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Precise measurements of gamma ray energies and intensities in the 166mHo decay
Nuclear Instruments and Methods 203 North-Holland Publishing Company
339
(1982) 339-341
PRECISE MEASUREMENTS OF GAMMA RAY ENERGIES AND INTENSITIES IN THE -Ho DECAY S.S SOOCH, Ravinder KAUR, Nirmal SINGH and P.N . TREHAN Dapnrrmenr of Physics, P.'yab Unir-irr, Clm'uifgarh-160014, Mdia Received 9 November
1981
and in revised form 1 April
1982
Gamma-rayenergies of 46 transitions in the decay of "°""' Ho have been mcasured precisely using a 64 .1 cat' (i¢I Li) deu."ctor. I his isotope is suggested as a calibrating source for the efficiency of Ge(Li) detectors in the region from 80 keV -, 14 .% keV.
The photopeak efficiency of a Gc(Li) detector is usually determined by usingaselected set of gamma ray sources having peaks distributed uniformly over a specified range of energies. For this purpose, the gamma ray intensities of the sources to be used must be known precisely. A number of radioactive sources, such its . "Co. 6)CO, t33B a 152Eu, tut-Ag, s'Y, -Cs, "'Mn . 22 Na have been used for calibration purposes by various found to be a convenient single workers. "'"'Ho is ,. source for such calibration work . It decays by ß t66Er with subsequent emission emission to the levels of of a number of well separated and fairly strong gamma rays . Its long life (Tt;2= 1200 y) makes it still more useful as a universal source for calibration of Ge(Li) detectors . The use of t66'Ho provides -a single source for intensity as well as energy calibration of Gc(Li) detectors in theenergy region of 80-1450 keV . t66mHo' were obtained The radioactive sources of from the National Bureau of Standards, Washington, D.C., U.S.A . in the form of HoCl 3 solution. Two types of sources were used for the' gamma ray singles spectra measurements . In one type, the source was evaporated on a mylar film in a circular region of about 3 mm diameter by the National Bureau of Standard for us . In the second type, a line source of about 3 mm diameter and about 10 mm length in cylindrical perspex holder was prepared at our own laboratory from the liquid source supplied by NBS. The count rate of these sources was less than 1000 counts per second and thus no pile-up corrections were necessary. The singles data were taken by placing the sources at a distance of 25 cm from theGe(Li) detector to avoid summing corrections. The self-absorption correction to the intensities was not applied because of the small thickness of the source. The gamma ray singles spectra were taken with a 64.1 cm3 Ge(Li) detector (Ortec) coupled to a 4096channel analyser (NDI00).'This set-up has an energy 0167-5087/82/0000-0000/$02.75 O 1982 North-Holland
resolution (fwhtn) of 2.1 . keV f, the 1 .332 McV gamma rays of 6"Co . The relative efficiency calibration of the Gc(Li) detector at 25 cm geometry was done using standard sources of "'Co. `2 Eu, l ' 7 Cs and '"Fu obtained from the National Bureau of Standards and using liquid sources of t t"'"Ag, t"Ba and "Se obtained from BARC, Bombay, India. The precise clues of intensities of gamma rays of these sources have been taken from the tabulation given in ref. l . The -error in the efficiency calibration amounts to about 2`I for low energy gamma rays (up to 200 keV) and -~ ISO for the higher energy region (above 200 keV). The data for efficiency calibration and for the intensity measurements have been analysed using the winput, program 'SAMPO' [21. This program itself interpolate,, the efficiencies at the required energies from the efficiency data, forthe calibration sources into it . For the gamma ray energy and intensity measurements in .- 'H ., four sufficiently long run spectra were analysed and for the final results weighted average was taken . Fig. I shows a typical. gamma ray singles speetrum of to-Ho obtained with the Ge(Li) detector, In all, 46 gamma-rays have been assigned to this decay in the present work. This spectrum also includes a number 1 of additional peaks due to trace contaminationof ;° Eu which was found along with the 1- Ho source, The energies and intensities of various gamma rays from the present work arf listed in table 1 . The intensity results of Reich andCline [31 and those of Sampson 141 are also given in this table for comparison . The results of the present work are, in general, in agreement with those of previous workers [3,4]. However, in the present case the intensities are determined to a greater precision. The ""Ho is recommended as a single source for calibration of Ge(Li) detectors in the 80-1450 keV region . The use of a single source has an
S.S. Sna-h et ul. - mn"~lln
340
Table 1 Gamma-ray energies and intensities in the decay of Gamma ray energy (keVl 80.572(15) 94.68(3) 119.08(4) 121 .30(10) 135.x1(10) 140.81(10) 160.09(10) 161.75(8) 184.42121 190 .81(2) 214 .79~4) 215 .91(4) 231 .39(3) 259.76(2) 280.46(2) 300.77(2) 339.67(4) 365.74(3) 410.92(2) 451 .50(2) 464.80(3) 496.88(5) 520.86(5) 529 .79(3) 570.97(3) 594.36(3) 611 .53(3) 6e.0(1) 644.51(6) 670.49(2) 691,24(3) 711f) 736.68(5) 752 .27(3) 778 .81(3) 810.28(2) 8».57(2) 875.60(4) 951,00(4) 1010.25(5) 1120.3ä(4) 1146.86(4) 1241.51(4) 1282 .07(4) 1400.73(4) 1427.25(4)
Ho .
Relative intensity Present work
Reich and Cline [3[
17.8(4) 0.22(l) 0 .27(2) 0 .45(2) 0.14(1) 0 .06(1) 0.14(1) 0.15(1) 100 0.31(1) 0.61(2) 3.67(9) 0.30(1) 1 .53(3) 41 .0(5) 5 .17(8) 0.21(1) 3 .49(6) 15 .9(2) 4.17(5) 1 .67(3) 0.18(3) 0.22(3) 13,3(2) 7.65(9) 0.77(2) 1 .86(4) 0.12(1) 0.19(1) 7.53(9) 1 .87(4) 75 .7(8) 0.51(2) 17 .0(2) 4.25(6) 80.1(8) 13.5(2) 0.99(4) 3.89(6) 0.11(1) 0.35(1) 0 .30(l) 1 .21(4) 0.29(1) 0.74(2) 0.72(2)
Iz1(8) 0.19(t) 0.25(3) 0.36(4) 0 .14(I) 0 .059(14) 0 .134(14) 0.15(1) 100 0.30(3) 0.75(10) 3.6(3) 0.33(3) 1 .50(8) 40.7(20) 5.12(26) 0.23(3) 3.44(18) 15.8(8) 4 .18(20) 1 .68(II) 119(7) 7.86(40) 0.96(5) 1 .90(11) 0.22(7) 0 .25(3) 7.88(40) 2 .09(11) 80 .2(40) 0.14(4) 17 .9(10) 4.51(23) 85.7(42) 14.5(8) 1 .08(8) 4.15(20) 0.12(1) 0.31(3) 0 .30(3) 1.37(7) 0.31(3) 0 .75(4) 0.ß1(4)
Sampson [4) 17.51(50) 0.221(1l) 0.z22(11) 0.337(13) 0 .126(10) 0 .059(9) 0 .109(8) 0 .135(8) ()0 0.304(14) 0.586(20) 3.54(10) 0.284(14) 1 .446(43) 40.79(115) 5.12(15) 0.234(15) 3 .327(96) 15,25(43) 4 .02(12) 1 .651(51) 13.10(37) 7.53(22) 0.773(30) 1 .951(61) 0.122(16) 0 .213(19) 7 .37(21) 1 .871(58) 74.48(221) 0.506(24) 16.57(47) 4.17(12) 78.66(223) 13.34(38) 0.993(29) 3.71(ll) 0.096(7) 0 .327(13) 0 .271(13) 1 .142(34) 0.246(12) 0.686(21) 0.667(21)
S.S. Sooc')t el nl
106
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1 200 2200
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I 400 2400
i 600 2600
Fig. 1 . Gamma-ray singles spectrum of 1°°"' Ho.
I 800 2800
I I 1000 1200 3200 3000 CHANNEL NUMBER
advantage over the multiple sources . as in this case the errors dueto source-to-detector geometry areeliminated . References [11 A handbook of radioactivity measurement procedures, NCRP Reports No. 58 (1978) .
1 It) 3400
1 1600 3600
I 1800 3800
N ~ C
N N N
1
1
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1 2000 4000
[21 J.T. Rouui and S.G. Prussin, Nucl . Insu . and Meth. 72 (1969) 125. 131 C.W. Reich and J .E. Cline, Nucl . Phys. AI: a (1970) 181 . (41 T.E . Sampson, Nucl . Insu. and Meth. 150 :1978) 361 .
339
(1982) 339-341
PRECISE MEASUREMENTS OF GAMMA RAY ENERGIES AND INTENSITIES IN THE -Ho DECAY S.S SOOCH, Ravinder KAUR, Nirmal SINGH and P.N . TREHAN Dapnrrmenr of Physics, P.'yab Unir-irr, Clm'uifgarh-160014, Mdia Received 9 November
1981
and in revised form 1 April
1982
Gamma-rayenergies of 46 transitions in the decay of "°""' Ho have been mcasured precisely using a 64 .1 cat' (i¢I Li) deu."ctor. I his isotope is suggested as a calibrating source for the efficiency of Ge(Li) detectors in the region from 80 keV -, 14 .% keV.
The photopeak efficiency of a Gc(Li) detector is usually determined by usingaselected set of gamma ray sources having peaks distributed uniformly over a specified range of energies. For this purpose, the gamma ray intensities of the sources to be used must be known precisely. A number of radioactive sources, such its . "Co. 6)CO, t33B a 152Eu, tut-Ag, s'Y, -Cs, "'Mn . 22 Na have been used for calibration purposes by various found to be a convenient single workers. "'"'Ho is ,. source for such calibration work . It decays by ß t66Er with subsequent emission emission to the levels of of a number of well separated and fairly strong gamma rays . Its long life (Tt;2= 1200 y) makes it still more useful as a universal source for calibration of Ge(Li) detectors . The use of t66'Ho provides -a single source for intensity as well as energy calibration of Gc(Li) detectors in theenergy region of 80-1450 keV . t66mHo' were obtained The radioactive sources of from the National Bureau of Standards, Washington, D.C., U.S.A . in the form of HoCl 3 solution. Two types of sources were used for the' gamma ray singles spectra measurements . In one type, the source was evaporated on a mylar film in a circular region of about 3 mm diameter by the National Bureau of Standard for us . In the second type, a line source of about 3 mm diameter and about 10 mm length in cylindrical perspex holder was prepared at our own laboratory from the liquid source supplied by NBS. The count rate of these sources was less than 1000 counts per second and thus no pile-up corrections were necessary. The singles data were taken by placing the sources at a distance of 25 cm from theGe(Li) detector to avoid summing corrections. The self-absorption correction to the intensities was not applied because of the small thickness of the source. The gamma ray singles spectra were taken with a 64.1 cm3 Ge(Li) detector (Ortec) coupled to a 4096channel analyser (NDI00).'This set-up has an energy 0167-5087/82/0000-0000/$02.75 O 1982 North-Holland
resolution (fwhtn) of 2.1 . keV f, the 1 .332 McV gamma rays of 6"Co . The relative efficiency calibration of the Gc(Li) detector at 25 cm geometry was done using standard sources of "'Co. `2 Eu, l ' 7 Cs and '"Fu obtained from the National Bureau of Standards and using liquid sources of t t"'"Ag, t"Ba and "Se obtained from BARC, Bombay, India. The precise clues of intensities of gamma rays of these sources have been taken from the tabulation given in ref. l . The -error in the efficiency calibration amounts to about 2`I for low energy gamma rays (up to 200 keV) and -~ ISO for the higher energy region (above 200 keV). The data for efficiency calibration and for the intensity measurements have been analysed using the winput, program 'SAMPO' [21. This program itself interpolate,, the efficiencies at the required energies from the efficiency data, forthe calibration sources into it . For the gamma ray energy and intensity measurements in .- 'H ., four sufficiently long run spectra were analysed and for the final results weighted average was taken . Fig. I shows a typical. gamma ray singles speetrum of to-Ho obtained with the Ge(Li) detector, In all, 46 gamma-rays have been assigned to this decay in the present work. This spectrum also includes a number 1 of additional peaks due to trace contaminationof ;° Eu which was found along with the 1- Ho source, The energies and intensities of various gamma rays from the present work arf listed in table 1 . The intensity results of Reich andCline [31 and those of Sampson 141 are also given in this table for comparison . The results of the present work are, in general, in agreement with those of previous workers [3,4]. However, in the present case the intensities are determined to a greater precision. The ""Ho is recommended as a single source for calibration of Ge(Li) detectors in the 80-1450 keV region . The use of a single source has an
S.S. Sna-h et ul. - mn"~lln
340
Table 1 Gamma-ray energies and intensities in the decay of Gamma ray energy (keVl 80.572(15) 94.68(3) 119.08(4) 121 .30(10) 135.x1(10) 140.81(10) 160.09(10) 161.75(8) 184.42121 190 .81(2) 214 .79~4) 215 .91(4) 231 .39(3) 259.76(2) 280.46(2) 300.77(2) 339.67(4) 365.74(3) 410.92(2) 451 .50(2) 464.80(3) 496.88(5) 520.86(5) 529 .79(3) 570.97(3) 594.36(3) 611 .53(3) 6e.0(1) 644.51(6) 670.49(2) 691,24(3) 711f) 736.68(5) 752 .27(3) 778 .81(3) 810.28(2) 8».57(2) 875.60(4) 951,00(4) 1010.25(5) 1120.3ä(4) 1146.86(4) 1241.51(4) 1282 .07(4) 1400.73(4) 1427.25(4)
Ho .
Relative intensity Present work
Reich and Cline [3[
17.8(4) 0.22(l) 0 .27(2) 0 .45(2) 0.14(1) 0 .06(1) 0.14(1) 0.15(1) 100 0.31(1) 0.61(2) 3.67(9) 0.30(1) 1 .53(3) 41 .0(5) 5 .17(8) 0.21(1) 3 .49(6) 15 .9(2) 4.17(5) 1 .67(3) 0.18(3) 0.22(3) 13,3(2) 7.65(9) 0.77(2) 1 .86(4) 0.12(1) 0.19(1) 7.53(9) 1 .87(4) 75 .7(8) 0.51(2) 17 .0(2) 4.25(6) 80.1(8) 13.5(2) 0.99(4) 3.89(6) 0.11(1) 0.35(1) 0 .30(l) 1 .21(4) 0.29(1) 0.74(2) 0.72(2)
Iz1(8) 0.19(t) 0.25(3) 0.36(4) 0 .14(I) 0 .059(14) 0 .134(14) 0.15(1) 100 0.30(3) 0.75(10) 3.6(3) 0.33(3) 1 .50(8) 40.7(20) 5.12(26) 0.23(3) 3.44(18) 15.8(8) 4 .18(20) 1 .68(II) 119(7) 7.86(40) 0.96(5) 1 .90(11) 0.22(7) 0 .25(3) 7.88(40) 2 .09(11) 80 .2(40) 0.14(4) 17 .9(10) 4.51(23) 85.7(42) 14.5(8) 1 .08(8) 4.15(20) 0.12(1) 0.31(3) 0 .30(3) 1.37(7) 0.31(3) 0 .75(4) 0.ß1(4)
Sampson [4) 17.51(50) 0.221(1l) 0.z22(11) 0.337(13) 0 .126(10) 0 .059(9) 0 .109(8) 0 .135(8) ()0 0.304(14) 0.586(20) 3.54(10) 0.284(14) 1 .446(43) 40.79(115) 5.12(15) 0.234(15) 3 .327(96) 15,25(43) 4 .02(12) 1 .651(51) 13.10(37) 7.53(22) 0.773(30) 1 .951(61) 0.122(16) 0 .213(19) 7 .37(21) 1 .871(58) 74.48(221) 0.506(24) 16.57(47) 4.17(12) 78.66(223) 13.34(38) 0.993(29) 3.71(ll) 0.096(7) 0 .327(13) 0 .271(13) 1 .142(34) 0.246(12) 0.686(21) 0.667(21)
S.S. Sooc')t el nl
106
w v m
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r
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105
W 104 2 Z a U w tn h Z
N v v m
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341
lnnmHo dc.vir
m v O m
p v
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n
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W v~p
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v N v v n ^p N N
103
O m v, N
v
m rin
1 200 2200
102
I 400 2400
i 600 2600
Fig. 1 . Gamma-ray singles spectrum of 1°°"' Ho.
I 800 2800
I I 1000 1200 3200 3000 CHANNEL NUMBER
advantage over the multiple sources . as in this case the errors dueto source-to-detector geometry areeliminated . References [11 A handbook of radioactivity measurement procedures, NCRP Reports No. 58 (1978) .
1 It) 3400
1 1600 3600
I 1800 3800
N ~ C
N N N
1
1
v P P p v
1 2000 4000
[21 J.T. Rouui and S.G. Prussin, Nucl . Insu . and Meth. 72 (1969) 125. 131 C.W. Reich and J .E. Cline, Nucl . Phys. AI: a (1970) 181 . (41 T.E . Sampson, Nucl . Insu. and Meth. 150 :1978) 361 .