SCT and TRT put to the test

3 March 2008

A cosmic ray crossing the TRT and all four layers of the SCT barrel. The Atlantis event display shows the reconstructed track in the TRT bottom sector and the eight space points recorded in the SCT silicon strip layers. The data for this event were recorded at a signal threshold of 1.2 fC rather than the normal 1.0 fC to accelerate the timing adjustment in these first tests.

From February 18th to 20th, the SCT team took the opportunity to run for the first time a major section of the detector integrated in the ATLAS readout and control for three days, together with the TRT.

These preparation tests for the next ATLAS M6 combined run were a chance to try global ATLAS integration with a large fraction of the real detector cooled and powered. The tests focused first on the integration of SCT readout system into ATLAS run control together with online monitoring. The second day of running was then dedicated to adjusting the SCT barrel readout timing for cosmic triggers and the first cosmic tracks were reconstructed in SCT and TRT within hours. It is remarkable, and very rewarding, to see this complex system of DAQ, DCS, offline software, online monitoring, power supplies, and cooling working together all at once. The offline reconstruction of this first cosmic dataset has already proven very helpful for testing the data processing from byte-stream converters to track reconstruction and give us important feedback on detector tuning and operation.

While this marks a great milestone for the commissioning, it is a truly remarkable achievement for all the recent intense effort on engineering and evaporative cooling. Everybody involved with the evaporative cooling and heater effort went out of their way, working long hours, nights and weekends, to get the SCT barrel and end-caps cooled, and so enabled us to do this test in parallel to their ongoing commissioning for the pixel cooling system.



Heinz Pernegger