The U.S. Department of Energy Office of Science has approved the project baseline (Critical Decision 2, the integrated scope, cost, and schedule) and the start of construction (Critical Decision 3) for the Gamma-Ray Energy Tracking Array (GRETA) project, a new high-resolution gamma-ray detector system that will be used at FRIB.

GRETA is designed to reveal new details about the structure and inner workings of atomic nuclei, and to elevate our understanding of matter and the stellar creation of elements. GRETA will be combined with the existing detector array—the Gamma-Ray Energy Tracking In-beam Nuclear Array (GRETINA)—to create a full spherical array. Lawrence Berkeley National Laboratory (Berkeley Lab) has led in the creation of GRETINA and now GRETA.

A collaboration of scientists from Berkeley Lab, Argonne National Laboratory, Michigan State University, Oak Ridge National Laboratory, and Washington University designed and constructed GRETINA. GRETINA was the first stage of GRETA.

The GRETA detector array will incorporate 12 GRETINA detector modules. The GRETA detector array is designed to surround samples, forming a spherical shell to more completely and precisely measure the energy and 3D position of gamma rays propagating in the detectors. Gamma rays are highly penetrating, highly energetic forms of light that are emitted from excited nuclear states.

“These approvals by the DOE Office of Science following extensive review mark a tremendous step forward for the GRETA project, and we are excited to see its completion. GRETA is a key instrument for the scientific breakthroughs that FRIB will enable when it opens in 2022,” said FRIB Laboratory Director Thomas Glasmacher.

For more information, see the article on the Berkeley Lab website.