高通量试验堆(HFETR)辐照<sup>40</sup>Ar-<sup>39</sup>Ar定年样品条件初探

李军杰; 刘汉彬; 张佳; 金贵善; 张建锋; 韩娟; 石晓

doi:10.3799/dqkx.2019.006

高通量试验堆(HFETR)辐照⁴⁰Ar-³⁹Ar定年样品条件初探

doi: 10.3799/dqkx.2019.006

核工业北京地质研究院, 北京 100029

基金项目:

国家重点研发计划项目 2017YFC0602600

详细信息

作者简介:
李军杰(1986-), 男, 工程师, 博士研究生, 主要从事⁴⁰Ar-³⁹Ar同位素定年技术方法研究

通讯作者:
刘汉彬

中图分类号: P597
计量
- 文章访问数: 5062
- HTML全文浏览量: 2041
- PDF下载量: 82
- 被引次数: 0
出版历程
- 收稿日期: 2019-01-16
- 刊出日期: 2019-03-15

Primary Research of High Flux Engineering Test Reactor(HFETR) for Irradiation of ⁴⁰Ar-³⁹Ar Dating Samples

Beijing Research Institute of Uranium Geology, Beijing 100029, China

摘要

摘要: 国内目前用于⁴⁰Ar-³⁹Ar定年样品辐照的反应堆较少且开堆频率低，样品辐照周期长，且不同类型样品辐照条件缺乏系统研究.首次对高通量试验堆（HFETR）用于⁴⁰Ar-³⁹Ar定年样品的辐照工作进行了研究.通过辐照一定质量的黑云母标准物质ZBH-25，确定了辐照孔道³⁹Ar_K产率，为不同年龄和不同含钾量样品的辐照时间提供了参考依据.辐照孔道轴向中子通量梯度仅为3.3%/cm，且均呈二次曲线特征分布（R²>0.99），中子通量在径向上存在差异，最大差异达到7.1%/cm；通过辐照纯的钾盐和钙盐，得出辐照孔道内校正因子（³⁶Ar/³⁷Ar）_Ca的值为（3.52±0.11）×10^-4，且在样品辐照罐内不同位置基本一致，而校正因子（⁴⁰Ar/³⁹Ar）_K和（³⁹Ar/³⁷Ar）_Ca的值在辐照样品罐内存在明显的差异；Cd皮对于降低校正因子（⁴⁰Ar/³⁹Ar）_K的影响在样品罐底部更加明显，而在样品罐顶部几乎没有影响，这可能是由辐照孔道内中子能谱的差异造成的；以FCs透长石为中子通量监测物质，对标准物质ZBH-25黑云母和BSP-1角闪石进行了年龄测定，ZBH-25黑云母获得了理想的坪年龄，证明此反应堆满足⁴⁰Ar-³⁹Ar定年样品辐照的要求；BSP-1角闪石的坪年龄准确度和精度较差，与样品本身异常老的年龄和较低的K/Ca比有关，对于此类样品，准确确定干扰校正因子并合理延长照射时间对获得高精度⁴⁰Ar-³⁹Ar定年结果非常重要.
- 高通量试验堆 /
- ⁴⁰Ar-³⁹Ar定年 /
- 样品辐照 /
- 中子通量梯度 /
- 干扰校正因子 /
- 地质年代学
Abstract: The domestic reactors which could be utilized for the irradiation of ⁴⁰Ar-³⁹Ar dating samples are not only rare but the operation frequency is very low, which makes the period of the irradiation for samples extremely long.Besides, the optimized parameters of irradiation for different kinds of samples are short of systematic research.To solve the above-mentioned problems, primary research was done on the HFETR in the application of the irradiation of ⁴⁰Ar-³⁹Ar dating samples for the first time.Through the irradiation of certain amount of biotite standard ZBH-25, the production efficiency of ³⁹Ar_K is determined, which could provide the basis for the irradiation time for samples with different ages or potassium contents.The axial neutron flux gradient of the irradiation channel, which shows approximative conic function (R²>0.99), is only 3.3%/cm.However, the radial flux gradient is much more obvious, which is as high as 7.1%/cm.The interference factors are determined through the irradiation of pure potassium salt and calcium salt.It is found that the (³⁶Ar/³⁷Ar)_Ca factor is uniform with the value (3.52±0.11)×10^-4, but the interference factors (⁴⁰Ar/³⁹Ar)_K and (³⁶Ar/³⁷Ar)_Ca are scattered at different positions of the irradiation channel.The shielding effect of cadmium for the decrease of the interference factor of (⁴⁰Ar/³⁹Ar)_K is prominent at the bottom of the sample vessel but negligible at the top of the sample vessel, which may result from the difference of the neutron spectrum along the axial direction of the irradiation channel.Taking the international standard sanidine FCs as neutron flux monitor, the domestic standards biotite ZBH-25 and hornblende BSP-1 are dated.Excellent plateau age is obtained for the ZBH-25 biotite standard, indicating that the HFETR could satisfy the requirement of the sample irradiation.However, the precision and accuracy of the plateau age of the BSP-1 hornblende is somewhat worse, which maybe has something to do with the relatively old age and low ratio of the K/Ca.Precise determination of the interference factors and proloning of the irradiation time are necessary for the improvement of the age quality for such kind of sample.
- HFETR /
- ⁴⁰Ar-³⁹Ar dating /
- sample irradiation /
- neutron flux gradient /
- interference factor /
- geochronology

HTML全文

图 1 石英管内辐照样品位置示意图

Fig. 1. The position of the irradiated sample in the quartz tube

下载: 全尺寸图片幻灯片

图 2 铝板平面图(a)和辐照样品罐结构(b)

Fig. 2. Ichnography of the aluminum plate (a) and structure of the irradiated sample vessel (b)

下载: 全尺寸图片幻灯片

图 3 ³⁹Ar_K产率曲线(a)和不同年龄样品的辐照时间与⁴⁰Ar^*/³⁹Ar_K值关系(b)

Fig. 3. The ³⁹Ar_K production efficiency (a) and relationship of the ⁴⁰Ar^*/³⁹Ar_K value and irradiation time to the samples with different age (b)

下载: 全尺寸图片幻灯片

图 4 不同径向位置的轴向方向中子通量梯度变化曲线

Fig. 4. Curves about the neutron flux gradient along with the axial direction at different radial positions

下载: 全尺寸图片幻灯片

图 5 中子通量径向平面分布

Fig. 5. The position of the irradiated sample in the quartz tube

下载: 全尺寸图片幻灯片

图 6 辐照孔道不同位置校正因子变化

Fig. 6. The interference factor changes at different position of the irradiation channel

下载: 全尺寸图片幻灯片

图 7 ZBH-25黑云母和BSP-1角闪石坪年龄谱图

Fig. 7. Plateau age of biotite ZBH-25 and hornblende BSP-1

下载: 全尺寸图片幻灯片

表 1 不同类型辐照样品测试的接收器配置

Table 1. The detector configuration for the different kinds of irradiated samples

接收器	H2	H1	AX	L1	L2	CDD
钙盐	⁴⁰Ar	³⁹Ar	³⁸Ar	³⁷Ar	³⁶Ar	-
	-	⁴⁰Ar	³⁹Ar	³⁸Ar	³⁷Ar	³⁶Ar
	-	-	-	-	-	³⁹Ar
钾盐	⁴⁰Ar	³⁹Ar	³⁸Ar	³⁷Ar	³⁶Ar	-
钾盐	-	⁴⁰Ar	³⁹Ar	³⁸Ar	³⁷Ar	³⁶Ar
监测物质	⁴⁰Ar	³⁹Ar	³⁸Ar	³⁷Ar	³⁶Ar	-
	-	⁴⁰Ar	³⁹Ar	³⁸Ar	³⁷Ar	³⁶Ar
	-	-	-	-	-	³⁷Ar
注：H2、H1、AX、L1和L2为法拉第杯, 其中H2放大器高阻为10¹¹ Ω，其余4个法拉第杯的放大器高阻为10¹² Ω；CDD为二次电子倍增器.采用表中加粗的接收杯强度值.

下载: 导出CSV

表 2 BSP-1角闪石⁴⁰Ar-³⁹Ar年龄测试数据

Table 2. The ⁴⁰Ar-³⁹Ar dating data of hornblende BSP-1

温度(℃)	$ {{\left(\frac{^{40}\text{Ar}}{^{39}\text{Ar}} \right)}_{\text{m}}}$	$ {{\left(\frac{^{36}\text{Ar}}{^{39}\text{Ar}} \right)}_{\text{m}}}$	${{\left(\frac{^{37}\text{Ar}}{^{39}\text{Ar}} \right)}_{\text{m}}} $	³⁹Ar_K×10_mol^-14	$ \frac{^{40}\text{A}{{\text{r}}^{*}}}{^{39}\text{Ar}}$	³⁹Ar_K(%)	$ \frac{\text{K}}{\text{Ca}}\pm 1\sigma $	视年龄(Ma, 1σ)
900	577.126	0.152	0.484	0.085	532.370	0.43	0.20±0.03	2 176.83±10.48
1 000	1 795.387	0.070	0.374	0.083	1 775.423	0.45	0.22±0.04	3 936.52±10.58
1 100	613.571	0.063	1.121	0.152	595.495	0.81	0.08±0.01	2 321.51±7.05
1 200	474.078	0.009	0.954	6.360	471.955	34.69	0.10±0.01	2 026.69±6.15
1 300	453.681	0.004	0.961	1.050	452.899	57.68	0.09±0.01	1 976.65±6.05
1 400	427.166	0.105	0.937	0.109	424.479	5.95	0.09±0.01	1 899.36±5.94
注：表中下标m表示测试值，下标mol表示摩尔值.样品质量为0.02 g，辐照参数J=0.004 33±0.000 02.

下载: 导出CSV

参考文献(28)

Brereton, N. R., 1970.Corrections for Interfering Isotopes in the ⁴⁰Ar/³⁹Ar Dating Method.Earth and Planetary Science Letters, 8(6):427-433. https://doi.org/10.1016/0012-821x(70)90146-9
Clauer, N., Zwingmann, H., Liewig, N., et al., 2012.Comparative ⁴⁰Ar/³⁹Ar and K-Ar Dating of Illite-Type Clay Minerals:A Tentative Explanation for Age Identities and Differences.Earth-Science Reviews, 115(1-2):76-96. https://doi.org/10.1016/j.earscirev.2012.07.003
Coble, M.A., Grove, M., Calvert, A.T., 2011.Calibration of Nu-Instruments Noblesse Multicollector Mass Spectrometers for Argon Isotopic Measurements Using a Newly Developed Reference Gas.Chemical Geology, 290(1-2):75-87. https://doi.org/10.1016/j.chemgeo.2011.09.003
Dalrymple, G.B., Alexander, E.C., Lamphere, M.A., et al., 1981.Irradiation of Samples for ⁴⁰Ar/³⁹Ar Dating Using the Geological Survey TRIGA Reactor.U.S.Geological Survey, Professional Papers 1176, 18.
Dalrymple, G.B., Lanphere, M.A., 1971.⁴⁰Ar/³⁹Ar Technique of K-Ar Dating:A Comparison with the Conventional Technique.Earth and Planetary Science Letters, 12(3):300-308. https://doi.org/10.1016/0012-821x(71)90214-7
Kellett, D., Joyce, N., 2014.Analytical Details of Single-and Multi-Collection ⁴⁰Ar/³⁹Ar Measurements for Conventional Step-Heating and Total-Fusion Age Calculation Using the Nu Noblesse at the Geological Survey of Canada.Geological Survey of Canada, Technical Note 8, 1-21.
Koppers, A.A.P., 2002.ArArCALC-Software for ⁴⁰Ar/³⁹Ar Age Calculations.Computers & Geosciences, 28(5):605-619. https://doi.org/10.1016/s0098-3004(01)00095-4
Mark, D.F., Barfod, D., Stuart, F.M., et al., 2009.The ARGUS Multi-Collector Noble Gas Mass Spectrometer:Performance for ⁴⁰Ar/³⁹Ar Geochronology.Geochemistry, Geophysics, Geosystems, 10, Q0AA02. https://doi.org/10.1029/2009gc002643
Mei, S.L., Zhang, K.X., Wardlaw, B.R., 1998.A Refined Succession of Changhsingian and Griesbachian Neogondolellid Conodonts from the Meishan Section, Candidate of the Global Stratotype Section and Point of the Permian-Triassic Boundary.Palaeogeography, Palaeoclimatology, Palaeoecology, 143(4):213-226. https://doi.org/10.1016/s0031-0182(98)00112-6
Merrihue, C., Turner, G., 1966.Potassium-Argon Dating by Activation with Fast Neutrons.Journal of Geophysical Research, 71(11):2852-2857. https://doi.org/10.1029/jz071i011p02852
Mitchell, J.G., 1968.The Argon-⁴⁰/Argon-³⁹ Method for Potassium-Argon Age Determination.Geochimica et Cosmochimica Acta, 32(7):781-790. https://doi.org/10.1016/0016-7037(68)90012-4
Podosek, F.A., 1971.Neutron-Activation Potassium-Argon Dating of Meteorites.Geochimica et Cosmochimica Acta, 35(2):157-173. https://doi.org/10.1016/0016-7037(71)90055-x
Renne, P.R., Balco, G., Ludwig, K.R., et al., 2011.Response to the Comment by W.H.Schwarz et al. on "Joint Determination of ⁴⁰K Decay Constants and ⁴⁰Ar^*/⁴⁰K for the Fish Canyon Sanidine Standard, and Improved Accuracy for ⁴⁰Ar/³⁹Ar Geochronology" by P.R.Renne et al. (2010).Geochimica et Cosmochimica Acta, 75(17): 5097-5100.https://doi.org/ 10.1016/j.gca.2011.06.021
Renne, P.R., Knight, K.B., Nomade, S., et al., 2005.Application of Deuteron-Deuteron (D-D) Fusion Neutrons to ⁴⁰Ar/³⁹Ar Geochronology.Applied Radiation and Isotopes, 62(1):25-32. https://doi.org/10.1016/j.apradiso.2004.06.004
Renne, P.R., Swisher, C.C., Deino, A.L., et al., 1998.Intercalibration of Standards, Absolute Ages and Uncertainties in ⁴⁰Ar/³⁹Ar Dating.Chemical Geology, 145(1-2):117-152. https://doi.org/10.1016/s0009-2541(97)00159-9
Rutte, D., Pfänder, J.A., Koleška, M., et al., 2015.Radial Fast-Neutron Fluence Gradients during Rotating ⁴⁰Ar/³⁹Ar Sample Irradiation Recorded with Metallic Fluence Monitors and Geological Age Standards.Geochemistry, Geophysics, Geosystems, 16(1):336-345. https://doi.org/10.1002/2014gc005611
Sang, H.Q., Wang, F., He, H.Y., et al., 2006.Intercalibration of ZBH-25 Biotite Reference Material Untilized for K-Ar and ⁴⁰Ar-³⁹Ar Age Determination.Acta Petrologica Sinica, 22(12):3059-3078 (in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=ysxb98200612022
Scaillet, S., 2000.Numerical Error Analysis in ⁴⁰Ar-³⁹Ar Dating.Chemical Geology, 162(3-4):269-298. https://doi.org/10.1016/s0009-2541(99)00149-7
Stacey, J.S., Sherrill, N.D., Dalrymple, G.B., et al., 1981.A Five-Collector System for the Simultaneous Measurement of Argon Isotope Ratios in a Static Mass Spectrometer.International Journal of Mass Spectrometry and Ion Physics, 39(2):167-180. https://doi.org/10.1016/0020-7381(81)80031-9
Turner, G., 1971.Argon 40-Argon 39 Dating:The Optimization of Irradiation Parameters.Earth and Planetary Science Letters, 10(2):227-234. https://doi.org/10.1016/0012-821x(71)90010-0
Vermeesch, P., 2015.Revised Error Propagation of ⁴⁰Ar/³⁹Ar Data, Including Covariances.Geochimica et Cosmochimica Acta, 171:325-337. https://doi.org/10.1016/j.gca.2015.09.008
Wang, H., Xiang, Y.X., Xu, T.Z., et al., 2017.Verification of Neutron Flux Calculation Method for HFETR.Nuclear Power Engineering, 38(S1):154-156 (in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=hdlgc2017z1037
Wang, S.S., Hu, S, L., Sang, H.Q., et al., 1992.BSP-1 Hornblende, a 2 Ga Age Standard as Flux Monitor of ⁴⁰Ar-³⁹Ar Dating.Acta Petrologica Sinica, 8(2):103-127 (in Chinese with English abstract).
Yang, L.K., Wang, F., He, H.Y., et al., 2009.Achievements and Limitations of ⁴⁰Ar/³⁹Ar Dating on Young Volcanic Rocks.Seismology and Geology, 31(1):174-185 (in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=dzdz200901016
桑海清, 王非, 贺怀宇, 等, 2006.K-Ar法地质年龄国家一级标准物质ZBH-25黑云母的研制.岩石学报, 22(12):3059-3078. http://d.old.wanfangdata.com.cn/Periodical/ysxb98200612022
王皓, 向玉新, 徐涛忠, 等, 2017.高通量工程试验堆(HFETR)材料辐照中子注量率计算方法验证.核动力工程, 38(S1):154-156. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=hdlgc2017z1037
王松山, 胡世玲, 桑海清, 等, 1992.氩-氩定年法国际标准物质BSP-1角闪石的研制.岩石学报, 8(2):103-127. doi: 10.3321/j.issn:1000-0569.1992.02.001
杨列坤, 王非, 贺怀宇, 等, 2009.年轻火山岩氩同位素体系定年技术最新进展及问题.地震地质, 31(1):174-185. doi: 10.3969/j.issn.0253-4967.2009.01.016