Scintillation counters installed for Inner Detector system test
Three large scintillation counters built at Hampton University have been installed at CERN. The counters are being used in the system tests for the Inner Detector. This is the last test before the ID is lowered into the ATLAS cavern.
The counters provide a cosmic-ray trigger and timing signal that will be used to test the readout systems for the SCT and TRT barrel regions.
In the photo, starting from the top left and going clockwise, we see one counter placed above the Inner Detector, a picture of a counter as it was being built at Hampton, a counter below the ID, and finally a picture of the third counter in the space below the floor. This third counter is actually aligned with the other two.
The plots show the distribution of the measured time difference between pairs of counters. The good timing (better than 0.5ns) will allow some selection on muon time-of-flight. The plots are courtesy of Wouter Hulsbergen and Beniamino Di Girolamo.