Charge collection and noise analysis of heavily irradiated silicon detectors

Measurements performed on high-resistivity silicon detectors irradiated with proton and neutron flueuces, up to 3.5 x 10(14) p/cm(2), and 4.0 x 10(15) n/cm(2) respectively, are presented. The charge collection efficiency (CCE) and the output noise of the devices have been measured to carry out a detector performance study after irradiation. The CCE is found to slowly decrease for fluences increasing up to approximately 1.8 x 10(14) p/cm(2). For higher particle fluences, the device inefficiency increases rapidly because full depletion could not be reached (up to 75% for the highest flueuce: 4 x 10(15) n/cm(2)). A complete analysis of the noise of the irradiated devices has been carried out assuming a simple model which correlates the main noise sources to the fluence and the leakage current. A linear dependence of the square of the noise amplitude on the fluence has been observed: a value of the leakage current damage constant has been found to be in good agreement with the values reported in literature, obtained with current-voltage (IV) analysis. An extension of the noise analysis is carried out considering the detectors irradiated with very high flueuces, up to 4 x 10(15) n/cm(2).