Tiny optoelectronic module plays a key role in the world’s largest physics experiments; new module will be 75 times faster than the current fiber-optic data link on Large Hadron Collider’s ATLAS experiment

The SMU fiber-optic data link (above) was made specifically for ATLAS and its extremely harsh low-temperature, high-radiation environment. More than 1,500 of the data link modules are installed on ATLAS. A second-generation link, which is five times faster but with a smaller footprint, is slated for the next upgrade of the LHC detectors. A planned third-generation data link, being funded by DOE, will be 75 times faster.(Credit: www.smuresearch.com)

A tiny optoelectronic module designed in part by SMU physicists plays a big role in the world’s largest physics experiment at CERN in Switzerland, where scientists are searching for the “God” particle.

The module, a fiber-optic transmitter, sends the Large Hadron Collider’s critical raw data from its ATLAS experiment to offsite computer farms. From there, thousands of physicists around the world access the data and analyze it for the long-sought-after particle, the Higgs boson.

Now as a result of SMU’s role on the LHC data link, SMU Physics Research Professor Annie Xiang has won a three-year research and development grant with $67,500 in support annually from the U.S. Department of Energy to advance the design of the optoelectronic module.

The grant calls for a customized multi-channel optical transmitter that can be deployed on many of the world’s high-energy particle detectors.

Xiang is principal investigator for SMU’s Data Links Group in SMU’s Physics Department, working in the Optoelectronics Lab of Physics Professor Jingbo Ye. She coordinates the lab’s development of optical data transmission systems for particle physics experiments.

More than 1,500 data link modules are installed on ATLAS
“We made the first-generation fiber-optic data link specifically for ATLAS and its extremely harsh low-temperature, high-radiation environment,” Xiang said.

More than 1,500 of the first-generation data link modules are installed on the calorimeter detectors of ATLAS. The link’s job is to reliably offload a continuous flood of raw data without failure or error. Scientists scour the data for signs of the Higgs boson, which has been theorized for decades but never actually observed. It is believed the Higgs gives mass to the matter that we observe.

A second-generation data link, which SMU also helped design, is slated for deployment in the next upgrade of the LHC in coming years. The current data link installed in ATLAS can transmit up to 1.6 gigabits a second in a single channel, which equates to writing an HD DVD in one minute, Xiang said. The second-generation link, a 5 gigabit transceiver, has a smaller footprint than the current link, but can transmit three times faster and is qualified for even higher radiation. “Many thousands of the second-generation link can be expected across the LHC detectors,” Xiang said.

The data link being supported by DOE will be even faster. A transmitter only, it will have a transmission capacity of 120 gigabits a second, or 75 times faster than the data link currently installed on ATLAS, Xiang said.

DOE project will customize off-the-shelf commercial components for on-detector installation
To design the links, SMU’s team and its collaborators start with qualified commercial transmitters and receivers, then customize them for the LHC detectors, Xiang said. They will repeat that process to develop the data link being supported by DOE.

Called a “generic” module, the link supported by DOE isn’t specified for any particular detector, but rather will be available to deploy on detectors at the LHC, at Fermi National Accelerator Laboratory (Fermilab) and others.

The module — a 12-channel transmitter — must be high speed and low footprint, and able to withstand an extremely cold and high-radiation environment, while at the same time maintaining low mass and low power consumption, Xiang said.

The DOE award is part of a collaborative project with Fermilab, the University of Minnesota, The Ohio State University and Argonne National Laboratory, with a total funding of $900,000. SMU designed the first-generation module in collaboration with Taiwan’s Academia Sinica. SMU collaborated on the second-generation module with CERN, Oxford University and Fermilab.

Ye and Xiang are members of SMU’s ATLAS team, which is led by SMU Physics Professor Ryszard Stroynowski. — Margaret Allen

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