Test of BGO-bars for electromagnetic shower calorimeters

We have tested 20 cm long BGO bars, to be employed in a position sensitive calorimeter, using 137Cs source and 200 to 550 MeV electrons. The spatial resolution of sigma x = 3.1 cm was obtained for 550 MeV electrons incident on a BGO bar of 10 x 10 x 200 mm3. The effective attenuation length of light in the BGO bar was as long as 137 cm, including the internal transmittance as well as the reflection on the surface. The use of thin layers of BGO bars as an active converter in front of the main BGO blocks was tested with respect to the obtainable energy resolution. No sizable degradation occurs in the energy resolution after summing up all the signals