AN INVESTIGATION INTO THE RADIATION-DAMAGE OF THE SILICON DETECTORS OF THE H1-PLUG CALORIMETER WITHIN THE HERA ENVIRONMENT

The silicon detectors used in the H1-PLUG calorimeter have shown incre asing aging effects during the '94 run period of the electron proton s torage ring HERA. These effects were particularly manifest as degradat ion of the signal to noise level and the calibration stability. The re asons for this behaviour have been found to be correlated with radiati on damage to the silicon oxide passivation edges of the detectors in s trong and fluctuating increases of the leakage currents and in severe changes of the flat band voltages. Depletion voltages however are foun d to be stable and therefore bulk damage of the silicon can be exclude d. A comparison with measurements made by thermoluminescence dosimeter s as well as related laboratory experiments suggest that the aging is due to very low energetic electrons and photons.