First low-energy particle accelerator beam created in the US

The first low-energy particle accelerator beam has been created by nuclear astrophysicists underground in the US, the University of Notre Dame reports.

The aim of the project, called CASPAR (Compact Accelerator System for Performing Astrophysical Research), is to gain a better understanding about how stars burn and what elements they create while doing so. The researchers will do this by recreating nuclear fusion processes that are responsible for energy generation and elemental production in stars.

Researchers at the University of Notre Dame, led by Michael Wiescher, Freimann Professor of Nuclear Physics, and research assistant Professor Dan Robertson, built the 50ft low-energy particle accelerator.

This was then transported in pieces and assembled 4,850 feet underground at the Sanford Underground Research Facility (SURF), in South Dakota, as a result of a collaboration with researchers from the South Dakota School of Mines and Technology and the Colorado School of Mines.

CASPAR is one of two underground accelerators in the world, the other being at the Laboratory for Underground Nuclear Astrophysics (LUNA) near the Gran Sasso Mountain in Italy. Being underground means the project is shielded from cosmic radiation which can interfere with highly sensitive physics experiments.

Noting the differences between CASPAR and LUNA, Wiescher said: “CASPAR is unique since it covers a broader energy range than the LUNA accelerator. It allows us, for the first time, to explore reactions of stellar helium burning, which take place in stars like Betelgeuse, at laboratory conditions.

“Through these studies, we will learn about the origin of oxygen and carbon as the most important ingredients of biological life in the universe, and we will learn about the mechanisms stars have developed to produce gradually heavier elements through neutron fusion processes.”