We have observed exclusive $\gamma\gamma$ production in
proton-antiproton collisions at $s**(1/2)=1.96$~TeV, using data
from 1.11~$+-$~0.07~fb${-1}$ integrated luminosity taken by the
Run~II Collider Detector at Fermilab. We selected events with two
electromagnetic showers, each with transverse energy $E(t) > 2.5$
GeV and pseudorapi+dity $|\eta| <$ 1.0, with no other particles
detected in $-7.4 < \eta < +7.4$. The two showers have similar
$E(t)$ and azimuthal angle separation $\Delta\phi \sim \pi+$; 34 events
have two charged particle tracks, consistent with the QED process $p
\bar{p} --> p + e+e- + \bar{p}$ by two-photon exchange, while 43
events have no charged tracks. The number of these events that are
exclusive $\pi+0\pi+0$ is consistent with zero and is $<$ 15 at
95\% CL. The cross section for $p\bar{p} \to p+\gamma\gamma+\bar{p}$
with $|\eta(\gamma)| < 1.0$ and $E(t)(\gamma) > 2.5$ GeV is
$2.48\,{+0.40}_{-0.35}(\mathrm{stat})\,{+0.40}_{-0.51}(\mathrm{syst})\,
\mathrm {pb}$.
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Updated: Wednesday, 2012 February 29 09:11:16 CST automatically from input from Stephanie A Schuler