JAMSTEC Rep. Res. Dev., Volume 12, March 2011, 27 _ 35 1,2* 1 1 1 1 210 Pb 210 Pb 214 Pb MCA 210 Pb MCA MCA 210 Pb 214 Pb 2010 10 4 2010 12 10 1 2 * 237-0061 2-15 046-867-9794 ogurik@jamstec.go.jp 27
210 Pb, 214 Pb Investigation of analytical methods of 210 Pb and 214 Pb nuclides Kazumasa Oguri 1,2*, Saiko Sugizaki 1, Koichi Iijima 1, Tatsuhiko Sakamoto 1, and Hiroshi Kitazato 1 We introduced gamma ray analysis system in order to measure recent sedimentation rates by 210 Pb method and to obtain dose rates of quartz grains in sediments for optically stimulated luminescence (OSL) dating. Because both 210 Pb method and OSL dating require precisional values of the radionuclide concentrations, we compared 210 Pb and 214 Pb concentrations determined by MCA emulation software of the system, Covell's method and curve fitting method, respectively. 210 Pb concentrations in some samples determined by the MCA emulation software showed higher values to compare with other methods. The cause would be in an automatic definition of the baseline by the software during the calculation of the net area of 210 Pb peaks. Keywords: Gamma-ray spectrometry, Covell's method, Curve fit method, 210 Pb, 214 Pb Received 4 October 2010 ; Accepted 10 December 2010 1 Institute of Biogeosciences (Biogeos), Japan Agency for Marine-Earth Science and Technology (JAMSTEC) 2 Marine Technology Center (MARITEC), Japan Agency for Marine-Earth Science and Technology (JAMSTEC) *Corresponding author: Kazumasa Oguri Institute of Biogeosciences (Biogeos), Japan Agency for Marine-Earth Science and Technology (JAMSTEC) 2-15 Natsushima-cho, Yokosuka 237-0061, Japan Tel. +81-46-867-9794 ogurik@jamstec.go.jp Copyright by Japan Agency for Marine-Earth Science and Technology 28 JAMSTEC Rep. Res. Dev., Volume 12, March 2011, 27 _ 35
K. Oguri et al., A 2008 2010 210 Pb 137 Cs 210 Pb 214 Pb Fig. 1 ORTEC, GWL-12030 10 cm, MCA7800 ORTEC, 659 ORTEC, 672 NIM NEC, PC-9801BX4 A/D Fig. 1. Overview of a gamma ray analysis system. 1. JAMSTEC Rep. Res. Dev., Volume 12, March 2011, 27 _ 35 29
210 Pb, 214 Pb Investigation of analytical methods of 210 Pb and 214 Pb nuclides ADC1821 0.5keV 4096 1 2048keV MCA YK08-11 1 cm 60 3 g 12 mm 226 Ra 222 Rn Uranium- Thorium Ore DL-1a Canadian Centre for Mineral and Energy Technology 3 g 10 100 OSL 210 Pb 46.5keV 214 Pb 351.9keV 86400 86400 345600 133 Ba 60 Co 0.5keV/ A/D Table. Radionuclides used for energy calibration, their gamma ray energy and the emission rates.. Radionuclide for Gamma ray Emission energy calibration energy (ke V) rate (%) 133 Ba 80.998 36 133 Ba 276.397 7.5 133 Ba 302.851 19.6 133 Ba 356.005 67 133 Ba 383.851 9.4 60 Co 1173.21 99.92 60 Co 1332.46 100 MCA MCA MCA.csv MS Windows wpkview http://rcwww.kek.jp/hmatsu/specanal/.csv Microsoft, Excel 210 Pb 214 Pb Covell, 1959 30 JAMSTEC Rep. Res. Dev., Volume 12, March 2011, 27 _ 35
K. Oguri et al.,, 1992 N p Fig. 2 n i N L N R (1) (2, 3) N net N n N L N net N P L 1 n i, i= L 2 N P R 0 i= L 0 N R n i L N L R 2 i= R 1 R N P n i N R 2 2 L N L N R R (4) (5) L R L ( R 1 R 2 L 0 R 0 )( R 0 L 0 1), ( L 1 L 2 1) ( R 1 R 2 L 2 L 1 ) (6, 7) L 0 R 0 L 1 L 2 R ( )( R 0 L 0 1) ( R 2 R 1 1) ( R 1 R 2 L 2 L 1 ) 210 Pb 214 Pb 1.5 MCA 1980 2000 F (x) a bx e n i 1 a+bx n h i W i p i i h i 2 2.7726 ( x p ) 1 2 Wi (8) F (x) a bx e h i 2 2.7726 ( x p ) 1 2 Wi wpkview.csv Synergy Software, Kaleida Graph 9 N net (9) Fig. 2. Peak area calculation by Covell's method (Cited after Science and Technology Agency, 1992). 2. 1992 2 p 2 1 W N net h i i e dx h i W i 2.7726 ( x ) (10) 210 Pb 40 53.5keV 214 Pb JAMSTEC Rep. Res. Dev., Volume 12, March 2011, 27 _ 35 31
210 Pb, 214 Pb Investigation of analytical methods of 210 Pb and 214 Pb nuclides 345.5 359keV Fig. 3 210 Pb 210 Pb 214 Pb MCA (10) 17 210 Pb 214 Pb 2.92 0.39keV 3.27 0.44keV Fig. 4(1) (4) MCA 210 Pb 214 Pb Fig. 4 (1) MCA 210 Pb Fig. 4 (1) 210 Pb MCA 1:1 Fig. 4 (2) 214 Pb 0.08Bq g -1 Fig. 3. An image applying curve fit method using with a Kaleida Graph. 3. Kaleida Graph 32 JAMSTEC Rep. Res. Dev., Volume 12, March 2011, 27 _ 35
K. Oguri et al., Fig. 4. Comparison of 210 Pb and 214 Pb concentrations calculated with MCA emulation software, Covell's method and curve fit method: (1) Comparison of 210 Pb concentrations between Covell's method and MCA emulation. (2) Comparison of 210 Pb concentrations obtained by Covell's method and curve fit method. (3) Comparison of 214 Pb concentrations obtained by Covell's method and MCA emulation. (4) Comparison of 214 Pb concentrations obtained by Covell's method and curve fit method. Dashed lines in each figure represent relationship of 1:1. "N" in the graph represents the values that MCA emulation software detected another peak around the 210 Pb or 214 Pb peaks and the baseline area for the calculation was automatically shifted. 4. MCA 210 Pb 214 Pb (1) MCA 210 Pb (2) 210 Pb (3) MCA 214 Pb (4) 214 Pb 1:1 N MCA JAMSTEC Rep. Res. Dev., Volume 12, March 2011, 27 _ 35 33
210 Pb, 214 Pb Investigation of analytical methods of 210 Pb and 214 Pb nuclides MCA MCA Fig. 4 (3) 0.08Bq g -1 3 1:1 Fig. 4 (4) MCA 210 Pb 1991 MCA 1.5 MCA 210 Pb 214 Pb DL-1a 86400 46.5keV 210 Pb 53keV 63.3keV 234 Th Fig. 5 (1) 351.9keV 214 Pb 338.3keV 228 Ac Fig. 5 (2) MCA 351.9keV 214 Pb 35.8% Fig. 5 (2) 214 Pb 210 Pb 4.05% Fig. 5 (1) 210 Pb 214 Pb Fig. 4 (1) N MCA 210 Pb 2.4 MCA 214 Pb Fig.4 (3) N 1.3 210 Pb Fig. 5. 210 Pb (1) and 214 Pb (2) peaks obtained to measure DL-1a reference material. 5. DL-1a 86400 210 Pb (1) 214 Pb (2) 34 JAMSTEC Rep. Res. Dev., Volume 12, March 2011, 27 _ 35
K. Oguri et al., 210 Pb 210 Pb 214 Pb MCA 3 210 Pb MCA 2.4 214 Pb 0.08Bq g -1 MCA 1.3 210 Pb Covell, D.F. (1959), Determination of gamma-ray abundance directly from total absorption peak, Anal. Chem., 31 (11), 1785-1790. 1992 134-143 1980 112-116 1991 2000 15 133-137 6500 A 2008 2010 20244084 JAMSTEC Rep. Res. Dev., Volume 12, March 2011, 27 _ 35 35