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Cross-section measurement for the 206Pb(n, α)203Hg reaction induced by neutrons around 14 MeV
Nuclear Instruments and Methods in Physics Research B 349 (2015) 130–132
Contents lists available at ScienceDirect
Nuclear Instruments and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb
Cross-section measurement for the 206Pb(n, a)203Hg reaction induced by neutrons around 14 MeV Shuqing Yuan a, Yueli Song a, Fengqun Zhou a,⇑, Yong Li a, Mingli Tian a, Changlin Lan b a b
Electric and Information Engineering College, Pingdingshan University, Pingdingshan, Henan Province 467000, PR China School of Nuclear Science and Technology, Lanzhou University, Lanzhou, Gansu Province 730000, PR China
a r t i c l e
i n f o
Article history: Received 3 October 2014 Received in revised form 15 February 2015 Accepted 16 February 2015 Available online 6 March 2015 Keywords: Nuclear reaction Cross section Lead Activation technique
a b s t r a c t The cross section for the 206Pb(n, a)203Hg reaction has been measured in the neutron energy range of 13.5–14.7 MeV using the activation technique and a coaxial HPGe c-ray detector. The cross-section data of the 206Pb(n, a)203Hg reaction which are scaled to the evaluated values of the 93Nb(n, 2n) 92mNb reaction are reported to be 0.99 ± 0.07, 1.23 ± 0.11, and 1.39 ± 0.12 mb at 13.5 ± 0.2, 14.4 ± 0.2, and 14.7 ± 0.2 MeV incident neutron energies, respectively. The results are discussed and compared with experimental data found in the literatures, with the results of published empirical formulae and the evaluated values of the databases. The comparison shows that the value of our excitation curve at 14.5 MeV is close to the estimation obtained from the published empirical formula based on the statistical model with dependence on the Q-value and odd–even effect taken into consideration. Ó 2015 Elsevier B.V. All rights reserved.
1. Introduction
2. Experiment
During the running of the future fusion power reactor, a large number of neutrons around 14 MeV from d–T reaction will not only cause serious displacement damage of fusion-reactor structural materials, but also induce (n, a), (n, p), etc. nuclear transmutation reactions of the structural materials which may produce helium and hydrogen, and then cause vacancies and voids in materials. They will induce the property change of fusion-reactor materials which shorten service life and affect safe running. Therefore, the cross sections on lead which is an important fusion-reactor structural material isotopes induced by neutrons around 14 MeV are of special importance for the design, evaluation and construction of fusion reactors. The cross section for the 206Pb(n, a)203Hg reaction induced by neutrons around 14 MeV has been measured at six laboratories [1–6], but these measurements differ by as much as a factor of 5–6 and four of them obtained data at only one energy [1,3,4,6], thus it is necessary to make further measurements to strengthen the reliability of the databases. In the present work, the cross section of the 206Pb(n, a)203Hg reaction was measured in neutron energies of 13.5–14.7 MeV using the activation technique. The results measured are discussed and compared with experimental data found in the literatures, and with the results of published empirical formulae and the evaluated values of the databases.
The irradiation of the samples was carried out at the ZF-300-II Intense Neutron Generator at Lanzhou University. The neutrons with the yield of about (1–3) 1012 n/s, were produced by the T(d, n)4He reaction with an effective deuteron beam energy of 125 keV and a beam current of 20 mA. The thickness of the tritium–titanium (T–Ti) target used in the generator was 0.9 mg/ cm2. The variation of the neutron yield was monitored by a U-fission chamber so that the correction could be made for the fluctuation of the neutron flux during the irradiation. The evaluated cross-section values of the 93Nb(n, 2n) 92mNb reaction were selected as the monitor to measure the cross-section values of the 206 Pb(n, a)203Hg reaction. The reaction yields were obtained by absolute measurement of the c-ray activities of the residual nuclei using a coaxial HPGe c-ray detector. The natural lead foils of 99.99% purity and 0.25 mm thickness were made into circular samples with a diameter of 20 mm. Each of them was sandwiched between natural niobium foils of the same diameter, all the niobium foils with purities better than 99.9% and 0.2 mm in thickness. The groups of samples were irradiated at the fixed positions about 2–5 cm away from the center of the T–Ti target and at the angles 0°–140° relative to the deuteron beam direction. The neutron energies for these fixed positions were determined beforehand by the method of cross section ratios for 90Zr(n, 2n)89m+gZr and 93Nb(n, 2n)92mNb reactions [7]. The c-ray activities of 92mNb, 89m+gZr, and 203Hg were determined by a CH8403 coaxial HPGe c-ray detector (sensitive volume
⇑ Corresponding author. Tel./fax: +86 0375 2077266. E-mail address: [email protected] (F. Zhou). http://dx.doi.org/10.1016/j.nimb.2015.02.045 0168-583X/Ó 2015 Elsevier B.V. All rights reserved.
131
S. Yuan et al. / Nuclear Instruments and Methods in Physics Research B 349 (2015) 130–132
Thiswork Begun et al. (2002)[1] Filatenkov et al. (1999) )[2] Grallert et al. (1993) [3] Junqian Yuan et al. (1993) [4] Maslov et al. (1972) [5] Yuwen Yu and Gardner (1967)[6]
3.0
Cross section(mb)
2.5 2.0 1.5 1.0 0.5 0.0 13.4
13.6
13.8
14.0 14.2 14.4 14.6 Neutron energy( MeV)
Fig. 1. Cross section of the
206
14.8
15.0
Pb(n, a)203Hg reaction.
Table 1 Reactions and associated decay data of activation products. Reaction
Abundance of target isotope (%)
Half-life of product
Ec (keV)
Ic (%)
206
24.1 100
46.612d 10.15d
279.1967 934.44
81.46 99.07
Pb(n, a)203Hg 93 Nb(n, 2n)92mNb
Table 2 Summary of cross section measurements. Reaction
206
This work
Pb(n, a)203Hg
93
Nb(n, 2n)
Literature values
En (MeV)
r (mb)
En (MeV)
r (mb)
Refs.
13.5 ± 0.2 14.4 ± 0.2 14.7 ± 0.2
0.99 ± 0.07 1.23 ± 0.11 1.39 ± 0.12
14.5 ± 0.2 13.47 13.64 13.88 14.05 14.28 14.41 14.47 14.68 14.85 14.6 14.38 14.2 ± 0.2 14.6 ± 0.2 14.1
0.56 ± 0.03 0.283 ± 0.027 0.346 ± 0.033 0.4 ± 0.039 0.406 ± 0.032 0.522 ± 0.039 0.47 ± 0.026 0.616 ± 0.048 0.652 ± 0.045 0.732 ± 0.059 0.57 ± 0.04 1.2 ± 0.2 0.527 ± 0.07 0.673 ± 0.07 2.7 ± 0.41
[1] [2] [2] [2] [2] [2] [2] [2] [2] [2] [3] [4] [5] [5] [6]
13.5 ± 0.2 14.4 ± 0.2 14.7 ± 0.2
456.6 ± 13.7 459.8 ± 13.8 459.6 ± 13.8
[11] [11] [11]
92m
Nb
Table 3 Comparison of our data with semi-empirical predictions at 14.5 MeV. Refs.
Neutron energy (MeV)
Cross section of the 206 Pb(n, a)203Hg reaction (mb)
Habbani and Osman [12] Forrest [13] Junhua Luo et al. [14] Konobeyev et al. [15]
14.5 14.5 14.5 14.5
1.51 1.10 0.85 0.54
110 cm3, made in the People’s Republic of China) with a relative efficiency of 20% and an energy resolution of 3 keV at 1.33 MeV. In order to determine the c-ray activity of 203Hg, the lead samples
were measured after having been cooled for more than 18 times of the half-life (51.873 h) of 203gPb to avoid the effect of the c-ray (279.1967 keV) from 203gPb which come from the 204Pb(n, 2n)203mPb and 204Pb(n, 2n)203gPb reactions. The efficiency of the detector was calibrated (the detail described in Ref. [8]) by using the standard c-ray source, Standard Reference Material 4275 from the National Institute of Standards and Technology, Washington, DC, USA. The absolute efficiency calibration curve was obtained at 2 cm from the surface of the germanium crystal. The error in the absolute efficiency curve at 2 cm was estimated to be 1.5%. The decay characteristics of the product radionuclides and the natural abundance of the target isotopes under investigation are summarized in Table 1 [9].
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S. Yuan et al. / Nuclear Instruments and Methods in Physics Research B 349 (2015) 130–132
Table 4 The error sources and the uncertainties of the measured cross section (in %). Reaction
Standard cross section
Selfabsorption of c-rays
Weight of samples
Efficiency of c-ray full energy peak
Coincidence summing effect of cascade c-rays
Counting statistics
Sample geometry
Fluctuation of the neutron flux
Total
206
3.0
1.0
0.1–0.15
1.5
1.0
0.5–7.58
1.0
1.0
7.1–8.9
Pb(n, a)203H
3. Results and discussion
4. Conclusions
The cross section measured was calculated using the activation formula proposed by Xiang zhong et al. [10]. For purpose of comparison, the cross section measured in the present work and the values given in the literatures were summarized in Table 2 and plotted in Fig. 1. The cross-section values of the monitor reaction 93Nb(n, 2n)92mNb (obtained by interpolating the evaluated values of Wagner et al. [11]) were also listed in Table 2. We also compared our experimental results with the estimations obtained from the empirical formulae [12–15] (in Table 3). Corrections were made for c-ray self-absorption in the sample, for c-ray coincidence summing effects, for fluctuation of the neutron flux during the irradiation and for sample geometry. The uncertainties in our result were from the counting statistics, detector efficiency, monitor reaction cross section, weight of samples, self-absorption of c ray, coincidence summing effect of cascade c-rays, sample geometry. The error sources and the uncertainties of the measured cross section are shown in Table 4. It can be seen from Table 2 and Fig. 1 that the value of our excitation curve at 14.38 MeV is in agreement, within experimental error, with that of Junqian Yuan et al. [4], and that the cross-section value of Yuwen Yu and Gardner [6] at 14.1 MeV is higher than our value as much as 2 times and higher than those of Begun et al., Filatenkov et al., Grallert et al. and Maslov et al. [1–3,5] as much as 5–6 times. The corresponding value of our excitation curve is higher than that from Refs. [1– 3,5] as much as 2–3 times. It can be seen from Table 3 that the value of our excitation curve at 14.5 MeV is closer to the estimation value obtained from the published empirical formula based on the statistical model with dependence on the Q-value and odd–even effect taken into consideration [12] and is also closer to the empirical value calculated from Ref. [13], but is higher than estimation values of other empirical formulae [14,15]. The evaluated values of the 206Pb(n, a)203Hg reaction from ENDF/B-VII.1 (USA, 2011), JEFF-3.2 (Europe, 2014), and ROSFOND-2010 (Russia, 2010) [16] are all 0.236, 0.3868 and 0.4494 mb at 13.5, 14.4059 and 14.6977 MeV, respectively, while its evaluated values from CENDL-3.1 (China, 2009) [16] are 1.187, 2.3035 and 2.9068 mb at 13.5, 14.4 and 14. 7 MeV, respectively. It can be seen that our value at 13.5 MeV is closer to the evaluated value from CENDL-3.1 (China, 2009) and the others are lower than the evaluated values from CENDL-3.1 (China, 2009) and that the evaluated values from ENDF/B-VII.1 (USA, 2011), JEFF-3.2 (Europe, 2014), and ROSFOND-2010 (Russia, 2010) are all lower than our values.
The cross-section values of the 206Pb(n, a)203Hg reaction induced by neutrons around 14 MeV were obtained. In our experiment, the natural lead foils of 99.99% purity was used as target material, the interfering reactions were avoided and the HPGe detector employed had better resolution than NaI(Tl). Furthermore, while c-ray yields were measured and then turned into cross-section values, the most recent and accurate nuclear data so far were adopted. All these mentioned above should make our results more accurate and reliable. Our results are useful for verifying the accuracy of nuclear models used in the calculation of cross sections and for the further strengthening of the databases, and may also be useful for the design, evaluation and construction of fusion reactors. Acknowledgements The authors are grateful to the group of the Intense Neutron Generator at Lanzhou University for performing irradiation work. This work was supported by the Research Program for Basic & Forefront Technology of Henan Province, China (Grant Nos. 132300410302 and 142300410287) and the Program for Science & Technology Outstanding Innovation Talents in Pingdingshan City of Henan Province, China (Grant No. 2012060). References [1] S.V. Begun, I.M. Kadenko, V.K. Maidanyuk, V.M. Neplyuev, V.A. Plujko, G.I. Primenko, V.K. Tarakanov, J. Nucl. Sci. Technol. Suppl. 2 (2002) 425. [2] A.A. Filatenkov, S.V. Chuvaev, V.N. Aksenov, V.A. Yakovlev, A.V. Malyshenkov, S.K. Vasil’ev, M. Avrigeanu, V. Avrigeanu, D.L. Smith, Y. Ikeda, A. Wallner, W. Kutschera, A. Priller, P. Steier, H. Vonach, G. Mertens, W. Rochow, Report RI252, Leningrad, 1999. [3] A. Grallert, J. Csikai, Cs.M. Buczko, I. Shaddad, Report INDC(NDS)-286, IAEA, Austria, 1993. [4] Junqian. Yuan, Yongchang. Wang, Jingkang. Yang, Jiuzi. Qiu, Nucl. Tech. 16 (1993) 518 (in Chinese). [5] G.N. Maslov, F. Nasyrov, N.F. Pashkin, Report YK-9, Russia, 1972. [6] Yu. Yuwen, D.G. Gardner, Nucl. Phys. A 98 (1967) 451. [7] V.E. Levis, K.J. Zieba, Nucl. Instr. Meth. 174 (1980) 141. [8] Fengqun. Zhou, Yimin. Zhang, Fei. Tuo, Yanling. Yi, Xiangzhong. Kong, Appl. Radiat. Isot. 64 (2006) 815. [9] R.B. Firestone, V.S. Shirley, Table of Isotopes, Wiley, New York, 1996. [10] Xiangzhong. Kong, Rong. Wang, Yongchang. Wang, Jingkang. Yang, Appl. Radiat. Isot. 50 (1999) 361. [11] M. Wagner, H. Vonach, A. Pavlik, B. Strohmaier, S. Tagesen, J. Martinez-Rico, Phys. Daten Phys. Data 13 (1990) 183. [12] F.I. Habbani, K.T. Osman, Appl. Radiat. Isot. 54 (2001) 283. [13] R.A. Forrest, AERE-R 12419, Harwell Laboratory, 1986. [14] Junhua. Luo, Fei. Tuo, Fengqun. Zhou, Xiangzhong. Kong, Nucl. Instr. Meth. B 266 (2008) 4862. [15] A.Yu. Konobeyev, V.P. Lunev, Yu.N. Shubin, Nucl. Instr. Meth. B 108 (1996) 233. [16] ENDF/B-VII.1 (USA, 2011), JEFF-3.2 (Europe, 2014), ROSFOND-2010 (Russia, 2010), CENDL-3.1 (China, 2009)-Evaluated Nuclear Data File (Database Version of October 22, 2014, Software Version of January 16, 2015), IAEA Nuclear Data Services..
Contents lists available at ScienceDirect
Nuclear Instruments and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb
Cross-section measurement for the 206Pb(n, a)203Hg reaction induced by neutrons around 14 MeV Shuqing Yuan a, Yueli Song a, Fengqun Zhou a,⇑, Yong Li a, Mingli Tian a, Changlin Lan b a b
Electric and Information Engineering College, Pingdingshan University, Pingdingshan, Henan Province 467000, PR China School of Nuclear Science and Technology, Lanzhou University, Lanzhou, Gansu Province 730000, PR China
a r t i c l e
i n f o
Article history: Received 3 October 2014 Received in revised form 15 February 2015 Accepted 16 February 2015 Available online 6 March 2015 Keywords: Nuclear reaction Cross section Lead Activation technique
a b s t r a c t The cross section for the 206Pb(n, a)203Hg reaction has been measured in the neutron energy range of 13.5–14.7 MeV using the activation technique and a coaxial HPGe c-ray detector. The cross-section data of the 206Pb(n, a)203Hg reaction which are scaled to the evaluated values of the 93Nb(n, 2n) 92mNb reaction are reported to be 0.99 ± 0.07, 1.23 ± 0.11, and 1.39 ± 0.12 mb at 13.5 ± 0.2, 14.4 ± 0.2, and 14.7 ± 0.2 MeV incident neutron energies, respectively. The results are discussed and compared with experimental data found in the literatures, with the results of published empirical formulae and the evaluated values of the databases. The comparison shows that the value of our excitation curve at 14.5 MeV is close to the estimation obtained from the published empirical formula based on the statistical model with dependence on the Q-value and odd–even effect taken into consideration. Ó 2015 Elsevier B.V. All rights reserved.
1. Introduction
2. Experiment
During the running of the future fusion power reactor, a large number of neutrons around 14 MeV from d–T reaction will not only cause serious displacement damage of fusion-reactor structural materials, but also induce (n, a), (n, p), etc. nuclear transmutation reactions of the structural materials which may produce helium and hydrogen, and then cause vacancies and voids in materials. They will induce the property change of fusion-reactor materials which shorten service life and affect safe running. Therefore, the cross sections on lead which is an important fusion-reactor structural material isotopes induced by neutrons around 14 MeV are of special importance for the design, evaluation and construction of fusion reactors. The cross section for the 206Pb(n, a)203Hg reaction induced by neutrons around 14 MeV has been measured at six laboratories [1–6], but these measurements differ by as much as a factor of 5–6 and four of them obtained data at only one energy [1,3,4,6], thus it is necessary to make further measurements to strengthen the reliability of the databases. In the present work, the cross section of the 206Pb(n, a)203Hg reaction was measured in neutron energies of 13.5–14.7 MeV using the activation technique. The results measured are discussed and compared with experimental data found in the literatures, and with the results of published empirical formulae and the evaluated values of the databases.
The irradiation of the samples was carried out at the ZF-300-II Intense Neutron Generator at Lanzhou University. The neutrons with the yield of about (1–3) 1012 n/s, were produced by the T(d, n)4He reaction with an effective deuteron beam energy of 125 keV and a beam current of 20 mA. The thickness of the tritium–titanium (T–Ti) target used in the generator was 0.9 mg/ cm2. The variation of the neutron yield was monitored by a U-fission chamber so that the correction could be made for the fluctuation of the neutron flux during the irradiation. The evaluated cross-section values of the 93Nb(n, 2n) 92mNb reaction were selected as the monitor to measure the cross-section values of the 206 Pb(n, a)203Hg reaction. The reaction yields were obtained by absolute measurement of the c-ray activities of the residual nuclei using a coaxial HPGe c-ray detector. The natural lead foils of 99.99% purity and 0.25 mm thickness were made into circular samples with a diameter of 20 mm. Each of them was sandwiched between natural niobium foils of the same diameter, all the niobium foils with purities better than 99.9% and 0.2 mm in thickness. The groups of samples were irradiated at the fixed positions about 2–5 cm away from the center of the T–Ti target and at the angles 0°–140° relative to the deuteron beam direction. The neutron energies for these fixed positions were determined beforehand by the method of cross section ratios for 90Zr(n, 2n)89m+gZr and 93Nb(n, 2n)92mNb reactions [7]. The c-ray activities of 92mNb, 89m+gZr, and 203Hg were determined by a CH8403 coaxial HPGe c-ray detector (sensitive volume
⇑ Corresponding author. Tel./fax: +86 0375 2077266. E-mail address: [email protected] (F. Zhou). http://dx.doi.org/10.1016/j.nimb.2015.02.045 0168-583X/Ó 2015 Elsevier B.V. All rights reserved.
131
S. Yuan et al. / Nuclear Instruments and Methods in Physics Research B 349 (2015) 130–132
Thiswork Begun et al. (2002)[1] Filatenkov et al. (1999) )[2] Grallert et al. (1993) [3] Junqian Yuan et al. (1993) [4] Maslov et al. (1972) [5] Yuwen Yu and Gardner (1967)[6]
3.0
Cross section(mb)
2.5 2.0 1.5 1.0 0.5 0.0 13.4
13.6
13.8
14.0 14.2 14.4 14.6 Neutron energy( MeV)
Fig. 1. Cross section of the
206
14.8
15.0
Pb(n, a)203Hg reaction.
Table 1 Reactions and associated decay data of activation products. Reaction
Abundance of target isotope (%)
Half-life of product
Ec (keV)
Ic (%)
206
24.1 100
46.612d 10.15d
279.1967 934.44
81.46 99.07
Pb(n, a)203Hg 93 Nb(n, 2n)92mNb
Table 2 Summary of cross section measurements. Reaction
206
This work
Pb(n, a)203Hg
93
Nb(n, 2n)
Literature values
En (MeV)
r (mb)
En (MeV)
r (mb)
Refs.
13.5 ± 0.2 14.4 ± 0.2 14.7 ± 0.2
0.99 ± 0.07 1.23 ± 0.11 1.39 ± 0.12
14.5 ± 0.2 13.47 13.64 13.88 14.05 14.28 14.41 14.47 14.68 14.85 14.6 14.38 14.2 ± 0.2 14.6 ± 0.2 14.1
0.56 ± 0.03 0.283 ± 0.027 0.346 ± 0.033 0.4 ± 0.039 0.406 ± 0.032 0.522 ± 0.039 0.47 ± 0.026 0.616 ± 0.048 0.652 ± 0.045 0.732 ± 0.059 0.57 ± 0.04 1.2 ± 0.2 0.527 ± 0.07 0.673 ± 0.07 2.7 ± 0.41
[1] [2] [2] [2] [2] [2] [2] [2] [2] [2] [3] [4] [5] [5] [6]
13.5 ± 0.2 14.4 ± 0.2 14.7 ± 0.2
456.6 ± 13.7 459.8 ± 13.8 459.6 ± 13.8
[11] [11] [11]
92m
Nb
Table 3 Comparison of our data with semi-empirical predictions at 14.5 MeV. Refs.
Neutron energy (MeV)
Cross section of the 206 Pb(n, a)203Hg reaction (mb)
Habbani and Osman [12] Forrest [13] Junhua Luo et al. [14] Konobeyev et al. [15]
14.5 14.5 14.5 14.5
1.51 1.10 0.85 0.54
110 cm3, made in the People’s Republic of China) with a relative efficiency of 20% and an energy resolution of 3 keV at 1.33 MeV. In order to determine the c-ray activity of 203Hg, the lead samples
were measured after having been cooled for more than 18 times of the half-life (51.873 h) of 203gPb to avoid the effect of the c-ray (279.1967 keV) from 203gPb which come from the 204Pb(n, 2n)203mPb and 204Pb(n, 2n)203gPb reactions. The efficiency of the detector was calibrated (the detail described in Ref. [8]) by using the standard c-ray source, Standard Reference Material 4275 from the National Institute of Standards and Technology, Washington, DC, USA. The absolute efficiency calibration curve was obtained at 2 cm from the surface of the germanium crystal. The error in the absolute efficiency curve at 2 cm was estimated to be 1.5%. The decay characteristics of the product radionuclides and the natural abundance of the target isotopes under investigation are summarized in Table 1 [9].
132
S. Yuan et al. / Nuclear Instruments and Methods in Physics Research B 349 (2015) 130–132
Table 4 The error sources and the uncertainties of the measured cross section (in %). Reaction
Standard cross section
Selfabsorption of c-rays
Weight of samples
Efficiency of c-ray full energy peak
Coincidence summing effect of cascade c-rays
Counting statistics
Sample geometry
Fluctuation of the neutron flux
Total
206
3.0
1.0
0.1–0.15
1.5
1.0
0.5–7.58
1.0
1.0
7.1–8.9
Pb(n, a)203H
3. Results and discussion
4. Conclusions
The cross section measured was calculated using the activation formula proposed by Xiang zhong et al. [10]. For purpose of comparison, the cross section measured in the present work and the values given in the literatures were summarized in Table 2 and plotted in Fig. 1. The cross-section values of the monitor reaction 93Nb(n, 2n)92mNb (obtained by interpolating the evaluated values of Wagner et al. [11]) were also listed in Table 2. We also compared our experimental results with the estimations obtained from the empirical formulae [12–15] (in Table 3). Corrections were made for c-ray self-absorption in the sample, for c-ray coincidence summing effects, for fluctuation of the neutron flux during the irradiation and for sample geometry. The uncertainties in our result were from the counting statistics, detector efficiency, monitor reaction cross section, weight of samples, self-absorption of c ray, coincidence summing effect of cascade c-rays, sample geometry. The error sources and the uncertainties of the measured cross section are shown in Table 4. It can be seen from Table 2 and Fig. 1 that the value of our excitation curve at 14.38 MeV is in agreement, within experimental error, with that of Junqian Yuan et al. [4], and that the cross-section value of Yuwen Yu and Gardner [6] at 14.1 MeV is higher than our value as much as 2 times and higher than those of Begun et al., Filatenkov et al., Grallert et al. and Maslov et al. [1–3,5] as much as 5–6 times. The corresponding value of our excitation curve is higher than that from Refs. [1– 3,5] as much as 2–3 times. It can be seen from Table 3 that the value of our excitation curve at 14.5 MeV is closer to the estimation value obtained from the published empirical formula based on the statistical model with dependence on the Q-value and odd–even effect taken into consideration [12] and is also closer to the empirical value calculated from Ref. [13], but is higher than estimation values of other empirical formulae [14,15]. The evaluated values of the 206Pb(n, a)203Hg reaction from ENDF/B-VII.1 (USA, 2011), JEFF-3.2 (Europe, 2014), and ROSFOND-2010 (Russia, 2010) [16] are all 0.236, 0.3868 and 0.4494 mb at 13.5, 14.4059 and 14.6977 MeV, respectively, while its evaluated values from CENDL-3.1 (China, 2009) [16] are 1.187, 2.3035 and 2.9068 mb at 13.5, 14.4 and 14. 7 MeV, respectively. It can be seen that our value at 13.5 MeV is closer to the evaluated value from CENDL-3.1 (China, 2009) and the others are lower than the evaluated values from CENDL-3.1 (China, 2009) and that the evaluated values from ENDF/B-VII.1 (USA, 2011), JEFF-3.2 (Europe, 2014), and ROSFOND-2010 (Russia, 2010) are all lower than our values.
The cross-section values of the 206Pb(n, a)203Hg reaction induced by neutrons around 14 MeV were obtained. In our experiment, the natural lead foils of 99.99% purity was used as target material, the interfering reactions were avoided and the HPGe detector employed had better resolution than NaI(Tl). Furthermore, while c-ray yields were measured and then turned into cross-section values, the most recent and accurate nuclear data so far were adopted. All these mentioned above should make our results more accurate and reliable. Our results are useful for verifying the accuracy of nuclear models used in the calculation of cross sections and for the further strengthening of the databases, and may also be useful for the design, evaluation and construction of fusion reactors. Acknowledgements The authors are grateful to the group of the Intense Neutron Generator at Lanzhou University for performing irradiation work. This work was supported by the Research Program for Basic & Forefront Technology of Henan Province, China (Grant Nos. 132300410302 and 142300410287) and the Program for Science & Technology Outstanding Innovation Talents in Pingdingshan City of Henan Province, China (Grant No. 2012060). References [1] S.V. Begun, I.M. Kadenko, V.K. Maidanyuk, V.M. Neplyuev, V.A. Plujko, G.I. Primenko, V.K. Tarakanov, J. Nucl. Sci. Technol. Suppl. 2 (2002) 425. [2] A.A. Filatenkov, S.V. Chuvaev, V.N. Aksenov, V.A. Yakovlev, A.V. Malyshenkov, S.K. Vasil’ev, M. Avrigeanu, V. Avrigeanu, D.L. Smith, Y. Ikeda, A. Wallner, W. Kutschera, A. Priller, P. Steier, H. Vonach, G. Mertens, W. Rochow, Report RI252, Leningrad, 1999. [3] A. Grallert, J. Csikai, Cs.M. Buczko, I. Shaddad, Report INDC(NDS)-286, IAEA, Austria, 1993. [4] Junqian. Yuan, Yongchang. Wang, Jingkang. Yang, Jiuzi. Qiu, Nucl. Tech. 16 (1993) 518 (in Chinese). [5] G.N. Maslov, F. Nasyrov, N.F. Pashkin, Report YK-9, Russia, 1972. [6] Yu. Yuwen, D.G. Gardner, Nucl. Phys. A 98 (1967) 451. [7] V.E. Levis, K.J. Zieba, Nucl. Instr. Meth. 174 (1980) 141. [8] Fengqun. Zhou, Yimin. Zhang, Fei. Tuo, Yanling. Yi, Xiangzhong. Kong, Appl. Radiat. Isot. 64 (2006) 815. [9] R.B. Firestone, V.S. Shirley, Table of Isotopes, Wiley, New York, 1996. [10] Xiangzhong. Kong, Rong. Wang, Yongchang. Wang, Jingkang. Yang, Appl. Radiat. Isot. 50 (1999) 361. [11] M. Wagner, H. Vonach, A. Pavlik, B. Strohmaier, S. Tagesen, J. Martinez-Rico, Phys. Daten Phys. Data 13 (1990) 183. [12] F.I. Habbani, K.T. Osman, Appl. Radiat. Isot. 54 (2001) 283. [13] R.A. Forrest, AERE-R 12419, Harwell Laboratory, 1986. [14] Junhua. Luo, Fei. Tuo, Fengqun. Zhou, Xiangzhong. Kong, Nucl. Instr. Meth. B 266 (2008) 4862. [15] A.Yu. Konobeyev, V.P. Lunev, Yu.N. Shubin, Nucl. Instr. Meth. B 108 (1996) 233. [16] ENDF/B-VII.1 (USA, 2011), JEFF-3.2 (Europe, 2014), ROSFOND-2010 (Russia, 2010), CENDL-3.1 (China, 2009)-Evaluated Nuclear Data File (Database Version of October 22, 2014, Software Version of January 16, 2015), IAEA Nuclear Data Services.