Speaker
Dr
Robert Bainbridge
(Imperial College London)
Description
The CMS silicon strip tracker (SST), comprising a sensitive area of over 200m2 and
10M readout channels, is unprecedented in its size and complexity. The readout system
is based on a 128-channel analogue front-end ASIC, optical readout and an
off-detector VME board, using FPGA technology, that performs digitization, zero
suppression and data formatting before forwarding the detector data to the CMS online
computing farm. Commissioning such a large-scale readout system requires
sophisticated procedures that can optimally configure and synchronize the entire
readout system and provide calibration parameters that are used by both hardware and
the CMS reconstruction software. The software implementation for the commissioning
procedures is divided between the CMS online and offline frameworks, known as XDAQ
and CMSSW, respectively. Data acquisition loops for each of the commissioning tasks
have been implemented within the XDAQ framework. These loops configure and control
the readout system hardware and local trigger system, and perform event building
using tools provided by the CMS TriDAS group. The data analysis modules, which
receive the event data stream and calculate optimized hardware configurations and
calibration constants, have been implemented within CMSSW. This design, using both
the online and offline frameworks, ensures that the commissioning software is
sufficiently flexible for online operation using either the local DAQ resources
allocated to each sub-detector or the global resources of the online computing farm.
The latter option offers significant improvements in detector readout speeds and CPU
processing power, thus reducing turn-around times between physics runs. We present an
overview of the SST data acquisition system, focusing on the commissioning procedures
and their software implementations within the online and offline frameworks. Results
and performance studies will also be presented, based on experiences gained when
commissioning a complete slice of the SST readout system and during integration
activities of the final silicon strip tracker.
Primary authors
Dr
Laurent Mirabito
(Institut de Physique Nucleaire de Lyon)
Dr
Robert Bainbridge
(Imperial College London)
