  A compact and fast electromagnetic calorimeter prototype was designed, built,
and tested in preparation for a next-generation, high-rate muon g-2 experiment.
It uses a simple assembly procedure: alternating layers of 0.5-mm-thick
tungsten plates and 0.5-mm-diameter plastic scintillating fiber ribbons. This
geometry leads to a detector having a calculated radiation length of 0.69 cm, a
Moliere radius of 1.73 cm, and a measured intrinsic sampling resolution term of
(11.8\pm1.1)/\sqrt{E(GeV)}, in the range 1.5 to 3.5 GeV. The construction
procedure, test beam results, and GEANT-4 comparative simulations are
described.
