Characterization of neutron irradiated silicon microstrip detectors

Radiation effects on silicon microstrip detectors have been investigated on sensors similar to the ones that will be installed in the forward tracker of CMS. Sensors have been built starting from a high resistivity (about 6 kΩ cm) n-type substrate, 〈1 1 1〉 crystal lattice orientation. Some of the wafers have been exposed to a neutron beam with a 1 MeV equivalent neutron fluence of 1.1×1014 neutron/cm2. Depletion voltage, reverse current, bulk and interstrip capacitance have been measured in laboratory before and after irradiation, directly on the full size structures. Detectors built with these structures have then been tested with a 90Sr source in laboratory. Device properties and performances with respect to signal to noise ratio are presented, emphasizing their dependence on irradiation.