In the coming years, the LHC accelerator will be upgraded into a particle factory ten times more powerful. Nikhef is helping with preparations for the upcoming deluge of measurement data. Part 4 of a summer series on the work being done on the HiLumi LHC.
About five million times per second, the more intense beams in the HiLumi LHC at CERN will collide with one another in the detectors. And at each collision, an estimated 200 protons collide simultaneously—ten times more than in the old LHC. This is a tremendous goldmine for physicists, but also a demanding jumble of signals for the detectors and the surrounding equipment.
To cope with this deluge of data, a great deal of new technology is needed for existing experiments. Nikhef is involved in a number of projects aimed at harvesting as much measurement data as possible from the more powerful CERN accelerator for physics research.
The two most important Dutch projects both relate to the ATLAS detector, the world’s largest particle detector and co-discoverer of the Higgs boson in 2012.
The first is a new component at both ends of the inner detector: the High Granularity Timing Detector (HGTD). These new HGTD subdetectors consist of two large discs stacked on top of each other, equipped with sensors, readout systems, and cooling.
Each HGTD subdetector has a total of four stacked layers of pixel sensors, which can register the passage of a particle with picosecond precision. Thanks to this precise timing, signals from nearly simultaneous proton collisions can still be distinguished from one another and analyzed.
The HGTD hardware was largely designed and built by other institutions, but Nikhef has played a significant role over the past five years in developing the readout system for these detectors. In particular, a great deal of work has been done on the systems’ precise time measurement, including studies of their sensitivity to the harsh physical conditions inside the ATLAS detector, near the beam.
The second HiLumi-related Nikhef initiative is FELIX, a specialized interface that allows the detectors’ specialized digital electronics to communicate with standard computers and networks. Nikhef is one of the founders of the system, which is now being further adapted for the HiLumi era. FELIX stands for Front End LInk eXchange.
FELIX is an electronic interface module that connects an experiment’s specialized radiation-resistant detector electronics to the data networks outside the experiment. Standard network cards are unsuitable for this purpose and are usually too slow. Such a connection is literally custom-built digital hardware, requiring programmable FPGA microelectronics—a specialty of Nikhef’s Electronics Technology department.
Nikhef engineers and physicists in Amsterdam are developing a new version of FELIX, which will be used flexibly in the ATLAS detector, always programmable for the desired task under the intense HiLumi conditions. FELIX is gradually becoming the standard interface for ATLAS and will certainly be used for the new HGTD subdetectors. However, the universal FELIX adapter can also be used in other CERN experiments, such as LHCb and ALICE.
Nikhef is currently discussing the setup of a taskforce for data acquisition in the coming years to bring together expertise and form a DAQ toolbox for all Nikhef accelerator experiments.
The deluge of measurement data from the HiLumi LHC also places heavy demands on the computer systems and networks used to record and distribute the data throughout the research community. In Part 5 of this summer series, we’ll discuss Nikhef’s efforts in the field of ICT.
Next week: Computers and networks capable of keeping pace with the HiLumi LHC
