MEAN RECOIL ION AND ELECTRON LONGITUDINAL MOMENTUM IN=20
          HE SINGLE IONIZATION BY PROTON AND ANTIPROTON IMPACT
=20
         V. D. Rodr\'{\i}guez$^\sharp$ and P. D. Fainstein$^\ast$

$^\sharp$Departamento de F\'{\i}sica, Universidad de Buenos Aires, =
FCEyN, 1428
Buenos Aires, Argentina=20
$^\ast$Centro At\'omico Bariloche and Instituto Balseiro, 8400 S. C. de
Bariloche, R\'{\i}o Negro, Argentina


We report  CDW-EIS theoretical calculations of mean recoil ion and =
electron
longitudinal momentum in  He  single  ionization  by  proton  and =
antiproton
impact as a function  of  the  impact  energy  from  50  KeV  to 1 MeV.  =
At
intermediate energies the mean momenta  of both electron and recoil-ion =
are
significatively  different for proton and antiproton  impact.    At  =
larger
energies mean values for proton and antiproton  cases  approach one to =
each
other as the Born approximation turns out to be valid.