  This Letter applies the concept of `jets', as constructed from calorimeter
cell four-vectors, to jets composed (primarily) of photons (or leptons). Thus
jets become a superset of both traditional objects such as QCD-jets, photons,
and electrons, and more unconventional objects such as photon-jets and
electron-jets, defined as collinear photons and electrons, respectively. Since
standard objects such as single photons become a subset of jets in this
approach, standard jet substructure techniques are incorporated into the photon
finder toolbox. We demonstrate that, for a single photon identification
efficiency of 80% or above, the use of jet substructure techniques reduces the
number of QCD-jets faking photons by factors of 2.5 to 4. Depending on the
topology of the photon-jets, the substructure variables reduce the number of
photon-jets faking single photons by factors of 10 to 10^3 at a single photon
identification efficiency of 80%.
