Physicists from Eötvös Loránd University (ELTE) participated in a large-scale experiment that measured the temperature of quark-gluon plasma, the hottest material ever created. This material was present in the moments after the birth of the universe and was approximately 3.3 trillion degrees Celsius, 220,000 times hotter than the center of the Sun.
The experiment was conducted at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory, in the STAR detector (Solenoidal Tracker at RHIC), where researchers collide gold nuclei at near light speed, creating what is known as quark-gluon plasma. This material was present in the moments after the birth of the universe, in the first millionth of a second after the Big Bang.
Experiments with this material have been going on for a long time, but this is the first time that electron-positron pairs have been used to measure the temperature of this material, both in its early and late stages of development.
Their findings were published in the journal Nature Communications.
“This result is very important because this temperature was measured independently of previous measurements, and at different moments in time during the cooling of the medium. This paves the way for experimentally determining the collision energy required to create quark matter,” said Máté Csanád, head of the ELTE RHIC-Hungary research group. The Hungarian researcher participated in the recently published STAR article and the analysis verification as an internal reviewer requested by the experiment.
Máté Csanád said that members of the ELTE research group (Márton Nagy, Dániel Kincses, and their students) have long been involved in recording data for the STAR experiment. He noted that
ELTE researchers have the important task of analyzing the data, with a particular focus on femtoscopic measurements (a technique of measuring the size and the dynamics of the system created in heavy-ion collisions).
Quark-gluon plasma is the state of matter that existed immediately after the birth of the universe. At that time, everything was so hot and dense that neither atoms nor atomic nuclei, nor their building blocks, protons and neutrons, could form.
Gold nuclei are collided in the huge particle accelerator at Brookhaven National Laboratory. At the moment of collision, the protons and neutrons in the nuclei “fall apart,” creating this ancient state of matter, quark-gluon plasma, for a very short time.
Researchers are trying to observe this tiny, fleeting moment to learn as much as possible about how the hot “cosmic soup” after the Big Bang formed the world we live in today—that is, how quarks and gluons began to assemble into protons, neutrons, and later atomic nuclei and atoms.
“We want to map out what you could call the most fundamental ‘phase diagram’ that we know of,” Frank Geurts, a researcher at Rice University and spokesperson for STAR, told Scientific American about the results. He noted: “What could be more interesting than the phase diagram of the fundamental building blocks of the universe?”
However, the future may be written by another experiment, as the RHIC STAR experiment is bidding farewell with this special result: After 25 years of operation, the laboratory will be shut down so that construction of a larger facility called the Electron-Ion Collider can begin in its place. It is scheduled to be completed in 2030 to further explore the secrets of matter and the universe.
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Via elte.hu, Scientific American; Featured image: Pexels
