This article is part of our exclusive IEEE Journal Watch series in partnership with IEEE Xplore.
Deep in the belly of the Large Hadron Collider (LHC), about 400 million particle collisions are happening in a single second. But as the LHC undergoes upgrades and becomes the High Luminosity-LHC, the number of collisions will increase to an astounding ~1.5 billion collisions or more per second. Capturing all these events via detectors and analyzing the staggering amount of data created from each experiment is no easy feat.
Fortunately, a team of scientists have been working for years to create a chip that is capable of digitally examining all 1.5 billion of these collisions in the blink of an eye. Their new chip is described in a study published May 28 in IEEE Open Journal of the Solid-State Circuits Society.
The large hadron collider’s hefty computing requirements
The LHC, a massive underground facility straddling the border of France and Switzerland, has been smashing particles together since 2008, revealing critical insights into the fundamental laws of physics. However, the system needs a break about every decade to undergo maintenance and technical upgrades. In anticipation of these upgrades, researchers at Columbia University, including Peter Kinget in the electrical engineering department, have been designing two specialized chips with collaborators at the University of Texas, Austin.
Both chips are designed for the LHC’s ATLAS detector, which investigates a wide range of physics phenomena, from the Higgs boson to extra dimensions and particles that could make up dark matter. The massive detector—at 46 meters long and 25 m high—is lined with tens of thousands of specialized chips to record collision events.
The first chip designed by Kinget and his colleagues is called a “trigger” analog-to-digital converter (ADC) chip. It’s helpful for sifting through the immense amounts of data—roughly 60 petabytes of raw data—created upon particle collisions.
Kinget says the ATLAS detector is like a giant 3D camera taking pictures at a very, very high rate. Meanwhile, the trigger system is quickly screening these ‘pictures,’ searching for events that may be useful for further analysis. The trigger system tells the detector to disregard the data that is not of interest, while saving the data of interest. The finalized trigger ADC was incorporated into the ATLAS detector during the last shutdown ending in 2022.
More recently, they finished designing and testing a second, higher resolution ADC that reads out the signals from the detector and converts it to digital data for analysis. The challenge, however, is that the ADC must be able to cope with the extreme amount of radiation that’s created upon particle collisions.
“This environment around this beam is one of the most intense environments you can imagine,” says Kinget. “As a result… very intense radiation is being generated.”
Rui Xu, a PhD student in Kinget’s lab who helped design the second, ADC chip, says the level of radiation the chip undergoes is similar to what a satellite would experience after eight years in high orbit around Earth.
Designing a radiation-proof chip
Unfortunately, this intense radiation can hinder the chip’s ability to record data accurately.
Digital data is conveyed through a series of ones and zeroes. But as the ADC converts electrical signals into this digital format, upset caused by radiation could cause a ‘one’ to be recorded as a ‘zero,’ or vice versa, essentially corrupting the data. Therefore, the researchers created their ADC using a technique that provides a triple-check measure to ensure that the digital data has been converted and stored correctly. The chances that the data would be corrupted three times is very unlikely, Kinget points out.
After designing their ADC, the researchers subjected it to radiation using medical equipment at a hospital in Boston to evaluate how it performs under intense radiation and estimate how it would perform in the LHC. The results suggest the chip is up to the task, and it is now being readied for integration and installation in the next LHC upgrade scheduled to start in 2026.
The stakes are high for the chips to work. As Kinget notes, hardware upgrades only come every decade, so there’s a lot of pressure on engineers and scientists to have their technology working flawlessly at the time of installation. But the payoff will be high if the chip performs well—allowing more than a billion collisions per second to be detected.
Kinget emphasizes that this research has been the result of a great deal of collaboration, not just with experts within Columbia University, such as physicists John Parsons and Gustaaf Brooijmans, but also physicist Tim Andeen and electrical engineer Nan Sun at the University of Texas, Austin and many teams from around the world that have made the LHC work possible. As of 2022, more than 5,500 scientists across 42 countries have contributed to ATLAS alone. “It’s been nice for us to be part of that,” says Kinget.