Kerstin Perez is looking for imprints of dark matter. The invisible substance embodies 84% of the matter in the universe and is considered a powerful cosmic glue, preventing entire galaxies from separating. And yet the particles themselves barely leave a trace on ordinary matter, thwarting all detection efforts so far.
Perez, a particle physicist at MIT, hopes that a high-altitude balloon experiment, which will launch in the Antarctic stratosphere at the end of 2022, will detect indirect signs of dark matter, in the particles it leaves behind. Such a discovery would greatly illuminate the elusive nature of dark matter.
The experiment, which Perez is co-leading, is the General AntiParticle Spectrometer, or GAPS, a NASA-funded mission that aims to detect the products of dark matter annihilation. When two particles of dark matter collide, it is believed that the energy from this interaction can be converted into other particles, including anti-euterons, particles that then travel through the galaxy as cosmic rays that can enter the stratosphere. earthly. If there are any antideuterons, they should come from all parts of the sky, and Perez and his colleagues hope GAPS will be at the right altitude and sensitivity to detect them.
“If we can convince ourselves that this is really what we are seeing, it might help point us in the direction of what dark matter is,” says Perez, who was appointed this year to the physics department of Canada. MIT.
In addition to GAPS, Perez’s work focuses on developing methods to search for dark matter and other alien particles in supernovas and other astrophysical phenomena captured by terrestrial and space telescopes.
“We measure so much about the universe, but we also know that we are completely missing huge chunks of what the universe is made of,” she says. “There must be more building blocks than the ones we know of. And I chose different experimental methods to pursue them.
Born and raised in West Philadelphia, Perez was a self-proclaimed “indoor child”, primarily in the arts and crafts, drawing and design, and construction.
“I had two glue guns and remember getting into dollhouse building not because I cared so much about dolls, but because it was something you could buy and build.” », She remembers.
Her plans to pursue fine art took a turn in her freshman year, when she attended her first physics class. Material that was difficult for her classmates came more naturally to Perez, and she enrolled the following year in both Physics and Calculus, taught by the same teacher with infectious wonder.
“One day he did a bypass that took up two-thirds of the board, and he stood back and said, ‘Isn’t that so beautiful? I can’t erase it. And he drew a frame around it and worked for the rest of the class in that little third of the board, ”Perez recalls. “It’s that kind of enthusiasm that came to me. “
So motivated, she left after high school for Columbia University, where she pursued a major in physics. Wanting experience in research, she volunteered in a nanotechnology lab, imaging carbon nanotubes.
“That was my turning point,” Perez recalls. “All of my experience in building, creating, and the will to design things came together in this physics context. From that point on, I was sold for research in experimental physics.
She also took a modern physics course taught by Janet Conrad of MIT, who was then a professor at Columbia. The class introduced the students to particle physics and the experiments underway to detect dark matter and other exotic particles. The detector that generated the most buzz was the Large Hadron Collider at CERN in Geneva. The LHC was to be the largest particle accelerator in the world and commissioning was imminent.
After graduating from Columbia, Perez flew west to Caltech, where she had the opportunity to attend CERN as part of her graduate studies. This experience was invaluable, as it helped calibrate one of the LHC’s pixel detectors, designed to measure well-known ordinary particles.
“This experience taught me that when you turn on your instrument for the first time, you have to make sure that you can measure very well the things that you know to be there, before you can pretend that you are watching something new,” explains Perez.
In front of the class
After finishing her work at CERN, she started to come up with a new idea. While the LHC was designed to artificially crush particles to search for dark matter, smaller projects attacked the same particles in space, their natural environment.
“All the evidence we have for dark matter comes from astrophysical observations, so it makes sense to look for clues,” Perez explains. “I wanted to have the opportunity to, from scratch, design and fundamentally build an experiment that could tell us something about dark matter.”
With this idea, she returned to Columbia, where she joined the core team that worked to get the GAPS balloon experience off the ground. As a postdoctoral fellow, she developed a cost-effective method to fabricate the over 1000 experiment silicon detectors and has since continued to lead the experiment silicon detector program. Then, in 2015, she accepted a teaching position at Haverford College, near her hometown.
“I was there for a year and a half and absolutely loved it,” Perez says.
While at Haverford, she immersed herself not only in her research in physics, but also in teaching. The college offered a program for professors to help them improve their lessons, with each professor meeting with a trained undergraduate student each week to observe and provide feedback on their teaching style. Perez was matched with a student of color, who once shared with her a less than welcoming experience she had in an introductory class, which ultimately discouraged her from declaring a major in computer science.
Listening to the student, Perez, who has often been the only woman of color in advanced physics classes, labs, experimental teams, and faculty rosters, recognized a kinship and a calling. From that moment, in addition to her physics work, she began to explore a new direction of research: belonging.
She reached out to social psychologists to understand issues of diversity and inclusion, as well as systemic factors contributing to under-representation in physics, computer science, and other STEM disciplines. She has also collaborated with educational researchers to develop classroom practices to encourage belonging among students, with the motivation to retain underrepresented students.
In 2016, she accepted an offer to join the physics faculty at MIT and brought with her the work on inclusive education that she started at Haverford. At MIT, she balanced her research in particle physics with teaching and building a more inclusive classroom.
“It’s easy for instructors to think, ‘I have to completely revamp my schedule and reverse my class, but I have so much research and teaching is a small part of my job that frankly doesn’t often get rewarded. “Said Perez. “But if you look at the research, it doesn’t take a lot. It’s the little things we do, as teachers who are in front of the class, that have a big impact.