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Published August 25, 1969 | public
Journal Article Open

Antiproton-proton annihilation into electron-positron pairs and gamma-ray pairs


Experimental limits have been set on the cross sections for p+p→e++e- for antiprotons with incident momenta of 1.47 and 2.40 GeV/c. These results imply upper limits on the magnitude of the proton form factors for timelike four-momentum transfer of 5.1 and 6.6 (GeV/c)2. The reaction p+p→γ+γ has been studied at the same incident momenta. This process has apparently been observed for incident antiproton momentum of 1.47 GeV/c, while an upper limit for the two-photon annihilation cross section is found at 2.40-GeV/c incident momentum.

Additional Information

©1969 The American Physical Society. Received 24 March 1969. We wish to thank John Madey, John Gallivan, Peter Mazur, Jerome Mar, Ken Young, and Edward Olsen, all of the California Institute of Technology, for their help with the experiment. We are grateful to many people at Brookhaven National Laboratory for their help and hospitality. Particularly, we would like to thank T. Blair, R. Gibbs, A. P. Schlafke, J. Hennesy, J. Lepicki, Dr. J. R. Sanford, and the members of the AGS crew. Tow of us (A.W.M. and T.F.Z.) wish to thank Dr. Lyle Smith for the generous assistance which he provided during the early stages of the experiment.


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