Tests of the GRETINA triple cluster prototype detector

The GRETINA prototype detector consists of a cluster of 3 tapered regular hexagonal HPGe capsules in a common cryostat. The Ge crystals have 36 segments (6 longitudinal x 6 transverse) and a central contact for a total of 111 channels, each instrumented with a cold FET stage. A number of tests have been performed and will be the subject of this presentation. Acceptance tests include: mechanical dimensions, liquid nitrogen holding time, and energy resolution. Characterization tests, which are of importance for the performance in tracking arrays, were carried out and include ``singles'' segment boundaries scans (Am --source) and ``coincidence'' scans for pulse shape analysis (Cs source). Preliminary results of an in-beam experiment using the reaction $^{12}$C($^{82}$Se,4n)$^{90}$Zr at 285MeV establish a position resolution (RMS) of $\sigma \quad \sim $2mm .