  For the first time, the reaction gamma d -> Lambda n K+ has been analyzed in
order to search for the exotic pentaquark baryon Theta+(1540). The data were
taken at Jefferson Lab, using the Hall-B tagged-photon beam of energy between
0.8 and 3.6 GeV and the CEBAF Large Acceptance Spectrometer (CLAS). No
statistically significant structures were observed in the nK+ invariant mass
distribution. The upper limit on the gamma d -> Lambda Theta+ integrated cross
section has been calculated and found to be between 5 and 25 nb, depending on
the production model assumed. The upper limit on the differential cross section
is also reported.
