Analysis of petal longterm test data for the CMS-experiment

The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) in Geneva will start end of 2008. One of the experiments at the LHC is the multipurpose detector CMS (Compact Muon Solenoid). A key part of the CMS detector is the tracking system, that is composed of a silicon pixel detector forming the innermost part, surrounded by silicon strip sensors. Currently, it is the largest silicon detector in the world with an active area of 198 m2. The strip tracker itself consists of four subdetectors. One of these are the tracker end caps (TEC) with an active area of 82 m2. Besides this large aperture, their position in the forward region plays a key role for physics analysis due to the fact that many of the interesting events are expected to be boosted in the forward region (pp collider). This area splits up into 10,288 sensors with 3,988,765 channels in total. In several steps the modules constructed and tested before being mounted onto the final substructures (petals). An important longterm test has been performed which qualifies the petals to be installed into the detector. The focus of the present work is in the longterm test. The test procedure is described. A method for identification and classification of defect channels is presented. This method has been developed based on the test results of a previous test ('ARC-test'), which has examined each module before the assembly onto the petals. A cross-check has been performed to compare the results with data from a subsequent test ('sector-test'), that is performed after the petals have been integrated into the TEC. A good agreement shows the consistency of the presented results. With the help of this method a channel defect rate of approximately 0.09% can be measured. Further defects like 'dead' components became visible after integration of the petals into the TEC and raised this number up to 0.33% defect and non-recoverable channels. (orig.)