Silicon sensors for the CMS Preshower

The paper is a summary of a research and development program, conducted during the past three years on the CMS Preshower silicon sensors with the goal at defining the specifications. The main point was the radiation hardness of these devices, resulting from the specific design: metal lines wider than the p+ implants and a series of guard rings, and to the production technology: a deep n+ layer on the ohmic side. An acceptable noise and a uniform charge collection were guaranteed by an appropriate choice of the interstrip region width. About 65 sensors, of different designs and coming from six manufacturers, were irradiated with neutrons and protons and thoroughly tested before and after irradiation. The results of the tests and the final specifications are presented.