TITLE: EFFECTIVE SOMMERFELD PARAMETERS IN DOUBLE PHOTOIONIZATION

AUTHORS: M. A. Kornberg (1) and V. D. Rodriguez (2)

AFFILIATIONS: (1) Max-Planck-Institut fuer Quantenoptik,
                  Hans-Kopfermann-strasse 1, D-85748 Garching, Germany 
              (2) Departamento de Fisica,
                  Universidad de Buenos Aires, FCEyN, 1428 Buenos Aires, Argentina

SUMMARY: We present calculations of the fivefold differential cross section (FDCS)
for double photoionization of helium. Our results are obtained using for the final
double-continuum state a product of three Coulomb wave functions, with the Sommerfeld
parameters modified to describe the strength of interaction of any two particles 
affected by the third particle. Calculations are compared with recent measurements.