A research project at the Sanford Underground Research Facility, or SURF, has hit a milestone after scientists restarted the program.
A mysterious purple glow has turned back on a mile underground. It’s part of the Compact Accelerator System for Performing Astrophysical Research, or CASPAR.

CASPAR is a small particle accelerator, like the Hadron Collider on a much smaller scale, designed to simulate the conditions inside of a star. That’s where many elements – like carbon and oxygen – are made.
Notre Dame physics professor Dan Robertson explains the nuts and bolts of the machine.
“We basically accelerate particles from one end of a system, our system is low-energy because that’s where the research we’re interested in takes place in stellar environments," Robertson said. "It’s surprisingly low-energy, even though that’s not how a lot of people think of it when they see the stars burning. We produce these ions, accelerate them, and basically drive them to smash into another material at the other end of the beamline.”
That glow accompanying the newly repowered machine is a plasma tube, and what researchers call the “heart” of CASPAR.
“This is where everything begins," Robertson said. "It’s where we create our first building blocks, before we can accelerate them to create our second state of building blocks to, funny enough, investigate the building blocks of the universe.”
Now, it’s time for the scientific minds to get to work with their activated accelerator.
“What’s coming next would be the first accelerated beam," Robertson said. "So, once we have the plasma you can see – that pinkish purplish glow – the next state or phase of the system is to accelerate those particles to their end station. To the target station, to actually start those experiments, those interactions, we need.”
CASPAR researchers expect the first particle beam to fire late summer or early autumn.