A new particle detector is ready to probe 'ashes' of the Big Bang after passing its 'standard candle' test

The debris or "ashes" of quark gluon plasma created at the Brookhaven National Laboratory. (Image credit: Brookhaven National Laboratory)

A new particle detector has passed a crucial test that shows it is ready to detect the "ashes" left over from a unique primordial soup that filled the universe immediately after the Big Bang.

The sPHENIX detector is the latest experiment at the Relativistic Heavy Ion Collider (RHIC) ring accelerator located at Brookhaven National Laboratory in Upton, New York. The second most powerful particle accelerator in the world, after the Large Hadron Collider (LHC), the RHIC smashes together protons and ions of heavy elements like gold at speeds approaching the speed of light to create "quark-gluon plasma," the state of matter that existed fleetingly after the Big Bang.

This state of matter exists only at extremely high temperatures and densities and is a "soup" of free quarks and gluons, the fundamental particles that make up protons. Understanding quark-gluon plasma could reveal what conditions in the universe were like in its first microseconds and how this gave way to protons and neutrons — and eventually, the matter that populates the cosmos today.

The key test passed by sPHENIX to prove it is ready to measure the properties of quark-gluon plasma is called a "standard candle" in particle physics. This isn't to be confused with Type 1a supernovas, the "standard candles" that astronomers use to measure cosmic distances.

In this case, "standard candle" refers to a measurement of a well-established constant that can be used to assess the precision of a detector. The sPHENIX project passed this benchmark by precisely measuring the number of particles created when two gold ions smash together at close to the speed of light, and by gauging the collective energy of these particles.

The detector was also able to determine the number of charged particles launched during a head-on collision between gold ions and those launched in a glancing collision between gold ions.

sPHENIX found that 10 times more particles were created in head-on collisions and that these particles had 10 times the energy of those generated during a glancing collision.

Physicists created three different shapes of quark-gluon plasma blobs using the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. This plasma is an exotic type of matter that filled the universe in the first milliseconds after the Big Bang. — Blue quark-gluon plasma blobs created using the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. (Image credit: Javier Orjuela Koop)

"This indicates the detector works as it should," Gunther Roland, a sPHENIX Collaboration team member and a professor of physics at Massachusetts Institute of Technology (MIT), said in a statement. "It's as if you sent a new telescope up in space after you’ve spent 10 years building it, and it snaps the first picture. It's not necessarily a picture of something completely new, but it proves that it's now ready to start doing new science."

Quark-gluon plasma doesn't hang around

Particle accelerators like the RHIC fling particles around at almost light speed in opposite circular beams, which, when they meet, release a huge amount of energy. This energy can appear in the form of a quark-gluon plasma.

This quark-gluon plasma didn't stick around for long at the beginning of the universe, however, and its existence in particle accelerators is equally short-lived. When the quark-gluon plasma is generated, it lasts for just a sextillionth of a second. During its existence, it has a temperature of many trillions of degrees; its particles act in concert as a "perfect fluid" rather than a collection of random particles.

As the plasma cools, this exotic state vanishes, and the quark-gluon plasma forms protons and neutrons, which race away from the site of the initial particle collisions.

"You never see the quark-gluon plasma itself — you just see its ashes, so to speak, in the form of the particles that come from its decay," Roland explained. "With sPHENIX, we want to measure these particles to reconstruct the properties of the quark-gluon plasma, which is essentially gone in an instant."

The sPHENIX detector is the newest experiment at Brookhaven National Laboratory&rsquo;s Relativistic Heavy Ion Collider (RHIC) — The sPHENIX detector is the newest experiment at Brookhaven National Laboratory’s Relativistic Heavy Ion Collider (RHIC) (Image credit: Brookhaven National Laboratory)

The sPHENIX detector, which is the size of a two-story house and weighs about 1,000 tons, sits between the two main beams of the RHIC waiting to be bombarded with particles from collisions. sPHENIX is the next generation replacement for the Pioneering High Energy Nuclear Interaction Experiment (PHENIX) and is capable of catching and measuring 15,000 particle collisions per second.

It's systems allow it to act like a huge 3D camera tracking the number of particles produced in these collisions, their energies and even their trajectories.

"SPHENIX takes advantage of developments in detector technology since RHIC switched on 25 years ago, to collect data at the fastest possible rate," team member and MIT researcher Cameron Dean said. "This allows us to probe incredibly rare processes for the first time."