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Constance Walter

The mood was almost festive in the CASPAR cavern. After a nearly one-year delay, collaborators began putting together the backbone of the accelerator in which researchers will attempt to mimic nuclear fusion in stars. By January 2016, the collaboration hopes to begin calibrations and other tests on the accelerator.

Equipment for the Compact Accelerator System for Performing Astrophysical Research experiment arrived at Sanford Lab early last week. Within 24 hours and with the help of a stellar Sanford Lab team, the equipment had been moved from the surface to the cavern. "That's pretty amazing," said Dan Robertson, Assistant Research Professor at Notre Dame. 

"Our goal is to create the same reactions that happen in stars that are a bit 'older' than our sun," said Dr. Frank Strieder, Principal Investigator for the project and a Professor at South Dakota School of Mines & Technology. "If we can do that, it could help complete our picture about how the elements in our universe are built."

Essentially, all elements are created in stars. Those that are heavier than iron are what interest us, added Manoel Couder, Assistant Professor at Notre Dame. "All of the rock in this mine was made from those elements. We want to know in which stellar environment they were created."

Before they can begin the actual experiments, the collaboration needs to put together the accelerator. That takes time and patience. Next is the beam line, a collection of steel tubes through which the particles will be fired. Finally, there's the target, a gas cell filled with neon-22 (22Ne), an isotope that releases the same neutrons that fuel the nuclear reactions in stars and produce a large amount of the heavy elements. 

Not only are there a lot of moving parts, said Robertson, but there is a 25 degree bend in the accelerator so the entire system has to align perfectly. "We're shooting billions of very small particles toward our target and particles generally don't like to go where you want them to go," Robertson said. "They have to be confined, steered and monitored at all times." To ensure the particles reach the target, the team will install magnets to direct them from point A to point B and probes to monitor the beam. 

The accelerator also includes vacuum technology. "When you shoot a beam into air, it will travel a very short distance - maybe one foot," Strieder said. "As this is 50 feet long, that will not work." The vacuum removes the friction that occurs as particles travel through the beam tubes, allowing them to travel much longer distances.

The collaboration includes undergraduates, graduate students and post-doctoral research assistants from Notre Dame and the SD Mines. "Being a part of building a lab from the ground up is exciting," said Zach Meisel, a PostDoc from Notre Dame. "It's a unique experience and I'm glad to be a part of it."