Photodetachment of the Positronium Negative Ion (Ps^-) and the ¹D-wave e^--Ps scattering

The photodetachment cross section of Ps^- has been computed in both the length and velocity forms [1-5]. However, for small wave lengths there exists a discrepancy between the calculations of this cross section that used different types of wave functions [3-5]. To see if we could resolve this discrepancy, we computed the cross section. We extended the calculations of Refs. [1-3] by improving the accuracy of the bound-state and ¹P continuum variational wave functions of the e^- -Ps system. Also, since the continuum ¹D wave function of the e^--Ps system is needed for the two-photon detachment cross section of Ps^- we have begun a Kohn variational calculation to determine ¹D phase shifts for e^--Ps scattering for energies below the Ps(n=2) threshold.

[1] S. J. Ward and M. R. C. McDowell, Europhys. Lett. 1, 167 (1986).

[2] S. J. Ward, Thesis, University of London, Unpublished, (1986).

[3] S. J. Ward, J. W. Humberston and M. R. C. McDowell, J. Phys. B 30, 127 (1987).

[4] A. Igarashi, S. Nakazaki, and A. Ohsaki, Phys. Rev. A 61, 032710 (2000).

[5] A. Igarashi, I. Shimamura and N. Toshima, New J. Phys. 2, 17 (2000).