The universe began around 14 billion years ago with a single point that contained a vast array of fundamental particles, according to the mainstream theory known as the Big Bang. Under the pressure of extreme heat and energy, the point swelled and then expanded to become the universe as we know it. This expansion continues to this day.

Unraveling the mysteries of what happened in that first moment is a key topic in nuclear physics research. Rosi Reed, associate professor, and Anders Knospe, assistant professor ― both in the Department of Physics ― are at the forefront of this research, probing the nature of this initial matter created, the quark-gluon plasma, a fluid composed of subatomic particles. With support from the National Science Foundation, they built a highly specialized detector to measure aspects of the universe that had never been measured before.

Reed and Knospe set up their event plane detector at the Relativistic Ion Collider (RHIC) at Brookhaven National Laboratory on Long Island, New York, one of only two active particle colliders. They conduct experiments to advance their collaborative and individual research into the strong nuclear force, one of the four fundamental forces in nature, along with gravity, electromagnetism, and the weak nuclear force. The strong force holds the atomic nuclei together.

Their detector is part of the sPHENIX initiative, a “radical redesign” of the original PHENIX (Pioneing High Energy Nuclear Interaction eXperiment) facility, designed to study high-energy collisions of heavy ions and protons. It will include new components that greatly improve scientists’ ability to learn more about quark-gluon plasma.

“At the collider, we can see what – in the first 10 microseconds or so – the universe looked like,” Reed explains.

Their event plane detector is designed to measure the trajectories of fundamental charged particles after collision.

“If you have two nuclei colliding, unless it’s a head-on collision, you’ll have different orientations of the nuclei with a line connecting their centers, either horizontally or vertically. That’s what it’s called the plan of events,” Knospe explains. . “In addition to mapping the plane of the event, the detector will help us quantify the violence of a collision. By simply measuring the number of particles, we can estimate whether it was a head-on collision or a a very visible peripheral collision.”

Building the detector was a labor-intensive process. A number of students, some with support from a National Science Foundation Research Experiences for Undergraduates award, worked with Reed and Knospe to build parts of it, including the scintillator panels. The panels light up when hit by a charged particle, allowing the particle’s position to be measured.

The detector, designed to be an “add-on” to sPHENIX, “looks like two discs and will, essentially, go on either side of sPhenix, just inside the magnet,” she says. “The discs will measure where two charged particles or ions collide and help answer many questions and determine important measurements.”

Reed, whose work focuses on examining particle jets, or spray particles, that fly off high-energy collisions, says that among the key scientific questions that collecting and analyzing data could help to answer are: why is there more matter than antimatter in the universe? Why did the Big Bang create cold spots and hot spots that in some cases merge into galaxies and other features? His work is supported by a CAREER award from the National Science Foundation.

Knospe focuses on using heavy subatomic particles called quarkonia to probe quark-gluon plasma and characterize its properties in detail. His work is supported by a CAREER award from the Department of Energy.

Ultimately, Reed and Knospe’s collider work will provide insight into the strong force or, as Knospe puts it, “how this great soup of all these subatomic particles came together to become this new state of matter or really, the very oldest.”