Modern Chem

Move over, protons; scientists at the Department of Energy’s Collider Detector at Fermilab (CDF) discovered two rare types of Sigma-b baryon particles.

The discovery was made last month, leaving some scientists to question the correctness of the standard thought that the nucleus is made of only protons and neutrons.

The CDF is composed of 500 physicists from around the world who work together at the federally funded Fermi National Accelerator Laboratory to bring new discoveries and advancements in understanding matter and energy.

Baryons are particles that contain three quarks. Scientists consider quarks to be the most fundamental building blocks of matter.

There are six different types of them: up (u), down (d), strange (s), charm (c), bottom (b), and top (t).

Protons and neutrons are each made of three quarks, u-u-d and d-d-u, respectively. But scientists at the CDF discovered two new baryons composed of up and bottom quarks (u-u-b), as well as down and bottom quarks (d-d-b).

“These particles are like rare jewels that we mined out of our data,” said CDF spokesperson Jacobo Konigsberg. “Piece by piece, we are developing a better picture of how matter is built out of quarks. We learn more about the subatomic forces that hold quarks together and tear them apart. Our discovery helps complete the ‘periodic table of baryons.’ ”

Robert Roser, another CDF spokesperson at Fermilab, stated, “This information is one more piece of the puzzle in trying to understand how you can make matter out of these small atomic particles.”

Physicists use Fermilab’s Tevatron collider, billed as the world’s most powerful particle accelerator, to re-create the conditions of the universe as it was in the moments after the big bang.

In the Tevatron, protons and antiprotons are accelerated by an electric field until they approach the speed of light. The particles then collide, releasing a significant amount of energy and transforming into mass. The physicists then study the properties of these particles.

Over a period of five years, the Tevatron produced over more than 100 trillion high-energy proton-antiproton collisions. The CDF experiment identified 103 u-u-b particles (positively charged Sigma-b particles) and 134 d-d-b particles (negatively charged Sigma-b particles).

Using the data from the CDF detector, Carnegie Mellon professors Manfred Paulini and James Russ study a wide variety of phenomena in particle physics.

Aside from research at Fermilab, they are also looking into cosmic rays and trying to find out where these high-energy particles come from.

Paulini and Carnegie Mellon postdoctoral researcher Soon Jun led the CDF detector simulation project.

“Simulating particle decays using computer programs and tracing particle trajectories through a computer image of the CDF detector are essential for understanding where in the real detector we might have missed recording Sigma-b particles,” Paulini said.

“I think particle physics is moving to its very excited times again because different fields of physics are coming together to answer the same question, ‘What happened in the early universe and where did everything come from?’ ” Paulini said.

“I think a lot will be discovered in the next 10 years. It’s a privilege to be a part of this revolution in science.”