Silicon sensors development for the CMS pixel system

The CMS experiment will operate at the Large Hadron Collider (LHC). A hybrid pixel detector located close to the interaction region of the colliding beams will provide high resolution tracking and vertex identification which will be crucial for b quark identification. Because of the radiation environment of the LHC, the performance of the sensors must be carefully evaluated up to a fluence of 6 multiplied by 10**1**4n//e//qcm **-**2. We expect that the sensors will be operated partially depleted during their operation at the LHC and we have implemented an n**+ on n sensor design. We have irradiated prototype sensors to a dose of 1 multiplied by 10 **1**5n //e//qcm**-**2. We present the results of our testing before and after irradiation.