The H1 Central Silicon Tracker

Since 1997, the H1 detector at the HERA collider at DESY, Hamburg has been equipped with a two layer silicon vertex detector (CST). The CST uses double sided, double metal layer sensors; it is read out with a specifically designed analog pipeline chip (APC), the signals are transmitted optically. The whole detector has a thickness of only 0.40 g/cm, corresponding to 1.4%X0. An asymptotic impact parameter resolution of 57 μm has been achieved. 1, the detector was redesigned for the HERA luminosity upgrade. It has been equipped with a new version of the readout chip APC that has been produced in radiation hard DMILL technology.