“Understand the fundamental nature of the universe,” reads the sticky-note on the desktop computer of Isobel Ojalvo, assistant professor of physics. It serves as a reminder of her greatest aspiration, her motivation to take steps each day toward uncovering something new.
Ojalvo recalls pondering such existential questions in a classroom at age 11. Having always been inclined toward math, she took to science as an avenue to explore the questions that kept her up at night.
“I’ve been kind of on a quest for my entire life of understanding the fundamental structure of the universe,” she said.
This quest led to her interest in mysteries such as dark matter, cosmic inflation, and what happened at the very beginning of the universe. Now, throughout a decade of research at the world’s largest particle accelerator, the Large Hadron Collider (LHC) at CERN in Geneva, Switzerland, Ojalvo is making sizable contributions to the field of high-energy particle physics.
At the 17-mile-long underground tube, researchers accelerate protons toward each other at near the speed of light. The resulting debris can reveal much about the matter that makes up the universe. But with protons smashing together every 25 nanoseconds, these collisions create so much data that storing it all is impossible.
Ojalvo’s work has focused on improving the electronic systems, called trigger systems, which run algorithms to decide which events in the detector are worthy of storing, and which can be thrown away.
Ojalvo spent many years working on the trigger systems at one of the LHC’s two main detectors, the Compact Muon Solenoid (CMS) detector. For this system, Ojalvo has commissioned and installed hardware, developed new high-speed algorithms, written and managed online software, and spent many hours on call. She began this work while she was a graduate student, spending her summers at CERN and the rest of the year studying at the University of Wisconsin-Madison. In 2012, during her second summer at CERN, the discovery of the Higgs boson — a long-predicted particle that gives the universe its mass — marked a dramatic turning point in the field of particle physics, and Ojalvo was there to witness it first-hand.
“It was pretty exciting to be there at the time,” she said. “It was especially exciting to see what people working together could achieve.”
To learn more about the Higgs and how it interacts with other particles, Ojalvo narrowed her focus to studying another elusive particle, the tau lepton. This particle is nearly identical to the electron, but has a much higher mass. Because the strength of the connection, or coupling, of a particle with the Higgs boson is directly proportional to the particle’s mass, the tau lepton is an ideal channel for understanding the Higgs coupling.
But there is a catch. This particle decays very quickly and is thus difficult to detect.
“Every once in a while, somebody comes up to me and says, ‘it’s a particular type of crazy person who decides to look at the tau lepton,’” Ojalvo said.
To pin down the elusive tau, Ojalvo and her team had to develop special techniques as well as upgrades to the CMS trigger systems. The team wrote new algorithms that help the system work more efficiently in collaboration with engineers and physicists at the Institute for Research and Innovation in Software for High Energy Physics (IRIS-HEP), led by Princeton senior research physicist Peter Elmer.
Ojalvo is intentional about creating a diverse and supportive environment for other researchers, and she is aware of the adversity commonly faced by women and other minorities in her field. After learning from experience, she aims to show her lab members the importance of resilience, and of mutual support and respect.
Pallabi Das, a postdoctoral research associate who works with Ojalvo, said that the diverse backgrounds of Ojalvo’s lab members contribute to the success of their work.
“It’s a very collaborative environment, and all the students are very enthusiastic because Isobel herself is enthusiastic,” Das said. “She encourages people to go forward, to be bold in whatever we do, and to speak up.”
The LHC is currently the only high-energy collider in the world, and while it will operate for many years to come, Ojalvo hopes there will be future construction of a more powerful collider.
“I think in the long term that we have to not be complacent about the future of particle physics,” said Ojalvo, whose work is funded by the U.S. Department of Energy. “We need to think about what future colliders can do, and what role the U.S. will play in this research.”