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γ-ray energies for 40K, 108Ag and the 226Ra decay chain
NUCLEAR
INSTRUMENTS
AND M E T H O D S
166 (1979) 5 4 7 - 5 4 9 ;
(~) N O R T H - H O L L A N D
PUBLISHING
CO.
7-RAY ENERGIES FOR 4°K, l°8mAg AND THE 2Z6Ra DECAY CHAIN* R. G. HELMER, R. J. G E H R K E and R. C. GREENWOOD
Idaho National Engineering Laboratory, EG & G Idaho, Inc., Idaho Falls, Idaho 83401, U.S.A. Received 23 July 1979 The energies of several y rays from long-lived sources have been measured to provide calibration lines for Ge semiconductor detectors. Energy values obtained are: for 4°K, 1460.830(5)keV; and for ~°8mAg 433.936(4), 614.281 (4)and 722.929(4)keV. Values for thirteen ),-rays in the 226Ra decay chain from 609-2447 keV are also given.
The energies of several 7-rays emitted in the decay of 4°K (1.28×109 y), l°SmAg (127 y) and the 226Ra (1.60×103y) decay chain have been measured. Since these isotopes have long halflives they may conveniently be used for energy calibration of y-ray spectra. (The latter two isotopes are also useful for relative detector efficiency calibrations.) This work is a continuation of our previously reported ~-ray energy studies~-4). The energies Work performed under the auspices of the US Department of Energy.
reported in refs. 3 and 4 and in the present work are all on an energy scale based on the measurement by Kessler et al. 5) of the absolute wavelength of the 411 keV, y-ray from the decay of ~98Au. This wavelength, combined with a conversion factor from the latest adjustment of the fundamental constants6), corresponds to 411.80441(108) keV. The characteristics of the sources used in this study were as follows. The ~°8mAg source also contained ~l°mAg which was used as the principal calibration isotope. The 4°K source consisted of 320 mg of KCl enriched to 79% in 4°K and was coun-
TABLE I Measured y-ray energy differences. Parent isotope
40K
108mAg
226Ra chain
Transitions in difference
1460-1384 (1 lOmAg) -1475 (1 lOmAg) -1505 (J 10rnAg) 433-446 614-620 722-706 -744
(110mAg) (ll0mAg) (110mAg ) (ll0rnAg)
609-602 (124Sb) -620 (110rnAg) 768-790 (124Sb) 806-790 024Sb) 1408-1489 (144Ce-Pr) 1509-1489 (144Ce--Pr) 1661-1674 (58Co) 1684-1674 (58Co) 1729-1674 (58Co) 1764-1729 (226Ra) 2118-2034 (56Co) -2185 (144Ce--Pr) 2204-2185 (laace---Pr) 2447-2598 (56Co)
Number of measurements
a2
Average difference Value (eV)
Uncertainty am (eV)
8 8 8
0.68 a 0.42 0.49
76 530 14 961 44 207
8 5 5
4 4 4 4
0.35 0.71 1.92 1.47
12 875 6 079 16 248 21 350
3 3 4 4
7 4 7 7 8 8 4 4 4 4 4 5 5 3
0.23 0.09 1.15 1.23 0.69 0.34 1.38 0.63 0.89 0.32 0.58 0.49 0.19 0.83
6 590 11 040 22 339 15 479 8l 155 20 069 13 409 9 302 54 915 34 898 83 801 67 106 18 426 150 765
2 4 8 8 6 7 11 19 10 8 11 13 20 9
a All values in this column are reduced - Z 2 values from the calculation of the average energy.
R. G. HELMER et al.
548 TABLE 2 )'-ray energies. Parent isotope 4°K
108mAg
226Ra chain
Calibration line or method 1384(110mAg) 1475(ll0mAg) 1505 (110mAg) 446( ] 10mAg) 620 (1 ]0m Ag) 706( ~10mAg) 744( ]l°m Ag) 602(]24Sb) 620( ~10mAg) 790(124Sb) 790024Sb) 1489 ( 144Ce-Pr) 1489(144Ce-Pr) 1674(58Co) 1674 (58Co) 1674(58Co) 1729(226Ra) 2034(56Co) 2185(144Ce-Pr) 609 + 1509 sum 2185 ( ]44Ce-Pr) 609+ 1684 sum 2598 (56Co)
y-ray energy (keV) Individual Average 1460.830(8) 1460.827(6) 1460.833 (6)
722.930 722.927 609.320(4) 609. 320 (5)
2118.560(15) 2118.556(14) 2118.545(9)
ted in a 1.5 cm diameter bottle. The 226Ra source was sealed by welding between two 0.025 cm thick stainless steel disks to retain the radon datighter activity. The measurement and spectral analysis techniques used have been described previously~'2). All spectra were measured with source-detector distances such that the shifts 7) in the apparent peak energies, due to differences in source-detector distance between these sources and the calibration sources, were negligible. These measurements give the energy differences listed in table 1. The associated uncertainty is computed from the uncertainties for the peak positions involved and the consistency of the individual values as indicated by the reduced - x 2 value given. The y-ray energies determined from these energy differences are given in table 2. The three uncertainties given in this table are: the measurement uncertainty, ~rm, including the contributions from the calibration line and that in table 1; the energy scale uncertainty, at, of 2.63 ppm3-5); and the total uncertainty, at, which is the sum in
~Yrn
Uncertainties (eV) ar
at
1460.830
4
3.8
5
433.936 614.281 722.929
4 4 4
1.2 1.6 1.9
4 4 4
609.320
3
1.6
4
768.373 806.191 1408.005 1509.229 1661.321 1684.032 1729.645 1764.543 2118.551
10 10 7 8 14 21 13 16 7
2.0 2.1 3.7 4.0 4.4 4.4 4.5 4.6 5.6
10 10 8 9 15 21 14 16 9
2204.091 2293.347 2447.695
13 21 15
5.8 6.0 6.4
14 22 16
quadrature of o-m and at. The energies of the calibration lines were taken from refs. 3 and 4. The usefulness of the 4°K ?~-ray energy for calibration purposes may be quite limited since, besides being difficult to obtain a source of convenient size, this line appears in the background radiation spectrum. Due to the variation in the apparent energy of a peak with source position7'8), the observed background peak is not at the energy given in table 2. For the closed-ended coaxial detector, ND-5, the observed peak energy was 1460.83, 1460.93 and 1461.02 keV for ?,-rays entering from the front, side and back, respectively, of the detector. These values were determined relative to the calibration ),-rays entering the front of the detector. The apparent energy of the 4°K peak in the background is then some average of these values which depends on the spacial origin of the background radiation.
The authors wish to acknowledge the assistance of V. J. Novick in the measurement of these spectra.
y-RAY E N E R G I E S
References
1) R.C. Greenwood, R.G. Helmer and R.J. Gehrke, Nucl. Instr. 2) R.G. Instr. 3) R.G. Instr. 4) R.C.
and Meth. 77 (1970) 141. Helmer, R,C. Greenwood and R.J. Gehrke, Nucl. and Meth. 96 (1971) 173. Helmet, R.C. Greenwood and R.J. Gehrke, Nucl. and Meth. 155 (1978) 189. Greenwood, R.G. Helmet and R.J. Gehrke, Nucl.
549
Instr. and Meth. 159 (1979) 465. 5) E.G. Kessler, R. D. Deslattes, A. Henins and W.C. Sauder, Phys. Rev. Letters 40 (1978) 171. 6) E. R. Cohen and B.N. Taylor, J. Phys. Chem. Ref. Data 2 (1973) 663. 7) R. G. Helmet, R.J. Gehrke and R.C. Greenwood, Nucl. Instr. and Meth. 123 (1975) 51. s) K. Shizuma, H. Inoue, Y. Yoshizawa, E. Sakai and M. Katagiri, Nucl. Instr. and Meth. 157 (1978) 117.
INSTRUMENTS
AND M E T H O D S
166 (1979) 5 4 7 - 5 4 9 ;
(~) N O R T H - H O L L A N D
PUBLISHING
CO.
7-RAY ENERGIES FOR 4°K, l°8mAg AND THE 2Z6Ra DECAY CHAIN* R. G. HELMER, R. J. G E H R K E and R. C. GREENWOOD
Idaho National Engineering Laboratory, EG & G Idaho, Inc., Idaho Falls, Idaho 83401, U.S.A. Received 23 July 1979 The energies of several y rays from long-lived sources have been measured to provide calibration lines for Ge semiconductor detectors. Energy values obtained are: for 4°K, 1460.830(5)keV; and for ~°8mAg 433.936(4), 614.281 (4)and 722.929(4)keV. Values for thirteen ),-rays in the 226Ra decay chain from 609-2447 keV are also given.
The energies of several 7-rays emitted in the decay of 4°K (1.28×109 y), l°SmAg (127 y) and the 226Ra (1.60×103y) decay chain have been measured. Since these isotopes have long halflives they may conveniently be used for energy calibration of y-ray spectra. (The latter two isotopes are also useful for relative detector efficiency calibrations.) This work is a continuation of our previously reported ~-ray energy studies~-4). The energies Work performed under the auspices of the US Department of Energy.
reported in refs. 3 and 4 and in the present work are all on an energy scale based on the measurement by Kessler et al. 5) of the absolute wavelength of the 411 keV, y-ray from the decay of ~98Au. This wavelength, combined with a conversion factor from the latest adjustment of the fundamental constants6), corresponds to 411.80441(108) keV. The characteristics of the sources used in this study were as follows. The ~°8mAg source also contained ~l°mAg which was used as the principal calibration isotope. The 4°K source consisted of 320 mg of KCl enriched to 79% in 4°K and was coun-
TABLE I Measured y-ray energy differences. Parent isotope
40K
108mAg
226Ra chain
Transitions in difference
1460-1384 (1 lOmAg) -1475 (1 lOmAg) -1505 (J 10rnAg) 433-446 614-620 722-706 -744
(110mAg) (ll0mAg) (110mAg ) (ll0rnAg)
609-602 (124Sb) -620 (110rnAg) 768-790 (124Sb) 806-790 024Sb) 1408-1489 (144Ce-Pr) 1509-1489 (144Ce--Pr) 1661-1674 (58Co) 1684-1674 (58Co) 1729-1674 (58Co) 1764-1729 (226Ra) 2118-2034 (56Co) -2185 (144Ce--Pr) 2204-2185 (laace---Pr) 2447-2598 (56Co)
Number of measurements
a2
Average difference Value (eV)
Uncertainty am (eV)
8 8 8
0.68 a 0.42 0.49
76 530 14 961 44 207
8 5 5
4 4 4 4
0.35 0.71 1.92 1.47
12 875 6 079 16 248 21 350
3 3 4 4
7 4 7 7 8 8 4 4 4 4 4 5 5 3
0.23 0.09 1.15 1.23 0.69 0.34 1.38 0.63 0.89 0.32 0.58 0.49 0.19 0.83
6 590 11 040 22 339 15 479 8l 155 20 069 13 409 9 302 54 915 34 898 83 801 67 106 18 426 150 765
2 4 8 8 6 7 11 19 10 8 11 13 20 9
a All values in this column are reduced - Z 2 values from the calculation of the average energy.
R. G. HELMER et al.
548 TABLE 2 )'-ray energies. Parent isotope 4°K
108mAg
226Ra chain
Calibration line or method 1384(110mAg) 1475(ll0mAg) 1505 (110mAg) 446( ] 10mAg) 620 (1 ]0m Ag) 706( ~10mAg) 744( ]l°m Ag) 602(]24Sb) 620( ~10mAg) 790(124Sb) 790024Sb) 1489 ( 144Ce-Pr) 1489(144Ce-Pr) 1674(58Co) 1674 (58Co) 1674(58Co) 1729(226Ra) 2034(56Co) 2185(144Ce-Pr) 609 + 1509 sum 2185 ( ]44Ce-Pr) 609+ 1684 sum 2598 (56Co)
y-ray energy (keV) Individual Average 1460.830(8) 1460.827(6) 1460.833 (6)
722.930 722.927 609.320(4) 609. 320 (5)
2118.560(15) 2118.556(14) 2118.545(9)
ted in a 1.5 cm diameter bottle. The 226Ra source was sealed by welding between two 0.025 cm thick stainless steel disks to retain the radon datighter activity. The measurement and spectral analysis techniques used have been described previously~'2). All spectra were measured with source-detector distances such that the shifts 7) in the apparent peak energies, due to differences in source-detector distance between these sources and the calibration sources, were negligible. These measurements give the energy differences listed in table 1. The associated uncertainty is computed from the uncertainties for the peak positions involved and the consistency of the individual values as indicated by the reduced - x 2 value given. The y-ray energies determined from these energy differences are given in table 2. The three uncertainties given in this table are: the measurement uncertainty, ~rm, including the contributions from the calibration line and that in table 1; the energy scale uncertainty, at, of 2.63 ppm3-5); and the total uncertainty, at, which is the sum in
~Yrn
Uncertainties (eV) ar
at
1460.830
4
3.8
5
433.936 614.281 722.929
4 4 4
1.2 1.6 1.9
4 4 4
609.320
3
1.6
4
768.373 806.191 1408.005 1509.229 1661.321 1684.032 1729.645 1764.543 2118.551
10 10 7 8 14 21 13 16 7
2.0 2.1 3.7 4.0 4.4 4.4 4.5 4.6 5.6
10 10 8 9 15 21 14 16 9
2204.091 2293.347 2447.695
13 21 15
5.8 6.0 6.4
14 22 16
quadrature of o-m and at. The energies of the calibration lines were taken from refs. 3 and 4. The usefulness of the 4°K ?~-ray energy for calibration purposes may be quite limited since, besides being difficult to obtain a source of convenient size, this line appears in the background radiation spectrum. Due to the variation in the apparent energy of a peak with source position7'8), the observed background peak is not at the energy given in table 2. For the closed-ended coaxial detector, ND-5, the observed peak energy was 1460.83, 1460.93 and 1461.02 keV for ?,-rays entering from the front, side and back, respectively, of the detector. These values were determined relative to the calibration ),-rays entering the front of the detector. The apparent energy of the 4°K peak in the background is then some average of these values which depends on the spacial origin of the background radiation.
The authors wish to acknowledge the assistance of V. J. Novick in the measurement of these spectra.
y-RAY E N E R G I E S
References
1) R.C. Greenwood, R.G. Helmer and R.J. Gehrke, Nucl. Instr. 2) R.G. Instr. 3) R.G. Instr. 4) R.C.
and Meth. 77 (1970) 141. Helmer, R,C. Greenwood and R.J. Gehrke, Nucl. and Meth. 96 (1971) 173. Helmet, R.C. Greenwood and R.J. Gehrke, Nucl. and Meth. 155 (1978) 189. Greenwood, R.G. Helmet and R.J. Gehrke, Nucl.
549
Instr. and Meth. 159 (1979) 465. 5) E.G. Kessler, R. D. Deslattes, A. Henins and W.C. Sauder, Phys. Rev. Letters 40 (1978) 171. 6) E. R. Cohen and B.N. Taylor, J. Phys. Chem. Ref. Data 2 (1973) 663. 7) R. G. Helmet, R.J. Gehrke and R.C. Greenwood, Nucl. Instr. and Meth. 123 (1975) 51. s) K. Shizuma, H. Inoue, Y. Yoshizawa, E. Sakai and M. Katagiri, Nucl. Instr. and Meth. 157 (1978) 117.