Status and performance of the new innermost layer of silicon detector at Dط

The Dط experiment at the Fermilab Tevatron collider currently operates one of the largest silicon detectors in the world. The new Dط inner-layer detector (Layer 0) was installed during the spring 2006 Tevatron shutdown. It features a novel-type, low mass, radiation-hard layer of silicon at a very small radius. The Layer 0 sensors are connected to the readout chips outside the tracking volume via fine-pitched Kapton flex circuit cable (analog cable). The layer 0 is now fully operational and is integrated part of the Dط silicon microstrip tracker (SMT). Preliminary performance of Layer 0 is described.