We have performed a search for radiative b-hadron decays using
events produced in p anti-p collisions at s**(1/2) = 1.8 TeV and collected by the
Collider Detector at Fermilab. The decays we considered were B-bar0_d ->
K-bar*0(-> K- pi+)gamma, B-bar0_s --> phi(-> K+ K-) gamma,
Lambda0(b) --> Lambda(-> p pi-)gamma, and their charge conjugates. Two
independent methods to identify photons from such decays were employed. In
the first method, the photon was detected in the electromagnetic
calorimeter. In the second method, the photon was identified by an
electron-positron pair produced through the external photon conversion
before the tracking detector volume. By combining the two methods we obtain
upper limits on the branching fractions for the B-bar0_d, B-bar0_s, and
Lambda0(b) radiative decays, which, at the 95% confidence level, are found
to be B(B-bar0_d --> K-bar*0 gamma) < 1.4 x 10-4, B(B-bar0_s --> phi
gamma) < 1.6 x 10-4, and B(Lambda0(b) --> Lambda gamma) < 1.9 x 10-3.
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Updated: Monday, 2003 January 13 11:43:41 CST automatically from input from "Carol I. Picciolo"