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Cross sections for the reaction pp -• e + e~ have been measured at s = 8.9,12.4, and 13.0 GeV 2 . The cross sections have been analyzed to obtain the proton electromagnetic form factors in the timelike region. We find that GM(Q 2 ) OC q~Aoc 2 {q 2 ) for q 2 > 5 (GeV/c) 2 .The understanding of nucleon structure is one of the central problems of hadronic physics. Measurements of the electric and magnetic form factors, GE and GM> &S functions of the four-momentum transfer q 2 provide experimental information relating to the nucleon structure. A large body of precise data obtained primarily from elastic scattering of electrons by protons and deuterons now exists for these form factors, with the form factors of the proton known up to q 2 = 31 (GeV/c) 2 [1]. However these data are primarily for spacelike momentum transfers (q 2 < 0). Results for GM in the timelike region (s --q 2 c 2 > 0) exist only for a small interval near threshold, 4m 2 c 4 < s < 5.6 GeV 2 . These data include precise measurements recently obtained at the Low Energy Antiproton Ring (LEAR) facility at CERN from the reaction pp -• e + e~ [2]. For larger momentum transfers only upper limits have been established by earlier e + e~ -* pp and pp -> e + e~ experiments [3]. Perturbative QCD predicts [4] that for large momentum transfers Q A \GM\/^Pshould be nearly proportional to the square of the running coupling constant for strong interactions, OL 2 (q 2 ). Recent data [1] for large spacelike momentum transfers are in remarkable agreement with this prediction for q 2 as small as 5 (GeV/c) 2 . It is of great interest to find out if a similar behavior holds for timelike momentum transfers.In this Letter we present the results of our measurements of the cross section for the reactionat y/s = 3.0, 3.5, and 3.6 GeV. These measurements were made as a part of Fermilab experiment E-760, which is dedicated to the study of charmonium by resonant formation in pp annihilations [5]. The differential cross section for process (1) can be expressed in terms of the proton magnetic and electric form factors as [6] da _ 7ra 2 (hc) 2 d(cos<9*) SEP 4772 |G M | 2 (1 + cosV) + -^|O s | 2 sin 2^*where E and P are the center of mass energy and momentum of the antiproton, and 0* is the angle between the e~ and the p in the center of mass system.

Heavy hypernuclei are produced in the annihilation of antiprotons in U. The delayed fission of heavy hypernuclei and hypernuclei of fission fragments are observed by using the recoil-distance method in combination with measurement of secondary electron multiplicity.