year 6.1(6) 63.5(5) 4.16(13) 17.0(5) 84(3)
16.16(13) 63.5(5) 16(3)
210Pb α 206Hg 1.9(3)∙10−6 22.20(22) year – 3792(20) 3720(20) – –

The measurement results for sample without correction, with both methods of exponential corrections, and after aging process.

Sample ID as+bC, min-1 ⋅ g-1 {\boldsymbol {a}}_{\boldsymbol {s + b}}^\boldsymbol {C}\boldsymbol {,}\,{{\bf{min}}^{{\bf{ - 1}}}}\,{\bf{ \cdot }}\,{{\bf{g}}^{{\bf{ - 1}}}} SQP(E) F14C Radiocarbon age, 14C year
GdS-4657 6.420(18) 806.35(30) 0.8318(45) 1480(43)
Immediate, without correction
GdS-4657 6.272(55) 806.35(30) 0.8120(79) 1673(78)
Exponential correction
Subtraction approach
GdS-4657 6.275(24) 806.35(30) 0.8124(48) 1669(48)
Exponential correction
System of equations approach
GdS-4684 6.345(31) 809.89(44) 0.8115(54) 1678(53)
After aging process
eISSN:
1897-1695
Język:
Angielski
Częstotliwość wydawania:
Volume Open
Dziedziny czasopisma:
Geosciences, other
Kanał RSS czasopisma