Large Systems

STFC Technology is contributing to the design and construction of instrumentation for the experiments being built for the Large Hadron Collider (LHC) at CERN. Consisting of 80,000 radiation-tolerant ASICs and many hundreds of large FPGAs this is just one example of the large complex bespoke systems we produce for customers worldwide.

The ATLAS detector (A Toroidal LHC Apparatus) will produce an unprecedented flood of data. Of the billions of particle interactions that occur every second, only a small fraction contain data useful for analysis. The experiments rely on several levels of sophisticated processing to successively reduce the data volume by selecting only interesting events.

We are designing and building trigger systems to make these decisions. One such system searches for patterns in the energy deposited in the detector by particles produced in the collisions. The trigger will discard approximately 999 events for every one that contains useful data.

While the system is deciding which events to record, memory buffers hold detector data. The high cost of these memories means they must be kept to a minimum. As a result, the system has less than a microsecond to process the data and to decide whether to record or reject an event.

Recent developments in the performance of Field Programmable Gate Arrays (FPGAs) allow us to deliver a highly integrated system that can also be re-programmed in situ. It will therefore be possible to implement improved or alternative trigger algorithms during the lifetime of the experiment. This leads to a more flexible and future-proof design than one based around traditional Application Specific Integrated Circuits (ASICs).