\({\bar {\mathrm {H}}^{+}}\) production from collisions between positronium and keV antiprotons for GBAR


In the framework of the GBAR (Gravitational Behaviour of Antihydrogen at Rest) experiment, cross sections for antihydrogen ion (\(\bar {\mathrm {H}}^{+}\)) production in collisions between antiprotons (\(\bar {\mathrm {p}}\)) and excited positronium atoms (Ps), with intermediate production of antihydrogen (\(\bar {\mathrm {H}}\)), have been computed using a perturbative theory, namely Continuum Distorted Wave - Final State (CDW-FS). The results suggest to use antiprotons at 1, 2 or 6 keV with, respectively, Ps(3p,3d), Ps(2p) or no Ps excitation. A simulation using these cross sections is under development to investigate the reaction chamber geometry and the parameters of the different beams (positrons, antiprotons and laser). This simulation, focusing on Ps(3d), predicts at least one \(\bar {\mathrm {H}}^{+}\) ion per pulse of 3·106 \(\bar {\mathrm {p}}\) at 1 and 6 keV, and highlights both the interest of positronium excitation and the need for short pulses of particles.

This is a preview of subscription content, access via your institution.


  1. 1.

    The GBAR Collaboration: CERN-SPSC-2011-029, SPSC-342 (2011)

  2. 2.

    Debu P.: GBAR. Hyperfine Interact. 212, 51 (2012)

    Article  ADS  Google Scholar 

  3. 3.

    Pérez, P., Sacquin Y.: The GBAR experiment: gravitational behaviour of antihydrogen at rest. Class. Quantum Grav. 29, 184008 (2012)

    Article  ADS  Google Scholar 

  4. 4.

    Walz, J., Haensch, T.: A proposal to measure antimatter gravity using ultracold antihydrogen atoms. Gen. Relativ. Gravit. 36, 561–570 (2004)

    Article  MATH  ADS  Google Scholar 

  5. 5.

    Oelert W., et al.: ELENA: An Upgrade to the Antiproton Decelerator. Report CERN-SPSC-2009-026/SPSC-P-338 (2009)

  6. 6.

    Cassidy, D.B., Crivelli, P., Hisakado, T.H., Liszkay, L., Meligne, V.E., Perez, P., Tom, H.W.K., Mills, A.P. Jr.: Positronium cooling in porous silica measured via Doppler spectroscopy. Phys. Rev. A 81, 012715 (2010)

    Article  ADS  Google Scholar 

  7. 7.

    Comini, P., Hervieux P.-A.: \(\bar {H}\) and \(\bar {H}^{+}\) production cross sections for the GBAR experiment. J. Phys.: Conf. Ser. 443, 012007 (2013)

    ADS  Google Scholar 

  8. 8.

    Comini, P., Hervieux P.-A.: \(\bar {H}^{+}\) ion production from collisions between antiprotons and excited positronium: cross sections calculations in the framework of the GBAR experiment. New J. Phys. 15, 09522 (2013)

    Article  Google Scholar 

  9. 9.

    Mitroy J.: An L2 calculation of positron-hydrogen scattering at intermediate energies. J. Phys. B: At. Mol. Opt. Phys. 29, L263 (1996)

    Article  ADS  Google Scholar 

  10. 10.

    Kernoghan, A.A., Robinson, D.J.R., McAlinden, M.T., Walters, H.R.J.: Positron scattering by atomic hydrogen. J. Phys. B: At. Mol. Opt. Phys. 29, 2089 (1996)

    Article  ADS  Google Scholar 

  11. 11.

    Mitroy J.: Formation of antihydrogen by the charge-transfer reaction. Phys. Rev. A 52, 2859 (1995)

    Article  ADS  Google Scholar 

  12. 12.

    Mitroy, J., Ryzhikh G.: The formation of antihydrogen by the charge transfer reaction. J. Phys. B: At. Mol. Opt. Phys. 30, L371 (1997)

    Article  ADS  Google Scholar 

  13. 13.

    Roy S., Sinha C.: Formation of negative hydrogen ion in positronium-hydrogen collisions. Eur. Phys. J. D 47, 327 (2008)

    Article  ADS  Google Scholar 

  14. 14.

    McAlinden, M.T., Blackwood J.E., Walters H.R.J.: Positron scattering by the negative hydrogen ion. Phys. Rev. A 65, 032711 (2002)

    Article  ADS  Google Scholar 

  15. 15.

    Fojón, O.A., Rivarola, R.D., Gayet, R., Hanssen, J., Hervieux P.-A.: Continuum-distorted-wave-final-state approximation in positron-hydrogenic atom (ion) collisions with positronium formation. Phys. Rev. A 54, 4923 (1996)

    Article  ADS  Google Scholar 

  16. 16.

    Hanssen, J., Hervieux, P.-A., Fojón, O.A., Rivarola, R.D.: Positronium formation in positron-metastable-helium collisions. Phys. Rev. A 63, 012705 (2001)

    Article  ADS  Google Scholar 

Download references

Author information



Corresponding author

Correspondence to Pauline Comini.

Additional information

Proceedings of the 11th International Conference on Low Energy Antiproton Physics (LEAP 2013) held in Uppsala, Sweden, 10–15 June, 2013

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Comini, P., Hervieux, PA. & Biraben, F. \({\bar {\mathrm {H}}^{+}}\) production from collisions between positronium and keV antiprotons for GBAR. Hyperfine Interact 228, 159–165 (2014). https://doi.org/10.1007/s10751-014-1030-y

Download citation


  • Antihydrogen
  • Positronium