Speaker
Description
Summary
The ATLAS Semiconductor Tracker (SCT) will be a central part of the tracking system
of the ATLAS experiment and is one of the major new silicon detector systems for LHC.
The final system comprises about 4000 individual detector modules with nearly 16000
silicon sensors and more than 6 million readout channels. It has been assembled and
is currently being tested as part of the ATLAS Inner Detector Integration effort at
LHC point 1. The testing of the readout and control systems constitutes one of the
vital tasks for the assembled detectors.
The SCT readout system is based on the ABCD3TA, a binary ASIC designed in the DMILL
technology. Each module is read out by 12 ABCD3TA ASICs mounted on a hybrid circuit.
Each chip provides binary readout of 128 detector channels. The amplified and shaped
input signal is compared to a programmable threshold having two components: a single
8-bit DAC applied across the whole chip, and a channel-specific 4-bit DAC designed to
compensate for channel-to-channel variations. In ATLAS, an optical scheme will be
used to transmit data from the detector modules to the off-detector electronics and
to distribute Timing, Trigger and Control (TTC) data from the counting room to the
front-end electronics. The performance of the whole chain of data and control
transmission is verified in each step of the detector assembly.
After a brief overview of the SCT detector system and its expected tracking
performance, the presentation will focus on the system integration of the SCT and in
particular in the installation and testing of the readout system. The final stage
assembly of the SCT and the final integration with the Transition Radiation Tracker
(TRT) is carried out in the ATLAS SR1 clean-room. Using a silicon test system, which
can characterize up to one million readout channels simultaneously, the SCT detector
function and performance is tested through the different integration stages, from
single barrels up to the final tests as part of the Inner Detector (ID) just before
its installation in the pit. Particular attention will be given to the electronics
tests results such as electrical connections checks, noise and gain measurements, as
well as temperature and leakage current measurements. The outcome of these tests is
essential for the validation of the grounding, shielding and cooling system. The
detector control system installation will be highlighted as well.
