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Three-dimensional imaging of atomic four-body processes

Abstract

To understand the physical processes that occur in nature we need to obtain a solid concept about the ‘fundamental’ forces acting between pairs of elementary particles. It is also necessary to describe the temporal and spatial evolution of many mutually interacting particles under the influence of these forces. This latter step, known as the few-body problem, remains an important unsolved problem in physics. Experiments involving atomic collisions represent a useful testing ground for studying the few-body problem. For the single ionization of a helium atom by charged particle impact, kinematically complete experiments have been performed1,2,3,4,5,6 since 1969 (ref. 7). The theoretical analysis of such experiments was thought to yield a complete picture of the basic features of the collision process, at least for large collision energies8,9,10,11,12,13,14. These conclusions are, however, almost exclusively based on studies of restricted electron-emission geometries1,2,3. Here, we report three-dimensional images of the complete electron emission pattern for the single ionization of helium by the impact of C6+ ions of energy 100 MeV per a.m.u. (a four-body system) and observe features that have not been predicted by any published theoretical model. We propose a higher-order ionization mechanism, involving the interaction between the projectile and the target nucleus, to explain these features.

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Figure 1: Schematic experimental set-up for three-dimensional imaging of atomic processes.
Figure 2: Three-dimensional images of electrons ejected in 100 MeV per a.m.u. C6+ + He collisions.
Figure 3: Triply differential single ionization cross-sections for selected electron emission planes.
Figure 4: Triply differential single ionization cross-sections for the perpendicular plane for 2 MeV per a.m.u. C6+ + He collisions.

References

  1. Ehrhardt, H., Jung, K., Knoth, G. & Schlemmer, P. Differential cross sections of direct single electron impact ionization. Z. Phys. D 1, 3–32 (1986)

    ADS  CAS  Article  Google Scholar 

  2. Stefani, G., Avaldi, L. & Camilloni, R. On the relevance of the final ionic state to the (e,2e), TDCS. J. Phys. B 23, L227–L231 (1990)

    ADS  CAS  Article  Google Scholar 

  3. Lahmam-Bennani, A. Recent developments and new trends in (e,2e) and (e,3e) studies. J. Phys. B 24, 2401–2442 (1991)

    ADS  Article  Google Scholar 

  4. Murray, A. J., Woolf, M. B. J. & Read, F. H. Results from symmetric and non-symmetric energy sharing (e,2e) experiments in the perpendicular plane. J. Phys. B 25, 3021–3036 (1992)

    ADS  CAS  Article  Google Scholar 

  5. Röder, J., Ehrhardt, H., Bray, I., Fursa, D. V. & McCarthy, I. E. Absolute triple differential cross-section for electron-impact ionization of helium at 40 eV. J. Phys. B 29, 2103–2114 (1996)

    ADS  Article  Google Scholar 

  6. Schulz, M. et al. Triply differential single ionization cross-sections in coplanar and non-coplanar geometry for fast heavy ion-atom collisions. J. Phys. B 34, L305–L311 (2001)

    CAS  Article  Google Scholar 

  7. Ehrhardt, H., Schulz, M., Tekaat, T. & Willmann, K. Ionization of helium: angular correlation of the scattered and ejected electrons. Phys. Rev. Lett. 22, 82–92 (1969)

    ADS  Article  Google Scholar 

  8. Bray, I. & Stelbovics, A. T. Explicit demonstration of the convergence of the close-coupling method for a Coulomb three-body problem. Phys. Rev. Lett. 69, 53–56 (1992)

    ADS  CAS  Article  Google Scholar 

  9. Rescigno, T. N., Baertschy, M., Isaacs, W. A. & McCurdy, C. W. Collisional breakup in a quantum system of three charged particles. Science 286, 2474–2479 (1999)

    CAS  Article  Google Scholar 

  10. Belkic, Dz. A quantum theory of ionisation in fast collisions between ions and atomic systems. J. Phys. B 11, 3529–3552 (1978)

    ADS  CAS  Article  Google Scholar 

  11. Crothers, D. S. F. & McCann, J. F. Ionisation of atoms by ion impact. J. Phys. B 16, 3229–3242 (1983)

    ADS  CAS  Article  Google Scholar 

  12. Jones, S. & Madison, D. H. Evidence of initial-state two-center effects for (e,2e) reactions. Phys. Rev. Lett. 81, 2886–2889 (1998)

    ADS  CAS  Article  Google Scholar 

  13. Madison, D., Schulz, M., Jones, S., Foster, M., Moshammer, R. & Ullrich, J. Comparison of theoretical and absolute experimental fully differential cross sections for ion-atom impact ionization. J. Phys. B 15, 3297–3314 (2002)

    ADS  Article  Google Scholar 

  14. Crothers, D. S. F. et al. Magnetically quantized continuum distorted waves. Phys. Rev. Lett. 88, 053201–053204 (2002)

    ADS  CAS  Article  Google Scholar 

  15. Ullrich, J. et al. Recoil-ion, momentum spectroscopy. J. Phys. B 30, 2917–2974 (1997)

    ADS  CAS  Article  Google Scholar 

  16. Whelan, C. T., Allan, R. J., Walters, H. R. J. & Zhang, X. in (e,2e) and Related Processes (eds Whelan, C. T., Walters, H. R. J., Lahmam-Bennani, A. & Ehrhardt, H.) Vol. 414 of Series C: Mathematical and Physical Sciences 1–32 (Kluwer, Dordrecht, 1993)

    Google Scholar 

  17. Marchalant, P., Whelan, C. T. & Walters, H. R. J. Second-order effects in (e,2e) excitation-ionization of helium to He+ (n = 2). J. Phys. B 31, 1141–1178 (1998)

    ADS  CAS  Article  Google Scholar 

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Acknowledgements

We thank W. Schmitt, R. Mann, R. Dörner, T. Weber, Kh. Khayyat, A. Cassimi, L. Adoui, J. P. Grandin and staff members of the CIRIL for their help performing the experiment at the GANIL; thanks to R. E. Olson and J. Fiol for discussions. The support of the Deutsche Forschungsgemeinschaft within the Leibniz-program, by GSI, the European Union, the NSF and by CIRIL (GANIL at Caen) is acknowledged.

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Schulz, M., Moshammer, R., Fischer, D. et al. Three-dimensional imaging of atomic four-body processes. Nature 422, 48–50 (2003). https://doi.org/10.1038/nature01415

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