Characterization of silicon pixel detectors with the $n^{+} n/p^{+}$ and double-sided multiguard ring structure before and after neutron-irradiation

The lifetime of silicon detectors in a severe radiation environment at CERN LHC depends strongly upon careful detector design and material selection, due to the anticipated radiation-induced damage. We fabricated recently more radiation-tolerant CMS forward pixel sensors with new designs of silicon pixel detectors with the n/sup + //n/p/sup +/ and double-sided multiguard ring structure. Electrical characterization of such devices was performed before and after irradiation to neutron fluences (1 MeV equivalent) up to 6*10/sup 14/ n/cm/sup 2/, measuring leakage current, potential distribution over the guard rings and full depletion voltage. Studies on the radiation hardness using oxygen-enriched silicon substrates are being presented separately. (7 refs).