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Atom-trap trace analysis of 41Ca/Ca down to the 10–17 level

Nature Physics volume 19, pages 904–908 (2023)Cite this article

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Abstract

The cosmogenic isotope 41Ca with a half-life of 99,000 years can, in principle, serve as a tracer for environmental processes at an age scale beyond the reach of 14C. With accelerator mass spectrometry, the ratio of 41Ca/Ca has been measured down to the 10−15 level in natural samples. A wide range of potential applications, such as the burial dating of bones and exposure dating of rocks, require measuring even smaller 41Ca/Ca ratios in the range of 10−16 to 10−15. Here we achieved this by employing the atom-trap trace analysis method in which individual 41Ca atoms are selectively captured in a magneto-optical trap and counted by detecting their fluorescence. We realized a precision of 12% on the 41Ca/Ca ratio at the level of 10−16 and achieved a detection limit at the level of 10−17, which is below the distribution of natural abundances. We verified the accuracy of the 41Ca/Ca results through a series of measurements of reference samples, and performed demonstration analyses on bone, rock and seawater samples. Our table-top method has the potential to explore the suitability of 41Ca as a tracer.

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Fig. 1: Single-atom detection.
Fig. 2: MOT fluorescence of Ca isotopes as a function of the trap laser frequency at 423 nm.
Fig. 3: Reference sample measurements.

Data availability

Source data are provided in Extended Data Tables 2 and 3 and available via Zenodo at https://doi.org/10.5281/zenodo.7489164 (ref. 35).

References

  1. Raisbeck, G. M. & Yiou, F. Possible use of 41Ca for radioactive dating. Nature 277, 42–44 (1979).

    Article  ADS  Google Scholar 

  2. Gusonne, N. et al. Calcium Stable Isotope Geochemistry (Springer, 2016).

  3. Jorg, G., Amelin, Y., Kossert, K. & von Gostomski, C. L. Precise and direct determination of the half-life of 41Ca. Geochim. Cosmochim. Acta 88, 51–65 (2012).

    Article  ADS  Google Scholar 

  4. Taylor, R. E. Dating techniques in archaeology and paleoanthropology. Anal. Chem. 59, A317–A331 (1987).

    Article  Google Scholar 

  5. Schaefer, J. M. et al. Cosmogenic nuclide techniques. Nat. Rev. Methods Primers 2, 18 (2022).

    Article  Google Scholar 

  6. Fink, D., Klein, J., Middleton, R., Vogt, S. & Herzog, G. F. 41Ca in iron falls, grant and estherville: production-rates and related exposure age calculations. Earth Planet. Sci. Lett. 107, 115–128 (1991).

    Article  ADS  Google Scholar 

  7. Welten, K. C. et al. Terrestrial ages, pairing, and concentration mechanism of Antarctic chondrites from Frontier Mountain, Northern Victoria Land. Meteorit. Planet. Sci. 41, 1081–1094 (2006).

    Article  ADS  Google Scholar 

  8. Welten, K. C., Caffee, M. W., Hillegonds, D. J., Masarik, J. & Nishiizumi, K. Identifying large chondrites using cosmogenic radionuclides. Nucl. Instrum. Methods Phys. Res. B 268, 1185–1188 (2010).

    Article  ADS  Google Scholar 

  9. Johnson, R. R. et al. Calcium resorption from bone in a human studied by 41Ca tracing. Nucl. Instrum. Methods Phys. Res. B 92, 483–488 (1994).

    Article  ADS  Google Scholar 

  10. Sharma, M., Bajzer, Z. & Hui, S. K. Development of 41Ca-based pharmacokinetic model for the study of bone remodelling in humans. Clin. Pharmacokinet. 50, 191–199 (2011).

    Article  Google Scholar 

  11. Jackson, G. S. et al. Biomedical graphite and CaF2 preparation and measurement at PRIME Lab. Nucl. Instrum. Methods Phys. Res. B 361, 358–362 (2015).

    Article  ADS  Google Scholar 

  12. Henning, W. et al. Calcium-41 concentration in terrestrial materials: prospects for dating of Pleistocene samples. Science 236, 725–727 (1987).

    Article  ADS  Google Scholar 

  13. Fink, D., Middleton, R., Klein, J. & Sharma, P. 41Ca: measurement by accelerator mass spectrometry and applications. Nucl. Instrum. Methods Phys. Res. B 47, 79–96 (1990).

    Article  ADS  Google Scholar 

  14. Fink, D., Klein, J. & Middleton, R. 41Ca: past, present and future. Nucl. Instrum. Methods Phys. Res. B 52, 572–582 (1990).

    Article  ADS  Google Scholar 

  15. Steinhof, A. et al. A 82Kr pilot beam for the accelerator mass-spectrometry of 41Ca. Nucl. Instrum. Methods Phys. Res. B 52, 391–397 (1990).

    Article  ADS  Google Scholar 

  16. Merchel, S. et al. A multi-radionuclide approach for in situ produced terrestrial cosmogenic nuclides: 10Be, 26Al, 36Cl and 41Ca from carbonate rocks. Nucl. Instrum. Methods Phys. Res. B 268, 1179–1184 (2010).

    Article  ADS  Google Scholar 

  17. Wallner, A. et al. Fluorides or hydrides? 41Ca performance at VERA’s 3-MV AMS facility. Nucl. Instrum. Methods Phys. Res. B 268, 799–803 (2010).

    Article  ADS  Google Scholar 

  18. Rugel, G. et al. The first four years of the AMS-facility DREAMS: status and developments for more accurate radionuclide data. Nucl. Instrum. Methods Phys. Res. B 370, 94–100 (2016).

    Article  ADS  Google Scholar 

  19. Sasa, K. et al. The 6 MV multi-nuclide AMS system at the University of Tsukuba, Japan: first performance report. Nucl. Instrum. Methods Phys. Res. B 437, 98–102 (2018).

    Article  ADS  Google Scholar 

  20. Wallner, A. et al. Accelerator mass spectrometry with ANU’s 14 million volt accelerator. Nucl. Instrum. Methods Phys. Res. B 534, 48–53 (2023).

    Article  ADS  Google Scholar 

  21. Wendt, K. & Trautmann, N. Recent developments in isotope ratio measurements by resonance ionization mass spectrometry. Int. J. Mass Spectrom. 242, 161–168 (2005).

    Article  Google Scholar 

  22. Chen, C. Y. et al. Ultrasensitive isotope trace analyses with a magneto-optical trap. Science 286, 1139–1141 (1999).

    Article  Google Scholar 

  23. Lu, Z. T. et al. Tracer applications of noble gas radionuclides in the geosciences. Earth-Sci. Rev. 138, 196–214 (2014).

    Article  ADS  Google Scholar 

  24. Moore, I. D. et al. Counting individual 41Ca atoms with a magneto-optical trap. Phys. Rev. Lett. 92, 153002 (2004).

    Article  ADS  Google Scholar 

  25. Hoekstra, S., Mollema, A. K., Morgenstern, R., Wilschut, H. W. & Hoekstra, R. Single-atom detection of calcium isotopes by atom-trap trace analysis. Phys. Rev. A 71, 023409 (2005).

    Article  ADS  Google Scholar 

  26. Raab, E. L., Prentiss, M., Cable, A., Chu, S. & Pritchard, D. E. Trapping of neutral sodium atoms with radiation pressure. Phys. Rev. Lett. 59, 2631–2634 (1987).

    Article  ADS  Google Scholar 

  27. Mills, M. et al. Efficient repumping of a Ca magneto-optical trap. Phys. Rev. A 96, 033402 (2017).

    Article  ADS  Google Scholar 

  28. Fu, Y. C., Zhou, W. J., Cheng, P. & Zhang, L. Y. A new capability for 41Ca analysis using CaF3– at the Xi’an-AMS. Nucl. Instrum. Methods Phys. Res. B 438, 162–165 (2019).

    Article  ADS  Google Scholar 

  29. Rugamas, F. et al. Angular profiles of molecular beams from effusive tube sources: I. Experiment. Meas. Sci. Technol. 11, 1750–1765 (2000).

    Article  ADS  Google Scholar 

  30. Dunai, T. J. Cosmogenic Nuclides: Principles, Concepts and Applications in the Earth Surface Sciences (Cambridge Univ. Press, 2010).

  31. Gosse, J. C. & Phillips, F. M. Terrestrial in situ cosmogenic nuclides: theory and application. Quat. Sci. Rev. 20, 1475–1560 (2001).

    Article  ADS  Google Scholar 

  32. Borchers, B. et al. Geological calibration of spallation production rates in the CRONUS-Earth project. Quat. Geochronol. 31, 188–198 (2016).

    Article  Google Scholar 

  33. Schaefer, J. M. et al. Greenland was nearly ice-free for extended periods during the Pleistocene. Nature 540, 252–255 (2016).

    Article  ADS  Google Scholar 

  34. Marrero, S. M., Phillips, F. M., Caffee, M. W. & Gosse, J. C. CRONUS-Earth cosmogenic 36Cl calibration. Quat. Geochronol. 31, 199–219 (2016).

    Article  Google Scholar 

  35. Xia, T.-Y. et al. Source data associated with the article ‘atom-trap trace analysis of 41Ca/Ca down to the 10−17 level’. Zenodo https://doi.org/10.5281/zenodo.7489164 (2023).

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Acknowledgements

We thank D. Sheng, A.-W. Liu, Q.-X. Li and G. Jin for helpful discussions. We thank T.-F. Xu and Y. Yang for providing the seawater sample. This work is supported by the Innovation Program for Quantum Science and Technology through grant no. 2021ZD0303100 to T.-Y.X., W.-W.S., W.J., G.-M.Y., H.-M.Z., T.X. and Z.-T.L.; the National Natural Science Foundation of China through grant no. 41727901 to T.-Y.X., W.-W.S., S.E., W.J., G.-M.Y., H.-M.Z., T.X. and Z.-T.L.; the Strategic Priority Research Program of the Chinese Academy of Sciences through grant no. XDB21010200 to T.X. and Z.-T.L.; and Innovation Program for Quantum Science and Technology through grant no. 2021ZD0303101 to T.-Y.X., W.-W.S., S.E., W.J., G.-M.Y., H.-M.Z., T.X. and Z.-T.L.

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Author notes

  1. These authors contributed equally: T.-Y. Xia, W.-W. Sun.

Authors and Affiliations

  1. CAS Center for Excellence in Quantum Information and Quantum Physics, School of Physical Sciences, University of Science and Technology of China, Hefei, China

    T.-Y. Xia, W.-W. Sun, S. Ebser, W. Jiang, G.-M. Yang, H.-M. Zhu, T. Xia & Z.-T. Lu

  2. Hefei National Laboratory, University of Science and Technology of China, Hefei, China

    W. Jiang & Z.-T. Lu

  3. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an, China

    Yun-Chong Fu

  4. Shaanxi Key Laboratory of Accelerator Mass Spectrometry Technology and Application, Xi’an AMS Center of IEECAS, Joint Xi’an AMS Center between IEECAS and Xi’an Jiaotong University, Xi’an, China

    Yun-Chong Fu

  5. CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, China

    F. Huang & G.-D. Ming

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Contributions

T.X. and Z.-T.L. conceived the research and supervised the project. T.-Y.X., W.-W.S., S.E., W.J., G.-M.Y., H.-M.Z., T.X. and Z.-T.L. developed the ATTA apparatus, W.-W.S. performed the ATTA measurements, T.-Y.X. developed the procedure for calcium extraction and preparation, G.-D.M. and T.-Y.X. developed the procedure for extracting calcium from granite, Y.-C.F. performed the AMS measurements, and G.-D.M. and F.H. collected the granite sample. W.-W.S., T.-Y.X., W.J., T.X. and Z.-T.L. analysed the data and discussed the results. T.-Y.X., W.-W.S., T.X. and Z.-T.L. wrote the paper. All the authors reviewed the paper.

Corresponding authors

Correspondence to T. Xia or Z.-T. Lu.

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Competing interests

T.-Y.X., T.X., W.-W.S., Z.-T.L. and W.J. have applied for a patent on the basis of this work (Chinese patent application no. CN115201172A, in substantive examination). The other authors declare no competing interests.

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Nature Physics thanks Marc Caffee, Stewart Freeman and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data

Extended Data Fig. 1 Schematic diagram of an ATTA apparatus for 41Ca/Ca analysis.

The oven, transverse cooling (TC), transverse focusing (TF), Zeeman slower (ZS), and magneto-optical trap (MOT) are aligned coaxially. The atom chopper rotates to block the atom beam while detecting 41Ca in the MOT. The purple arrows represent 423-nm laser beams that cool, load, and detect the Ca atoms. The blue arrows represent 453-nm repump laser beams.

Extended Data Fig. 2 Energy level diagram of the neutral Ca atom.

The purple and blue arrows represent the atomic transitions for cooling and trapping at 423 nm and for repump at 453 nm, respectively. The percentages are branching ratios of spontaneous decay channels. Dashed lines represent inter-combination transitions.

Extended Data Fig. 3 Time sequence of single-atom detection.

Status of atom beam, Zeeman slower (ZS) laser, magneto-optical trap (MOT) laser, and CCD camera are shown. The repump laser beam (453-nm) is kept on constantly. The atomic beam is switched by a mechanical chopper with 18-ms rising/falling edges. A 500-ms period is divided into three phases: loading, detection and releasing. Single 41Ca atoms are captured into the MOT in the loading phase, detected in the detection phase, and released from the MOT in the releasing phase.

Extended Data Table 1 Configurations of laser beams for cooling and trapping
Full size table
Extended Data Table. 2 Reference samples calibrated by AMS
Full size table
Extended Data Table 3 41Ca/Ca ratios of reference samples measured by ATTA
Full size table
Extended Data Table 4 Relative uncertainties in 41Ca/Ca measurements
Full size table

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Xia, TY., Sun, WW., Ebser, S. et al. Atom-trap trace analysis of 41Ca/Ca down to the 10–17 level. Nat. Phys. 19, 904–908 (2023). https://doi.org/10.1038/s41567-023-01969-w

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