LHC Smashes Highest Man-Made Temperature Record
Just a couple of short months ago, we reported that Brookhaven National Laboratory's Relativistic Heavy Ion Collider had made the Guinness World Records for achieving the "Highest Manmade Temperature" — a whopping 4 trillion degrees Celsius, 250,000 times hotter than the center of the sun.
That was the work of the lab's PHENIX collaboration, designed to study the formation and characteristics of the quark-gluon plasma (QGP), a state of matter believed to have existed for ten-millionths of a second after the universe's birth.
Even then, we noted that another experiment at the Large Hadron Collider (LHC), called ALICE (A Large Ion Collider Experiment), was nipping at the record's heels. The latest results from the LHC were just announced at the 2012 Quark Matter conference last week, and sure enough, the record has been beaten — actually, smashed.
Physicists want to know more about the QGP in order to further probe the extreme conditions that existed in the earliest moments of the cosmos. In those first fractions of a second, the universe was so hot that no nuclei could exist. Instead, there was the QGP, made of quarks and gluons (the massless particles that "carry" the force between quarks).
But making this exotic plasma in a laboratory requires enormous energies. Here's a short video detailing how Brookhaven's RHIC achieves them:
ALICE uses lead ions instead of gold ones to create a QGP. The LHC, with its much-higher energies, had no problem beating PHENIX's temperatures by some 38 percent, boosting the record for the hottest manmade material from around 4 trillion degrees Celsius to an eye-popping 5.5 trillion degrees Celsius (that's nearly 10 trillion degrees Fahrenheit).
As impressive as this achievement might be, smashing Guinness records really isn't the point. Unlike ATLAS and CMS, which are focused on hunting for the Higgs boson, ALICE is focused on studying the QCP and other conditions in the primordial universe.
The scientists on ALICE presented a bunch of new results at the conference, most notably concerning charmed particles — those that contain either a charm or anti-charm quark. Charm quarks are 100 times heavier than the more common up and down quarks that make up normal matter.
The heavier the particle, the more energy it takes to create it within a particle accelerator, and the more quickly it decays into lighter particles. This also makes it more difficult to study such a particle's properties. It's just not around long enough to get a good look, so to speak.
Enter the QGP, which serves to slow down charm quarks as they pass through it; in fact, the ALICE scientists reported that the quarks actually seem to be dragged along by the plasma's current. (Yes, the QGP has a flow.)
And sometimes, they found, those charm and anti-charm quarks recombine to form something called "charmonium." This notion dates back to the 1980s, when such an end product was proposed as a direct signature, or indicator, that a QGP had formed. It was first confirmed in 2000 at CERN's Super Proton Synchrotron.
Neither ALICE nor PHENIX has ever been about anything so simple as hitting the hottest manmade temperatures. It's just a nice feather in the cap. So don't expect PHENIX to rise from the ashes to topple ALICE's record in turn — its scientists are much too busy uncovering evidence that the QGP may morph from a frictionless liquid to a hadron gas, a more "normal" state of matter. It's a high-energy phase transition, analogous to how water can change into ice or steam, in response to certain temperature and pressure conditions.
The folks at Guinness won't likely update their records until ALICE officially verifies its final numbers, which will take a few more weeks, at least. And both ALICE and the CMS experment will continue collecting data. Expect to see more intriguing results about the unique properties of our early universe in the next year.
Images: (top) ALICE. Courtesy of CERN. (bottom) A visualization of a quark-gluon-plasma signature. Courtesy of Brookhaven National Laboratory.